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Selected Papers in Environmental Engineering
Edited and compiled by Prof. Dr. Eng. Isam Mohammed Abdel-Magid
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Introduction Health, safety and environmental are key issues in nowadays globalization and international trade and human rights agenda. Selected papers in environmental engineering book has been complied from sets of papers published in different reputable scientific journals of local, regional and international flavor. The book is thought to be of value to researchers, students and postgraduate candidates addressing similar issues. The trial is worth evaluation in helping socioeconomic and cultural aspects in the field. The format of the book was classified in five major domains that focused on water engineering areas, wastewater engineering issues, water management, water computer applications, and a general chapter. Chapter one focused on: optimum investment of rainwater harvesting techniques, water of the Nile, water treatment for rural areas, evaluation of slow sand filters in the Sudan, analysis of pipe networks by the finite element method, establishment of water quality guidelines, water conservation, bacteriological analysis of roof water tanks, and hotel water supply and plumbing system. Chapter two addressed: industrial contamination of water sources, waste stabilization ponds design parameters: The combined effect of time and organic load, prospects of wastewater reuse in irrigation, influence of local filter aids on sewage sludges dewatering practices, influence of additives on the rheological properties of sewage sludge, influence of lime and grease on dewaterability of sewage sludge design basis for sewage treatment units by the activated sludge process, regulations for wastewater reuse and discharge, evaluation of regulations for wastewater reuse and discharge, recycling of agricultural industrial waste, poultry wastewater treatment, wastewater reclamation and reuse, wastewater reclamation and reuse in petroleum refinery at Elgaily area north of Khartoum, effects of industrial pollutants on water resources in the Sudan, vulnerability of groundwater to pollution risk from onsite wastewater disposal systems with emphasis on Khartoum area, identification and assessment of pollutional aspects in vegetable oil manufacturing, effect of retention time and length to width ratio on the removal of BOD, SS and TS in septic tanks, effect of natural soil characteristics on the disposal of septic tanks final effluent, effects of additives on dewatering of sludge, and impact of irrigation and drainage on environmental health along the Nile Chapter three reviewed integrated water resources management and Global Water Partnership, water resources management, problems and policy alternatives, the way towards an environmental strategy for the Arab World, and reflections on drinking water quality guidelines for the Sudan Chapter four tackled certain water Computer Applications with emphasis on WESNET: An important utility in water distribution in network design, and development and utilization of web applications in management of water supply systems. The last chapter highlighted: role of the sanitary engineer in the country, preconditions and requirements for successful environmental policies in certain Arab countries, education trends, norms and development, vision to action in water and the media, effective water policies and planning strategies for national water authorities, and effective planning strategies for national water authorities. The completion of this work and the publication of the book would not have been possible without the real help of different people and organizations. In this regard thanks would go to Prof. Dr. ElZubair Beshir Taha Minister of Science and technology, Sayed Abdel Basit Abdel-Magid Minster of Culture, Mrs. Fatima Billia, all companies, authorities, organizations, committees, ministries, centers and institutions that permitted the republication of the papers. Author Ahlam Haboba, Khartoum, 10 June 2006
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Table of Contents Page Introduction
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Table of Contents Chapter One: Water Engineering 1.1 Optimum investment of rainwater harvesting techniques 1.2 Water of the Nile 1.3 Water treatment for rural areas with emphasis on Sudan 1.4 Evaluation of slow sand filters in the Sudan 1.5 Analysis of pipe networks by the finite element method 1.6 Establishment of water quality guidelines for the Sultanate of Oman 1.7 Water conservation in Oman 1.8 Bacteriological analysis of roof water tanks 1.9 Hotel water supply and plumbing system (A case study) Chapter Two: Wastewater Engineering 2.1 Industrial contamination of water sources in the Sudan 2.2 Waste stabilization ponds design parameters: The combined effect of time and organic load 2.3 Prospects of wastewater reuse in irrigation: Case study Sultan Qaboos University 2.4 The influence of local filter aids on sewage sludges dewatering practices 2.5 The influence of additives on the rheological properties of sewage sludge 2.6 The influence of lime and grease on dewaterability of sewage sludge 2.7 Design basis for sewage treatment units by the activated sludge process 2.8 The Omani regulations for wastewater reuse and discharge – A critical review 2.9 Evaluation of the updated Omani regulations for wastewater reuse and discharge 2.10 Recycling of agricultural industrial waste: The case of wastewater from sugar factories in the Sudan 2.11 Poultry wastewater treatment in Sudan 2.12 Wastewater reclamation and reuse 2.13 Wastewater reclamation and reuse in petroleum refinery at Elgaily area north of Khartoum 2.14 The effects of industrial pollutants on water resources in the Sudan
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2.15 Vulnerability of groundwater to pollution risk from onsite wastewater disposal systems with emphasis on Khartoum area 2.16 Identification and assessment of pollutional aspects in vegetable oil manufacturing in Sudan
2.17 The effect of retention time and length to width ratio on the removal of BOD SS and TS in septic tanks 2.18 The effect of natural soil characteristics on the disposal of septic tanks final effluent 2.19 Effects of additives on dewatering of sludge 2.20 The impact of irrigation and drainage on environmental health along the Nile Chapter Three: Water management 3.1 Integrated water resources management and Global Water Partnership 3.2 Oman water resources: Management problems and policy alternatives 3.3 Along the way towards an environmental strategy for the Arab World 3.4 Reflections on drinking water quality guidelines for the Sudan Chapter Four: Water Computer Applications 4.1 WESNET: An important utility in water distribution in network design 4.2 Development and utilization of web applications in management of water supply systems Chapter Five: General 5.1 The role of the sanitary engineer in Sudan 5.2 Preconditions and requirements for successful environmental policies in the Sultanate of Oman the Sudan and Egypt
5.3 Education trends norms and development 5.4 A vision to action in water and the media: the way forward in the Sudan 5.5 Effective planning strategies for national water authorities 5.6 Effective water policies and planning strategies for national water authorities
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Chapter One: Water Engineering Optimum Investment of Rainwater Harvesting Techniques1 By Osman Mohammed Nagger2, Aheed Ali Mohammed, Egbal Mohammed A/Raheem, Mona Mohammed Tom, Zubaida Mohammed Alseid, and Isam Mohammed Abdel-Magid3.
Abstract Water is life. It is the main constituent of all living organisms and the key factor providing them with the suitable environment. All civilization found and developed around water resources. As a result of the continuous growth in population and increase in water consumption rate, the gap between demand in terms of quantity and quality, and water supply is getting larger. Rainwater harvesting, (RWH) is one of the old techniques practiced by man to obtain his water requirements especially in areas where there is no continuous water supply (Surface or ground). In such areas rainwater is collected and stored during the rainy season and then used when there is no rain in dry season. The growing awareness of the RWH potentials, as a new source of water in Sudan made the technique very popular and wide spreading especially for domestic uses. The country is one of the world’s largest countries. Ranking first in Africa and 10th in the world, Sudan has multi climatic and topographic zones. The rainfall intensity in the country ranges from almost nil in the north to more than 1500 mm in the far south. The total amount of rainfall is estimated to be around 1000 km3 per annum. Part of this rainwater, if harvested, will solve much of the country’s water shortage problems. This paper briefly reviews the concept, types, components, potentials and techniques of water harvesting. It mainly concentrates on the optimum investment of one of the rainwater harvesting techniques, namely the Domestic rainwater harvesting (DRWH). The paper shows the need for water harvesting in Sudan and concludes with some guidelines for the optimum investment of rainwater harvesting. 1. Introduction The gap between water demand in terms of quantity and quality, and water supply is getting wider and wider. Due to this imbalance, people all over the world, are deeply concerned to bridge this gap by any means in order to survive. Rainwater harvesting as one of the old techniques ever practiced by man to obtain his water requirements is now coming to picture in a new fashion. The technique succeeded in providing a feasible solution for improving the living conditions of many millions of people facing serious water supply problems. Rainwater harvesting is an effective water conservation tool because it provide “free” water. There are many benefits to harvesting rainwater. It not only reduces dependence on ground water and the amount of money spent on water, but also reduces off-site flooding and erosion by holding rainwater on the site. If large amount of water are held in highly pervious areas, some of the water may percolate to the water table. In addition, rainwater harvesting can reduce salt accumulation in the soil, which can be harmful to root growth. Limitations of water harvesting are few and are easily met by good planning and design. 1
Published in the proceedings of the conference on water harvesting and the future of development in Sudan, Friendship Hall, Khartoum, 19-20 August 2003, pp. 433-444, Organized by UNESCO Chair in Water Resources.. 2 UNESCO Chair for Water Resources 3 Industrial Research and Consultancy Centre at Ministry of Science and Technology.
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2. Rain Water Harvesting: Definition and History An old technology is gaining popularity in a new way. Water harvesting is an old and ancient method for collecting water, practiced by man as long as life exists on this planet. Rainwater harvesting has many and different definitions. It can be defined as the “deliberate collection of rainwater from surface (catchment) and its storage to provide a supply of water” (UNEP, 1983) OR “a concentration of precipitation through runoff and storage for beneficial use” (Oweis et. al., 2001) OR “the collection, concentration and storage of water that runs off a natural or man made catchment surface” (IRC, 1992) the process is considered as distinct from the natural runoff of water into perennial rivers, which is then collected and stored in reservoirs. Rainwater harvesting techniques can be broadly classified into: roof top catchment systems, surface catchment systems, and runoff farming systems. Much of the early history of rainwater harvesting has its origins in many parts of the world. Many evident from the old civilizations developed in Africa, Asia, and Europe, showed that they had known rainwater harvesting. It is believed that early rainwater harvesting techniques are used in wadi runoff cultivation 9000 years ago in Negev Desert in Palestine and more than 4000 years ago in Egypt. In central Sudan where the Meroetic Kingdom dates back to seven thousands of years in history, runoff agriculture was traditionally used for crop production. In Yemen, rainwaterharvesting techniques were used to divert runoff water for irrigation purposes. The system used was believed to produce crops that might have fed as many as 300,000 peoples (Oweis et.al 2001). In North African countries like Libya, Tunisia, Algeria and Morocco, a number of types of rainwater harvesting techniques still exit. Water harvesting was also known in central and eastern Asia. Specifically speaking, it was known in China, India, and Pakistan since many thousands years ago. Their methods of rainwater harvesting applied in ancient times, are still in use today. In Europe, as per the United Nations Environmental Programme (UNEP, 1983) Report, the principal factor in locating towns, industrial and commercial centres is the availability of water for domestic and communal use. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rainwater to augment water from city’s aqueducts. And as recently as early in this century, rainwater was primary water source on many ranches, with stone and steel cisterns still standing today on homesteads upon which wells were long ago drilled. 3. Potentials for Water Harvesting The total amount of water that is received in the form of rainfall over an area is called the rainwater endowment of that area. Out of this, the amount that can be effectively harvested is called the water harvesting potential. The main factors affecting the water potential of an area are: • Rainfall characteristics (intensity, duration, distribution, pattern): Rainfall is the most unpredictable variable in the calculation. To determine the potential rainwater supply for a given catchment, reliable rainfall data are required, preferably for a period of at least 10 years. Also, it would be far better to use rainfall data from the nearest station with comparable conditions. The number of annual rainy days influences the need and design for rainwater harvesting. The fewer the annual rainy days in a region, the higher is the need for rainwater collection system. However, if the dry period is too long, big storage tanks will be needed to store rainwater. Hence in such regions, it is more feasible to recharge the rainwater into the groundwater storage.
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• Catchment characteristics (area, length, slope, soil type and cover): Runoff from a catchment depends also upon the area and type of the catchment over which it falls. All calculations relating to the performance of rainwater catchment systems involve the use of runoff coefficient to account for the different losses (e.g. infiltration, catchment surface wetting and evaporation), reducing the amount of runoff. The runoff coefficient for any catchment can be defined as the ratio of the volume of water that runs off a surface to the volume of rainfall that falls on the surface. Based on the runoff coefficient the water harvesting potential of a site could be estimated. Table (1) (following table) shows the values of runoff coefficient for some catchment surfaces. • Availability of runoff that can be harvested or/and how quickly and much this runoff occurs: this is an important factor in estimating the water harvesting potential of an area. Flash floods coming and passing I a fraction of a day needs an effective water harvesting system.
Table (1) Runoff coefficient for various catchment surfaces
Roof Catchment
Type of Catchment Coefficient - Tiles - Corrugated metal 0.8 0.9 sheets 0.7 – 0.9
Ground surface - Concrete coverages - Brick pavement Untreated ground - Soil on slopes less than 10% catchments - Rocky natural catchments Untreated ground - Soil on slopes less than 10% catchments - Rocky natural catchments Source: Pacey, Arnold and Cullis, Adrian 1989
0.6 – 0.8 0.5 – 0.6 0.0 – 0.3 0.2 – 0.5 0.1 – 0.3 0.2 – 0.5
4. Domestic Rainwater Harvesting Domestic Rainwater Harvesting is a subset of rainwater harvesting. It is a system used to harvest rainwater for domestic uses in urban areas as well as rural ones. The system can be as simple as a barrel or a container placed under a rain gutter for watering a garden or, as complex as an engineered, with complicated collection, conveying and storage components, multi-tank, pumped and pressurized construction to supply residential and irrigation needs. The system can be divided into primary and treatment processes as shown in Fig. (2). Catchment Surface
Conveyance
Storage
Filtering
Filtering
Delivery
Filtering
Fig. (2) Processes of Domestic Rainwater Harvesting Systems
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Need for Domestic Rainwater Harvesting in Sudan Generally, domestic rainwater harvesting is needed for the following; To meet the continuous increasing demand for water in rural and urban areas, To supplement domestic water requirements during summer, To relieve the burden on drainage system, To avoid flooding of roads, To indirectly augment the groundwater storage, To improve the groundwater quality by reducing pollution, and To reduce the soil erosion. Sudan is a large country with an area of 2.5 million km2. It has different climatic and topographic zones. The rainfall intensity in the country ranges from than 1500 mm in the far south to almost nil in the north (see fig. 4).
The total annual volume of rainfall is estimated to be 1000 km3. Despite these facts, most of the large towns in Sudan, with considerable amount of rainfall or runoff water from wadis and khors suffer due water shortage (see table 2). Part of the rainwater in the country, if harvested, will solve much of this severe water shortage problem in Sudan. The growing awareness of the RWH potentials, as a new source of water in Sudan made the technique very important and highly needed for rural and urban areas.
Table (2) Demand and supply in selected towns in Sudan
Town Alfashir Nyala
Gadaref Port Sudan Wau Juba
Demand, m3
Supply, m3
% of Deficit
20000 50000
10000 10000
50% 80%
25000
13000
70000 7000 20000
35000 1000 10000
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48% 50% 86% 50%
Components of Domestic Rainwater Harvesting The main components of a domestic rainwater harvesting system are: Catchments: A catchments area is the surface which directly receives the rainfall and from which water can be harvested and supplied to the system. It can be paved area like a terrace or a courtyard of a building or an unpaved area like a lawn or open ground. The amount of water harvested depends on the surface area, surface texture, and slope of the area. Gutters: Channels all around the edge of a sloping roof of collect and transport rainwater to the storage tank. Gutters can be semi-circular or rectangular and could be made using locally available material such as plain or folded galvanized iron sheet, semi-circular gutters of high density polyethylene (HDP) or polyvinyl chloride (PVC) material can be prepared by cutting those pipes into two equal semi-circular channels or medium size tree trunks cut vertically in half. The size of the gutter should be able to carry the flow during the highest intensity rain, and should be well supported. It is advisable to make them 10 to 15 per cent oversize. Conduits: Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like HDP or PVC or galvanized iron (GI), materials that are commonly used. The following table shows the recommended pipe diameter for draining out rainwater based on rainfall intensity and roof area.
Table (3) Pipe Diameter for various rainfall intensity and areas of catchment Pipe Diameter (mm) 50 65 75 100 125 150
50 13.4 24.1 40.8 85.4 -
Area of Catchment (m2) 75 100 125 150 Average Rate of Rainfall (mm/h) 8.9 6.6 5.3 4.4 16.0 12.0 9.6 8.0 27.0 20.4 16.3 13.6 57.0 42.7 34.2 28.5 80.5 64.3 53.5 83.6
200 3.3 6.0 10.2 21.3 40.0 62.7
Source: www.rainwaterharvesting. Org First-flushing: Since the first spell of rain carries a relatively larger amount of pollutants from the air and catchment surface, a valve called a first flush device is used to ensure that runoff from the first spell of rain is flushed out and does not enter the system. Filter: The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand, or/and gravel layers to remove debris and dirt from water before it enters the storage thank or recharge structure. Sand filters are commonly used. They are inexpensive and easy to construct. These filters are effective in removing turbidity (suspended particles like silt and clay), colour and microorganisms. In a simple sand filter that can be constructed domestically, the top layer comprises coarse sand followed by 5 – 10 mm layer of gravel followed by another 5 – 25 cm layer of gravel and boulders, or can be constructed with three concentric chambers in which outer chamber is filled with sand, the middle one with coarse aggregate and the inner-most layer with pebbles. In this way the
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area of filtration is increased for sand, in relation to coarse aggregate and pebbles. Rainwater reaches the center core and is collected in the sump where it is treated with few tablets of chlorine and is made ready for consumption. When rainwater is harvested in a large rooftop area, the filtering system should accommodate the excess flow. Storage unit: the storage tank usually represents most of the capital investment of a DRWH. The main objective in designing a tank is to minimize the cost while providing the required capacity. There are various options available for the construction of storage tanks with respect to the shape, size, and the material of construction. The shape of the tank can be cylindrical, elliptical, rectangular or square. Materials generally used in the construction of storage tanks are reinforced concrete, ferro-cement, and masonry, plastic or metal sheets. Storage tanks can be broadly divided into above ground and under ground tanks (cistern) Recharge Structure: Rainwater may be charged into the groundwater aquifers through any suitable structures like dug wells, bore wells, recharge trenches and recharge pits. 5. Design of a Domestic Rainwater Harvesting System There are a number of different design methods for a DRWH. The design is generally done for all units of the system. However, the optimum design concentrates mainly on the design of the storage unit (tank). It has been shown (Thomas and Rees, 1999) that to optimize economic return from a DRWH investment it requires use of very small cistern, so small that they meet only around half a household’s water demand. By contrast, to employ a 100% reliable sole domestic source requires cisterns 10 to 50 times larger: pursuit of this inappropriate service standard in the past has seriously over priced the DRWH and discouraged its general take up (Martinson and Thomas, 2003). A medium size tank gives high convenience and reliability. The idea is to adjust the daily demand to reflect both the diminishing unit value of water with increasing daily consumption. To ensure high dependability on the system, design of water-harvesting system should be based on the low (minimum) rainfall values rather than average ones. As a sample, some of the current methods for tank design are reviewed below. Tank Design The volume of the storage tank can be determined be the following factors: • Rainfall data and pattern, • Collection area, • Runoff coefficient of the surface, • Number of users, and • The per capita consumption rate The common methods used in determining the tank's capacity is 1. Demand method: this method is very simple. It assumes that sufficient water is available. Therefore, the required storage is found on the basis of the consumption rate. Example 1: Find the required tank capacity if the consumption/capita/day is 50 liters, the number of people per house is 4, and the longest average dry period is 20 days. Solution: Required capacity of tank is: 50 x 4 x 20 = 4000 liters. 2. Supply method: This method is used when there is uneven distribution of rain. The method is based on storing water when there is sufficient supply and using it during shortage of supply. 11
Example 2: Given the following information for a school, find the minimum required capacity of the storage tank. Number of teachers: 10, Consumption Rate20 liters per teacher per day Number of students: 200, Consumption Rate10 liters per student per day Roof Area = 600 m2, Runoff coefficient = 0.90, Average Annual Rainfall = 1000 mm Solution: Water demand per month = (10x20 + 200x10) x 30/1000 = 66 m2 Water that can be harvested (supplied) per month = 600x0.9x (1000/1000.12) = 45 m3 It is noticed that the supply i.e. harvested water is less than the demand. In such case, proper supply and demand water management is needed. Estimating the minimum required storage capacity for the example2 is shown in table (4)
Table (4) Estimation of minimum required tank capacity 1 Month
2 Rainfall (mm)
Jun. Jul. Aug. Sep. Oct Nov. Dec. Jan. Feb. Mar. Apr. May
100 135 120 110 100 90 80 50 40 30 70 75 1000
3 Rainfall Harvested (m3) 54 72.9 64.8 59.4 54 48.6 43.2 27 21.6 16.2 37.8 40.5 540
4 Cumulative Rainfall Harvested (m3) 54 126.9 191.7 251.1 305.1 353.7 396.9 423.9 445.5 461.7 499.5 540
5 Average Demand (m3) 45 45 45 45 45 45 45 45 45 45 45 45 540
6 7 Cumulative Column (4) – Demand Column (6) (m3) 45 9.0 90 36.9 135 56.7 180 71.1 225 80.1 270 83.7(max) 315 81.9 360 63.9 405 40.5 450 11.7 495 4.5 540 0
The min. volume of tank is taken as the greatest excess over the consumption i.e. 83.7 m3 6. Optimum Investment of Domestic Rainwater Harvesting Techniques Some guidelines for optimum investment of water harvesting techniques are: • Use the system where the Site Conditions are Favorable in terms of: o Intensity, duration and distribution of rainfall (for estimating the amount of runoff to be captured). o Availability of suitable roof catchment (area and type). o Suitable soil characteristics near the building foundation (underground tanks). o Avoid location of trees (to avoid falling leaves, seeds, and insects and birds droppings). o Availability of construction materials. • Sufficient Attention is paid to Operation and Maintenance Aspects in terms of: o High training levels should be given to system management and water quality protection o Guideline for O&M should be issued in simple and local language (e.g.: the seasonal timetable of cleaning and maintenance should be given) o Simple, clear and O&M drawings should be provided on site
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o Continuous assessment of O&M performance • Optimum size for the Water Harvesting System in terms of: o Amount of rainwater that can be collected (duration, pattern, and intensity) o The maximum amount of water needed with time o Building codes, regulations, legislations • Optimum Cost and Design of a Water Harvesting System in terms of: o Optimum architectural design for the given size o Selection of building materials (cost versus efficiency, and durability analysis) o Optimum structural design given the selected material and size o Optimum labor cost versus building technique o Minimum annual equivalent cost (cost/ (tank volume) relationship) o Availability of construction materials o Low operation and maintenance cost • Safety Precautions of the System o Health precautions: System inspection needs, contamination proof system is required, and impact of construction material on water quality specially in storage tanks o Design safety factors: Continuous water tightness and durability o Acceptability of the system
7. Conclusion Optimum domestic rainwater harvesting is an alternative water resource. In Sudan we should think of because it: • enhances sufficiency to water supply • reduces the cost for pumping groundwater • provides high quality water soft and low in minerals • is inexpensive, easy to construct, operate and maintain • is simple and can be adopted by individuals • reduces the soil erosion • is highly needed in many regions in Sudan
8. References 1. International Water and Sanitation Centre (IRC), 1992, “Water Harvesting: A Guide for Planners and Project Managers, Technical Report. 2. Martinson, D. B. and Thomas, T., 2003, “The Roof water Harvesting Ladder”, IRCSA, Mexico City, Mexico. 3. Oweis, T., Prinz, D. and Hachum, A., “Water Harvesting – Indigenous Knowledge for the Future of the Drier Environments”, International Centre for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. 4. Pacey, A., and Cullis, A., (1989), “Rainwater Harvesting: The Collection of Rainfall and Rainoff in Rural Areas”, Intermediate Technology Publications, London. 5. Thomas, T. and Rees, (1999), “Affordable Roof Water Harvesting in the Humid Tropics”, Proceedings of the 9th International Raina twater Catchments Systems Conference, Perlnia. 6. UNEP (1983), “Rain and Storm Water Harvesting in Rural Ateas”, Technical Report. 7. Vivian, G., (1974), “Conservation and Diversion Water Control System in the Ananszani Southwest”, University of Arizona, Tucson-Arizona, USA, Vol. 25.
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Water of the Nile (The quality)4 By Bashir Mohamed El – Hassan5 and Isam Mohmed Abdel-Magid6
Introduction It has always been assumed that the water of the Nile and its tributaries are safe from chemical, physical and bacteriological points of view. This assumption was mainly based on the rather limited water and land usages in contrast with the abundance of available water. This led to the rather indiscriminate use of water. The consequences, of such attitude, resulted in gradual deterioration of water quality, spread of waterrelated diseases and water shortages. This has been magnified by negligence, unawareness, lack of health education as well as lack of sound environmental planning for water resources. The research that has been carried so far by different health authorities suggested a direct link between water quality and the health status of the inhabitants. The increase in water use without proper water management and the adopted irrigation practices resulted in an increase of prevalence of certain diseases such as diarrhea, malaria, infectious hepatitis, typhoid, schistosomiasis, gastroenteritis… etc. Table 1 shows incidence of some water related diseases prevailing in some provinces in the Sudan: Table (1) Incidence of some water related diseases in some provinces of the Sudan. Disease % infected population of total province population Khartoum Blue Nile El Gezera Malaria 6 10 5 Eye diseases 6 5 3 Diarrhea NA 4 6 Dysenteries 5 4 3 Schistosomiasis 0.5 1.5 3 Typhoid NA 0.1 NA Infectious Hepatitis 0.4 0.5 0.3 No. of population per province 1.8 1.06 2.04 (millions)
Historical Background: This could be divided into two phases: Phase (1): It relates to the work that has been carried out by the Welcome Laboratories by Beam and others {1}. Phase (2): Started in 1953 by the establishment of the Hydro biological Research Unit (Talling and others, 8). The former work has been carried out with a bias to the health impact and relationship; whereas the latter work has been conducted from an ecological point of view.
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Published in the Proceeding of International; Conference on Water Resources Needs & Planning in Drought Prone Areas, Khartoum, Dec. 1986, pp 609 - 619 5 Dean, School of Hygiene, Khartoum, Sudan 6 Civil Engineering Dept., Faculty of Engineering & Architecture, University of Khartoum, Sudan
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Latecomers in this field included various research bodies and the water supply authorities. They covered to great extent health aspects, treatment methodologies and requirements together with consumer interests.
Results and Discussions Based on literature survey that has been accumulated in the various governmental departments, private collections and laboratory investigations carried by postgraduate candidates in different faculties of the University of Khartoum, a general view has been adopted. This is to survey historically the documented obvious changes in Nile water quality with emphasis on physical, chemical, bacteriological and biological parameters. The gathered data were subjected to analysis in order to focus on the quality trend changes, if any, and try to identify reasons that would justify these changes. A. Physical Parameters: Certain parameters were stressed upon due to practical laboratory limitations. The emphasis followed for parameters that could indicate any suspected changes. The selected parameters included suspended solids concentration, turbidity value and conductivity measurements. It is to be noted that the significance of other parameters such as temperature, taste, odor and color … etc, cannot be neglected. A. 1. Turbidity and suspended Solids: The measurements of turbidity for the Nile (as shown in Fig.1) revealed a seasonal fluctuation with a maximum occurring in July, August and September; while the minimum value resulted during December, January and February. The variation of suspended solids follows a similar seasonal variation to that of turbidity (Fig1) Figure (2) shows the general trend for dissolved solids variation for a span of ten years. The figures indicate the seasonal variation of turbidity and solids with a maximum during the food season and a minimum value during winter months. This could be attributed to the variable sediment load carried by the river during those months; as well as the mode of operation of dams along the river and the hydrological characteristics on the catchments areas The illustrated figures demonstrate also the trends of gradual increase of solids load over the years. This could be attributed, with reservation, to the changes that the river has been subjected to; such as dams control structures, agricultural schemes and industrial activities, along with increase of settlements of inhabitants alongside riverbanks. Likewise climatic conditions play role. B. 2. Conductivity: Figure (3) reveals the general trend of variation over a period span of 20 years. It is clear that the persistent trend signifies a higher conductivity value for the White Nile in comparison to that for the Blue Nile. The reason behind this could be traced down to difference in characteristics of the catchment areas, pattern and origin of river flow, water and land use activities around the rive basin. B) Chemical Characteristics: Although complete data on chemical analysis are available, yet the authors of this paper selected only those parameters that could be indicators of pollution or deterioration of river water quality. Therefore, picked parameters including chlorides, nitrogen compounds (N-NO3-) and dissolved oxygen. Unfortunately data on trace
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compounds, pesticides and fertilizers are not attainable; since they are not performed on routine bases and due to absence of monitoring stations. B.1 Chloride concentration: Figure (4) shows the obvious differences in chloride content between the White and Blue Niles; with the higher concentration always found in the White Nile along the years. Likewise, there is a gradual build up in chloride concentration in both rivers for the chosen span of twenty years. For instance, in absolute terms, the chloride content of the Blue Nile increased from a value of 5 mg/1 (1961) to about 20 mg/1 (1981); an increase of approximately four folds. The White Nile increase in chloride content from about 8 mg/t to around 22 mg/l (approximately three folds) The significant increase in chloride content could possibly indicate a gradual build up of pollution. This may be due either to natural or man-made activities. C. 2. Nitrogen compounds: (Organic and inorganic) The analysis of available data on nitrates, nitrites, ammonia, albimonid nitrogen suggests the absence of significant organic contamination over the years, This is contrary to the general belief. This may be ascribed to the high dilution factor and the rather efficient self-purification persisting in the rivers up to date. D. 3. Dissolved oxygen: Figure (5) indicates the rather stable variation of DO over a span of ten years. This conforms to the findings regarding nitrogen compounds.
C) Bacteriological Characteristics Table (2) shows bacteriological analysis of waters of the rivers in terms of fecal cloiform/100ml..The readings illustrate possible changes and seasonal variations. This could be reflection of effects of flow characteristics, flood, and catchment area contribution as well as effects of climatic factors such as temperature.
Table (2) Bacteriological analysis waters of rivers in terms of fecal cloiform/100ml Blue Nile White Nile Main Nile 5 – 1000 2 - 1750 5 - 2000 Table (1) demonstrates the rather high prevalence of the reported water related diseases, which is a good indicator of the water quality and the improper environmental management; together with poor health educational level.
Conclusions and Recommendations Graphs summarizing the findings of this paper show the seasonal variations as well as gradual changes in water quality of the Nile. These could be interpreted as being
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unfavorable conditions that if uncontrolled, or improperly managed, could lead to pollution of the water. The high subsistence of water related disease-vectors throw some light of the mismanagement as well as low socioeconomic status of the people. The deterioration of river water quality will undoubtly, interfere with any beneficial usages of the water locally and regionally. This calls not only for internal sound management of the river water quality, but also calls for close integration and coordination between countries of the river Nile basin. This is to activate the ongoing joint research among the countries of the river Nile Basin.
References 1. Beam, W, “Chemical Composition of Nile Water”, 2nd report, 1906, Nile waters, 3rd report, 1908; Welcome Research Laboratory, Khartoum. 2. El Moghraby, A. I. (Edi), 1984, "Water and Land Use in the Blue Nile Basin", Institute of Environmental Studies, University of Khartoum. 3. El Zubeir, M.E.G 1985: “A “Study on the Supplied Water Quality at Khartoum", M.Sc. Thesis. Civil Eng. Dept. University of Khartoum. 4. Habiballa, H.I. 1981, " A Comparative Study of the Resources of Domestic Water Supply in Khartoum and their Associated Problems”, M.Sc. thesis, Institute of Environmental Studies, University of Khartoum. 5. Mahgoub D.M. 1984, Coliform bacteria in the Nile at Khartoum:, M.Sc. Thesis, Inst. Environ. Studies, University of Khartoum. 6. Ministry of Energy and Mining, Records of water quality 1960 -1986" unpublished data, Khartoum Central Laboratory. 7. Mohamed, Y.A. 1982 " Study of water quality for the Blue Nile and White Nile", M.Sc. Civil Eng. Dept, University of Khartoum. 8. Talling J. F. 1957 "The longitudinal succession of water characteristics, in the White Nile", Hydrobiologia J. Vol. XI(1). 9. The Chemical Laboratories-Ministry of Health records and data, Unpublished, 1955 – 1956, 1961 – 1972.
17
18
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Water Treatment for Rural Areas with Emphasis on Sudan7 By Isam Mohammed Abdelmagid8 Introduction Water is of indispensable importance for human existence and survival. According to Huisman {1} 2-5 liters per day are required by an adult human, depending on climate and the amount of work performed. White et al. {2} indicated a minimum range of 1.8-3 l/day for survival in tropical areas. Water id also needed for cleaning, washing, bathing, laundry, etc. By virtue of their origin, human’s demand of a certain type of water that meets their needs and is satisfactory as far as taste, odor and appearance are concerned. Normally they do not bother about the bacteriological characteristics. This denotes that people may resort to a contaminated source, rejecting a wholesome one, on the basis of the above criteria and many people in Sudan are drawing meager supplies of water from polluted sources. A consideration of general conditions in Sudan may appear to show that water is found in abundance due to the existence of the Nile and its tributaries. Nevertheless, the situation concerning drinking water is very pressing. The west faces problems of desertification, the east has problems with salination, and the north suffers the same trouble as the west and more, while the south is full of swamps, sudds and flood lands. In view of water scarcity and prevalence of polluted sources, water supply projects need to be encouraged and initiated for socio-economic development and progress of the nation, taking into consideration the need to choose a safe, adequate, convenient, continuous and reliable source.
Water Sources Potability, palatability and accessibility are factors of prime importance to be considered in selection of a water source. The main resources in Sudan could be categorized as follows: Surface water: It originates mostly form rainfall and includes large rivers, ponds and small upland and seasonal streams, etc. Ground water: Investigations carried out by Rural Water Corporation indicated 1.4 km3/year of under ground runoff and 42 km3 in storage {3}. There is no doubt that the country would benefit immensely by monitoring and exploiting these resources in an economical and practical way. The situation of the groundwater relative to many parameters such as type and characteristics of soils, aquifer capacity, direction of flow, etc govern this. Good quality water could be expected to be found almost everywhere in Sudan, excluding Umm Ruwaba reservoirs where there is a high range of dissolved solids {3, 4}. Rainfall Harvesting rainwater for small villages or for individual households may be the best way of providing water supply where other sources are too remote, too expensive or extremely polluted. The amount of water to be collected depends on the quantity of rainfall, which is subject to the size of the catchment area, rainfall intensity duration and distribution. 7
Presented at a seminar on slow sand filtration held at the University of Khartoum, 13-17 November 1983. Published in Water International Journal, 9 (1984), pp. 112-115. 8 Faculty of Engineering and Architecture, University of Khartoum
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In Sudan the annual rainfall distribution decreases northward with a mean exceeding 1500 mm in the south and an average of 3 mm in the north {4}. Rainfall is normally collected and stored on appropriate places such as hafirs, fulas, tebeldy trees, etc. Intermittent streams are resorted to during rainy seasons. When their water starts to wane, people scoop holes (gemams) in the sand of the streambed to obtain their supply of water. Water treatment for rural regions involves the transformation of raw water into potable, palatable, and wholesome water using fairly simple techniques implemented at reasonable cost. Construction of sophisticated, difficult to build, operate and maintain purification plants should not be considered. Investigations to improve, update and adopt traditional treatment methods are needed in order to attain water that is hygienically safe, aesthetically attractive and economically justifiable for its intended purposes. It is whimsical to suggest delivering clean water to every consumer at his home or premises, but it is an ultimate goal to be achieved whenever finance, practicability and feasibility could allow it. Community involvement is vital for the success of the project and for ultimate maintenance and operation of the system and even for the acceptance of the introduced technology. Water treatment for rural fringes should cater to pathogenic organisms and toxic substances removal or considerable reduction; Likewise, reduction of suspended solids, iron and manganese, elimination of other water quality characteristics such as hardness, total dissolved solids and organic content, etc., would generally be reduced to acceptable limits.
Methods of Treatment Disinfection Destruction of pathogenic organisms that cause disease may be the sole treatment that could be applied in certain places due to lack of finance and absence of techniques, but the selected disinfectant must be effective, readily available, safe, easy to handle and cheap. Otherwise, the hygienic quality of the drinking water can be assured by boiling if people can afford the expenses incurred (e.g., fuel costs). Care should be taken to store the boiled water in the same container, if possible, to reduce recontamination while people are waiting for it to cool. Feachem et al. {5} reported that if a temperature of about 60o C could be maintained for only 20-30 minutes, pathogens such as cysts of Entamoeba histolytica, Giardia, Ascaris and Schistosome eggs would be destroyed. Sedimentation The removal of particulate matter and precipitates from raw water could be effectuated by gravity settling. Mann and Williamson {6} reported that introduction of protected storage for a period of 48 hours results in removal of the cercaria responsible for bilharzia infection. Sedimentation tanks should be properly designed and well maintained for their effectively utilization. Provision of covers reduces algal growth, discourages mosquito breeding and reduces contamination by birds, animals and young children. Coagulation and Flocculation Formation of flocs and large particles by introduction of chemicals enhances the process of sedimentation and aids filtration. In rural areas in Sudan it is difficult to obtain chemicals and there is also a lack of managerial skills and know-how. People have traditionally used both plants and soil materials for domestic treatment of highly turbid water. For example, in the northern regions of the country, horse beans, lentils or helba (fenugreek) are used as coagulants; groundnuts are being used in the Gezira province together with a clarifying clay soil called rauwag (these are powdered seeds of Moringa 21
oleifera). Fulmasri (Faba vulgaris), doleb (palm-fruits of Borassus sp.) and oshar shrub (Calotrpis procera) are also used in many parts of the country. Moringa oleifera leaves are sometimes used to cure diarrhoea, fever, bronchitis, and eye and ear infections. The juice from the leaves of Moringa oleifera has been found to inhibit the growth of E. coli, Micrococcus pyogenes, and Bacillus subtilis. This has been attributed to the absorption capacity of the montmorillonite composing the material {7}. The drawback of these coagulants and their usage is the ignorance about their constituents and their general effect on hygiene, likewise their scientific application i.e., dose required, pH influence, degree and time of mixing, etc. Therefore, further research should be encouraged along these lines. Filtration Filtration aims at the decrease of suspended and colloidal solids, reduction in the number of bacteria and other organisms, removal of odor, color and taste producing substances. Usage of slow sand filters for treating raw water in rural areas should be enhanced for the many advantages gained, such as elimination of suspended impurities and biodegradable organic mattes and hygienic safety acquired by removal of pathogenic organisms, etc. Slow sand filters can be built by using local materials and skills and labor and they do not require advanced mechanical and electrical equipment, likewise, they are simple and easy to operate and maintain. Their general disadvantages will not outweigh their merits in rural districts in Sudan since there is no problem of providing the necessary large area required, likewise, the number of unskilled laborers needed for the manual cleaning process could be found readily if the community is greatly involved throughout the stages of the project.
Conclusions Provision of good quality drinking water is essential for the rural poor. This should be acquired at minimal cost and by easy means; for example George {8} advocated introduction of two species of fish (Bangasius bangasius and herbivorous fishes like grass carp- Ctenopharyngodon idella) to eliminate Bilharzia snails in Sudanese irrigation canals. Large-scale irrigation projects (such as Gezira and Managel) have increased the occurrence of bilharzia and malaria; therefore, treatment of water consumed by settlers in their neighborhoods is crucial. Likewise, water in dam reservoirs creates a favorable environment for mosquitoes and chironomids. For safety purposes people draw water from the river at sites, which are not affected by dangerous currents and falling cliffs and riverbanks. It is a common scene to observe people crowding at the site, some washing their clothes, some having a bath, the richer washing their cars and water sellers or vendors going as far as possible into the water with bare feet accompanied by their animals to fill the khurog, and perhaps a child defecating in the vicinity. All of these practices and others help to increase the rate of pollution and enhance spreading of diseases. Some ground water sources in Sudan (Gebel Mara and near old Halfa) contain excessive quantities of nitrates, fluorides and sulfates {4}. Excessive concentrations of nitrates cause cyanosis in infants (methemoglobinemia). Although a certain amount of fluoride is beneficial to the enamel of the teeth and reduces dental decay, amounts beyond this cause mottling of the teeth and very high levels produce bony deformities as well {2}. Waste disposal localities should be situated further from the source of ground water; Cairnross and Feachem {9} stated that the minimum distance between them should be 30 m to avoid contamination. Care should be taken not to pollute an existing well by faeces, spilt water, vessels used to draw water, rubbish that may be thrown by naughty children, etc.; there are peaks of 22
water related diseases such as gastro-enteric diseases during the rainy season when faecal contaminants are washed into an unprotected water source. A point needs to be mentioned concerning water storage in homes. The common practices to keep the drinking water in jars constructed from baked clay called zeers. These jars cool the water and refresh it due to evaporation through their porous skeleton. Although the outside of the zeer is sometimes cleaned with bricks or char coal to remove accumulated dust and developing algal cells, the bacteriological quality of the water is questionable for a number of reasons such as frequency of use, lack of inside washing, misuse by children, water withdrawal by dirty and stained cups and so on. A research project conducted by Hammad and Dirar {10,11} in sebeel water collected from different places, showed that the water is faecally polluted with counts od faecal coliforms and faecal streptococci as high as 24--- per 100 ml. The bacteria load was noticed to --crease with rise in temperature of stored water. Zeer improvements should be made to achieve hygienic standards. These improvements may include provision of proper covers, application of taps for water egress from the zeer, thorough cleaning, proper location to protect it from atmospheric pollution and playing children, etc. People traveling far distances by lorry or animal take their supply of water in leather bags called girbas. These bags are kept in good shape and condition by painting them with local tar extracted from the plant handle (Citrullus coloynthis). According to ElHassen et al. {12} this tar might act as a dietary carcinogen, therefore, there is possible linkage of bladder cancer with chronic urinary schistosomiasis and water consumption from such girbas. Public health education will lead to elimination of such problems and public hygiene will therefore be preserved. This will eventually lead to better living standards and high productivity.
References 1. Huisman, L. (1978) Treatment Methods for Water Supplies in Rural Areas of Developing Countries, Delft University of Technology. 2. White, D. B., Bradley, D.J. and White, A.U. (1972) Water in Domestic Use, University of Chicago Press. 3. International Development, Environmental Training and Management in Africa.Water for Human Needs, Sudan, Seminar on Water for Human Needs, Khartoum University, November, 1982. 4. 5.
National Council for Research (1982) Water Resources in Sudan, Khartoum. Feachem, R.C., Garelick, H. and Mara,D. (1980) Health Aspects of Wastewater and Excreta Management, World Bank, John Hopkins University Press. 6. Mann, H.T. and Williamson, D. (1979) Water Treatment and Sanitation, Intermediate Technology Publishing, London. 7. Jahn, S.A. (1981) Traditional Water Purification in Tropical Developing Countries - Existing methods and potential application - Water purification project - Khartoum German Agency for Technical Cooperation, GTZ. 8. George, T.T.(1977) Critical appraisal of the water pollution problem in the Gezira canals with particular reference to agriculture, Proceedings 19th Annual Conference of Philosophical Society of Sudan, Khartoum,1977, p. 56. 9. Cairnross,S. and Feachem, R. (1982) Small community water supplies, IRC Technology Paper Series 181, The Hague. 10. Hammad, Z.H. and Dirar,H.A. (1982) Microbiological examination of sebeel water, Journal of Applied Environmental Microbiology, 43(6), p. 1238. 11. Hammad, A.J. (1978) Microbiological examination of sebeel water, B.Sc. Thesis, University of Khartoum, Faculty of Agriculture, 1978. 12. ElHassen,A. M., Zak,F. and Zakova, N. (1966) Bladder carcinoma in the Sudan and its relationship
to Schistosomiasis, ElHakim, 20, p. 74.
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Evaluation of Slow Sand Filters in the Sudan9 By Dr. ISAM MOHAMMED ABDEL-MAGID10, DR. HAYDER A. ABDEL-RAHMAN11, DR. 12 BASHIR MOHAMMED EL-HASSAN & ENG. MOHAMMED ELMAHDI ELSIDDIQ13
Introduction: Slow sand filtration technique has been introduced in the Sudan as a means of water purification around the year 1945. The first slow sand filter being constructed is in a village in the Gezira area, due to scarcity or salinity of the ground water resources in these areas. Since then a sizable number of these filters have been introduced in the Gezira area. Having proved their suitability it led to their utilization in New Halfa Agricultural Scheme and lately in the Rahad Scheme and in other parts of the country. The increased interest in many developing countries has led to the formulation of the slow sand filtration project which is successfully managed by International Reference Centre for Community Water Supply and Sanitation (IRC); The Hague, The Netherlands. The slow sand filtration project has been conducted in three stages namely, experimental, demonstration and evaluation phases. Many developing countries showed interest and took active part in the implementation of the slow sand filtration project (e.g. Ghana, India, Kenya, Thailand besides Sudan). In the selected study area below is comprised of the following zones: Gezira scheme zone; New Halfa Agricultural scheme zone; and Rahad scheme zone. The actual number of filters in these zones amount to more than 200 units. The filters are diverse with regard to the design features and operation techniques. Therefore any scientific evaluation would require a sizable sample yet to be distributed in a wide area. Due to many constraints [e.g. geographical distribution, study period time factor, allocated budget and many other constraints] the evaluation was limited regarding size of samples and bias to sampling procedures. This would enable inclusion of, as much as possible, the different designs prevalent to the study area. The project area being selected is highly populated and characterized by a relatively high per capita income. In fact it has a very high share in the national income of the country. The major agricultural products include cotton, groundnuts, cereals, vegetables, and livestock, etc. The community water supply in these schemes is being provided as a service. This philosophy led to many problems regarding the management and operation of water supply schemes. Because of this, plans are formulated to revise the situation. It is observed that the extensive availability and use of water for irrigation through canalization generated many water related diseases such as gastroenteritis, schistosomiasis. These diseases were never known before in the area. Objectives Slow Sand Filtration is considered an appropriate technology that needs least attendance, unskilled labor for construction and operation, and requires relatively minimum finance. Therefore, evaluation of existing slow sand filtration plants, with regard to adopted 9 First published in The Arab Construction World Journal, July-August 1993, pp 30-31 10 Assistant Professor, Department of Civil Eng, College of Engineering, Sultan Qaboos University 11 Assistant Professor, Department of Soils & Water, College of Agriculture, Sultan Qaboos University 12 Dean, Faculty of public & Environmental Health, P.O.Box 205, University of Khartoum, Khartoum, Sudan 13 National Corporation for Water, Khartoum, Sudan
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designs, construction methods, operation, performance and maintenance aspects, is needed to justify the suitability of Slow Sand Filtration technique to provide wholesome water for rural sectors. This frame constituted the main objectives of this work. Materials and Methods The relevant data concerning the usage of slow sand filters in the Sudan has been collected from the known three organizations that are extensively using slow sand filters for community water supply. These organizations are: The Gezira scheme [having their headquarters in Barakat]; Rahad scheme [having their headquarters in Khartoum]; and Regional administration for water [having their headquarters in the Eastern Region in Kasala]. Several field trips has been organized to the study area by a number of professional engineers, scientists and laboratory personnel. Whence, condition of the treatment plants had been evaluated through discussions, observations and sample analysis. The above activities had been substantiated with specially designed questionnaires. One questionnaire, written in English, is intended for collection of scientific and technical operation data from the appropriate sources, such as engineers, designers, companies, etc... Another questionnaire, written in Arabic, is to assist in collection of data from plant operators and users along with community leaders. Physical, chemical, and bacteriological relevant tests were conducted for the samples collected. This was done in accordance to the Standard Methods for Examinations of Water and Wastewater {1}. Discussion It has been noticed that in most of the investigated plants the design and construction are meeting acceptable standards. However, investigations revealed that the operation and maintenance activities lag behind. This may be due to inappropriate training of treatment-plant operators, lack of proper supervision, shortages of staff and qualified sanitary or environmental engineers. Likewise, facilities for maintenance and operation are not readily available at the site except at El-Fao town and villages’ number 10 and 40. The raw water quality, especially during the flood season (see figures 1 and 2), is not suitable for slow sand filtration in absence of pretreatment. In many cases presedimentation is used as a pretreatment method. This method was not effective since the silt load is high [tanks are not frequently cleaned] and the detention time is short. It is also noticed that there is a striking difference between water collected from Gezira and Rahad canals. Since the former scheme is an old one [canal banks, walls and bottom are relatively stable], water collected from it contains less silt. While in the latter scheme the canals are still not stable and subjected to continuous erosion, the phenomenon of which would lead to high silt load. A situation similar to that in the Gezira scheme is observed to exist in New Halfa Agricultural Scheme.
25
Theoretically, canals are expected to act as pre-sedimentation basins, but in fact in the Gezira scheme there is a noticeable growth of algal colonies within the canals. This is due to the system of irrigation used (night storage), and presence of high nutrients-load discharged to these canals. This situation induced complications and reduction in efficiency of treatment plants. In some plants the algal growth was significant to the extent that they are creating flow obstructions. This eventually developed septic conditions and obnoxious odors within the tanks. In other plants the existence of weeds is so high to the extent that the tank volume is reduced. In such a situation the design parameters are no longer valid. Likewise, presence of weeds harbors insects and snails. Water quality control measures are not normally used. Even if these measures exist, they are not effective due to lack of skilled personnel and method of know-how. Control equipment lack spare parts and proper operation and maintenance. Like wise, management problems, such as coordination between concerned organizations for plant’s operation and maintenance, led to the expected deterioration in treatment within plants. It is noticed that only about three filters, out of more than 200 filters in the evaluated zones, are fitted with coagulation facilities. In plants where coagulation is used the coagulant dose, preparation, dosing and mixing procedures are arbitrary determined. This ultimately resulted in uneconomic and inefficient operation. Storage and handling of coagulants are not carried according to known and accepted procedures as applicable to such facilities. Distribution of the flow in the sedimentation basin is questionable; likewise erratic behavior of sedimentation basin occurred.
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Concerning slow sand filters the design parameters are theoretically implied but actually deviations are noticed. This is true for filter media specifications, supernatant water level, flow rates and operational conditions. Clear water pump in some plants is a potential hazard and a source of pollution (e.g. Wad El Turabi). This is due to irrelevant location of the pump, height of clear water well and lack of pump housing and/or protection. Disinfection is practiced in few plants. Even within them the disinfection equipments are not catered for properly, with the result that the disinfectant dose and effectiveness is doubtful. Some of the filters are subject to pollution by storm runoff and dusty winds due to their low walls and absence of suitable covers. It is also very clear that plant operators are ignorant of processes governing plant operation. This is due to their low level of general education, lack of training, improper supervision and scarcity of reasonable management. Conclusions and Recommendations A) Management The evaluation performed resulted in the following recommendations: 1) Provision of a recognized water treatment section or unit is vital for organizations dealing with massive water supply schemes such as Gezira, Rahad and New Halfa Agricultural Scheme. A qualified Sanitary Engineer or his/her equivalent should head formulated section or unit. 2) The proposed water treatment section - as outlined in point 1 above - should be well equipped to fulfill the needed requirements such construction, operation, and maintenance. 3) Organization and management charts suggested by the authorities in the three schemes should be implemented. 4) Training aspects should be strengthened for all personnel involved in the treatment plants, especially plant operators. Likewise it is advised to secure materials such as relevant manuals, guidelines, and leaflets. 5) Condition of service of personnel involved should be improved to a satisfactory level e.g. increasing salaries, improving services, ameliorating housing conditions, establishing work security and safety levels.. etc. Technical Aspects Design parameters of the slow sand filters should be reviewed in accordance with the findings of the slow sand filtration project. Review may include filtration rate, filter media specifications, inlet and outlet structures, and their operation and maintenance. Attention should be given to: 1) Provision of appropriate screens that suit prevailing conditions in evaluated schemes and in the country at large. 2) Installation of pretreatment units (impounding, coagulation.etc), whenever necessary, for production of reasonable water quality that could be treated efficiently through slow sand filters. 3) Furnishing proper cleaning facilities for plant units to ensure smooth operation of plant. 4) Regular removal of algal blooms. 5) Choice of suitable filtration media (with respect to: specification, quantity, quality, washing, re-sanding, and depth). 6) Provision of proper drainage system.
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7) Continuous and well-supervised maintenance of the plant. 8) Proper dosing and monitoring of the residual disinfectant. 9) Proper plant protection and housekeeping (fencing, adjusting height of treatment units, using covers, removing wild plants and weeds). Social Aspects 1) Community participation and involvement is of paramount importance for successful installation and operation of the treatment plant. This should be encouraged from the beginning of the feasibility stage. 2) Health education is vital for the achievement of expected benefits from provision of safe water via slow sand filters. This will ensure eradication of water related diseases. Awareness of the community involved regarding the relation between water, disease and personal hygiene should be well demonstrated e.g. by seminars, posters, films, group discussions...etc. 3) It is essential to create a village water committee to ensure continuous and efficient operation of the plant. References 1) American Public Health Association (1980). "Standard methods for examination of water and waste-water." 16th. ed. Inc. Washington D.C. 2) ElHassen, A. M., Zak, F. and Zakova, N. (1966) Bladder carcinoma in the Sudan and its relationship to Schistosomiasis, ElHakim, 20, p. 74. 3) George, T. T. (1977) Critical appraisal of the water pollution problem in the Gezira canals with particular reference to agriculture, Proceedings 19th Annual Conference of Philosophical Society of Sudan, Khartoum, 1977, p. 56. 4) Huisman, L. "Slow Sand Filtration" Delft University of Technology 1977. 5) Huisman, L. (1978) Treatment Methods for Water Supplies in Rural Areas of Developing Countries, Delft University of Technology. 6) International Development, Environmental Training and Management in Africa.Water for Human Needs _ Sudan, Seminar on Water for Human Needs, Khartoum University, November, 1982. 7) IRC Occasional Paper Series "Guidelines for Operation and Maintenance of Slow Sand Filtration Plants in Rural Areas of Developing Countries" Rijswijk 1983. 8) National Council for Research (1982) Water Resources in Sudan, Khartoum. 9) Personal contacts with concerned Engineers, operators, personnel... in The Gezira, Rahad and New Halfa Agricultural Schemes. 10) Van Dijk, J. C. and Oomen, J. H. C. M. "Slow Sand Filtration for Community Water Supply in Developing Countries- A Design and Construction Manual" IRC Tech. Paper Ser. 11, The Hague 1978. 11) W.H.O. Report (1961). "Diarrhoeal Diseases in the Sudan." W.H.O. Geneva. 12) W.H.O. Report (1984). "Guidelines for drinking water quality." Vol. 1, 2, & 3, 1984, W.H.O. Geneva.
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-Analysis of Pipe Networks by the Finite Element Method14 By Hassan Abdel Mageid15, Abdel Wahid Hago16 And Isam Mohamed Abdel Magid17
Abstract In this paper, the finite element technique used in the analysis and design of water distribution networks will be presented. The method was applied successfully to the solution of three different networks. In order to demonstrate the feasibility of the approach and to show some merits and demerits of the finite element method, a comparison was made on a digital computer with the standard Hardy Cross method. In all cases the finite element method was shown to provide superior performance. Moreover, the programmes were run on three different machines {Wang vs 100, Apple IIe, and IBM microcomputer} to show the effect of increasing storage capacity, machine accuracy, and time saving
Introduction The finite element method for the analysis of water distribution network has recently received considerable attention {1,2}. This is almost entirely due to the existence of digital computers, which make tedious, iterative calculation more amenable to quick solution. In addition, obtaining a solution to these problems has important economic and design significance, especially in developing countries. There are several methods that may be used for the analysis of flow in complex networks, varying and graphical techniques to the use of electrical analyzers. Also with the wide distribution of fast computers the hydraulic analysis of pipe network has developed rapidly {3- 5}. The most widely used method analysis is that developed by Hardy Cross {3}. Although the method is old and rather unsophisticated it is still a viable method of analysis. Actually, this method is well suited for solution by hand; and is easily adapted for machine computation {6}. However, there are several disadvantages to this method such as: 1. A lot of time and tedious work is exhausted in assuming initial flows: 2. Limitations in usage for large flows resulting in convergence problems; 3. An occasional incorrect assumption for direction of flow; and 4. Complications in the method for complex systems such as reservoirs, interior pumps, valves etc. Collins and Johnson {1} discussed two iterative procedures for solving a network that satisfied the node and loop equilibrium. One procedure always converges, although slowly, from any starting assumption. The other, using the Newton Raphson technique {7} converges rapidly from a reasonable assumption of flow in each pipe but may not converge at all when initial assumption of flow in unrealistic. Jeppson and Davis {8} described the three alternative formulations of the governing equations in which pipe flows, junction heads or corrective loop flows are the unknowns. They also described the most commonly used solution methods {Hardy
14
First published in Water International Journal, 16 {1991}, pp 96-101 Civil engineer, Civil Aviation, Khartoum, Sudan 16 Civil Engineering Department, Sultan Qaboos University, P. O. Box 32483, Sultanate of Oman. 17 M. IWRA, Civil Engineering Department, Sultan Qaboos University, P. O. Box 32483, Sultanate of Oman. 15
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Cross, Newton Raphson, and linear theory}. Computer programmes based on these methods were also described {5, 9, 10}. Epp and Fowler {9} have described methods for improving the solution efficiency for some of the methods when applied to large networks. Liu {1} presented a Newton-Cross combined procedure that he compared with the Hardy Cross Method alone, and later, separately with the Newton method. He concluded that the Hardy Cross method corrects the heads one at a time, while the Newton-Cross combined method computes all corrections at the same time. The latter is much easier to code than the former. Wood and Charles {5} used linear network theory, modified to account for the nonlinear head loss, to solve for the flow distribution in hydraulic networks. Benjamin {12} presented a method for water distribution network based on three different aspects of unsteady flow models, all related to, but not limited to, microcomputers. The method of characteristics {MOC} was utilized as the numerical method.
General Description of the finite element method Application of the finite element method to a structural problem demands the subdivision of the structure into a number of discrete elements. Each of these elements must satisfy three conditions {1}: 1. Equilibrium of forces; 2. Compatibility of strains; and 3. The force displacement relationship specified by the geometric and elastic properties of the discrete element An equivalent set of conditions for a pipe network exist; hence, the ability to draw the analogy: 1. The algebraic sum of the flows at any joint or node must be zero. 2. The value of the piezometric head at a joint or node is the same for all pipes connected to that joint; and 3. The flow-head relationship {such as Darcy-Weisbach or Hazen-Williams} must be satisfied for each element or pipe. For Direct application of the finite element method involving a matrix solution, a linear relationship is required to define the element or pipe. See Fig. 1.
Li
Qj
Qk
Figure (1) Pipe Element Hence there is a relationship of the form: q=ch (1) In which q = flow; h = head loss and c = the hydraulic properties of the pipe (to be assumed). The solution technique can be subdivided into three steps: 1. An initial value of the pipe coefficient. c, is selected for each pipe and is then combined to yield the system matrix coefficient {C}. The system matrix is then solved for the value of piezometric head at each joint. 2. The individual pipe flows, q, are computed by means of Eq. (1) using the difference between the determined piezometric heads. These flows are then substituted in the Darcy-Weisbach equation to calculate the pipe head losses. 30
If the pipe head losses obtained from the Darcy-Weisbach equation correspond to those obtained from the matrix solution, then the unique solution, satisfying both the Darcy-Weisbach equation and the linear equation (1) has been found. 3. If there is a difference between the values of head loss calculated by the two methods, the values of c are changed to cause the problem to converge to a solution.
Analysis of Pipe Network Figure 2 is used to show the application of the finite element method. Nodes and pipes are numbered for identification purposes. As a sign convention, any external flow at a joint will be positive when fluid is input and negative when actual consumption occurs. Applying the equilibrium flow criteria at each node then: Q1 = q1 + q2 Q2 = q1 + q3 + q4 + q5 Q3 = q2 + q3 + q6 + q8 (2) Q4 = q4 + q6 + q7 + q9 Q5 = q5 + q7 + q8 Q6 = q9 Q 6
6 2
q4
q9
4 q1 Q1
1
q3
q2
q7 q6
q5 q8
5 Q5
3 Figure (2) Pipe Network
But the pipe flow in individual elements are given by: q1 = c1 (H1 – H2) q2 = c2 (H1 –H3) q3 = c3 (H2 –H3) q4 = c4 (H2 –H4) (3) q5 = c5 (H5 – H2) q6 = c6 (H3 – H4) q7 = c7 (H4 – H5) q8 = c8 (H3 – H5) q9 = c9 (H4 – H6). Applying the sign convention on the flow in the element, it will be noted that while the flow at one end, j. of the element will be input (i.e positive) it is an output (i.e negative) at the other end, k, of the element. It follows that, if the flow in element m, whose ends are nodes j and k, is given b y qm = cm (Hj –Hk) at end j, the same flow when considering end k will be qm = cm (Hk- Hj). Thus, substituting Eqs. 3 in Eqs.2, observing the sign concention, and writing in matrix form we get:
31
⎡ Q1 ⎤ ⎡(c1 + c 2 ) ⎢ ⎥ ⎢ − c1 ⎢Q 2 ⎥ ⎢ ⎢Q 3 ⎥ ⎢ − c 2 ⎢ ⎥=⎢ ⎢Q 4 ⎥ ⎢ 0 ⎢Q ⎥ ⎢ 0 ⎢ 5⎥ ⎢ ⎢⎣Q6 ⎥⎦ ⎢⎣ 0
− c1 (c1 + c 3 + c 4 + c 5 ) − c3 − c4 − c5 0
− c2 − c3 (c 2 + c 3 + c 6 + c 8 ) − c6 − c8 0
0 0 − c4 − c5 − c6 − c8 (c1 + c 3 + c 4 + c 5 ) − c 7 − c7 − c9 0
0 ⎤ ⎡H1 ⎤ ⎥ 0 ⎥ ⎢⎢ H 2 ⎥⎥ 0 ⎥ ⎢H 3 ⎥ ⎥=⎢ ⎥ − c9 ⎥ ⎢H 4 ⎥ 0 ⎥ ⎢H 5 ⎥ ⎥ ⎢ ⎥ − c 9 ⎥⎦ ⎢⎣ H 6 ⎥⎦
(4)
In compact form Q=CH (5) In which C = the network characteristics matrix; H = the network head vector, and Q = the network consumption vector.
Implementation of the Finite Element Procedure Data input The input data consists of the following: a) The number of nodes, elements, known consumption node, known head nodes, and fluid properties: b) The element number, its diameter, its length, and the number of its first and second node connectivity: and c) The node number and its known head or consumption.
Computation of Pipe Coefficients The Darcy-Weisbach equation states the relationship between the head loss and the flow in a pipe as: ⎛ fL ⎞ 2 ⎟q = C1 q 2 (6) h1 = ⎜⎜ 2 ⎟ 2 gDA ⎝ ⎠ fL (7) With C1 = 2gDA 2 in which h1 = head loss (m); f = friction factor; L = length of pipe (m); D = diameter of pipe (m); A = cross sectional area of pipe (m2) ; g = acceleration of gravity (ms2); and q = flow discharge (m3/s). To calculate the friction factor, f, the following expression was used {5,13}: 0.134 (8) f = 0.094 K 0.225 + 0.53 K + 88.0 K 0.44 Re1.62 k In which K = e/D, e = roughness coefficient, and Re = Reynolds number The initial value of pipe coefficient, Co, was chosen to correspond to Re = 200,000 in each pipe, a typical value for practical problems {1}. Accordingly, and since qD Re = , the initial flow in the pipe becomes: Aν ν A (9) q o = 200000 D in which A = area of the pipe (m2), D = diameter (m), and ν = kinematic viscosity of the fluid (m2/s). The value of head loss, h, corresponding to the flow qo can be calculated from Eq.6. The pipe coefficient is then found from Equation 1 as q (10) co = o ho
32
This initial value of the pipe coefficient, co, for each pipe was then combined, according to the geometry of the network, to obtain the initial network characteristic matrix, [Ci]o.
Assembly of the Matrix Using a standard finite element procedure, the assembly process to form the global matrix can be summarized. Starting with a zero matrix, the following operations are performed for each element: 1. Add coefficient – Ci to position (k, k) and (j, j); and 2. Add coefficient – Ci to position (k, j) and (j, k), according to the connectivity table. Once all elements are considered the [c] matrix is assembled.
Boundary Conditions Before the total system of equations can be solved, it is necessary to introduce proper boundary conditions for at least some of the nodes of the network. The two possible types of boundary conditions involve specifying either head or consumption for any given node. The introduction of the boundary conditions for prescribed heads can be implemented by performing the following steps: 1. Add the contribution of the prescribed unknown Hj to the vector of nodal consumption [Q]. 2. Zero the jth column and jth row of the matrix [C]. 3. Make the (j,j) coefficient of matrix [C] equal to 1. 4. Make the jth coefficient of the vector nodal consumption equal to Hj A boundary condition of the second type, where the discharge rather than the head is prescribed, is handled by simply placing the value of the prescribed discharge or consumption in the proper position in the vector of nodal consumption. Solution of the System of equations The solution of the simultaneous algebraic equations was done using the Gauss elimination technique {7}. The solution of the system of equations could provide the values of the previously unknown nodal heads. With these, discharges could be computed for every element using Equation 1.
Adjusting the value of c {1} During the checking procedure, the flow qc, for each pipe calculated via Equation 1, and the matrix solution were used to determine the head loss, hc, from the DarcyWeisbach equation. The first procedure used in the development of the programme was to obtain the correction of the c value for each pipe by assuming that the point (hc, qc) was the unique solution. Thus, the correct linear relationship was defined by the straight line joining this point to the origin and is defined by the equation. q H= c q (11) hc q The new value of c was then set equal to c . When all pipe coefficients were hc corrected in a similar way the flow distribution obviously was altered, and this method can be an over-correction when the matrix was resolved. To dampen this over-correction effect, an averaging technique was introduced. The corrected vale of c is taken to be the mean of the c value defined by Equation 11 and the value of c used to obtain the matrix solution.
33
Application to Some Problems In order to demonstrate the feasibility of the finite element approach, two different computer programmes were developed and applied to three example networks. The programme FEMNET, developed in this study, which was based on the finite element technique, was applied to three water supply networks. Then to the same networks, the programme HRDYX {also developed in this study}, based on the Hardy Cross technique of balancing flow was also applied for comparison and checking of results. The two programmes were run on three different machines {apple IIe, Wang vs 100, IBM micro-computer} to see the effect of storage capacity, time saving and to test machine accuracy. Application to Network A This simple network has been taken from Civil Engineering Handbook {15}. The network consists of 10 elements and 8 nodes and is shown in Fig. 3 Input and withdrawals at the nodes are shown there, while pipe characteristics are given in Table 1. The water level in the tank at node 1 is 300 ft. The network was solved using the HARDYX programme in 6 iterations. When the FEMNET programme was applied to the network the same solution was achieved in 16 iterations. Q 22 1 5 1 2 7 3 3
2 4
4
8
9 0.44 5
6
10
0.44 6 1.32 7
8
Table (1) Pipe Characteristics for Network A Pipe 1 2 3 4 5 6 7 8 9 10
Diameter, ft 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50
Length., ft 2000 2000 3000 2500 5000 2000 2500 1500 4000 1500
Application to Network B This network was taken from Lius's IAHR conference paper {11}. The network consists of 35 elements and 20 nodes, Fig. 4, and a complete listing of the characteristics of each pipe in the network is provided in Table 2. In applying the HARDYX programme to this example network, the magnitude and direction of flow in each pipe were assumed. When this programme ran on the Wang vs 100, the solution converged in 95 iterations in 1.23 minutes. On the apple IIE it
34
converged, in the same number of iterations, but in 8 minutes. When the network was solved using the FEMNET programme, the time and effort spent in assuming the initial flows was eliminated and the same solution was achieved in only 23 iterations and in approximately 1.5 minutes when ran on the Wang vs 100. When the programme was run on the Apple IIe, the solution converged in the same number of iterations but in a longer time. This difference in time is mainly due to storage capacity and accuracy of the machine used. Also this example indicated the feature of saving time and effort needed for initial assumption of flows, and the ease of input data for the FEMNET programme over the HADYX programme.
Table (2) Pipe Characteristics for Network B Pipe 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
Diameter, ft 5.00 5.00 1.67 2.50 2.50 1.67 2.50 2.50 2.50 2.50 0.83 1.67 3.00 1.67 2.50 1.67 1.67 1.60 2.50 1.67 1.67 3.50 2.50 2.50 2.50 2.00 3.33 4.00 2.50 2.00 1.67 2.50 1.67 2.00 1.67
Length, ft 5100 5900 3000 5600 4900 3000 4900 3100 6200 10200 6800 3000 5750 3000 3600 3000 5000 3400 6000 4000 2900 4000 3750 3000 4000 3000 7500 5500 5000 4000 3000 6500 4500 4000 3000
36.2
6.0 29
17
25.0
27
24 25 41.2
15
8.0
23
30
14
22
19
1
4
9.0
3
12
4.0
21
18
34
11
5.0
35
12 9
4 23.5
6.0
8 6
6 7
10
5 6.0
Figure 4. Network B
35
8
20 14
6.0 5
10
13
9
2 2
0.3
17
11 7.8
1.9
19
13
33
31
20
3
7.3
18
28 16
1 Reservoir 600' HIGH Q = 214.30 FS
17.7 32
15
2.4 7
1.0
Application to Network C This network is in Elobied Town, which lies in West Sudan {14}. This is a more practical problem, due to its complexity and the increased size of the network. It consists of 137 elements and 89 nodes and combines an existing network and its new extensions. Full details of the network can be found in Ref. 14. It was assumed that the pipes were commercial steel, each with a roughness element size of 0.03mm. When this network was solved using the HARDYX programme, more than 7 days were spent in making initial assumptions to balance the network before the solution began. The solution was achieved in 77 iterations. In applying the FEMNET programme, the properties of the pipes and the configuration of the network were the only requirements. In contrast with HARDYX the same solution was achieved in only 17 iterations. The two programmes were run on the Wang vs 100, Central Processing Unit {CPU}. The time required for HARDYX was approximately 5 minutes, while that for FEMNET was 3.5 minutes
Conclusions From the study of the various networks, it can be concluded that the major advantages of the finite element method over the Hardy Cross method include: i. The speed of convergence and the apparent lack of convergence problems ii. No need for an initial guess of the flow distribution iii. Flexibility in applying the boundary conditions iv. Ease of modifying and extending the network without interrupting the whole system. v. The absence of artificial loops vi. The choice of flow-head loss relationship vii. Ease of input data The ability to account for temperature effects. viii. ix. The unlimited network size {depending only on computer storage capacity). Although the effect of pumps, boosters, pressure reducing valves, non-return valves, etc. were not included in this paper, they can easily be incorporated in the program if their actual head flow relationships are known. This could be considered in subsequent research papers. Finally, it can be said that the finite element method requires the formulation and solution of the entire set of network equations. The large active computer space 36
requirement for these computations determines the maximum size of network, which can be handled by this method, and this depends on the computer used.
References 1.
2.
3.
4.
5.
6.
7. 8.
9.
10.
11.
12.
13.
14.
15.
Collins, A.G. & Johson, R.L. "Finite Element Method for Water Distribution Networks " Journal of American Water Works Association, Vol. 67, No. 7, 1975 pp. 385 -389 Gientke, F.J. "Finite Element Solution for Flow in Noncircular conduits, "Journal of the Hydraulics Division Proceedings of the American Society of Civil Engineers, Vol. 100, No HY3. 1974, pp. 425 – 442 Lam, C.F. & Wolla, M.L., "Computer Analysis of Water Distribution Systems, Part 1 Formulation of Equations”, Journal of the Hydraulics Division, Proceeding of the American Society of Civil Engineers Vol. 98 No. HY2 , 1972, pp. 335-344. Lam. C.F. & Wolla M. L. "Computer Analysis of Water Distribution Systems. Part II Numerical Solution”, Journal of the Hydraulics Division, Proceeding of the American Society of Civil Engineers. Vol. 98. No HY3, 1972, pp. 447-460 Wood, D.J. & Charles, Co.., "Hydraulic Network Analysis Using Linear Theory”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 98. No HY7, 1972, pp. 1157-1170 Shamir, U. & Howard, C.D., "water Distribution Systems analysis”. Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 94. No HY1, 1968, pp. 219 -234 Henrici, P., Elements of Numerical Analysis, John Viley & Sons Inc., New York, New York, U.S.A., 1967 Jeppson, R.W & Davis, A.L., "Pressure Reducing Valves in Pipe Network Analysis”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 102, No HY7, 1976, pp. 897 -1001 Epp, R. & Fowler, A.G., “Efficient Code for Steady State Flows in Networks”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 96, No HY1, 1970, pp. 43 -56 Mc Cormich, M. and Bellay, C. J., "A Computer Programme for the Analysis of Networks of Pipes and Pumps”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 38, No 3, 1968, pp. 51 -58 Liu , K.T., "The Numerical Analysis of Water Supply Networks by a Digital Computer”, Proceeding IAHR 13th Congress, Kyoto, Japan, 31 Aug. - 5 Sept. 1969, pp. 35 – 42 Wylie, E.B., "The Micro Computer and Pipeline Transients”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 109, No HY12, 1983, pp. 1723 -1739 Wood D.J. "Slurry Flow in Pipe Networks”, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, Vol. 102, No HY1, 1980, pp. 57 -70 Abdel Magied, H., “Analysis and Design of Networks using Finite Element Method”, M.Sc. Thesis, Department of Civil Engineering, University of Khartoum, 1987 Standard Handbook for Civil Engineers, McGraw – Hill Inc, New York, New York U.S.A., 2nd ed., 1976, pp 21-1 to 21-124.
37
Establishment of Water and Wastewater Quality Guidelines for the Sultanate of Oman: A Critical Overview18 By Isam Mohammed Abdel-Magid and Allaaldeen Al Zawahry19 Abstract This paper focuses on formulation and adoption of guidelines and standards that would be appropriate to the Sultanate of Oman. The impact of quality parameters on industrial sectors is numerous. Usage of hygienically safe and wholesome water would add inputs to industries. Likewise proper disposal of industrial wastes according to predetermined criterion would safeguard the environment. This demands formulation, updating and implementation of guidelines that would properly serve the water sector in the Omani various and varying districts and regions. Introduction: Water quality criteria demand adoption and enforcement of standards and regulations. This is necessary and vital to the water and wastewater authorities in the Sultanate of Oman. The merits incurred are unaccountable. Thus, efforts addressing the formulation and implementation of such a valuable measure need to be greatly encouraged {1}. National standards concerning quality control that need to be implemented for The Sultanate of Oman need to deal with the following characteristics and features {1,2,4,12,13,14,15}: * The differing climates within the Sultanate of Oman, * The cultural and social habits within the various regions or states (Wilaiats) of the country, * The type of diet and eating patterns, * Socio-economic status of citizens, * Opinions, beliefs, taboos and local habits and customs, * Availability, reliability and accessibility of the needed amounts of water. * Existence of efficient and suitably run treatment plants..etc * Methods used for disposal of human, animal and municipal waste. * Industries established within the country and their national impact. * Industrial expansions and growth. * Regulations governing disposal and discharge of industrial and agricultural effluent along surrounding environs.
* Annexation and extension of services and amenities. The above outlined elements are difficult to satisfy for the whole Oman through one standard. Therefore, the adoption of guidelines rather than standards would primarily be the reasonable approach. The employed guidelines need to be interpreted into local standards in different regions whenever applicable. This is to be done in such a way that flexibility is attained together with any variations in social and economic obligations. Guidelines and standards aim at the upgrading of treated water quality to recommended values. Nonetheless, in many circumstances, this does not mean that the satisfaction of the consumer may be attained. Hence, the ultimate use of treated water, after leaving any authorized water- processing station, needs critically to be reviewed. Generally, water in Oman may greatly be ill-used. Consequently, deterioration through any or all of the following may be noted: * System used for water distribution in certain sites. This is especially important in absence of distribution mains.
18 Greater portion of this paper has been published in The Arab Water World Journal, vol. 16 issue 5, Sept.- Oct. 1992,pp 18-22 19 Department of Civil Engineering, College of Engineering, Sultan Qaboos University, P.O.Box 32483, Muscat, Sultanate of Oman
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* Water handling through: water vendors, sellers and contractors, * Water abstraction and collection systems and methods, * Water storage facilities at homes (e.g. Jahlas [porous earthen pots], roofstorage tanks, girbas [animal-skin containers], barrels, plastic vessels...etc), * Techniques employed for irrigating domestic plants, * Missing awareness towards threats associated with polluted and contaminated water. It is to be noted that the advertisement and local information media [television, newspapers, national press] are shouldering a valuable and a notable task with respect to community awareness and education, * Heritage and traditions concerning water handling and management, * Belief and social values, * Tariffs and charging systems selected for consumers...etc. The recent reductions in tariffs for farmers are of greater help and should prove valuable and worthwhile. To be able to implement, evaluate and follow up any adopted standards, ways and means for proper surveillance should be secured. This includes the following: optimum required number of well-trained staff and personnel, continuous flow of laboratory supplies and equipment, and proper supervision. Such a task would make use of the competent transportation system in the country. Likewise, it would establish appropriate links between different authorities working in the environmental domain. It is to be pointed out that the already formed and used Omani standards for drinking water quality resemble greatly the WHO13 standards. Table (1) follows a pattern set in accord with the classifications established by the Ministry of Commerce and Industry. To achieve reasonable comparison, the WHO standards and the WHO guidelines were incorporated in the same table. Drinking water standards were generally grouped in three categories. The first class addresses physical water characteristics such as total solids concentration, taste, odour, colour, and turbidity; see table (1). Table 1 Drinking Water Standards (Some examples of recommended concentrations) Physical characteristics Characteristic Oman Regulations5
Total solids Taste Odour Colour Turbidity
HDL MPL 500 -1500 unobjectionable
Absent Absent
WHO Standards13 HDL* MPL** 500 1500 mg/l unobjectionable offensive for most of the consumers not Odour unobjectionable 5.25units
*
WHO Guidelines15
15 TCU 5 NTU+
Highest desirable level Maximum permissible level + [Preferably <1 for disinfection efficiency] The second group, of drinking water standards, concerns chemical water characteristics. These are further subdivided into four main sub groups; which include: toxic substances, **
39
chemical substances of health significance, chemical substances that affect drinking water quality, and the minimum residual chlorine to be used for effective chlorination. Table (2) summarizes these arrangements. Table (2): Drinking Water Standards: Chemical characteristics i] Toxic Substances Characteristic Oman Regulations WHO Standards WHO Guidelines MPL HDL MDL mg/L Lead (as Pb) 0.1 -0.1 0.05 Selenium (as Se) 0.01 -0.01 0.01 Arsenic (as As) 0.05 -0.05 0.05 Cadmium (as Cd) 0.01 -0.01 0.005 Cyanide (as CN) 0.05 -0.05 0.1 Mercury (Total as Hg) 0.001 -0.001 0.001 ii] Chemical substances of health significance Characteristic Oman Regulations WHO Standards WHO Guidelines MPL HDL MDL mg/L Fluoride (as F) 0.8 1.5 Nitrate (as NO3) 45 45 10 (as N) iii] Chemical substances that affect drinking water quality Characteristic Oman Regulations WHO Standards WHO Guidelines HDL MPL HDL MPL mg/L Total dissolved solids 500 1500 500 1500 1000 Copper (as Cu) 0.05 1.5 0.05 1.5 1.0 Iron (as Fe) 0.1 1.0 Magnesium (as Mg) (Not more than 30 mg/L if there are 250 mg/L of sulfate; if there is less sulfate, magnesium up to 150 mg/Lmay be allowed) Manganese (as Mn) 0.05 0.5 0.05 0.5 0.1 Zinc (as Zn) 5.0 15.0 5.0 15.0 5.0 Calcium (as Ca) 75 200 75 200 Chloride (as Cl) 200 600 200 600 250 200 400 200 400 400 Sulfate (as SO4) Phenolic compounds 0.001 0.002 0.001 0.002 ** (as phenol) 100 500 100 500 500 Total hardness(as CaCO3) pH range (7-8.5); (7-8.5) 6.5-8.8 (6.5-9.2) (6.5-9.2) iv] Minimum residual chlorine: Minimum concentration of residual chlorine for effective chlorination should not be less than 0.2 - 0.5 mg/L in treated water {5}. ** Chlorophenols are reported in WHO guidelines as organic substances of health significance. Examples include: pentachlorophenol with a guideline value of 10; 2,4,6Trichlorophenol with a guideline value of 10 and an odour threshold concentration of 0.1 µg/L. The first subgroup of chemical substances points to inorganic constituents of health significance as classified by WHO Guidelines together with the fluoride and nitrates [mentioned in second subgroup] added to them chromium. The third subgroup in the chemical substances generally points to aesthetic quality parameters. It is rather difficult to outline these substances as affecting potability aspects.
40
The subgroups eliminated two major drinking water quality criterion namely those regarding organic constituents of health significance and radioactive materials. The third class of standards tackles biological and bacteriological parameters. Table (3) covers bacteriological quality aspects for both treated and untreated water. The resemblance to WHO standards is clear. WHO guidelines would undoubtedly offer a better classification. This is especially when water supply systems in Oman are thought of [Figure (1)]; e.g. Falaj [surface-carrying water structure], groundwater, desalinated water, rain, bottled water...etc.
Table 3 Bacteriological characteristics 1] Omani standards {5} 1.1] Treated water: * No sample should contain E.coli in 100 ml. * No sample should contain more than 10 viable microorganisms of the coliform group per 100 ml. * Throughout any year, 95 % of samples should not contain any microorganisms in 100 ml. 1.2] Untreated water * No sample should contain E.coli in 100 ml. * No sample should contain more than 10 viable microorganisms of the coliform group per 100 ml. 2] WHO bacteriological standards for water in the distribution system: {13} * Throughout any year, 95 % of samples should not contain any coliform organisms in 100 ml. * No sample should contain E.coli in 100 ml. * No sample should contain more than 10 coliform organisms per 100 ml. * Coliform organisms should not be detectable in 100 ml of any two consecutive samples. 3] WHO guideline values for bacteriological quality: {4,15} 3.1] Piped supplies: * Treated water entering the distribution system: Faecal coliforms 0 per 100 ml; and Coliform organisms 0 per 100 ml. * Untreated water entering the distribution system: Faecal coliforms 0; 3 Coliform organisms in any one sample, 0 in any two consecutive samples, 0 in 98 % of yearly samples per 100 ml. * Water in the distribution system: Faecal coliforms 0; 3 Coliform organisms in any one sample, 0 in any two consecutive samples, 0 in 98 % of yearly samples per 100 ml. 3.2] Un-piped supplies: Faecal coliforms 0 per 100 ml; and Coliform organisms 10 per 100 ml. 3.3] Bottled drinking water: Faecal coliforms 0 per 100 ml; and Coliform organisms 0 per 100 ml. 3.4] Emergency supplies of drinking water: Faecal coliforms 0 per 100 ml; and Coliform organisms 0 per 100 ml. In case of waste-water and sludge treatment and disposal the Omani Regulations mainly has been divided into three broad areas. The first area marks parameters to be considered for wastewater reuse, discharge and sludge disposal6. Table (4) gives an outline of the Sultanate of Oman Regulations concerning wastewater reuse and discharge. As outlined in table (4) more emphases were placed on chemical substances. Radioactive materials are covered in a separate article, which do not permit reuse of wastewater or sludge containing radioactive material. {6}
41
Table 4 Parameters for reuse and discharge of waste-water6 Parameter Physical: Total Suspended Solids T.D.S Turbidity [NTU] Chemical: Aluminum Ammoniacal Nitrogen [as N] Arsenic Barium Beryllium BOD [5 days] Boron Cadmium COD Chloride Chlorine, Free Residual [After 60 min. contact time] Chromium Cobalt Copper Cyanide Dissolved Oxygen Fluoride Iron Lead Lithium Magnesium Manganese Mercury Molybdenum Nickel Oil and grease pH [pH units] Phenols Phosphorous [total as P] Selenium Sodium Sulphate Sulphide Organic Nitrogen [Kjeldahl] Total Nitrogen Total Organic Carbon Vanadium Zinc Bacteriological Total Coliforms [MPN/100 ml] Viable Pathogenic Ova & Cysts
Limits [not greater than] Maximum Monthly av. over any 4 consecutive weeks 1500 1000 15 10 5 2 5 1 5 1 0.2 0.05 2 1 0.3 0.1 15 10 2 1 0.03 0.01 100 50 350 250 0.5 0.5 0.5 0.5 0.3 0.1 2.0 2.0 5 0.5 10 150 1 0.005 0.05 0.5 5 6-9 1 30 0.05 200 400 0.1 10 50 50 1 5
0.1 0.1 0.2 0.05 2.0 1.0 1 0.1 2.5 30 0.2 0.001 0.01 0.2 2 6-9 0.1 20 0.02 70 200 0.05 5 30 20 0.1 2
23
2.2 (None detectable)
*
Not to be exceeded in any sample. Determined over last 7 days of completed analysis. + All units are mg/l unless otherwise stated. **
Disposal of sludge is limited to treated sludge with characteristics in agreement with that is as indicated in table (5).
42
Table 5 Limits for disposal of sludge {6} All units are in grams per ton of dry matter Parameter Limit (not greater than) Cadmium 30 Chromium 1000 Cobalt 100 Copper 1000 Lead 1000 Molybdenum 20 Nickel 200 Zinc 1000
The second area of the Omani regulations as related to wastewater and sludge treatment and disposal covers external building drainage {7}. The third area in filed of wastewater and sludge treatment and disposal has been allocated for regulations concerning septic and holding tanks8. Generally regulations or guidelines for wastewater and sludge disposal need to be split in divisions that cover specific relevant areas. Examples of these divisions may include: pretreatment guidelines, disposal of wastes in natural water bodies; disposal of industrial wastes in sewers; water reuse for agriculture; water used for swimming and recreation; and water used for particular purposes. Air pollution needs further greater attention. Conclusions and Recommendations: The adoption and implementation of guidelines and standards need to be preceded by actions such as: Survey and evaluation of the current position of water resources, Enlisting and registration of the different pollution-producing areas with a nationally formed body such as the authorized bodies within the Ministry of Municipalities and Environment. Identification and verification of pollution-producing groups. This is to be followed by portrayal of pollution streams issuing from each providing sector. Suggestions to be followed for selection of appropriate pretreatment or treatment frameworks. Establishment of well equipped national and regional reference laboratories such as the case in certain municipalities. A main national, educational, research oriented and training laboratory may be formulated through establishment of an Environmental and Public Health Engineering Institute. This Institute would be the focal point for many national and international agencies, research centres, laboratories, universities, organizations, and the like. The Sultan Qaboos University furnishes a promising platform for such an enterprise. Qualification and training of pertinent personnel to satisfy needed specifications and requirements, Escalating and expanding the running community education procedures and programs. Estimating origin of pollutants that are likely to invade the human body through the major three routes; namely: water, food and air in the Sultanate of Oman surroundings. Coordination between the different ministries, municipalities, institutions, organizations and the like. Figure (2) outlines a suggested system of coordination that may be followed for optimization and better utilization of resources. The
43
Ministry of environment acts as a focal point at the national and international levels. One of its major responsibilities is the coordination between authorities, donors, institutions and the like. This coordination would be the appropriate measure towards the success of policies and the accepted guidelines. The implementation of the law is the principal element for the adoption of guidelines, standards and regulations. Likewise, the importance of periodic surveillance of accomplishments, performance, Management and efficiency of systems cannot be over stressed. References 1. Abdel-Magid,I.M. and ElHassan,B.M. "Reflections on Drinking Water Quality Guidelines for The Sudan", J. Wat. Intern., 12(1),1987,33. 2. AWWA "Quality goals for potable water", J. Amer. Wat. Wks Assoc., 60(12), 1968. 3. Ayres,R.S. and Westcot,D.W."Water quality for agriculture" FAO,Rome,Irrigation and Drainage Paper 29, 1976. 4. Gorchev,H.G. and Ozolins,G "WHO guidelines for drinking water quality" A paper presented at the Intern. Wat. Supply Associ. Congr., 6-10 Sept. 1982, Zurich, Switzerland. 5. Ministry of Commerce and Industry "Sultanate of Oman Standards: Drinking water", personal communications. 6. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for wastewater reuse and discharge" Ministerial Decision 5/86 dated 17th May, Muscat, 1986. 7. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for external building drainage" Ministerial Decision 5/86 dated 17th May, Muscat, 1986. 8. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for septic tanks and holding tanks" Ministerial Decision 5/86 dated 17th May, Muscat, 1986. 9. Ongerth,J.E and Dewalle,F.B."Pretreatment of industrial discharges to publicly owned treatment works" J.Wat.Pollu.Contr.Fed. 52(8),Aug. 1980, 2246. 10. Pahren,H.R.;Lucas,J.B.;Ryan,J.A. and Dotson,G.K."Health risks associated with land applications of municipal sludge",J. Wat. Pollu. Contr. Fed., 51(11),Nov. 1979, 2588. 11. USEPA, "National interim primary drinking water regulations", US Enviro. protection Agency, Federal Register, Washington,DC, 1975. 12. WHO "European standards for drinking water", World Health Organization, 2nd Edi., Geneva, 1970. 13. WHO "International standards for drinking water", World Health Organization, 3rd Edi., Geneva, 1971. 14. WHO "International standards for drinking water", World Health Organization, 3rd Edi., Geneva, 1972. 15. WHO, "Guidelines for drinking water", World Health Organization, vol. 1,2 and 3,Geneva, 1984. 16. World Bank and WHO " Health aspects of waste water and excreta use in agriculture" Published by International Reference Centre for waste disposal,
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Switzerland, July 1985. Ministries
Water Resources
Regional Municipal
Agriculture & Fish
Electricit
Defense
Health Institutions
University
Technical & Educational Colleges
Meteorology
Organizations
PDO
National
International
National Research Council Ministries National Central Laboratory
Figure (2)
45
Water Conservation in Oman20 By Hayder A. Abdel-rahman21, and Isam Mohammed Abdel-magid22
Abstract Limited resources and growing needs for water has triggered a nationwide campaign for water conservation in the Sultanate of Oman. A land and soil survey study of Oman shows the availability of more arable land than present water resources could support. Groundwater is the main source for agricultural production. Over pumping at rates higher than the natural recharge has resulted in lowering of the ground water table, while seawater intrusion lead to an increase in soil salinity. A comprehensive water program is underway to (1) conserve water through efficient irrigation, use of soil additives, modern irrigation systems, agronomic management and institutionalization; and (2) augmentation of resources via introduction of more desalinization plants, more waste water treatment, use of brackish water, water fog collection, and water harvesting by building recharge dams.
Introduction Water, being a valuable natural resource, has been the focus of attention for many years. Nowadays, water is being considered as strategic commodity worldwide. With rising population sizes, introduction of more industrial sectors, and the increased share of agriculture in the Gross National Product water resources are being depleted at rates faster than their natural replenishment through the hydrologic cycle. About 97.5 % of the 1200 million Km3 world water reserves are in seas and oceans. Only about 2.5 % exists as fresh waters, 30 % of which is in the liquid form. Ninety-five percent of the fresh water is underground, while only 5 % forms the rivers and lakes. This renders five in a thousand part as easily and readily available to human beings. Worldwide, 70 % of the fresh waters are used for agriculture, 25 % for industry and 5 % for domestic use. In the case of Oman around 85 % of the fresh water is being utilized for agricultural purposes, 10 % for domestic consumption, and 5 % for industrial use (Figure 1) {1}.
20
First published in Water International Journal,18 (1993) pp 95-102 Assistant Professor, Department of Soils & Water, College of Agriculture, Sultan Qaboos University 22 Assistant Professor, Department of Civil Engineering, College of Engineeringm Sultan Qaboos University 21
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With the drought cycles, increasing desertification, limiting water resources, and the growing needs and demands, water conservation seems to be the only feasible way out. The International Conference on Water and the Environment held in Dublin2 focused on the issue and considered the situation to have reached dangerous limits. Recommendations were made to take prompt actions. Collaboration was called for among all countries in taking measures for water conservation through re-use, better management and adoption of modern technologies in irrigation. The Sultanate of Oman is totally dependent on irrigation for crop production. Within the Arab world also Egypt relies on irrigation for crop yield, whereas Saudi Arabia has got a 39 % dependency, Sudan 13 % and Algiers only reaches 5 %. Worldwide the overall dependency of the Arab countries achieves 21 %, Asia attains 33 % and while Africa barely reaches 2.7 % reliance.
Inventory of Resources
Oman’s Land Resources Oman is dividsible into four main physiographic regions: the mountainous regions, coastal plains, the accumulation plains and the desert (Figure 2). The mountainous regions include the Hajar arid mountains of the north and monsoon-affected mountains and plateaus of the Southern Dhofar region (Jabal Al-Qara mountains). The accumulation plains include the Northern Batinah plain, Salalah plain and the Northern interior plains. The coastal alluvial plains are mainly the Batinah and Salalah plains, where the wadis originating in the nearby mountains deposit their load of sand and finer particles before reaching the sea. The desert sand dunes occur in the western part of the country in Al-Rub Al-Khali and the Wahiba sands.
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FAO classifies only about 791,651 hectares of Omani land (2.52 %) as highly to moderately suitable for agriculture {3}. Nevertheless, another 1,431,406 hectares (4.55 %) are categorized as being marginally suitable and could be put under production with increased inputs. The soils of Oman are young calcareous soils. Their low organic matter characterizes them and total nitrogen with an unbalanced sodium-calcium-magnesium contents, prominent potassium deficiency and localized zinc, ion and phosphorus deficiencies. The Batinah area accounts for about 50 % of the cultivated area (20,750 ha). On the other hand Salalah plain accounts for about 6 % (2417 ha). Table (1) gives the distribution of the Omani area by land utilization and region. Water Resources and Use: Rainfalls pattern and occurrence are diverse within the country. Regular rainy seasons in the country are only found in the Dhofar Mountains in the south and Hajar Mountains in the north. The Interior regions (which constitute around two-thirds of the country) receive less than 50 mm of the average rainfall. The rainfall in the costal areas reaches about 100 mm. The Hajar Mountains receive 100 - 300 mm and the monsoon affected Dhofar region receives about 200 - 300 mm annually.
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Table 1 Land area distribution by Utilization and Region (areas in ha.) {4} Region Unused but Usable Total Under Crop if Improved Batinah and Capital 46126 20750.18 24861.32 Massandam 1120.46 1030.04 90.42 Jahar &Al Gharbi 2623.72 1954.48 608.80 Hajar & Al Sharqi 1955.58 1235.30 568.92 Jow &Buraimi 1312.52 885.50 427.02 Al Zahira 7202.36 3303.08 3899.28 Oman Interior 14494.92 5166.70 7087.30 Sharqiya & Gaalan 5817.68 4284.94 1514.04 Dhofar 2706.66 2413.62 293.04 TOTAL 83359.98 41023.84 39410.14
The Batinah catch basin (12,183 km2) receives about 2089 million cubic meters of water. With an estimate of 83.33 % (five sixths of catchment runoff) for the evaporation at the area and a 16.67 % conversion to runoff, the total amount of surface and subsurface water is about 348.3 million m3 (=2089 x [100-83.33]/100). Some 75.5 million m3 are withdrawn up plain and the amount of surface and subsurface water that reaches the coastal plain is 272.8 million m3 (=348.3-75.5). With 48.3 million m3 flowing to the sea, the estimated groundwater recharge (1979) is about 224.5 million m3 (=272.8-48.3). The discharge that is actually required to irrigate the area (1986) is 226.3 million m3which depletes the groundwater reservoir at the rate of about 1.8 million m3 per year (226.3-224.5). Projected estimates, at the current 22 % rate of increase in water demand, give a 45 million-m3 deficit annually. (See table 2, and Figure 3). The catch in the Salalah region by the monsoon-affected basin (910 km2) is about 282 million m3 annually. With an evaporation of 90 % and a 10 % conversion, about 28 million m3 is precipitated as surface and subsurface water. Nine million m3 of which is in the form of surface springs and 19 million m3 goes as subsurface water. About 6 % of the rainfall is converted into surface runoff (17 million m3), 60 % of which runs into the sea and the rest (seven million m3) infiltrates into the ground bringing the total groundwater recharge to 26 million m3 per year. The water use in 1982 was estimated as 22 million m3, 17 million m3 of which is for agriculture, but the 1990 estimates put the requirement at 32 million m3 and with only about 20 million m3 of the recharge being available, 6 million m3 left as a safeguard against sea water intrusion, a deficit of 12 million m3 occurs, 9 million m3 of which is supplied by the springs, and the underground water reservoir is depleted at the rate of 3 million m3 per year.5 The water balance for the rest of the country is still on the positive side but with the current rate of development, problems could also be encountered elsewhere. Seawater intrusions into groundwater aquifers have been noticed to be more profound in the Batinah area where increasing soils have been salinized. (See table 2 and Figure 4).
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Table 2 Water Balance at Batinah and Salalah Basins (Units in million m3) Deficit - 1.8 Runoff component Batinah Evaporation 1740.7 Up plain use 75.5 Runoff to sea 48.3 Groundwater 224.5 Total basin runoff 2089 Irrigation requirements 226.3 Groundwater yield 224.5
- 12.8 Salalah -253.8 9 19.2 282 32 19.2
Crops and Climate Table (3) gives the total Omani area as being divided under different crops together with their average annual yields. Out of the 54901 hectares (only about 6.9 % of the suitable agricultural area) irrigated in the Sultanate, 5370 ha are under vegetable cultivation, 9747 ha under field crops and 33,133 ha under fruit trees. Tomatoes and watermelon account for about 46 % of the area under vegetable production, whereas 91% of the areas under field crops produce Alfa alfa. Date palms account for about 75% of the area under fruits, with a percentage of 45.5 % of the total area. In any water conservation plan it is very important to know the varieties and areas of crops grown. The water use of crops should be estimated through extensive research work under the prevailing climatic conditions. Hot and humid summer conditions prevail over the coastal areas of the Sultanate, with a comparatively cool winter. In the Interior the climate is hot and dry in the summer and somewhat cool in the winter. The average temperature in the Sultanate is around 17.8 28.9oC, the hottest months being June and July ranging between 30.7oC in Saiq and 46.1oC in Fahoud. The coldest month is January being 9.4oC in Saiq and 24.0oC in Fahoud. The lowest ever temperature recorded was - 3.6oC in Saiq.
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Table 3 Crop Productions by Areas and Yields – 1988 {4} Area (ha) Yield (Tons/ha) Crop
Vegetables Tomato Pepper Onion Garlic Okra Water Melon Musk Melon Cabbage Potato Sub-Total
1212 610 560 150 53 1250 625 770 140 5370
22.19 9.02 13.75 8.00 13.21 19.04 13.12 23.25 25.00
Field Crops Alfa alfa Wheat Tobacco Sub-Total
8870 468 409 9747
38.00 1.50 4.89
Fruits Dates Lime Mango Banana Coconut Sub-Total Others TOTAL
25000 2400 3780 1625 328 33133 6651 54901
4.00 10.83 2.01 13.60 16.77
The 1990 estimates put the crop water requirements in the Batinah at 531 million m3 and 33 million m3 in the Salalah plain. The rest of the country requires 561 million m3 (table 4).6 With these values groundwater reservoirs will be depleted at rates higher than estimated, especially in the Batinah plains. As a result in the Batinah, soil salinity due to seawater intrusion is becoming a serious problem and a lot of date palm plantation can be seen withering away along this coastal plain. Table 4 Crop water requirements [million cm/year] {6} Region Fruit Fodder Total Vegetables Batinah 53.77 408.10 69.29 531.16 Oman Interior 15.55 72.68 42.46 130.69 Dhahira & Buraimi 11.18 59.60 26.63 97.41 Sharqiya & Gaalan 13.98 96.97 42.35 153.30 Masandam 1.89 14.62 6.46 22.97 Dhofar Total
4.10 100.47
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13.10 65.07
15.32 202.51
32.52 968.05
Water Conservation Measures Water conservation measures include using water when needed where needed with possible augmentation. Irrigation efficiencies are a measure of how effectively water is stored in the root zone for crop use. On farm irrigation efficiencies include application and storage efficiencies. Application efficiency is the percent of water stored in the root zone from that delivered to the field, whereas storage efficiency is the percent of water stored to that needed. In effect, the more water stored, by eliminating field losses of runoff and deep percolation, the higher are the efficiencies. This clearly outlines the significance of crop water use and consumptive use efficiencies. These efficiencies reflect measures of how beneficially water was used by the crop in terms of yield per unit amount of water delivered to the farm. Soil additives and water application methods greatly influence the ability of soils to store moisture. Soil additives: Omani soils are characterized by their low organic matter content and low-to-moderate moisture retention differences. Different forms of natural and processed organic matter in the forms of peat moss, cow dung, chicken manure, and hay straw are plowed into the soils to increase the fertility level and water movement and retention. Unfortunately, the biomass production in the country is not at the levels, which could effectively improve its soils. Field crop production, mainly Alfa alfa account for only about 16% of the area cultivated and is primarily utilized for animal production. In 1989 Oman had imported 17945 Tons of fertilizers 78 % of which (13744 Tons) were in the forms of
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organic manures.7 Even though organic matter could hold more moisture, yet it releases it quickly. This is one of the reasons that has triggered research for developing synthetic materials which would easily absorb moisture and slowly release it. These products are on commercial use now, and have proved to be effective. A seminar {8} organized by the private sector on "Water Conservation: A National Priority" held in Muscat on the 29th of February 1992, was meant to evaluate and introduce an absorbent- copolymer-water-management-medium which would increase the water holding capacity of the soil. Problems encountered in introduction and use of such additives has yet to be solved. Cost, technology and know-how needed to incorporate the material into the soil, farmer education and extension are but few problems. Agronomic management: Biomass production tends to be proportional to transpiration. However, there are significant opportunities for increasing production per unit of water (consumptive use efficiency), by crop selection, breeding and agronomic management. Drought and salt tolerant crop breeding is of great importance in this respect. Agronomic practices that can conserve water generally parallel those practices that give the maximum yield in the shortest time. Few efforts are being made to breed specifically for water use efficiency, but in the Sultanate research is being made to study the effect of quantity and frequency of irrigation on growth and yield of different crops to establish the best consumptive use efficiency. This should be the main concern since the Sultanate farmers are traditionally date and citrus growers, which account for almost 70 % of the total crop water requirements. The trees have already been established a condition which does not grant effective agronomic water management. Relatively salt sensitive citrus trees could be replaced with date palms, which are more tolerant. On the other hand the less water consuming fodder such as grasses could replace Alfalfa fodder. Modern Irrigation Systems: Traditionally, surface or gravity irrigation systems have been used in Oman. Water is pumped out of boreholes or led into the farm through the Aflaj (singular Falaj) systems. The Falaj is a sub-horizontal tunnel dug in the ground to tap an aquifer. Underground tunnels whose rate of descent is less than that of the ground surface, transport water collected from the aquifer. They eventually bring water to the surface continuously throughout the year. There are about 6000 active aflaj in the Sultanate providing 71 % of Oman's water supply and irrigate 55 % of the cropped land {9}. A sizeable amount of water is being lost in conveyance especially in places where the falaj spreads with no distinct channel. In surface irrigation systems only about 30 % of the water applied is stored in the root zone. The rest of the water is being lost to runoff and deep percolation beyond the root zone. This produces a condition that counts for the low efficiencies obtained. Generally, modern irrigation systems are adaptable to a wide range of crops and soils. They save water, but the initial cost incurred is very high especially when using an extensive pipe network or an advanced system such as center pivots. In adopting modern irrigation systems, a careful balance must be made between the crop water requirements and water needed to control salinity. Meeting only the evapotranspiration requirements would lead to salt build-up in the root zone. In this case, the crop water requirements should be met; a term which includes amounts, used for salt leaching, and that is needed to build plant tissues. Consumptive use is a term used to mean evapotranspiration and that amount stored within the plant system. Vast areas in the Sultanate, especially in the Batinah and Salalah are now being put under modern irrigation systems. The government is encouraging farmers to adopt these
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methods. The government bears 75 % of the overhead cost for areas less than 10 feddans (4.2 hectares), 50 % for areas greater than 10 but less than 50 feddans (21 ha) and 25 % for areas more than that. Nevertheless, modern irrigation farms still comprise less than 10 % of the cultivated area in the Sultanate. All new allocations of land for agriculture by the government are required to use modern irrigation systems. Extension services and all information media are employed to convince farmers to switch from their systems. Adoption of modern irrigation systems poses as the most significant method in water conservation practices and the savings could go up to 50 % over the traditional surface irrigation methods. Land fractionation and small farm holdings together with the high initial cost and farmer compliance are the challenges to be faced. In the Sultanate about 29 center pivot systems exist serving around 1300 ha. Augmentation: Possible techniques for increasing water supplies range from augmenting precipitation to transporting icebergs halfway around the world. Practical methods adopted in the Sultanate include desalinization, water harvesting (recharge dams), wastewater treatment and use, and trials of fog collection and use of brackish water. Desalinization: In the Sultanate, there are two desalinization plants, in the Capital area, using evaporators, the larger being in Ghobra. The 1989 account of the water production and consumption in the Capital area showed that desalinization plants supplied about 77 % of the water produced for domestic use with a yearly output of about 7026 million gallons. Total annual consumption was estimated as 9090 million gallons {7}. Problems associated with evaporators include formation of scales that limits the top temperature that can be used in distillation process. Other problems include: accelerated corrosion and sealing and high initial and operating costs. Plans are under their way to incorporate reverse osmosis techniques. In recent years the annual output of the desalinization plants were increased to about 8400 million gallons and a new plant with a capacity of 6 million gallons per day is being constructed at a cost of 57 million Omani Rials (US $ 147 million). Desalinized water is meant for domestic use but would save the water, which would otherwise be pumped out of the wells. Wastewater treatment: The Ministry of Health conducted a national seminar in collaboration with the WHO on wastewater reuse during 26-29 April 1992. The seminar discussed the state of water resources in Oman and reviewed the national, regional and world experience in effluent reuse. The economic aspects of wastewater reuse were discussed together with the health and environmental aspects. Recommendations were made to wastewater reuse for non-potable purposes and to be incorporated in a comprehensive water management program. The 1990 estimates of the Capital area [Muscat] inhabitants reached the value of 333,354 persons. With an average daily consumption of about 150 liters and assuming 70 % wastewater recovery, the total quantity of wastewater produced would be 35,000 cubic meters. This is enough to meet the daily requirements of only 437.5 hectares of a cropland using 8 mm per day. There are now a number of sewage treatment plants in operation in the Capital area. One in Darsait produces about 11,500 m3/day with input from the Greater Muttrah area. Another at Al-Ansab produces 5400 m3/day to be expanded in the future. This effluent is used for irrigating tree plantations in the Capital area from Darsait to Assahwah tower. A third treatment plant is at the University of Sultan Qaboos producing around 3000 m3/day and is used to irrigate the University tree
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plantation. Five other small treatment works exist in Maabaila, Al Khod, Murtafaa, Amrat and Diwan in Al Seeb. Table (5) gives an account of the existing sewage treatment works, their location, design capacity, actual flow rate of the effluent, and some of the averaged quality parameters, and the amount of wastewater utilized for irrigation purposes. Reuse is restricted to the irrigation of ornamental plants in the Capital area. The stringent regulations introduced for wastewater discharge and reuse are currently under revision in view of the existing experience. These regulations are established according to the Ministerial Decision number 5/86 addressing wastewater reuse and discharge. The reuse of wastewater was limited to irrigation of ornamental trees and shrubs, groundwater recharge in areas of no public exposure, and industrial closed circuit processes. Emphasis has been placed in the regulations towards physical quality parameters of total solids, suspended solids and turbidity. The bulk of the regulations addressed chemical parameters. The bacteriological quality was managed through the total coliforms and the viable pathogenic ova and cysts.10
Table 5 Sewage Treatment Plants (STP) at the Sultanate of Oman Description
Darsait
Design capacity
10800
Plant flow rate, m3/d 11500
BOD (mg/L)
SS
Ammonia (N)
Irrigation water,m3/d
10
10
1
800011500 2000-5000 800
AlAnsab 12000 5400 10 10 1 Shati 1350 800 10 10 1 AlQrum Mabella 1920 700 10 10 1 AlKoud 1200 700 20 30 Bowshar 400 400 10 10 1 AlAmerat 600 600 20 30 Jibroo 70 100 10 10 1 50 AlAynt 60 100 10 10 1 Total 28400 20300 17350 Saline waters: New knowledge in the plant and soil sciences and new irrigation techniques show that, with careful management, saline or brackish waters can be used to grow a variety of salt tolerant crops. With adequate leaching and drainage, water with concentrations of up to 6000 grams per cubic meter (0.6 %) will produce high yields from tolerant crops. Seawater contains up to 40,000 grams per cubic meter (4 %) whereas good quality irrigation waters contain up to 0.02 %. Successful trials have been made to produce salt tolerant crops in coastal sands with chemically treated waters containing up to 2 % salt. Extensive agriculture and over pumping has lead to seawater intrusions in the costal plains of the Batinah were more than 50 % of agriculture is practiced in the Sultanate. An inventory of the existing wells is being made and no new permits are issued in an effort to prevent or even reverse the water table decline. In the Sultanate research is underway to remove salinity stress from date plantations grown with brackish waters in the coastal areas of the Batinah by chemical treatments and modern trends of leaching. Atriplex, a grazeable saltbush, is being introduced as a
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first step towards establishing pasturelands for cattle through biosaline agricultural research programs. Water harvesting: Although rain falls infrequently in the Sultanate, it still comprises significant amounts of water; 10 mm of rain equals 100 cubic meters of water per hectare. Water harvesting captures and concentrates rainfall to irrigate crops, supply water for people and animals, or recharge groundwater. A water-spreading system controls water from ephemeral flows (infrequent or intermittent flow following heavy rains), a system of dams, dikes and ditches in the flood plain or wadi, then diverts and spreads the flood water. In the Sultanate, a total number of 58 recharge dams are projected with a total capacity of about 80 million m3. The total amount of rain lost to the sea and desert amounts to about 120 million m3 per year {11}. Table (6) gives the sites and specifications of the recharge dams, which has already been constructed. Other than those, there is a 1.63 Km long sea defense dam constructed at Khor Al Rusaq in Sur to prevent the intrusion of surface saline sea water and withhold part of the Wadi waters for recharge and leaching. Al- Khod recharge dam has the biggest storage capacity (11.55 million m3), followed by Wadi Al Maawil (10.00 million m3) which. Out of the 9062 meter length of the Wadi Hilti/Salahi dam 3250 meters is a diversion channel connecting the two dams to transfer water from W. Hilti dam (3040 m) to W. Salahi (2772 m) dam. A monitoring system is annexed to Wadi [valley] Al Khod dam for measuring the surface waters flowing in and to check the efficiency and maintenance works needed. Recharge dams are meant to connect part of the 120 Million cubic meters on rainwater lost yearly to the sea and desert. Lack of monitoring systems in most of the recharged dams made their assessment and evaluation rather difficult. Visual surveys, however, have indicated that on the average the dams have caught a sizable amount of runoff. With Wadi Tanoof occasionally filling up one disadvantage is that the dams have deprived the costal plains from the fertile silt and fine materials the streams used to carry down the valley. Fog collection: Weather modification was first sought of in 1946 and much has been learned since then. For example, cold fogs are routinely dissipated at a number of airports. Today seeding orographic clouds is an established practice. Fog consists of water droplets so small that their fall velocities are negligible. Fog particles, which contact vegetation may adhere, coalesce with other droplets and eventually form a drop large enough to fall to the ground. Condensation of the water vapor present in the air results in deposits of dew. The dew offers a source of water, which may be exploited locally. Rich, water-bearing fog and mist takes place in only few places of the world. In addition to parts of the coasts of certain Latin American countries, the same thing happens in Dhofar mountains of the Southern region of the Sultanate. Trials were to be made though the UNDP-World Bank water and sanitation program to collect fog using wire mesh. The solar chilled mesh sought would greatly enhance the process and increase yields. In studies conducted during the monsoon period at 865 meters a.s.l. the amount of water collected was 2.86 L/m2/hr at 4.2 meter height with a daily total of about 34.5 L/m2 of mesh13. Nevertheless, no matter how efficient the process is, fog collection would only constitute an insignificant amount to a localized area in the Sultanate for part of year and probably only to benefit grazing cattle by supplying pools of drinking water.
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Institutionalization The Ministry of Water Resources in the Sultanate has set a number of guides and rules to conserve water. Among those are: 1. Priority to water use is to humans, animals, agriculture and then industry. 2. A complete inventory of the wells, regardless of use, and contractors would be carried out all over the Sultanate. 3. No new wells would be dug except in areas where there is a good quality soil and excess water. 4. No new wells will be dug except licensed (after justification) and with the specifications set by the Ministry. 5. Wells should be deepened only for human use, animal use and irrigation of trees. 6. A phased water administration would be set to: • Install water meters on all wells • Collaborate with the Ministry of Agriculture to determine crops suited to different areas, crop value and water use. 7. All government-distributed lands should be irrigated from central wells through pipe networks. Modern irrigation systems should be installed in all those lands. 8. Construction of new recharge dams should continue following feasibility studies. 9. No wells should be dug in the vicinity (3.5 Km) of existing aflaj mother wells except for drinking water or to benefit existing wells. 10. There should be no exceptions to the rules set.
Conclusions 1. An integrated program is needed to conserve water in the country. This should start right from efficient water conveyance and through to the on-farm sound management schemes. 2. Government efforts should be coupled with an effective extension program of farmer education for collaboration and optimization of resources. 3. Attention should also be given to conserve water at home, in the growing industry, and other uses. 4. Available water resources are recommended to be used for the best soils. 5. Efforts for water harvesting need to be presented. Likewise, inventory making should continue together with investigations for new allocations using aerial and satellite images. 6. In adopting the modern irrigation systems, the know-how techniques should be locally available by training qualified personnel for operation and maintenance. Need not pointing the importance of surveillance, monitoring and better management measures. 7. Drought and salt-tolerant crop research should be shouldered and done. This would breed the most suitable crops with economic values, and that may turn the desert green.
References 1. Al Hayat Daily Newspaper, "Science and Technology", 15 February 1992 Issue #10600, 1992. 2. International Conference on "Water and the Environment", held in Dublin During 57
the Period 26-31 January 1992. 3. Ministry of Agriculture and Fisheries and Food and Agriculture Organization of the United Nations, " General Soil Map of the Sultanate of Oman ", 1990. 4. Ministry of Agriculture and Fisheries, Department of Agricultural Statistics, "Estimate of Cropped Area in the Sultanate", 1989. 5. Ministry of Agriculture and Fisheries, Directorate General of Water Resources and Irrigation, "Water Resources of the Sultanate of Oman", 1986. 6. Ministry of Water Resources, Sultanate of Oman,"National Water Resources, Master Plan 1990". 7. Development Council, Directorate General of the National Census, Sultanate of Oman,"National Census - Year Book, 1990". 8. Abdel-Rahman, H.A. "Water Conservation",( A Speech Delivered at the Seminar on "Water Conservation In Oman", Sponsored by the Al-Rawahy Co., held on Saturday 29 February 1992 at the Conference Hall, Oman Chamber of Commerce & Industry, CBD Area, Ruwi, Sultanate of Oman). 9. Al-Abri, B. S. H."An Explanation of Some of the Omani Afalj" Almatabi Aldhahabia, Ruwi, 1991. in Arabic "Albaian fi ba`ad Aflaj Oman". 10. Ministry of Environment and Water Resources (now Ministry of Environment and Regional Municipalities), Ministerial Decision 5/86 dated 17th May 1986, "Regulations for Wastewater Reuse and Discharge", Muscat, Sultanate of Oman. 11. Ministry of Agriculture and Fisheries, Directorate General of Water Resources and Irrigation, " Groundwater Recharge Schemes in the Sultanate of Oman ", 1986, 1991. 12. Schilfgaarde, J.V. and G.J. Hoffman. 1981. "Future Sources of Water", Proceedings of the ASAE Second National Irrigation Symposium, Lincoln, Nebraska, 20-23 October 1980. 13. Stanley Price, M.R., Al-Harthy, A.H., and Whitcombe, R.P., "Fog Moisture and its Ecological Effects in Oman", Ministry of Water Resources, Muscat, Oman, 1986.
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Bacteriological Analysis of Roof Water Tanks23 By Isam Mohammed Abdel-Magid24 and Awad Mohammed Abdel-Raheem25 The Sudanese keep their drinking water in jars made of baked clay and called 'zeers'. however, recently semi and multi-storey buildings owners started to install roof storage tanks to avoid fluctuations in main pressure and cater for temporary stoppage of water supply. WHO Diarrhoeal Diseases Team {9}, by Erwa {6} and by Hammad and Dirrar {5, confirmed contamination of zeer water by faecal organisms. Contamination of roof tanks is only investigated in the present study. Water samples were collected in sterile bottles containing 0.1 ml of 10% sodium thiosulfate solution. Equal portions of samples were collected from each tank and care was taken not to disturb the water at the bottom. However, samples were also collected, separately, when the tanks are almost empty. Samples were collected twice a week for six months, from each of five tanks distributed over Khartoum and each was analyzed. Colony count was done by the pour plate method using plate count agar. Results (Fig.1) show that the faecal colony count was ranging between 102 and 103. Erwa {6} and Hammad and Dirrar {5} reported more than 104 and 106/ml in zeer water, respectively. The three-tube procedure using lactose broth was adopted for estimating the most probable number (MPN) of coliform bacteria, according to the standard methods for examination of water and wastewater {1}. Only % of the samples showed that high total counts were contaminated with coliform bacteria. This fact was obtained as due to antagonistic action of some organisms in viable counts {5}. The confirmed test was done by the use of brilliant green bile broth. Differentiation of coliforms was made on eosin methylene blue agar. Colonies were then differentiated by the IMVIC tests. About 40.2% of the faecal coliforms were found to be Escherichia coli as indicated by the tests (Fig.2). This organism was reported as the most numerous types of coliforms in many studies {2,3,5}. Enterobacter aerogenes constituted 35.6%. Similar findings were also found in different localities {4,8}. Results of the present work signify a high degree of coliform contamination. This may be a reflection of pollution by ingress of dust, birds and insects, which was due to improper fitting of the lids. According to Goodman {7}, fitting lids must be dust proof but not airtight. Bacterial contamination and predominance of E. coli as indicated in the present work, render the water unsuitable for drinking purposes, as far as the WHO guidelines are concerned {10}. The use of a kitchen tap supplied directly from the mains and not from the storage tank, will avoid exposure not only to serious bacterial contamination but also harmful levels of copper and zinc. Possibility of back-siphonage might also have been a source of pollution. References: 1. American Public Health Association (1980). "Standard methods for examination of water and wastewater." 15th. ed. Inc.Washington D.C. 2. Bardsley, D.A. (1934). "A comparison of two methods of assessing the number of different types of coliforms in water." J. Hyg. 34;38-68. 3. Bardsley, D.A. (1938). Coliform bacilli in water. J. Hyg. 38:309-324. 23
First published in the Proceeding of the First National Conference on the Science and Technology of Buildings, 8-14 Dec. 1984, Khartoum, pp 253-255. 24 Department of Civil Engineering, Faculty of Engineering, University of Khartoum 25 Department of Crop Protection, Faculty of Agriculture, University of Khartoum
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4. Boizot, G.E. (1941). "An examination of the modified Eijkman method applied to pure coliform cultures obtained from water in Singapore." J.Hyg. 41: 566569. 5. Hammad, Z.H. and Dirrar, H.A. (1982). "Microbiological examination of sabeel water." Appl. Env Microb. 43: 1238-1243. 6. Erwa, H.H. (1977). "Bacterial examination of zeer water." Proc. 19th. Conf. Philos. Soc. Sudan, Khartoum, 17-21 April, pp 150-153. 7. Goodman, A.H. (1984). "Contamination of water within buildings." J. Public Health Eng. 12: 23-25. 8. Raghavachari, I.N.S. and Lyer P.V.S. (1939). "The coliaerogenes index of pollution used in the bacteriological analysis of water." Indian J. Med. Res. 26: 867-875. 9. W.H.O. Report (1961). "Diarrhoeal Diseases in the Sudan." W.H.O. Geneva. 10. W.H.O. Report (1984). "Guidelines for drinking water quality."W.H.O. Geneva.
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Hotel Water Supply and Plumbing System (A case study) By Isam Mohammed Abdel-Magid26 and Abdel-Fattah Hassan Ahmed27 Site Investigations Water is being supplied to the hotel from water mains via a pump to roof water storage tank that supplies approximately all necessary existing fixtures within the premises. Visual inspection of the galvanized steel piping system revealed that there is a widespread occurrence of corrosion. It has been observed that the hot water lines are more severely affected by corrosion than cold water lines. The tuberculation of the pipes could be detected in numerous places in the cold piping system while there is leakage in the hot water lines. Galvanized steel corrosion is normally characterized by pits in the pipe surface. These may eventually penetrate the pipe wall & cause leakage. As the pipe deteriorates, tubercles cover the developing pits. The tubercles cause partial blockage in the pipe & can eventually restrict the water flow to the point that the pipe must be replaced. Friction is increased in a pipe with tubercles or pits, increasing pumping costs. Leakage may result in substantial & costly water loss & create expenses from the damage attributed to the leak {5}. The existing corrosion is of tremendous significance to the hotel utilities. The exhibited corrosive characteristics causes: a. Health problems that result from dissolution of certain metal or other substances into the drinking water from the plumbing system. Graun & McCabe {2} have suggested that corrosion of distribution & household plumbing contributes to the metal content of drinking water, which may be related to cardiovascular disease rates. b. Aesthetic problems, which may be of concern especially to the guests who are subjected to rusty & turbid water. c. Economic problems: corrosion can cause plugging & premature failure of pipes. Plumbing system deterioration from corrosion frequently results in extensive & costly replacement. Failure usually occurs when corrosion has so damaged the structural integrity of the pipe that leakage becomes a problem. d. Socio-economical malfunctions & shortening of services life of unprotected household equipments.
The visual inspection of the water roof tank indicated that it is rusty in places, contaminated with birds’ droppings, ingress of dust & perhaps some pollutants. There is large algal growth especially at the cooling tower & chilled circuit. There is no recorded history of disinfection being carried out in the plumbing system prior to usage. The maintenance & cleaning activities were rather absent. Laboratory Analysis Samples were taken from a number of points for laboratory analysis. The chosen representative points included: main supply kitchen tap, roof tank, boiler, hot water, cooling tower, chilled circuit & water taps at the upper floors.
26 27
University of Khartoum WARC Engineering Company
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The analysis included bacteriological investigations and aggresivity. Table (1) summarizes the results. The corrosion potential indicators have been computed as the Langelier Index (found to be less than zero), Ryzenar Index (= 7 a value greater than 6), & Aggressiveness Index (= 9.4 a value less than 10). These values show that the main water supply is highly aggressive to the piping system. The bacteriological analysis conducted showed that there is contamination & pollution. The MPN of E.coli was high in the cooling tower, chilled circuit & roof tank approaching a value of 200/ml. There is smaller degree of pollution in the kitchen tap & other representative taps (2-10/ml). While the main water, boiler water & hot water lines were free from any bacteriological pollution.
Problem Identification The laboratory analysis revealed that there are two major problems that merit consideration. These problems are: corrosion due to the aggresivity of water & bacteriological contamination. Recommendations Shull {3} reports that the use of bimetallic phosphate prevents tuberculation of iron pipes, prevents the formation of discolored water & reduces staining of fixtures & clothes. Therefore, corrosion-reducing chemicals or corrosion inhibitors are advocated for this hotel water supply. This safeguard would not be effective with the existing degree of corrosion if the badly damaged pipes were not replaced. The existing bacteriological contamination could be attributed to the roof water tank that supplies the potable water to fixtures. Remedies may include: a. Installation of a ground water tank of adequate capacity to avoid fluctuation in water pressure and avoid back-siphonage and occurrence of negative pressure. b. Provision of a shelter to the roof tank with an appropriate insulation material to cater for temperature changes. c. Provision of a suitable screening at the tank outlet. d. Provision of a screen or a mosquito trap at the end of overflow. To eliminate pathogens, a proper chlorination of the plumbing system with the necessary required chlorine dose. It worth mentioning that respiratory diseases could result from contaminants in polluted cool air. The insulating material used in the hot water lines was neither adequate nor appropriate. Therefore, there is an urgent need for provision of an alternative insulating material that would minimize energy losses & protect the exteriors of the pipes. The removal of oxygen in order to minimize corrosion is important in the preparation of boiler feed water. This may be done mechanically by using a de-aerator or chemically by using sulfite or nitrite or an appropriate chemical. Monitoring & reporting of chemical, physical & bacteriological analysis need to be conducted at least twice a year for the water system. Samples must be taken at representative entry points.
References 1. Millette,J.R., Hammonds,A.F., Pansing,M.F., Hansen,E.C.,& Clark,P.J." Aggressive water: Assessing the extent of the problem" JAWWA 72(5), May 1980,262.
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a. 2. Craun,G.F. & McCabe,L.J. "Problem associated width metals in drinking water" JAWWA 67(11),1975,593. 2. Shull,K.E. "An experimental approach to corrosion control" JAWWA 72(5),May 1980,280. 3. Amer. Wat. Wks. Assoc. "Water quality & treatment: A handbook of public water supplies" McGraw-Hill Book Co., New York, 3rd Ed.,1971. 4. AWWA Committee Report "Determining internal corrosion potential in water supply systems." JAWWA, 76(8), 1984,83. 5. Sussman,S. & Portnoy,I.L. "Water composition changes in air conditioning equipment" JAWWA, 51,1959,953. 6. Eliassen,R.R.T., Shrinde,W.B. Davis "Expermintal performance of miracle water conditioner" JAWWA, 50, 1958,1371. 7. Hoyt,B.P. et.al "Evaluating home plumbing corrosion problems" JAWWA,71(12), Dec.1979,720. 8. Langelier,W.F. "The analytical control of anti-corrosion water treatment" JAWWA, 29(10), Oct.1936,1500. 9. WHO "Guidelines for drinking water quality" Geneva, Vol. 1,2,3. 1984.
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Reflections on Drinking Water Quality Guidelines for the Sudan28 By Isam M. Abdel-Magid29 and Bashir M. El Hassan30
Background Adoption and enforcement of standards and regulations for drinking water quality is of paramount importance to the water sector in the Sudan. The benefits gained are uncountable. Therefore, any efforts towards the formulation and implementation of such a valuable tool should be encourage by all concerned. The adopted national standards for the Sudan need to address the following peculiarities: • The varying climatic conditions within the Sudan. • The culture and habits in the different regions of the country. • The type of diet and available water. • Socio-economic status. • Belief taboos and local traditions. • Reliability and availability of the required quantities of water (the majority of the inhabited area in the Sudan is non-riverine). • Availability of efficient and properly operated treatment plants …etc. Since the above mentioned points are difficult to satisfy for the whole Sudan through one standard, adoption of guidelines rather than standards is therefore the realistic approach. The adopted guidelines need to be translated into local standards in different regions whenever applicable, bearing in mind that the flexibility should prevail and also the ever changing socio-economic parameters. Shortage of water along with economic, technological and political constraints have compelled water authorities to sacrifice water quality against quantity in so many places in the Sudan; since the problem is one of quantity. Quite a number of towns in the country are bound to face a gloomy future if the current trend of drought continues. Examples of these are reflected in towns in the Northern Kordufan and Darfour regions. The upgrading of the quality of the treated water to that recommended by the adopted standards, in many situations, does not mean the satisfaction of the consumer as deemed necessary. Hence, the fate of treated water after leaving any authorized water processing facility should be seriously reconsidered. Generally, water in the Sudan is greatly misused with consequent deterioration through any or all of the following: • System used for water distribution and metering.
28
Presented at a Seminar on Drinking Water Quality Standards, Khartoum, Sudan, March 8-13 1986, and published in the Water International J., 12 (1987), pp 33-35 29 Dept of Civil Eng. Faculty of Engineering, University of Khartoum, P.O. Box 321, Khartoum 30 School of Hygiene, University of Khartoum, P.O. Box 321, Khartoum
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Chapter Two: Wastewater Engineering Industrial Contamination of Water Sources in Sudan31 By Dr. El Hassan, B. M32. Dr. Abdel-Magid, I. M33 Introduction It is truly assumed for long that the Sudan water sources (surface + ground) were not exposed to contamination. Nevertheless, and due to intensification of human settlement, industrial expansions and agricultural growth the picture is nowadays changing. In certain circumstances there is confirmed contamination (industrial) and in others it is suspected (agricultural and domestic). If this trend continued then the availability of sufficiently wholesome drinking water supply would be endangered. Since more than half of the Sudan area (2.5x106 km2) is not riverain, therefore it is exposed to water shortages especially during the dry season (the latest drought, famine and desertification confirms that). It is known that more than 70% of our population live in these non-riverain parts, this is in addition to more than 40 x 106 domestic and wild animals; thus making them liable to hazards of drought. Water supply and management for domestic use has been the responsibility of two different sectors working at different levels: A: Urban Sector: historically used to be the responsibility of the Water and Electricity Company, then the Water and Electricity Administration and lately the Regional ministries of services; B: Rural sector: historically used to be the responsibility of land Use Board and Rural Water Development Departments, then the Rural Water Development Cooperation, then NAW and lately NWC at the central governmental level, with delegated responsibility to regional ministries. It merits pointing out that these sectors are still under revision. This instability led to a negative impact on the overall water sector performance. The status of water quality at the source suffered tremendously to many factors such as: - Lack of coordination between concerned bodies having activities related to water consumption, - The none existence of an authority of jurisdiction that would look after the welfare of water resources inspite of bylaws and regulations (1975 Environmental and Public Health Act), - Increased water use by the industry and agriculture, - The none-awareness of some of the concerned bodies and the community related to water; with the consequences of indiscriminately use of water and disposal of effluents. Results and methods Generally, our water sources are exposed to contamination through domestic, industrial or agricultural activities. Lately, the industrial contamination has assumed a serious dimension. This is so because many industrial units and factories use our, so far, wholesome river for dumping their waste. 31
Presented at the Seminar on the Drinking Water Quality Standards, Khartoum, Sudan, 8 – 13 March 1986 Dean, School of Hygiene 33 Civil Engineering Dept., Faculty of Engineering, University of Khartoum 32
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Most of the factories are located along the banks of the River Nile and its tributaries, for ease of process water abstraction, cooling water supply, and disposal of treated effluents. This opened the door for misuse of water bodies, since it is used mainly as a dumping site rather than intended reasons. We can forecast that before long the nation will be facing an unsolvable problem that will not only endanger our fresh water sources, but also will exhaust them and reduce capabilities in remedying actions. Table (1) shows the location and type of major factories that are liable to contaminate water bodies. Table (2) shows strength of waste disposed from some factories without treatment to water bodies. Tale (1) Strength of wastes disposed from some factories Type of industry Sennar sugar factory Red Sea Tannery Kamir & Sons soap factory Port Sudan Power station International spinning and weaving factory Elshiek Mustafa oil mill Port Sudan refinery Tire factory Port Sudan slaughter house
BOD (mg/l) 15003800 12002000 14008600 133-334 50-433
100-1200 400-410 233-367 30009600
COD (mg/l)
Oil & grease TS (mg/l) (mg/l) 9-18-
DS (mg/l) -
3000040000 80000103000 7033859 193434
2400-2600
5000070000 40388243284 7280486032 3121516
20002500 13952101923 71312770041 2161388
9111664 192669 3402271 360036160
325-533
9703932 63008563 120066584 2297635632
7561642 26538000 122047984 848011612
292217412 37-89 26-117
90-383 38-121 1009-8702
SS (mg/l) 2901010 35005000 46436211534 80014164 95-354
Temperature ºC
156214 3303647 8020210 1686426816
35-45
23-26 25-50 28-29 10-26
25-26 29-32 25-28
Discussions and Conclusions It is evident that the industrial pollution is assuming increasing dimensions as shown in the previous tables. Previously it has been safe (almost from any of the water courses) to use raw water. Unfortunately it is no longer the case, even at the remotest fringes of rural Sudan. For instance the evaluation of the UNICEF water supply project (1982) in south Kordofan revealed that almost all Hafeers are contaminated. Water related disease inveterate almost all the country. The general effect of these diseases, if not fatal, is to sap and bate the strength and productivity of the victims with a varying debilitability and sequel. Even The supplied drinking water in towns and villages is liable to contamination due to the embodied irregularities. For example, though Khartoum town is supplied with treated surface water, nonetheless, there is an increasing dependence on groundwater. This trend is likely to continue for years to come, the reason being the insufficiency of the existing five treatment plants. The outcome of this insufficiency is an overall shortage of the supplied water with low pressure in the network, which led to the noauthorized installation of private small pumps (in many cases) in the network, at the expense of the efficiency of the system and the quality of the supplied water. The picture takes an alarming dimension during summer. This allows for greater dependence on groundwater during that period, with the consequences that the
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consumer is supplied alternatively with potable surface water or untreated groundwater. The effect of such practices on consumer's health needs to be investigated; likewise any effects on the network. Some of the industrial factories as well as the inhabitants are practicing underground disposal methods, through systems such as soak-a-ways. This endangers the quality of groundwater in view of the town's increasing depending on this water source. The absence of effectively authorized body or agency to look after the quality and characteristics of industrial effluents is, annoyingly, noted. The felt negative attitude of the industrialists and the concerned official public personnel could be attributed to either negligence or non-awareness with respect to environmental hazards associated with the ill practices and malfunctions of waste disposal systems. For example, the sugar factories used to dispose large amounts of molasses, hot and muddy effluents into the rivers, thus depleting the dissolved oxygen, increasing the temperature suspended solids and oil and grease, endangering aquatic life...etc. Even the newly commissioned steam power station in Khartoum (III) is disposing a lot of excessive heat to the river. Some factories, such as the Friendship textile factory at El Hasahisa was commissioned without any facilities for industrial waste treatment and disposal, it seems that the designer took it for granted that the effluents will find their way to the Blue Nile, as the installed evaporation beds were a late solution The story of the tire factory at Port Sudan is well known, likewise the soap and detergent factory at Omdurman. In many cases factories are installed and commissioned without the prior knowledge of the environmental protection agencies. Lack of awareness of concerned bodies led to what is prevailing at ElHaj Yousif treatment plant. Hence the fear for our water resources is justifiable. The overall problem facing management of industrial waste sector could be summarized as: lack of awareness, lack of coordination, managerial and budgetary problems: Recommendations: 1. Formulation of a national environmental council (as shown below) in order to: - coordinate between all bodies concerned with industrial waste (ministries, institutions and societies) - develop standards and bylaws for the protection of the environment as well as minimization of waste water - encourage industrialist to reuse their wastes. - establish environmentally oriented data bank with emphasis on the protection of water resources, - coordinate between proposed regional laboratories, and to act as a focal point for water quality, and the existing national laboratory. National Environmental Council Law National Environmental Laboratory
Information Center
Regional Laboratories Local Institutions
International Organizations
Concerned Ministries
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Water and waste authorities
2. Encouragement of existing individual factories to have pretreatment units or treatment units to produce effluents in agreement with the adopted standards, 3. Introduction of community education at national levels in order to mobilize the people for environmental protection and water resources safe guard. 4. Initiation of research programmes in industrial wastes collection, transportation, treatment and reuse or disposal.
References 1. El Haj, K.O. H., "A technical study of Industrial Waste in Port Sudan", M. Sc. thesis, IES, University of Khartoum, 1984. 2. Ahmed, E. E. O., “Environmental Assessment of Industrial Waste of Khartoum North Industrial Area", M. Sc. Thesis, IES, University of Khartoum, 1982. 3. Shargawi, F., "Report on the Industrial Waste in the Sudan", WHO/EMRO Publications, 1976 4. UNICEF, "Report on South Kordofan Water Supply-An Evaluation Study", Khartoum 1982 5. Abbo, G. M. H., "Physiochemical Treatment of Tannery Wastes", M. Sc. thesis, Civil Eng. Dept., University of Khartoum 1985 دار اﻟﻨﺸﺮ ﺟﺎﻣﻌﺔ،" "اﻟﺼﻨﺎﻋﺔ واﻟﺒﻴﺌﺔ – ﻣﻌﺎﻟﺠﺔ اﻟﻤﺨﻠﻔﺎت اﻟﺼﻨﺎﻋﻴﺔ، م، ع، ﻋﺒﺪ اﻟﻤﺎﺟﺪ، م، ب، اﻟﺤﺴﻦ.6 1986 اﻟﺨﺮﻃﻮم 1986 دار اﻟﻨﺸﺮ ﺟﺎﻣﻌﺔ اﻟﺨﺮﻃﻮم،" "إﻣﺪادات اﻟﻤﻴﺎﻩ اﻟﺴﻮدان، م، ب، اﻟﺤﺴﻦ، ، م، ﻋﺒﺪ اﻟﻤﺎﺟﺪ ع.7
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Waste Stabilization Ponds Design Parameters: The Combined Effect of Time and Organic Load34 By Ali Mohamed Ziedan35, Isam Mohammed Abdel-Magid36 and Abdel Wahid Hago Mohammed37.
Abstract Waste Stabilization Ponds (WSP) are affected and governed by uncontrolled environmental conditions, as well as many other parameters (geometry and performance aspects). Usually, WSP are designed using empirical or rational procedures. These are based on some factors (such as temperature, detention time, photosynthesis, etc.); making use of correction factors for some of these parameters in an attempt to represent actual field conditions. In this investigation, analysis of data has been carried out to correlate the removal rate constant through two parameters namely: organic load and detention time, which are assumed to be the most effective.
Introduction WSP’s were considered as biochemical reactors by many researchers {12,13,14,15,16}. Therefore, the Kinetic reaction approach was the basic concept adopted for design in which the first-order removal rate constant, k, was considered the principal parameter for design {12,13,14}. The actual hydraulic flow regime, which is an important factor in design process, is not the same as used in the design procedure. Researchers and designers used to assume one of the ideal flow conditions, either plug flow, or completely mixed conditions {1,2,3,6,9,12}. Since compete mixing or plug flow conditions are difficult to establish in WSP without mechanical mixing {10} or without the aid of baffling {8}, the non-ideal flow condition {12} was assumed to depict the real hydraulic regime within the system. The design equation representing this condition is that of Wenner-Wilhelm {12,13,14}: ⎛ 0 .5 ⎞ 4a × exp⎜ ⎟ Loo d ⎠ ⎝ (1) = L1 (1 + a ) 2 exp⎛⎜ a ⎞⎟ − (1 − a ) 2 exp⎛⎜ − a ⎞⎟ ⎝ 2d ⎠ ⎝ 2d ⎠ Where: Loo, L1 = the BOD of effluent and influent respectively, mg/l. a = (1 + 4ktd)½ d = dispersion number; t = detention time in days, and k = first order BOD removal constant, d-1
34
Published in The Sudan Engineering Society Journal, Issue 30, June 1988, pp 24 - 29 Civil Engineering Dept., Faculty of Engineering & Architecture, Univ. of Khartoum 36 Civil Engineering Dept., Faculty of Engineering & Architecture, Univ. of Khartoum 37 Civil Engineering Dept., Faculty of Engineering & Architecture, Univ. of Khartoum 35
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According to Thirumurthi {12} temperature, influent waste qualities, nutrient deficiencies, organic load, and other biological factors can be accounted for by the value of K the removal rate constant, KT, was mainly considered as a function of temperature, and expressed by Arrhenius equation {3,6,9}: KT = K20 (θ) T – 20
(2)
Where, KT, K20 are the removal rate constant at any temperature T and at standard temperature 20°C, respectively; and θ is the temperature coefficient. The coefficient of temperature, θ, which is inversely proportional to the temperature, was found to vary from 1.036 at dispersion number equal to zero, or plug flow {13}, to 1.085 {5, 6} for at dispersion number equal to infinity, or complete mixing condition. For the assumed non-ideal flow, the coefficient of temperature, (θ), was calculated as 1.052 {17}. The removal rate constant, as a principle design parameter of the kinetic design procedure, was influenced by many parameters. It was found to decrease with temperature {7}, while at constant temperature it was found to decrease with increasing detention time and decreasing organic load {13}. Many attempts were made in order to estimate the design value of the removal rate constant, by using correction factors of either detention time {2}, or organic load {13}. The BOD removal rate was strongly influenced by hydraulic flow regime as well as the abovementioned parameters. The evaluation process for one factor needs to keep other factors constant, which is practically difficult at field conditions. Therefore, most of the parameters are acting at the same time, and then having a combined effect on the pond performance, such as organic load and detention time. Disregarding the effect of any of these parameters will not produce a sound quantification of the resulting retardation. The aim of this research is to develop other relations, based on the concept of combined effect of two parameters. Nevertheless, this approach needs further field research and long periods of monitoring, in order to estimate and refine the correction between the most effective parameters and the removal rate constant.
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Materials and Methods Base on the aforementioned argument, an attempt has been made to correlate K20, the organic load and detention time together. The required data used for analysis were collected by other investigators and used for different purposes {4,11,12,13}, Tables 1,2 and 3. The least squares regression analysis has been carried out using a computer programme of linear regression with two independent variables. Generally, the nonlinear equation was expressed as: K20 = A. LTs exp (C.t)
(3)
While the linear from of this equation becomes ln (K20) = ln (A) + B. ln (L) + C.t
(4)
Where: A, B, and C are constants; L is organic load in Kg/ha.d, or g/m3.d; t is the detention time, in days; and K20 is the removal rate constant at any time and any organic load at the reference temperature of 20°C. The multivariate regression analysis was carried out twice in order to estimate the proper correlation coefficients, 1 where reciprocal of time, , was considered firstly, and t secondly. The same t procedure was followed with both surface loading and volumetric loading.
Results and Discussions 1 , the regression analysis was carried out on the data of t table 2 and 3, the results are as shown in table 4. As indicated in coefficient, (COR =0.9948), and the least standard error of estimation, (SD = 0.0032) are higher and lower, respectively, than that of column II.
Using the first condition of
Table 4. Coefficients or regression for data in Tables 3 & 2, columns I and II respectively
Coefficient A B C COR SD
I 0.8691 8.2451 0.9948 0.0082
II 1.2990 -0.9559 -20.1230 0.9039 0.0148
It has been found that this correlated coefficient is higher than that obtained in case of separately counted parameters {17}, while the standard error of estimation is much less in this case. Therefore, the linear form of the suggested equation 4, becomes: In (K20) = - 4.245 + 0.369.In (L) + 8.245/t
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(5)
While the nonlinear form can be expected as: K20 = 0.157.L0.37 .exp(8.245/t)
(6)
Equation 6, for K20, can be substituted in equation 2, in order to estimate the design value of the removal constant that corresponds to any surface or volumetric organic load, and any temperatures as well. The computed value of K20 is used thereafter in equation 1. The results obtained in case of volumetric loading are shown in Table 5.
Table 5 – Coefficients of regression analysis for data in Tables 1,2 and 3 columns I, II, and III, respectively Coefficient I II III A -1.9260 -2.0493 -3.4388 B 0.6703 -0.3663 0.3919 C -21.2600 15.36900 7.3178 COR 0.6740 0.5498 0.9949 SD 0.0234 0.234 0.0032 It could be seen from the table third column has the higher correlation coefficient, (COR = 0.9949), and the lower standard error of estimation, (SD = 0.0032). Hence, the suggested equation, whereby the volumetric loading in g/m3d is considered, may be expressed as: K20 = 0.0321.L0.392 .exp (7.32/t)
(7)
In the second case, the normal detention time, t, is considered, for both surface and volumetric organic loading. The results of regression analysis, shown in Table 6 and Table 7, revealed high correlations and minimum standard errors of estimation
Table 6 Coefficients of regression analysis, load in kg/ha.d, for data of Tables 2 and 3, columns I and II respectively. Coef A B C COR SD
I -1.3440 08899 0.0500 0.9487 0.0100
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II -5.8106 0.8013 0.0046 0.9923 0.0046
Table 7 Coefficients of regression analysis, load in g/m3 d, for data of table 1, 2 and 3, columns I, II, III respectively. Coef I II III A -5.0774 -3.9733 -4.0829 B 0.4108 0.5026 0.7544 C 0.0849 0.0493 0.0036 COR 0.6849 0.7278 0.9932 SD 0.0143 0.0181 0.0041 From Tables 6 and 7, the results with best correlation are those shown in column III (COR = 0.9932 and SD = 0041). Therefore the equation of regression, considering surface loading becomes: K20 = 0.003 L0.08.exp (0.0046t)
(8)
Equation 8 can be expressed graphically, as shown in figure 1, and 2, where the removal rate constant K20 was plotted on log-log paper against organic load, figure 1. With a best fit, a family of parallel straight lines, of different detention times, represents equation 8. Also in figure 2, the removal rate constant was plotted against detention time on a semi log paper; a set of parallel straight lines of the best fit at different organic loads, are shown on the graph. Therefore from figures, 1 and 2, the removal rate constant at 20ºC may be estimated for any organic load at any detention time and then substituted in equation 2. It has been noticed from the results of the analysis obtained that the results, when volumetric loadings are considered, are characterized by higher correlation coefficients and lower standard error of estimation, in both trials. Bradley {3} mentioned that the volumetric loading is the preferred design criterion for completely anaerobic ponds, while Uhlman et. al. {16} regarded the volumetric loading rate as one of the most significant factors affecting the BOD removal rate constant.
Conclusions It has been realized during this study that all parameters, which are acting at the same time in the field conditions, have a combined effect on the BOD removal rate, as well as the overall performance of the WSP. The regression analysis was carried out for the removal rate constant against the corresponding organic load and detention time. The results showed high correlation coefficients ranged between 0.9932 and 0.9949 in case of surface loading, while the standard error of estimation ranged between 0.00320.0041 and 0.0032-0.0046, for both cases respectively. According to the previous discussion, the concept of combined effect, to be used in design, is expected to be more efficient than the classical procedures.
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References: 1. Ahmed, S.M.R.; " Choice and Layout of Various Types of Stabilization Ponds". Waste stabilization ponds, Report of seminar, Technical Publication No. 3, WHO/EMRO, 135 -154, Lahore, 1980 2. Arthur, J. P.; "the Development of Design Equations for Facultative Waste Stabilization Ponds in Semi- Arid Areas". Proc. Instn. Civ. Eng., 71(2), 197213, 1981 3. Bradley, R. M., "BOD Removal Efficiencies in Two Stabilization Lagoons in Series in Malaysia". J. Wat. Pol. Cont., 82 (1), 114-122, 1983 4. Finney, B.A., & middlebrooks, E. J., “Facultative Waste Stabilization Pond Design",. J. Wat Pol. Cont. Fed., 52 (1) , 134-147, 1980. 5. Gloyna, E.F.; "Basis for Waste Stabilization Pond Design". Water Resources Symposium –I, 397 - 408, Univ. of Texas, 1968. 6. Golyna, E.F.; "Waste Stabilization Ponds". WHO, Geneva, 1971 7. Grassmann, P., Sawistowisk, H.; "Physical Principles of Chemical Engineering". Pergamon Press, Oxford, 1971 8. Kilani, J.S., & Ogunrombi, J. A.; "Effects of Baffles on the Performance of Model Waste Stabilization Ponds". Wat. Res., 18(8), 941-944, 1984. 9. Mara, D. D.; "Sewage Treatment in Hot Climates". John Wiley & Sons, New York, 1976 10. Polparasert, C., & Bhattarai, K. K., "Dispersion Models for Waste Stabilization Ponds". J. Env. Eng., A.S.C.E., 111 (EEE1), 45 – 59, 1985. 11. Reynolds, J. R., Swiss, R. H., Macko, C. A., & Middlebrooks, E. J.; "Facultative Lagoon Performance" Prog. in Wat. Tech., 11(4/5), 361 – 376, 1979. 12. Thriumurthi, D.; "Design Principles of Waste Stabilization Ponds" . J. San. Eng. Div., A.S.C.E., 95 (SA2), 311-330, 1969. 13. Thirumurthi, D.; "Design Criteria for Waste Stabilization Ponds" . J. Wat. Pol. Cont. Fed., 46 (9), 2094 -2106, 1974. 14. Thhirumurthi, D.; "Design Guidelines for Incomplete Mixed or AerobicAnaerobic Aerated Langoons", Canadian J. of Civ Eng. 7(1), 27 – 35, 1980 15. Uhlmann, D.; "BOD Removal Rates of Waste Stabilization Ponds as a Function of Loading Retention Time, Temperature, and Hydraulic Flow Pattern". Wat Res., 13(2), 193 – 200, 1979. 16. Uhlmann, D., Recknogel, P. Sandring, G., Schwarz, S., & Eckelmann, G.; "A New Design Procedure for Waste Stabilization Ponds". J. Wat. Pol. Cont Fed. 55 (10), 1252 – 1256, 1983. 17. Zeidan, A.M., "The Influence of Some Parameters on Pond Design". M. Sc. Thesis, Civil Eng. Dept., Univ. of Khartoum, 1986
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Prospects of Wastewater Reuse in Irrigation: Case Study, Sultan Qaboos University38 By Dr. Alaa Eldin El-Zawahry39 and Dr. Isam Mohammed Abdel-Magid 40 Abstract: This paper gives a critical review and assessment of the existing Omani regulations for reuse of wastewater in irrigation. The regulations of reuse of wastewater in Oman are rather strict and closely follow potable water standards. Reuse of reclaimed wastewater would add its merit to the agricultural sector. This would demand formulation, updating and implementation of guidelines that would properly serve the water sector in Oman. Relaxed guidelines, rather than standards, are suggested, whereby every source of discharge of reuse is given a separate line of emphasis. A detailed case study of the reuse of wastewater in irrigation (S.Q.U.) has been investigated and analyzed. The analysis included the design parameters of the STP and effluent quality and quantity relationships.
Introduction Water is becoming an increasingly scarce resource in most of arid and semi-arid areas. Any source of water, which might be used effectively and economically to promote further development must be considered. At the same time, with high rate of population expansion, the need for increased food production is vital. The potential for irrigation to raise agricultural productivity has long been recognized. Wherever good quality water is scarce, water of less (marginal) quality has to be considered for use in agriculture. From the viewpoint of irrigation, use of marginal quality water requires more complex and more stringent monitoring than when good quality water is used. This paper addresses the agricultural use of domestic sewage with or without a proportion of industrial effluents that are discharged to public sewers in Oman. It should be noted that the quantity of wastewater available in most areas accounts for only a small fraction of the required total irrigation water. The use of municipal wastewater in irrigation not only conserves valuable water resources but also takes advantage of the nutrients contained in sewage to grow crops. Moreover, the Nitrogen and Phosphorous content of sewage might reduce or eliminate the requirements for commercial fertilizers. It is important to consider effluent reuse at the same time as wastewater collection, treatment and disposal. Additionally, sewage techniques for effluent discharge to surface waters may not always be appropriate for agricultural use. Some countries, for example Jordan and Saudi Arabia, have a national policy to reuse all treated wastewater effluents and have already made considerable progress. The Sultanate of Oman is known to be one of those arid countries, which has been environmentally conscious and gave conservation and prevention its utmost attention. Most of the wastewater treated in Oman is used for irrigation purposes especially in Muscat, the capital area.
38
Presented at the Second Gulf Water Conference on "Water in the Gulf Region Towards Integrated Management", Bahrain 5th - 9th November, 1994. Published in the Civil Engineering Research Magazine, AlAzhar University,Cairo, Vol. 16 (4), April 1994, pp.322-239. 39 Civil Engineering Department, College of Engineering, Sultan Qaboos University 40 Civil Engineering Department, College of Engineering, Sultan Qaboos University
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Wastewater Characteristics Domestic wastewater is comprised of water (about 99.9%) with relatively small amounts of suspended and dissolved solids (organic and inorganic). The levels of the major constituents of strong, medium and weak domestic wastewaters are summarized in Table 1. Table (1) Major Constituents of Typical Domestic Wastewater {15} Constituent Concentration, mg/l Strong Medium Weak Total solids 1200 700 350 Total Dissolved solids 850 500 250 (TDS)* Suspended solids 350 200 100 Nitrogen (as N) 85 40 20 Phosphorus (as P) 20 10 6 Chloride* 100 50 30 Alkalinity (as CaCO3) 200 100 50 Grease 150 100 50 BOD5** 300 200 100 Key * The amounts of TDS and chloride should be increased by the concentrations of these constituents in the carriage water. ** BOD5 is the biochemical oxygen demand at 20°C over 5 days and is a measure of the biodegradable organic matter in the wastewater. In arid and semi arid areas water consumption is often fairly low, in order of 100 l/c/d, and sewage tends to be strong or even very strong. From the point of view of health, the presence of pathogenic micro and macro organisms is the key factor, which may limit the use of wastewater in agriculture. The raw municipal water may include pathogenic viruses, bacteria, protozoa and helminths. Table 2 summarizes the possible levels of those pathogens in wastewater. The pathogens may survive in the environment for a long time as indicated in Table 3. Table (2) Possible Levels of Pathogens in Wastewater {5} Type of pathogen
Possible concentration per litre in municipal wastewater1 5000
Viruses
Enteroviruses2
Bacteria
Pathogenic E. coli3 Salmonella spp. Shigella spp. Vibrio cholerae Entamoeba histolytica Ascaris Lumbricoides Hookworms4 Schistosoma mansoni Taenia saginata Trichuris trichiura
Protozoa: Helminths:
? 7000 7000 1000 4500 600 32 1 10 120
Key ? Uncertain 1 Based on 100 lpcd of municipal sewage and 90% inactivation of excreted pathogens.
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2 Includes Polio, Echo, and Coxsackieviruses. 3 Includes Enteroxigenic, Enteroinvasive and Enteropathogenic E.coli. 4 Anglostoma duedenale and Necator americanus.
Table (3) Survival of Excreted Pathogens (at 20 - 30°C) {5} Type of pathogen Survival times in days In faeces, nightsoil In fresh water In the soil On crops and sludge and sewage Viruses <100 (<20) <120 (<50) <100(<20) <60(<15)* Enteroviruses Bacteria Faecal Coliforms < 90 (<50) < 60 (<30) < 70 (<20) <30 (<15) Salmonella spp. < 60 (<30) < 60 (<30) < 70 (<20) <30 (<15) < 30 (<10) < 30 (<10 <10 (< 5) Shigella spp < 30 (< 5) < 30 (<10) < 20 (<10) < 5 (< 2) Vibrio cholerae Protoz0a <30 (<15 <30 (<15) < 20 (<10) <10 (< 2) Entamoeba < 30 (<15 <30 (<15) < 20 (<10) <10 (< 2) histolytica cysts Helminths Many Many Many <60 (<30) Months Months Months Ascaris lunbricoides eggs Key * Figures in brackets show the usual survival time.
Quality Parameters in Agricultural use of Wastewater The quality parameters of importance in agricultural use of wastewater may be classified into two main groups that are based on their significance on health and agriculture. The principal health hazards associated with organic chemicals constituents of wastewater arise from the contamination of crops or groundwater. Hillman (1988) has drawn the attention to the particular concern attached to the cumulative poisons, heavy metals and carcinogens, mainly of organic nature. The guidelines for organic and toxic substance (WHO 1984) may be adopted directly for ground water. The possible accumulation for certain toxic plants (for example, cadmium and selenium) through eating crops irrigated with contaminated wastewater must be carefully assessed. The greatest health concern in agricultural use of wastewater is related to the pathogenic organisms. Shuval et.al. (1985) reported that in areas where raw untreated sewage is used to irrigate salad crops and/or vegetables eaten uncooked, transmission of helminthic diseases is likely to occur through the consumption of such crops. Shuval et. al. (1986) pointed out that negative health effects were only detected in association with the use of raw or poorly-settled wastewater. Moreover, inclusive evidence suggested that appropriate wastewater treatment could provide high level of health protection. Important agricultural water quality parameters would include several physical and chemical characteristics that are briefly discussed in the next section.
Wastewater quality guideline for agricultural use Wastewater treatment, crop restriction, control of wastewater application and human exposure control are the health protection measures which may be applied in agricultural use of wastewater.
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Microbiological quality guidelines for wastewater use in agriculture are shown in Table 4 (WHO, 1989). The guidelines are stricter than those of (WHO, 1973) design goals for wastewater treatment system. Table (4) Recommended Microbiological Quality Guidelines For Wastewater Use in Agriculture {17} Wastewater Category Reuse condition Exposed Intestinal Faecal b treatment expected Group coliforms nematodes (arithmetic mean (geometric mean to achieve required no. of eggs per no. per 100 mlc) microbiological quality litrec) d A Irrigation of crops Workers, ≤1 Series of ≤ 1000 likely to be eaten consumers stabilization ponds uncooked sports public designed to achieve microbiological fields, public d parks quality indicated, or equivalent treatment B Irrigation of Workers ≤ No standard Retention in cereal crops, recommended stabilization ponds industrial crops for 8-10 days or fodder crops, equivalent pasture and trees helminth and faecal coliform removal C Localized None N/A N/A Pretreatment irrigation of as required by crops in the irrigation category B if techno-logy, exposure of but not less workers and than primary the public sedimentation does not occur Key a
b c d
e
N/A
In specific cases, local epidemiological, socio-cultural and environmental factors should be taken into account, and the guidelines modified accordingly. Ascaris and Trichuris species and hookworms. During the irrigation period. A more stringent guideline (≤200 faecal coliforms per 100 ml) is appropriate for public lawns, such as hotel lawns, with which the public may come into direct contact. In the case of fruit trees, irrigation should cease two weeks before fruit is picked, and no fruit should be picked off the ground. Sprinkler irrigation should not be used. Not Available
The adequacy of water for irrigation relies, on many parameter such as climatic condition, soil, physical and chemical properties, grown crop salt tolerance. Ayers and
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Westcot (FAO 1985) classified irrigation water into three groups based on salinity, sodicity, toxicity and miscellaneous hazards as shown in Table 5. Table (5) Guidelines for Interpretation of Water Quality for Irrigation {4} Potential irrigation Unit Degree of restriction on use problem
s None
Slight to moderate
Severe
dS/m
< 0.7
0.7 - 3.0
> 3.0
mg/l
< 450
450 – 2000
> 2000
> 0.7 > 1.2 > 1.9 > 2.9 > 5.0
0.7 - 0.2 1.2 - 0.3 1.9 - 0.5 2.9 - 1.3 2.9 - 5.0
< 0.2 < 0.3 < 0.5 < 1.3 < 2.9
SAR
<3
3–9
>9
me/l
<3
me/l
<4
4 – 10
m3/l
<3
>3
mg/l
< 0.7
0.7 - 3.0
> 3.0
mg/l me/
<5 < 1.5
5 – 30 1.5 - 8.5
> 30 > 8.5
Salinity ECw1 or
TDS Infiltration SAR2 = 0 - 3 and ECw 3–6 6 – 12 12 – 20 20 – 40
Specific ion toxicity Sodium (Na)
Surface irrigation Sprinkler irrigation
>3
Chloride (Cl) > 10
Surface irrigation Sprinkler irrigation Boron (B)
Miscellaneous effects Nitrogen (NO3-N)3 Bicarbonate (HCO3) pH
Normal range 6.5 - 8.4
Key: 81
1 ECw means electrical conductivity in deciSiemens per metre at 25°C 2 SAR means sodium adsorption ratio 3 NO3-N means nitrate nitrogen reported in terms of elemental nitrogen
Successful Irrigation In arid and semi-arid areas a successful irrigation system based on the use of treated wastewater requires basic condition to be met. The required amount of water should be applied, the water must have acceptable quality, proper application schedule and irrigation method should be adopted, salt accumulation must be prevented by leaching, ground water table must be controlled by drainage and plant nutrients should be managed.
Wastewater Reuse in Oman Table (6) gives the total Omani area as being divided under different crops together with their average annual yields. Out of the 54901 hectares (only about 6.9 % of the suitable agricultural area) irrigated in the Sultanate, 5370 ha are under vegetable cultivation, 9747 ha under field crops and 33,133 ha under fruit trees. Tomatoes and watermelon account for about 46 % of the area under vegetable production, whereas 91 % of the area under field crops produce Alfa alfa. Date palms account for about 75 % of the area under fruits, with a percentage of 45.5 % of the total area (Abdel-Rahman and Abdel-Magid 1993). In any water conservation plan it is very important to know the varieties and areas of crops grown. The water use of crops should be estimated through extensive research work under the prevailing climatic conditions.
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Table (6) Crop Production by Areas and Yields – 1988 {11} Area (ha) Yield (Tons/ha)
Crop Vegetables 1212
22.19
610
9.02
560 150 53 1250 625 770 140
13.75 8.00 13.21 19.04 13.12 23.25 25.00
Tomato
Pepper Onion Garlic Okra Water Melon Musk Melon Cabbage Potato Sub-Total
5370
Field Crops 8870
38.00
Wheat
468
1.50
Tobacco
409
4.89
Alfa alfa
Sub-Total
9747
Fruits Dates Lime Mango Banana Coconut Sub-Total
25000 2400 3780 1625 328 33133
Others
6651
TOTAL
54901
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4.00 10.83 2.01 13.60 16.77
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The 1990 estimates put the crop water requirements in the Batinah at 531 million m3 and 33 million m3 in the Salalah plain. The rest of the country requires 561 million m3 (Table 7). With these values groundwater reservoirs will be depleted at rates higher than estimated (Abdel-Rahman and Abdel-Magid 1993).
Table (7) Crop water requirements [million cm/year]12 Fruit Fodder Total Region Vegetables
Batinah Oman Interior Dhahir & Buraimi Sharqiya & Gaalan Masandam Dhofar Total
53.77 15.55 11.18 13.98 1.89 4.10 100.47
408.10 72.68 59.60 96.97 14.62 13.10 665.07
69.29 42.46 26.63 42.35 6.46 15.32 202.51
531.16 130.69 97.41 153.30 22.97 32.52 968.05
The 1990 estimates of the Capital area [Muscat] inhabitants reached the value of 333,354 persons. With an average daily consumption of about 150 liters and assuming 70 % waste water recovery, the total quantity of waste water produced would be 35,000 cubic meters. This is enough to meet the daily requirements of only 437.5 hectares of a crop land using 8 mm per day. There are now a number of sewage treatment plants in operation in the Capital area. One in Darsait producing about 11,500 m3/day, with input from the Greater Muttrah area and another at Al-Ansab producing 5400 m3/day to be expanded in the future. Their effluent is used for irrigating tree plantations in the Capital area from Darsait to Assahwah tower. A third treatment plant is at the University of Sultan Qaboos producing around 3000 m3/day and is used to irrigate the University tree plantation. Five other small treatment works exist in Maabaila, Al Khod, Murtafaa, Amrat and Diwan in Al Seeb (Abdel-Rahman and Abdel-Magid 1993). Table (8) gives an account of the existing sewage treatment works, their location, design capacity, actual flow rate of the effluent, some of the averaged quality
85
parameters, and the amount of wastewater utilized for irrigation purposes. Reuse is restricted to irrigation of ornamental plants in the Capital area.
Table (8) Sewage Treatment Plants (STP) at the Sultanate of Oman SS Ammonia Irrigation Description Design Plant Flow BOD (N) water, m3/d capacity rate, m3/d (mg/L) Darsait 10800 11500 10 10 1 8000 - 11500 Al-Ansab 12000 5400 10 10 1 2000 - 5000 Shati Al-Qrum 1350 800 10 10 1 800 Mabella 1920 700 10 10 1 AlKoud 1200 700 20 30 Bowshar 400 400 10 10 1 Al-Amerat 600 600 20 30 Jibroo 70 100 10 10 1 50 Al-Aynt 60 100 10 10 1 Total 28400 20300 17350 In case of waste-water and sludge treatment and disposal the Omani Regulations mainly has been divided into three broad groups. The first group indicates parameters to be considered for wastewater reuse, discharge and sludge disposal (Ministry of Regional Municipalities and Environment (MRME), 1993). Table (9) outlines wastewater maximum quality limits set for concentrations of elements in wastewater and irrigation water. The standards for irrigation purposes, as outlined by Ayers and Westcot are incorporated in table (9) solely for comparison purposes. As shown in table (9) more emphases were placed on chemical substances. Radioactive materials are covered in a separate article in previous regulations MEWR 1986, which do not permit reuse of waste-water or sludge containing radioactive material.The discharge of wastewater or sludge containing radioactive material shall in addition to these Regulations be subject to Regulations laid down by the International Atomic Energy Agency or such other regulations that may be issued by the Ministry of Regional Municipalities and Environment]. ( Ministry of Environment, 1986). Biological and bacteriological characteristics as laid down by the Omani wastewater standards (MRME 1993) stressed on Fecal coliform bacteria and viable nematode. It merit mentioning that reuse conditions has not been clearly classified with district standard set for each. Secondly, to achieve stated limits appropriate selection of wastewater treatment units may ought to be mentioned whenever applicable.
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Table (9) Concentration of Elements in Wastewater and Irrigation Water (All units are in mg/l except otherwise stated) Parameter Physical Total Dissolved Solids SS Electrical Conductivity (µS/cm) Chemical Ag Al As B Ba Be BOD5 Cd Cl COD Co CN Cr Cu F Fe Hg Li Mg Mn Mo N Ammoniacal N Kjeldahl Nitrate as NO3 Na Ni Oil and grease Pb PH Phenol SSodium Absorption Ratio (SAR) Se SO4 V Zn Bacteriological Fecal Coliform Bacteria [per 100 ml] Viable Nematode Ova (per litre)
Wastewater11 Standard A+ Standard B+
Irrigation Water3 MAX-CT* MAX-20**
1500 15 2000
2000 30 2700
-
-
0.01 5 0.1 0.5 1 0.1 15 0.01 650 150 0.05 0.0.5 0.05 0.5 1 1 0.001 0.07 150 0.1 0.01 5 5 50 200 0.1 0.5 0.1 6-9 0.001 0.1
0.01 5 0.1 1 2 03 10 0.01 650 200 0.05 0.1 0.05 1.0 2 5 0.001 0.07 150 05 0.05 10 10 50 300 0.1 0.5 0.2 6-9 0.002 0.1
5 0.1 10.75 0.1 0.01 0.05 0.2 0.1 1 5 2.5 0.2 0.01 0.2 5 6 - 8.5 -
20 2 2 0.5 0.05 5 5 1 15 20 2.5 10 0.05 2 10 6 - 8.5 -
10 0.02 400 0.1 5
10 0.002 40 0.1 5
0.02 2
0.02 10
200
1000
<1
<1
Key + * **
Refer to table (11). Waters used continuously on all soils. Waters used up to 20 years on fine textured soils of pH 6-8.5. 87
In case of sludge reuse in agriculture, conditions for application to land has been divided according to three parameters that relate to: (i) maximum concentration based on dry solids, (ii) maximum annual application rate based on land area to be irrigated, and (iii) maximum permitted concentration in soil based on dry solids value. Table (10) gives the concentration of metals to each of the aforementioned categories.
Table )10) Re-use of Sludge in Agriculture - Conditions For Application to Land11 Metal
Maximum Maximum Maximum Permitted Concentration Application Rate Concentration in Soil (mg/kg of dry (kg/ha/yr)* (mg/kg of dry solids) Solids) Cadmium 20 0.150 3 Chromium 1000 10.000 400 Copper 1000 10.000 150 Lead 1000 15.000 300 Mercury 10 0.100 1 Molybdenum 20 0.100 3 Nickel 300 3.000 75 Selenium 50 0.150 5 Zinc 3000 15.000 300 After the spreading of sludge there must be a minimum period of three weeks before grazing or harvesting of forage crops Sludge use is prohibited: - on soils whilst fruit or vegetable crops, other that fruit trees, are growing or being harvested - for six months preceding the harvesting of fruit or vegetables which grow in contact with the soil and which are normally eaten raw. - on soils with a pH < 7.0 *
Based on a 10 - year average and a soil pH > 7.0 Reuse and discharge regulations further classify wastewater use for crops and vegetables, grass and ornamental areas, aquifer recharge, and method of irrigation. Table (11) illustrates these areas of application of wastewater. Any other reuse application would be subject to the approval of the concerned Ministry of Regional Municipalities and Environment.
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Table (11) Wastewater re-use: Areas of Application of Standards A and B (Table 9)11 A B Crops
Vegetables likely to be eaten raw. Fruit likely to be eaten raw within 2 weeks of any irrigation
Grass &
Public parks, Hotel lawns. Recreational areas. Areas with public access. Lakes with public contact (except Areas with no public places which may be used access │ for praying and hand washing) All controlled aquifer recharge Spray or any other method of aerial irrigation not permitted in areas with public access unless with timing control. Subject to the approval of the Ministry
ornamental areas
Aquifer recharge Method of irrigation Any other application
reuse
Vegetables to be cooked or processed. Fruit if no irrigation within 2 weeks of cropping. Fodder, cereal and seed crops Pastures
In general standards or regulations or guidelines for wastewater and sludge disposal are desirable to be divided in specific divisions that embody relevant areas. Suggested divisions may include: pretreatment, waste disposal in natural bodies of water; industrial waste disposal in sewers; water reuse for agriculture; water use for swimming and recreation; and water use for specific intentions.
Case Study: Sultan Qaboos University Sultan Qaboos University STP is designed to serve, ultimately a population of 10,300 capita, the existing population is 3000 capita. The design wastewater inflow is 204 l/c/d with a raw wastewater BOD of 392 mg/l. The design peak flow, using a peaking factor of 2, is 175 m3/hr. The main units of treatment on the scheme comprise: sewage inlet pumping station, communication and flow measurements, biological aeration and settlement, tertiary treatment, chlorination and sludge drying beds. The biological treatment sections operate on an extended aeration activated sludge principle with long period of retention given to the mixed liquor of sewage and activated sludge. The entire area of the University is covered by trees, grass and beautification as shown in Fig. (1). The STP outlet is totally used for irrigation purposes as shown in Fig. (2). During summer period, the STP outlet does not cover the irrigation consumption (50% only), potable water is used to cover the defiant for irrigation. Modern irrigation system (trickle and sprinkle) are used in S.Q.U. To optimize the irrigation consumption and application rate, the irrigation systems are fully automated. Based on the type of plantation, the application rates and time of application are operated using mechanical clocks that open/close valves on present time schedule. To overcome the problem of
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emitters clogging, the STP is provided by twin pressure sand filters. The water quality of the STP outlet used for irrigation is summarized in Table (12).
Table (12) SQU Final STP effluent water quality18 Parameter
Final Effluent
pH cm P.P. Alkalinity / Acid as CaCO3 mg/1 M.O. Alkalinity / Acidity as CaCO3 mg/1 mg/1 BOD5, Days @ 20°C COD mg/1 Total dissolved solids mg/1 Suspended solids mg/1 Residual chlorine (free) mg/1 Ammoniacal nitrogen as N mg/1 Oil and grease mg/1 Microbial activity MPN coliforms No./100 ml
7.1 NIL 65.0 13 26.3 486 7 0.2 < 0.1 NIL Nil
Table 12 shows that the physical, chemical and microbiological parameters that has been measured conform with the Omani discharge and reuse standards. This could be attributed to the extra treatment units used within the STP and the influent characteristics. According to the guidelines for interpretation of water quality for irrigation set by Ayres and Westcot 1976 the effluent may be classified as slight to moderate based on total dissolved solids content. It is to be indicated that Table 12 does not offer a good meant to assess the water quality to be used for irrigation purposes. As such more parameters are to be included such as salinity, SAR, sodium, chloride, boron concentration, etc.
Conclusion The study reflects the importance of using treated wastewater for irrigation purposes, especially in arid and semi-arid areas. Many quality parameters of importance in agricultural use of wastewater have to be carefully studied. The greatest health concern in agricultural use of wastewater is related to pathogenic organisms. Appropriate wastewater treatment could provide high level of health protection. In Sultanate of Oman several crops are cultivated. The irrigation waste consumption is based on the type of crop and the climatic conditions. The study indicated that there is a need for using treated wastewater to partially cover the shortage of irrigation of ornamental plants throughout the country and especially in the capital area. The Omani regulation has been divided into three broad groups; wastewater reuse, discharge and sludge disposal. More emphasis was placed on chemical substances. Biological and bacteriological characteristics are stressed upon through the Fecal coliform bacterial count and viable nematode ova. Sultan Qaboos University demonstrates a good example of the reuse of the treated wastewater. Due to the use of extra treatment units, the water quality of the STP effluent conform with the Omani standards. At present, the amount of irrigation water used covers the needs of the cultivated land during winter period and about 50% during summer period. Considering the ultimate design population, the STP is capable to discharge three times the amount of effluent which is expected to cover the deficit during the summer period. 90
References 1. Abdel-Magid, I.M.; and El-Zawahry, A., "Establishment of water quality guidelines for the Sultanate of Oman", Arab Water World J., Vol. 16 issue 5, Sep-October, 1992, pp 18 - 22. 2. Abdel-Rahman, H. A. and Abdel-Magid, I.M., "Water conservation in Oman", Water International J, Vol. 18(2) June 1993, pp 95 - 102. 3. Ayres, R.S. and Westcot, D. W. "Water quality for agriculture" FAO, Rome, Irrigation and Drainage Paper 29, 1976. 4. FAO. (1985) "Water quality for agriculture." R.S. Ayers and D. W. Westcot. Irrigation and Drainage Paper 29 Rev. 1. FAO, Rome. 71 p. 5. Feachem R. G., Bradley D. J., Garelick H. and Mara D.D. (1983) "Sanitation and Disease: Health Aspects of Excreta and Wastewater Management". John Wiley, Chichester. 6. Hillman P.J. (1988) "Health aspects of reuse of treated wastewater for irrigation." Ch. 5, "Treatment and Use of Sewage Effluent for Irrigation." M.B. Pescod and A. Arar (eds). Butterworths, Sevenoaks, Kent. 7. Kandiah A. (1990) Water quality management for sustainable agricultural development. Natural Resources Forum. 14 (1): 22-32. 8. Ministry of Agriculture and Fisheries (1989), Department of Agricultural Statistics, "Estimate of Cropped Area in the Sultanate". 9. Ministry of Commerce and Industry (1978)"Sultanate of Oman Standards: Drinking water", No. 8, General Department of Standards and weight, personal communications. 10. Ministry of Environment and Water Resources (1986) "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for waste-water reuse and discharge" Ministerial Decision 5/86 dated 17th May, Muscat. 11. Ministry of Regional Municipalities and Environment (1993) "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for external building drainage" Ministerial Decision 145/93 dated 13th June, Muscat. 12. Ministry of Water Resources (1990), Sultanate of Oman,"National Water Resources, Master Plan.” 13. Shuval, H.I. Adin, A., Fattal, B., Rawitz, E. and Yekutiel, P. (1986) Wastewater irrigation in developing countries: health effects and technical solutions". Technical Paper No. 51. World Bank, Washington D.C. 14. Shuval H. I., Yekutiel P. and Fattal B. (1985) "Epidemiological evidence for helminth and cholera transmission by vegetables irrigated with wastewater. Jerusalem - case study". Water Science and Technology 17 (4/5): 433-442. 15. UP Department of Technical Cooperation for development. (1985) The use of non-conventional water resources in developing countries. Natural Water Resources Series No. 14. United Nations DTCD, New York. 16. WHO. (1984) "Guidelines for Drinking Water Quality". Vol WHO, Geneva. 130 p. 17. WHO. (1989) "Health guidelines for the use of wastewater in agriculture and aquaculture". Technical Report No. 778. WHO, Geneva 74 p. 18. SQU, "Sewage treatment plant reports", Personal communication.
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The influence of Local Filter Aids on Sewage Sludge Dewatering Practice41 by Dr. Isam Mohammed Abdel-Magid42, Dr. Ahmed Hossam El-Din Hassan43, and Dr. Mohammed Ali Al-Hag Alloba44
Abstract In this investigation the filtration aspects of sewage sludge with and without addition of additives and filter aids were studied in an attempt: to acquire knowledge and understanding of the filtration-separation properties of these sludge. to indicate influence and effect of additives in facilitating the removal of water from sludge. to demonstrate factors that govern optimum performance of dewaterability upon the introduction of applied filter additives, and to evaluate the efficiency of various additives and additive sizes towards better filtration of sludge. The introduced filter aids to sewage sludge included Acacia nilotica (Garad) plantations, Clarifying soil (Rauwaq), and Fenugreek seeds (Helba), Trigonella foenum. The chosen additives were selected on basis of availability, applicability, usefulness, physical characteristics and economic aspects. Adsorption is demonstrated to be the major process influencing dewatering of sludge, to which additives were added, as shown upon comparison to recognized adsorbates such as activated carbon. Introduction One of the strenuous problems in the field of wastewater engineering is the dewatering of sewage sludge as produced in various treatment unit operations and processes. The cost of sludge treatment and final disposal can amount to as much as fifty percent of the capital and running cost of a sewage treatment plant (Coackley 1975). Sludge dewatering, or water withdrawal from sludge, is of significance for effective, efficient, reliable and ultimate disposal practices. It is an economic necessity required to lessen sludge volume demanding ultimate disposal and it retards biological decomposition and degradation (Abdel-Magid 1982, WPCF 1969). As such, efforts ought to be directed towards finding a suitably economic method to solve the sludge dewaterability problem through better selection and usage of appropriate filter aids and/or sludge conditioners. There are many factors that affect the dewatering characteristics of sewage sludge. These influential factors include: presence of fine particles, solids content, protein content, pH and particle charge, moisture content, shearing strength, anaerobic digestion, and filter aids used. Presence of fine particles has been demonstrated by many workers (Abdel-Magid 1982, Coackley 1975, Gale 1971, and Karr 1978) to worsen filtration properties of different types of sewage sludges. Presence of fine particles is considered to be the most 41 First published in the Bulletin of High Institute of Public Health, University of Alexandria, Vol. 25, no. 1, Jan. 1995,pp 145-153 42 Assis. Professor, Civil Eng. Dept., Faculty of Eng.,P.O. Box 33, Sultan Qaboos University, Muscat, Sultanate of Oman. 43 Headof Environ. Health Dept., Oman Inst. of Public Health, Ministry of Health, P.O. Box 393, Muscat, Sultanate of Oman. 44 Lecturer, Faculty of Public and Environ. Studies, Khartoum University, P.O. Box 205, Khartoum, Sudan.
92
important parameter behind the difficulties experienced during dewatering of sludge. As such the removal of fine particulate matter from sludge would considerably improve their filtration properties.
Materials and Methods Samples of digested sewage sludge were obtained from Darsaeit (Muscat, Oman) sewage treatment plant. The series of experiments carried out were to determine the influence of different filter aids on the dewatering aspects of digested sewage sludge. Digested sludge was employed since it is one of the common sludge found in practice, besides it is one of the most difficult to dewater due to its complex physical and chemical properties (Abdel-Magid 1982, Alloba 1987, and Coackley 1975). The series of experiments carried out were to fulfill the previously outlined objectives. The selected filter aids included the following: a) Acacia: acacias are robust, wide ranging plants frequently suited to harsh environs. They grow and coppice relatively rapidly yielding a source of protein in forest ecosystems (Doran et. al 1983). Acacia species used included those species found in abundance locally including A. nilotica and A. senegal which is known locally as Garad. b) Fenugreek: Fenugreek (Trigonella foenum) is an ancient plant indigenous to many places and they are locally termed Helba. c) Rauwaq: Rauwq are fluvial clays (clarifying soil), referred to locally as Rauwaq. They occur at specific sites along the banks of the rivers and streams and seacoasts. They always contain montomorillonite as a main constituent (Jan 1981). Filter aids were selected according to their adsorptive characteristics, availability and relatively cheap cost. The method selected for measuring how well sludge dewaters is the specific resistance to filtration. The specific resistance is the resistance to filtrate flow caused by a cake of unit weight of dry solids per unit filter area (Coackley 1975, and Abdel-Magid 1982) The device used in this work for specific resistance determination is the ordinary Buchner Funnel (See Figure 1). The specific resistance to filtration may be determined by the equation advocated by Carman-Coackley (Coackley 1953) as illustrated in equation (1). P × A2 dV = dt µ (r × C × V + rm × A)
(1)
where: V = Volume of filtrate, m3, t = Time of filtration, s, P = Vacuum pressure applied, Pa. In this work the standard vacuum level applied was 68.95 kN/m2. A = Area of filtration, m2. The value of A is taken to be equal to the filter paper area, (Gale 1971). µ = Viscosity of filtrate, N*s/m2. The viscosity coefficient is found from tables, (Shames 1992). r = Specific resistance to filtrate flow, m/kg,
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C = Solids content, kg/m3. The value of the solids content was determined from standard methods (APHA 1985). When an additive dose of Ci is added to a sludge dose of Co, the mixture will have a solids concentration of Cm as presented in equation 2 (Abdel-Magid 1982, Coackley 1974, Alloba 1987, Gale 1871). Cm = (Ci + Co)
(2)
rm = Resistance of the filter medium, /m. For conditions of constant pressure, the integration of equation (1) gives:
µ × Rm µ × r ×C t = ×V + 2 V 2× P× A P× A
(3)
Equation (3) may be expressed as indicated in equation (4). t = (b × V ) + a V
(4)
where: b=
µ ×r×C
(5)
2 × P × A2
& a = (µ*rm)/(P*A)
(6)
By plotting the values of (t/V) against values of (V) a straight line of slope (b) is obtained. The value of (b) is used to evaluate the specific resistance by making use of equation (4) as outlined in equation (7). r = 2*b*P*A2/µ*C
(7)
Where: b = Slope of the straight line of the plot of t/V versus V, s/m6. The influence of various sizes and fractions of additives on the filterability of sewage sludge was also investigated. A clean and dry sample of a particular additive under investigation was sieved into different size fractions according to the British Standard Methods (B.S. 1975). Permeability tests were conducted in an attempt to relate it to the specific resistance and to offer more information about characteristics and impact of added filter aids. It was observed that the clarity of digested sewage sludge supernatant increased upon introduction of certain species of additives. To study these phenomena more accurately, samples of sludge and additives were placed in 1 litre plastic tubes. Supernatant was withdrawn from each tube on specified time intervals. The optical density was measured for each supernatant sample drawn by a spectrophotometer type Perkin-Elmer, 550 S, UV/VIS at a wavelength of 423 nm. Adsorption capacities of different additives were evaluated to represent the degree of adsorption of sludge colloidal and particulate matter by added additives and filter aids.
94
The method used for this purpose is a dye solution method. This method was selected for its simplicity and rapidness (Abdel-Magid 1982, Alloba 1987). The dye solution being chosen as adsorbate was Methylene Blue dye from BDH chemicals of a molecular weight of 319.859. In the isothermal curve plots the amount of dye, which was adsorbed, Ym, was found from the empirical formula presented in equation (8). Ym = ([Ci - Co]*V)/(m)
(8)
Where: Ym = The amount of dye adsorbed at the plateau of the isotherms, mole/g adsorbent, Ci = Initial concentration, mole/L, Co = Equilibrium concentration, mole/L, V = Volume of dye solution added to the sample, L, m = Mass of sample used, g.
Results and discussions As a result of filtrability analysis indicated that the selected materials improved the filtering properties of sewage sludge examined. This could be attributed to the adsorption of the sludge particulate matter on the surface of the filter aids. This finding is in agreement with Coackley 1975, Abdel-Magid 1982, and Alloba 1987. The amount added is a function of the size and amount of the filter aid dosed. It was noticed that the smaller the additive size, the better the passage of filtrate as shown in figures 2, 3 and 4 for Acacia, Rauwaq and Helba respectively. The conformity of the improvement of dewatering of sludge with reductions in particle size was also noted for activated carbon as shown in figure 5. Figure 4 showed an optimum dosage for the different sizes of Helba used, after which deterioration in sludge filterability occurred. In the case of Fenugreek an optimum dose of 20 percent was obtained. This may be attributed to the high content of proteinaceous matter contained in the seeds. Kolousek and Coulson (1955) found that the protein nitrogen and alkali-insoluble nitrogen are remarkably high in Fenugreek seeds. Crude protein content estimated as 26.7 %, true protein as 25.1 %, digested protein 24.1% and amides as 1.6 % (Abu Al-Futuh 1975 and Nour and Magboul 1986).
95
96
97
98
The optical density measurements revealed that, the optical density decreased with the addition of more doses of filter aids as displayed in figures 6 and 7. Figures 6 and 7 also reveal that the clarity of the supernatant improved greatly upon addition of more doses of Rauwaq and Acacia seeds yet yielding different filterability efficiencies. The improvement obtained upon addition of smaller fractions of Rauwaq has been confirmed as indicated in figure 6. In the case of Fenugreek the clarity of the supernatant decreased greatly due to the color induced by the seeds themselves. Fenugreek contains pigments such as carotenes and flavonoid aglycone which add the yellow color to the supernatant (Abu-Al-Futuh 1975). Adsorption of solids by these filter aids is apparent and has been demonstrated to be of significance in the adsorption of methylene blue dye solution. The adsorption isotherms for Acacia, Fenugreek, and Rauwaq signified that these materials have a substantial adsorptive capacity as presented in figure 8. Conclusions From the work described in this study the following general conclusions emerged: 1. Addition of selected filter aids to digested sewage sludge improved greatly its filtration characteristics. 2. Better reduction in specific resistance of digested sludge was achieved upon increasing the dose of filter aid. 3. The smaller the filter aid size, the lower is the specific resistance, and consequently more filtrate egress. 4. The smaller the filter aid size, the better the adsorption process-governing uptake of sludge fines. 5. The higher the permeability coefficient of the filter aid, the lower is the specific resistance, hence more filtrate flow. Therefore for better dewaterability of sewage sludge and for the selection of a good filter aid, the filter aid need to be: permeable, porous, with an appreciable adsorptive capacity, and of a particle size close to size of sludge particles.
References 1) Abdel-Magid, I. M. (1982), The role of filter aids in sludge dewatering, Ph.D. thesis, University of Strathclyde, Glasgow, U.K. (unpublished). 2) Abdel-Magid, I. M. (1986), The influence of lime and grease on dewaterability of sewage sludge, The Sudan Engineering Society J., No. 29, 26. 3) Abu-Al-Futuh, I. M. (1975), Studies on Trigonella foenum, Graecum L., and its
99
4-hydroxyisolucine, Ph.D. thesis, University of Bath, (unpublished). 4) Alloba, M. A. E. (1987), The influence of filter aids on dewatering of sewage sludge, M.Sc. thesis, Faculty of Eng., University of Khartoum (unpublished). 5) APHA, AWWA, WPCF, (1985), Standard methods for the examination of water and wastewater, 16th ed., APHA, Washington, D.C. 6) British Standard Institution, (1975), Methods of testing soils for civil engineers. B.S. 1377. 7) Coackley, P. (1953), The dewatering treatment, Ph.D. thesis, London University. 8) Coackley, P. (1975), Development in our knowledge of sludge dewatering behaviour, 8th Pub. Health Eng. Conf. held in the Dept. Civil Eng., Loughbourough University of Technology, pp.5-32. 9) Doran, J. C. Jurabull, T. W., Boland, D. I. and Gunn, B. V. (1983), Handbook on seed of dry-zone acacias, FAO, United Nations, Rome. 10) Gale, R. S. (1971), Recent research on sludge dewatering, Water Pollution Research Laboratory, Stevenage, Herts, 531. 11) Jahn, S. A. (1981), Traditional water purification in tropical countries, German Agency for Technical Corporation (GTZ), pp. 19-29, 141-173. 12) Karr, P. R., and Keinath, T. M. (1978), Influence of particle size on sludge dewaterability, J. WPCF, 1911. 13) Kolousek, J. and Coulson, C. B. (1955), Amino acid content of the seed protein of Trionella foenum graecum L., and of the seed protein and thallus protein of Galega officianalis L., J. Science Food Agriculture, 6, 203. 14) Nour, A. A. M., and Magboul, B. I. (1986), Chemical and amino acid composition of Fenugreek seeds grown in Sudan, Food Chemistry, J., 21(1), 1. 15) Shames, I. H. (1992), Mechanics of fluids, McGraw-Hill International Editions, 3rd Ed., New York.
16) W.P.C.F., Sludge dewatering, Manual of practice number 20, Washington, D.C., Water Pollution Control Federation, 1969.
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The Influence of Additives on the Rheological Properties of Sewage Sludge45 By Dr. Isam Mohammed Abdel-Magid46
Abstract: The research undertaken to study the flow properties of sewage sludge indicated that it exhibits behavior characteristics of both Pseudo-and Bingham plastics with a slight thixotropic behavior. Increasing concentration of solids resulted in an increase in the viscosity-while superacolloidal solids lowered the viscosity, addition of porous additives increase the viscosity and altered the flow characteristics to a Bingham plastic one by adsorbing the superacolloidal fraction.
1. Introduction 1.1 Background: Most of the investigators who studied the rheology of sewage sludge have been concerned with pipe flow and transportation {1,2,3,}. However. Inskster {4} observed an increase in the viscosity upon addition of a coagulant to sewage sludge. He suggested that this might be due to the coalescence of sludge particles. The sludge particles carry a negative charge and when adsorption of ions takes place they will only be partially discharged, thus particles of sludge at different potentials will be attracted to each other and such action will tend to bind the particles together and thus increase the viscosity. However, Coackley {5,6} attributed this increase in the viscosity to the protein layer covering the sludge particles. He stated that the protein reacts with the heavy metal ions of the coagulant, which causes an unraveling of the natural structure and breaking of some cross-linking bonds and thus the viscosity is increased Before attempting to describe the work undertaken to study the influence of additives on the rheology of sewage sludge. A brief note about the rheological behaviour of liquids might be of value. 1.2 Theoretical Considerations: Rheology is the science of deformation and flow of matter. The basic instrument for rheological investigation is the viscometer, and the viscosity is one of the physical properties which is comparatively easily measured. Newton found that when water and similar liquids were subjected to shearing forces, the resisting stress τ. was directly proportional to the shearing rate dv/dy, i..e dv τ =µ dt Where the constant of proportionality µ was termed the liquid's viscosity, which for a given liquid at a given temperature is a characteristic physical constant. However, for many liquids the stress-rate relationship was not a simple ratio. Such liquids are broadly classed as non-Newtonian, and this group includes sewage sludge {1,2,3,4,7}. Real non-Newtonian fluids often show combinations of properties which impart a anomalous behaviours shown by changes in viscosity as the rate of shear stress is varied in magnitude, and for some fluids in the time of application. Such fluids 45 46
Published in The Sudan Engineering Society J., Issue no. 26, June 1984, pp 31-40 Civil Eng. Dept., Faculty of Engineering & Architecture, University of Khartoum
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possess a whole range of viscosity values depending on flow conditions and the characteristics of the fluid. In order to depict the rheological properties a flow curve must be constructed. Figure (1) illustrates the flow curves for some ideal liquids. The flow behaviour of a Newtonian fluid is linear curve at the slope of which gives the coefficient of viscosity. Such characteristics show that shearing commences instantaneously with the application of stress, since the fluid exhibits no internal connected structure, the viscosity is independent of the shear rate. The flow behaviour of a non-Newtonian fluid could not be characterized by a single parameter, viscosity, as in the case of a Newtonian fluid but requires a second parameter, a stipulated shear stress of shear rate. Non-Newtonian fluids could be classified as follows: a) Time-independent fluids: These may be subdivided into several groups. pseudoplastic (shear thinning) dilatant (shear thickening ) viscoplastic or Binham plastics Psecdoplastic materials are those which become increasingly less viscous as the rate of shear is increased. They are usually composed of long molecules, randomly oriented with no connected structure which when sheared tend to disengage and reform thereby reducing the viscous resistance between layers and causing the viscosity to gradually diminish as shear rate increases. The inherent elastic forces cause an immediate reveals of this procedure upon the reduction or removal of the shear rate, and the suspension reverts to its former state {2,9} Dilatance is the opposite of pseudoplasticity. This phenomenon is not common and is associated with suspensions of repelling particles. In the case of Bingham fluids a finite yield stress is required to initiate flow when the solid phase of a suspension is present in sufficient concentration to form a continuous but disoriented structure (curve D) This type of fluid will not recover after deformation but retains the new shape under the gravitational force. {1,2,3}.
b) Time Dependant Fluids: These fluids exhibit time-dependent flow characteristics that can be either spontaneously reversible or irreversible. thixotropic fluids rheopexy or ant thitxotropy Thixotropic fluids possess a structure which breaks down with time when sheared at a given rate until equilibrium is reached at which the internal forces tending to rebuild the structure are equal to the applied shearing force. Here further breakdown can only be induced by increasing the shear rate. When the shear rate is increased in predetermined increments to a maximum and then reduced to zero in the same way, hysterisis is seen if the fluid is thitotopic. The phenomenon seems to be caused by rutpture of week secondary bonds between molecules or particles {12} Arheopectic fluid behaves in the opposite manner to that of a thixotropic one it could be termed time-t hixotrop since the recovery of structure is dependant upon time alone {9} 2. Apparatus: The device used was a Ferrann portable viscometer model VM. This viscometer consists of a rotating outer cylinder driven by a small moter with a second cylinder situated coaxially within it.
102
The instrument is of the Couette coaxial cylinder type. The standard cylinders are made of duraluminiun the inner cylinder is suspended in jeweled bearings and the outer cylinder is driven at constant speed by specially designed two-phase synchronous motor of high torque. The resulting rotation of the liquid exerts viscous drag on the inner cylinder which is free to rotation against a calibrate spring with a pointer to show the angular deflection which is proportional to the viscosity the mechanism for driving and measuring is encased the top of the device with a glass for viewing the dial. The equipment is of robust design. The inner cylinder assembly is protected by the outer one against shocks except upward thrusts along the spindle axis. The jeweled bearing system is so designed that an axis displacement removes the load from the main bearing a balanced friction seating and spring system provides safe return action. The whole of the inner cylinder assembly may be clamped to facilitate the speedy remove of the cylinders for cleaning. To measure the viscosity of a fluid the cylinders at simply immersed in the fluid, the motor is switched on an the viscosity is read on the calibrated dial at the top of the instrument. Should there be any change in the viscosity due to causes as alteration in temperature, chemical composition or thixotropy of the fluid, these can be visualized continuously. Unique features of design eliminate the drag (end effect on the ends of the inner cylinder, thus ensuring that the whoe of the sample measured under uniform shear conditions. The rate shear can be applied for any particular duration of time and it can be altere to other two values simply at the fluid of a switch {11}. 3. Materials and Methods Materials Examined: The materials being investigated in this work were - digested sewage sludge - digested sewage sludge with different solids to centrations - different fractions of digested sewage sludge - digested sludge with different additive
4. Procedure. The instrument was verified for its accuracy, at the various speeds with different combinations of outer and inner cylinders that were available, by using three different oils, namely, Diesel oil, Zircon 5 insoluble oil, and aquicut 40 soluble oil. The viscosities of these oils were determined by a U tube capillary viscometer. These tests were carried out at the same temperature using a thermostat water bath for temperature control. The Standard deviation of the data obtained was checked for each oil, and the coefficient of variation was found to be of the order of 3%. The viscometer was hence, deemed sufficiently accurate for work to be undertaken. The procedure adopted for the tests was as follows: 1. 500ml of the sample were poured gently into a clean and dry glass beaker, which was then placed in the thermostatic water bath that kept the temperature steady at 20ºC. 2. The appropriate cylinders chosen for the test were titled into the viscometer, and then immersed in the sample such that the outer cylinder was just covered by the sample and had a minimum clearance from the bottom of the beaker of 13 mm {11}. Care was taken to ensure that the sample completely filled the inner annulus. The cylinders were allowed to attain the temperature of the sample fluid, if this temperature is different to that of the cylinders, then sufficient heat may be transferred to or from the sample isolated within the annular gap to
103
cause a significant difference compared with temperature measured in the fluid surrounding the cylinder. 3. The lowest of the three gears was engaged and the viscometer switched on. The dial indicator needle rises steadily to a maximum value before falling off gradually in value. At the point of maximum defection a stop- watch was started, this being taken as time zero. 4. Readings were taken each minute for the next five minutes during which time the indicator had dropped to a constant value. At the end of this period the stop- watch was stopped, the second gear engaged thus stepping up the rate of shear, and the stop- watch re-started as new zero time was established. This procedure was repeated for the third good speed. 5. The viscometer was then switched off, withdrawn from the sample carefully, and new inner cylinders were fitted as instructed in the operating manual {11}. And the same procedure was repeated. 6. By using the various combinations of cylinders and gears it was possible to obtain a number of points (mp, G) with which to plot the flow curve as πρ versus G. Note: it is essential for the full success of the method that all apparatus coming into contact with the sample under test be scrupulously clean. Any impurities in the viscometer will cause false results to be obtained {13}. A typical example of the experimental date and calculations is shown in table 1.
5. Results and Discussions The initial tests performed on sewage sludge were conducted to study its flow properties. As illustrated in Figure 2, the apparent viscosity of digested sewage sludge decreases with time when the rate of shear is held constant. After increasing the rate of shear from 8.8 through 37.3 to 92.5 for duration of five minutes in each case the apparent viscosity of the sludge is observed to fall. Thixotropic rebuilding of apparent viscosity is evident when the shear rate was reduced to 13 after which the apparent viscosity is seen to decline as before and drops more dramatically when the rate of shear was augmented to 258. This result is in agreement with Mc Geachie {2} and Somerville {3}. Breakdown in the apparent viscosity comes about in two ways by time of application of shear rate, and by increasing shear rate, the latter causing a much more dramatic effect {2,3,12,14}. Thixotropic breakdown at higher rates was confirmed by the graph drawn in Figure 3: the plotted results of a test in which the shear rate was first increased and then decreased to zero {12} the displacement between the "Up" and "down" curves of the hysteresis loop indicates the degree of thixotropy. These results clearly indicate that digested sewage sludge is a non-Newtonian fluid as the shear stress; shear rate relationship does not follow the characteristic linear flow curves of a Newtonian fluid. When the shear rate was reduced to zero, the viscometer was noted to continue recording a low value which appears to indicate that the sludge possesses and inherent viscosity at rest, i.e., a yield stress, thus representing a Bingham plastic material. Experiments were undertaken to establish the relationship between viscosity and solids content of the sludge. Digested sewage sludge was diluted or concentrated to vary the solids concentration and each sample was analyzed in the Ferranti viscometer. The results of these tests were plotted in Figures 4 and 5. These graphs clearly show that the apparent viscosity of digested sludge increased as the total solids
104
content increased this finding is in agreement with Hatfield {1}, and Buzzel and Sayer {7}. Digested sewage sludge was fractionated into different fractions by centrifugation using Dalla valle's equation {16} to see the influence of the sludge particle size on viscosity. The rheological properties of each size fraction were examined and the results were plotted as shown in Figures 6 and 7. It was seen that the settleable solids fraction (greater than 100x10-6m) tend to acquire the lowest viscosity values with a decrease in yield stress. Addition of additives to digested sewage sludge resulted in an increase in the sludge viscosity as seen from the data obtain and plotted in Figures 8,9,10,11,12, and 13. In this study three different types of additives were those because of the various particle shapes they possess and for the different pores encountered (verified by a scanning electron microscope). The additives being tested were perlite, fly Ashland calcium carbonate, they were introduced to the sludge as a percent of the dry solids content of the sludge. Activated carbon was also used for comparative purposes. When the shear stress was plotted against the rate of shear for activated carbon, perlite and fly ash – Figures 8, 10 and 12 respectively- it was observed that the flow curves exhibited behaviour characteristics that could be well resembled by a Bingham plastic for al the different dosages of additives introduced. The apparent viscosity plots Figures 9, 11, and 13 – indicated an increase in the concentration of additives doses to the sludge. Addition of calcium carbonate was noted not to have significant effect or a greater influence on the viscosity.
6. Conclusions From this work the following points emerged : 1. The rheoological results clearly indicated that digested sewage sludge is not and ideal. Non-Newtonian fluid, i.e., it exhibits behaviour characteristics of both pseudo-and Bingham plastics with only a slight thioxotropic behaviour. 2. Sludge viscosity increased with an increase in the sludge solids concentration. 3. The Presence of supracolloidal solids tends to the viscosity of the sludge while preater concentration settleable solid to serves to increase its viscosity. 4. The supracolloidal solids fraction of digested sludge was found to revive the degree of thixortropic evident from Figure 3 by the rather bigger displacment between the "up" and "down" curves of the hysterisis loop. 5. Experimental results indicated that the addition of porous materials adsorb the supracolloidal solid thus increase the viscosity, and this may be accompanied, by a change in the pattern of the characteristic that of a pseudo-and Bingham plastic for digested to a Bingham plastic one
References 1. 2.
3. 4.
Hatfield, J., “The acidification of a raw sludge" Wat. Pollut. Contr. 68, 1969. 673 McGeachie, G., “The rhelogical properties of sewage related to the hydraulic transport of such sludge through pipelines”, M.Sc., University of Strathclyde, 1970. Somerville, J.P., "An investigation into the rheological properties of digested sewage sludge", M.Sc. University of strathclyde. 1971. Inkster, J.E., "Changes in the viscosity of humus during coagulation”, J. Inst. Sew. Purif. 11, 1945, 177
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5. 6.
7. 8. 9. 10.
11. 12. 13. 14. 15. 16.
Coackley, P., "The theory and practice of sludge dewatering”, J.Instn. Pub. Health Engrs. 64 (1), 1965. Coackley, P., "Development in our knowledge of sludge dewatering behaviour", 8TH. Pub. Health Eng. Conf. held in the civil Eng. Loughborough University of T 1975, 5 Buzzell, J. C. and Sawyer, C.N., "Biohemical vs. physical factors in digester failure”, J. Wat Pollut. Contr. Fed 35, 1963, 205 Dick, R.E. and Ewing B.B., “The rheology of activated sludge”, J.Wat. Pollut. Contr, Fed, 39(1), 1967 Harris, J., "Rheology and non-Newtonian flow". London., Longman, 1977. Hang, P.T. and Brindley, C.W., "Methylene Blue adsorption by clay minerals. Determination of surface areas and cation exchange capacities”, Clay and Clay Minerals 18, 1970,203. McKennel, R. (Ferranti LTD Manchester), "The measurement and control of viscosity and related properties", Instrumental Manual. 1960, section X1. Mewis, J., "Thixotropy. A general review", J. Non-Newtonian fluids Mechs. 6(1), 1979, 1. British Standard Institution, "Method for determination of the viscosity of liquids”, British standards 188, 1977. Karr, P. and Keinath, T.M., "Influence of particle size on sludge dewaterability", J. Wat Pollut. Contr. Fed. 5(8), 1978, 543, 1911 Abdel Magid I.M., “The role of filter aids in sludge dewatering", Ph D. Thesis, University of Strathclyde, 1982 Dallavalle, J.M., “Micromerities, the technique of fine particles”, London, Sir Isaac Pitman, 1948.
Table 1 Viscosity analysis Sample: Digested sludge Yield Stress, τ: 5 dynes/cm 2 Range of shear rate, G: 8.8 to 258 s-1 Range of apparent viscosity,µρ: 0.6 to 0.4 poise Temperature: 20° C Solids content: 2% Time (min) 0.00 5.00 0.00 5.00 0.00 5.00 0.00 5.00 0.00 5.00 0.00 5.00 0.00 5.00 0.00 5.00
Reading
C.F.
1.0 0.9 1.5 1.4 2.2 2.0 1.2 1.1 2.6 2.5 3.8 3.5 1.7 1.6 3.8 3.7
0.3944 0.09221 0.03718 0.2401 0.05614 0.02263 0.01026 0.02398
(µρ) (Poise) 0.394 0.355 0.138 0.129 0.082 0.074 0.288 0.264 0.146 0.140 0.086 0.079 0.174 0.164 0.091 0.089
G (s-1) 8.8
J (dynes/cm 2) 3.47 3.12 37.3 5.15 4.81 92.5 7.59 6.85 13.0 3.74 3.43 54 7.88 7.56 134.0 11.52 10.59 25.0 4.35 4.10 104.0 9.46 9.26
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Remarks Vmcyl C" speed 1 …….. …… 2 …..2 ….3 ….3 ….B ….1 …. ….2 …2 …3 …3 …A….! ….A …1 …2 …2
0.00 5.00
6.8 6.7
0.00967
0.066 0.065
258.0
Note: 1 poise –1 (dynes/cm 2) s = 10 –1 (N/m2) s
107
17.03 16.77
…3 …3
108
109
110
111
112
113
114
115
116
The Influence of lime and Grease Dewaterbility on Sewage Sludge47 By Isam Mohamed Abdel Magid48
Abstract The research has been undertaken to study the effect of lime addition on sludge dewaterbility revealed that filterability measurement are influenced by time. Divalent cations were found not to affect the filterability of sludge; thus the effect of lime is to reduce cake compressibility and lend structure and rigidity to the sludge that expedites the progression of the filtrate at high pressures. Grease was capable of deteriorating sludge dewaterbility and thus hampers its filterability. Lime may act as adsorbent adsorbing grease on the surface of its particles. 1. Introduction When grease is encountered in sufficient quantities it blinds screens, and causes clogging of filters, nozzles and sand beds {1}. Chemicals used to get rid of the problems created by the presence of grease. White and Baskerville {2} reported that the use of ferric chloride and lime to condition the sludge had solved the problem of server cloth blinding and low cake yields on a disc vacuum filter that dewaters sludge with high grease content and they related this to lime reaction with grease or fats. Also Coackley {3} suggested calcium reaction with grease. Webb {4} said that the grease content of primary sludge contributes greatly to their poor filtration characteristics, due partly to their ability to form an impervious film across the filtration medium. Webb concluded that the effect of specific resistance reduction must be due to the interaction of lime with the hydrophilic organic components of the sludge. Its effectiveness was explained in terms of a calcium complex with functional groups on the sludge solids. The formation of this calcium complex was thought to be the principal reason for improved filterability. Calcium carbonate formation reduced filtration rates because of the adverse effect of the fine precipitates solids on cake permeability. Sontheimer {5} stated that lime reacts with sludge components, particularly during longer contact periods, to form calcium salts and calcium addition compounds. To characterize the different sludge used he defined the lime bonding capacity as the amount of lime which is fixed to a predetermined quantity of solid waste. Analysis of different sludges indicated that raw-waste activated sludge and digested sludge had a higher lime bonding capacity than primary sludge. Sludge with higher lime bonding capacity required larger doses of conditioner and were more difficult to dewater. Sontheimer produced data showing that formation of calcium carbonate by the neutralization of added lime with calcium dioxide increased sludge filtration rates until all the free calcium had precipitated as calcium carbonate (However, this result dose not agree with Webb’s findings). When the calcium bonded to the sludge solids began to carbonate, sludge filtration rates decreased. Christensen and Stulc {6} suggested that calcium carbonate functioned as an inert filter aid and that the calcium reactions with the sludge impaired lime conditioning. Coackley {3} declared that the addition of lime improves the drying properties of the sludge. During the constant rate period the drying rate increases from 0.22 kg/m2/hr for untreated sludge sample to 0.32 kg/m2/hr for sludge with lime addition. The particle size analysis showed some small changes in the distribution of the particle after lime addition, and a skeleton of less compressible material is formed; as drying 47 48
Published in the Sudan Engineering Society Journal, Issue 29, December 1986, pp 26-32 Civil Eng. Dept. Faculty of Engineering and Architecture, University of Khartoum, Sudan
117
proceeds the moisture moves to the surface through the cake. The downward forces between the particles increases and a pressure gradient is formed In the presence of lime, the deformation of the particles under the applied load decreases. This ensures a stable voidage and hence a decrease in the resistance of moisture movement to the surface and increased rate of drying. A similar effect to that of digested sludge was observed when activated sludge was examined. Results of studies on the use of inert additives led Coakley to suggest that part of the function of the lime, most of which is insoluble and remains as finely divided solid in the cake, is to reduce the compressibility of the cake and create a stable structure which expedites the passage of the filtrate through the cake at high pressures. 2. Methods and Materials The sludges examined in this work were digested sewage sludge and raw sludge. The specific resistance test was performed using an ordinary Buchner funnel. The experimental procedure adopted was as follows: 1. The solids content of the sludge was determined. 2. A Whatman filter paper No. 1 was wetted with distilled water and placed in the funnel. When applying high pressures two papers were used, 3. It was ensured that the filter paper made contact around its periphery with the funnel. The vacuum applied to remove the excess moisture. 4. Lime was added to the sludge with different proportions ranging from 0.15 to 0.5g/g of the sludge. 5. 100 ml of the sample was poured carefully from the same height and at same rate of pouring into the funnel. 6. The filtration pressure was increased by a regulating valve at an even rate from zero to working pressure, and the stop watch was started, 7. The temperature of the filtrate was noted after each test and the viscosity value was obtained accordingly from {7}. 8. Triplicate test were performed in each case and the mean value was taken in order to calculate the specific resistance. The equation used for specific resistance determination was that developed by Coackley {8,9,10}: 2b P A 2 r= µ .C Where, r is the specific resistance. (m/kg); b is the slope obtained by plotting the ratio (time of filtration / filtrate volume) against filtrate volume (s/m6); P is the applied pressure (N/m2); A is area of filtration (m.2); µ is the filtrate viscosity ( Ns/in2); and C is the solids content (kg/m3). The compressibility coefficient s is computed from the specific resistance variation with pressure by Carman equation {11}: r = r' Ps in which r is the specific resistance to filtration at applied pressure P and r´ is a constant. 3. Results and Discussions The literature indicated that sludge dewatering characteristics altered rapidly with time. To obtain better understanding of the magnitude of these changes and the rate that they occur, raw sludge was refrigerated for one month. Specific resistance, r, pH. and solids content were determined periodically through this period. The results are present in the table (1):
118
Table (1) Effectiveness of refrigeration as a preservative to raw sludge Temperature 20° C Measurement Specific resistance, r x 10 13 m/kg pH Solids content (g/1)
Day 0 19.56
Day 1 19.61
Day 2 29.35
Day 3 29.6
Day 4 42.34
Day 7 42.85
Day14 Day31 50.34 51.56
5.6 50.0
5.6 50.0
5.5 50.0
5.5 46.0
5.4 44.6
5.4 40.0
5.2 43.9
4.0 42.0
As shown in the table, the specific resistance values began to increase after two days of storage and is deteriorated greatly after the thirty first day of storage. The solids concentration and the pH decreased with lime which was an indication of biological degradation. No fungus growth was observed during the storage period. Foul odors developed in the refrigerated sample. For these reasons majority of the analysis were confined to digested sewage sludge rather than to raw sludge. The purpose of the experimental programme described herein was to develop data that may provide insight into the sludge parameters of importance in conditioning with lime. The general approach has been to relate chemical addition to sludge filterability, Experiments were conducted to find the effect time exerts on sludge to which lime was added. It was observed, as shown in figure I; that the specific resistance deteriorates significantly after 24 hours for digested sewage sludge to which various doses of lime were introduced. This confirms Webb’s findings {4} that the filterability of primary sludge conditioned with lime, deteriorated on standing for 20 hours and a delayed filterability test should be performed when evaluating chemical conditioners. Paulsrud and Eikum {12} reported that the specific resistance increased with increasing storage time for primary sludge with no lime and with 50g Ca(OH)2 and 100g Ca(OH)2 per kg total suspended solids. They also found that the specific resistance increased with decreasing pH during storage, resulting in anaerobic conditions. The drainage rate of lime-stabilized sludge increased with increasing lime dosages, but decreased again during storage. While adding lime lo humus sludge. Taylor {13} found that the results obtainable by standing over-night before filtration were invariably much inferior to those from immediate filtration. This agrees with Graefen and Donges work {14}. However, these findings are in contradiction with Sontheimen, {5}. It was concluded from this work that the filterability measurements should he performed once lime was added to the sludge. A series of experiments were carried out by dosing lime to digested and raw sewage sludge to determine what levels of lime are required to condition those sludges. Graphically Figure 2 indicates that the reduction in the specific resistance is very low for digested sludge. There is no optimum dosage, expressed as a percentage of the dry solids of the sludge. Other divalent cations such as calcium chloride, magnesium chloride and magnesium hydroxide were being tried as conditioners to digested sludge but no reduction in the specific resistance was noted. This confirms Coackley and Wilson {15} statement that well digested and activated sludges are not greatly affected by divalent cations. So the effect of lime is to reduce the compressibility of the cake and create a stable structure that expedites the progression of the filtrate through the cake at high pressure. The compressibility coefficient was reduced by about addition by about 20 percent.
119
Upon the addition of lime to raw sludge, the specific resistance was greatly reduced al higher dosages as could be seen from figure (2). A known amount of lime was dissolved in distilled water, such that it acquired a solid content comparable to that of the sludge under examination. A specific resistance test was performed and it was found that the specific resistance of this sample was 67.67 x 109 m/kg at a pressure of 68.95 k N/m2. So the net effect lime exerts on the sludge, was to lower its specific resistance to the above mentioned value. The compressibility coefficient of this slurry was found to be 0.039 a value approaching zero; thus indicating that lime was an incompressible material thereby it lends structure and rigidity to the sludge. To understand whether the reduction in the specific resistance after lime addition was due to reaction of lime with grease present in the raw sludge or whether it is due to the lime acting as a filter aid giving the cake a support skeleton, experiments of grease extraction were performed. At the beginning of the work, raw sludge was used and the grease present in it was extracted according to the standard methods {16}, but due to the nature of the raw sludge and since it can not be preserved for long periods of time and because of the obnoxious odors created, it was abandoned and digested sludge was used instead. Various dosages of lime were added to a sample of digested sewage sludge and the specific resistance was found accordingly. This served as a control. Another set of experiments was performed on the same sludge to which standard grease was added. The standard grease prepared was composed of margarine because it resembles and duplicates the grease found in the sludge (Tables 2 and 3). As could be seen from figure 3, lime addition affected the filterability of the sludge, but it was not lowered greatly except when higher values of lime were added. It was observed that the specific resistance of the digested sewage sludge increased after grease addition, indicating that grease was capable of dewaterability and thus hampering its filterability. A set of experiments was done to see the effect lime exerts on grease. This was accomplished by adding a fixed amount of grease and varying the amount of lime added to the digested sewage sludge. As could be seen from table 4, no final conclusions could be drawn since the amount of grease extracted varies with the amount of lime added. Nonetheless in all the experiments performed, a small amount of grease was extracted and this might depict that effect of lime on grease was not chemically but rather physically in the sense that lime acts as an adsorbent adsorbing grease on the surface of its particles.
120
Table (2) Composition of total Grease as Reported by Various Workers Reference number {17} {18} {19} {20} {21} Range Unsa ponfiable matter 22 15 15-20 24 12 12-24 as % total grease Saturated fatty Acids as % 71 57 83 86 52 52-86 total fatty acids Free fatty acids As% total 5 53 26 48 5-53 fatty acids Oleic acids As % total 52 79 97 97 48 52-97 unsaturated acids Total grease as % organic 33 27 23 23-33 matter Iodine value (IV) 31 34-54 31-54 Table (3) Composition of Margarine {22.23} Saturated fatty Acids 82% Unsaturated fatty acids 52% Free fatty acids Less than 10% Iodine value 53 Melting point 33-39°C Water content 16% Vitamin A 8-10 µ g/g Vitamin D 0.07-0.08 µ g/g Calorific content 8 ca1/g Table (4) Grease Extracted from Digested Sludge after Lime Addition Lime added (g/g) Grease recovered as % dry solid Zero 11.4 0.15 10.3 0.20 5.9 0.25 7.6 0.30 9.2 0.35 8.9 0.40 4.1 0.45 7.3 0.50 6.6 4. Conclusions From this work it could be concluded that: 1. Filterability measurements should he performed once lime was added to sewage sludge. 2. Divalent cations do not greatly affect the dewaterability of sewage sludge. 3. Lime effect is to reduce cake compressibility and lend structure and rigidity to the sludge. This expedites the egress of filtrate at high pressures, 4. Grease is capable of deteriorating sludge dewatering characteristics5. Lime may act as an adsorbent for grease.
121
References 1. 2. 3.
4. 5. 6. 7. 8. 9. 10. 11. 12.
13. 14.
15. 16. 17. 18. 19. 20. 21. 22.
Gicreas, F.W., Sanderson. W.W. and Elmer. R.P."Two new methods for the determination of grease in sewage" Sew. Indus. Wastes, 25, 1953, 1379—90, White, M.J.D. and Baskerville, R.C. "A solution to a problem of filter cloth blinding" Effluent and Wat, Treat. J. 1974, 503-5, Coackley. P, "Development in our knowledge of sludge dewatering behavior" 8lh Pub. Health Eng- Conf. held in the Dept. of Civil Eng., Lough bou rough University of Techno. 1275, 5-32. Webb, L.J. "A study of conditioning sewage sludge with lime" Wat. Pollut. Contr. Fed., 73, 1974, 192-206. Sonthcimcr. H. "Effect of sludge conditioning with lime on dewatweing" Proc. 3rd Inter. Confer. Advances in Wat, Pollut. Research, Munich. Pergamon, 2, 1967, 165-94. Christensen, C.L. and Stulc. D.A. "Chemical reactions affecting filtrabilily in Ironlime sludge conditioning" 1, Wat. Pollut- Contr. Fed., 51(10). 1979, 2499-2512. Weast. R-C. "Handbook of chemistry and physics" 57th Edi.. 1977. Coackley, P. "Research on sewage sludge" Report No, 3 carried out in the Chadwick lab. Dept. of Civil Eng. University College London. 1954. Coackley, P. "Research on sewage sludge carried out in the Civil Eng, Dept. of University College, London" J. Proc. Inst. Sew. Purif. 1.1955, 59-72. Coackley. P. "The theory and practice of sludge dewatering "J. Instn, Pub, Health Engrs. 64 (1). 1965, 34-47. Carman. P.C. "Fundamental principles of industrial filtration." Trains. lnstn. Chem. Engrs. 16, 1938, 168-88, Paulsrud. B. and Eikum. A.S. "Dewatering properties of lime stabilized, sewage sludge” Wat. Pollut. Research Proc. 8th Inter confer., Sydney, Australia 1977, Jcnkins Pergamon, 337-346. Taylor. G. "Some humus sludge conditioning experiments" J. Proc, Inst. Sew, Purif1957, 242-51. Graefcn, H. and Donges, H., J. "Studies on parameters affecting sludge dewatering in pressure filters" Advances in Wat. Pollut, Research Proc, 5lh Inter. Conf. Held in San Francisco and Hawaii. 1.1970, Jenkins, Pergamon. 1130/1 - 1130/10. Coackley, P. and Wilson, F., "Flocculation with special reference to water and wastewater engineering" Filter, and separ., 1971, 61-5. Standard Methods for the Examination of Water and Waste Water" 15th Edi.. 1980. Amer. Pub. Health Assoc,. Washington. D.C. Hatfield. J. "The, acidification of a raw sewage sludge" Wat. Pollut confer, 86, 1969, 673-8. Hcukelekian. H. and Balmat. T-J.L. "Chemical composition or the particulate fractions of domestic sewage" Sew, and Indus. Wastes. 31.1959, 413-23. Mueller. P. and Hcukclckian. H. "Transformation of some lipids in anaerobic: sludge digestion." Sew. and Indus. Wastes. 30, 1958, 1108-20. Hunter, J.V. and Heikelekian. H. “The composition of domestic sewage fractions" J. Wat.Pollut. Contr. Fed- 37, 1965. 1142-62. Viswanathan, C.V,. Bai , B.M, and Pillai. S.C. "Fatty matter in aerobic and anaerobic sewage sludge" J. Wat. Pollut.Contr. Fed. 34. 1962, 189-194. Van Den Berghs LTD. "Facts about margarine" London, Taylor, Unilever research Div., 1969.
23. Williams, P.N. and Andersen. A J.C. "Margarine" London. Pergamon Press, 1965.
122
Design Basis for Sewage Treatment Units by The Activated Sludge Process49 By Dr. Chalabi, M. F50. and Dr. Abdel-Magid, I. M.51
Abstract The activated sludge process is considered to be one of the most efficient and reliable methods of sewage treatment. It is also the most suitable method of treatment if the final effluent is to be disposed in the canals, streams, lakes, rivers, or sea, without pollution or danger to aquatic life. This paper is concerned with the design basis of the different units used in treating raw domestic sewage by the activated sludge process. Besides it gives design basis of the units used for processing the separated sludge. These units include digestion tanks, vacuum filters, and flash dryers for the production of a high grade and hygienic nitrogen phosphorous fertilizer {1.2.3.9.}. The daily sewage flow rate arriving to the treatment works is determined from the water consumption. This ranges from 150 to 300 liters per capita per day depending upon social economic status of the consumers. The units of the treatment works are designed on the basis of a maximum hourly influent flow rat equal to one sixteenth of the daily flow rate). This is due to the fact that half of the domestic sewage flow is discharged during a period of 8 hours whereas the other half is discharged during a period of 16 hours. The physical and chemical analysis of an average sample of the sewage to be treated is necessary for the design. It enables estimating capacity and power requirements of the different materials handling equipment including sludge pumping sets and air compressor units, sludge digestion tanks, filters and dryers. The analysis should ordinarily be made on composite samples prepared in the following manner: individual samples are mixed together or composite on the basis of the volume of flow of the sewage at the time each sample was taken. During the early morning hours, as from 2 A.M. to 5 A.M. the flow of sewage is least in volume and weakest in strength as well. The greatest flow and the strongest sewage concentration as regards organic matter usually occur from 8 A.M. to 1 P.M. and there is secondary but small peak in the later afternoon. The design bases of the different units are presented in the same sequence and order of arrangement of the units in the treatment works.
49
Published in World of Engineering Journal, pp 4 - 6 Professor in Chemical Engineering, Faculty of Engineering, United Arab Emirates 51 Lecturer in Civil Engineering, Faculty of Engineering, United Arab Emirates 50
123
Grit chambers: Grit chambers function mainly for removing grit particles having a specific gravity of 2.5 and diameters exceeding 0.15 mm. Such particles are so light that they settle down under laminar flow conditions, within Stoke's law range. The setting velocity could be estimate as:
U1 =
g D 2 (P − Pf
)
= 9.81 ×
(0.15)2
×
(2.5 − 1) 10 3
= 0.0184 m / s 18 µ f 18 × 0.001 10 6 If a minimum detention period of one minute is allowed for, then such particles will fall a vertical distance of 0.0184(60) =1.1 meters. Thus the depth of flow in grit chambers is limited not to exceed 1.1 meters. If the velocity of sewage along the cross sectional area of flow is limited not to exceed 0.30 m/second, then the chamber length will be limited to 0.30 x 60 = 18 meters. Pre-Aeration tanks: Pre - aeration tanks function for removing oil and grease by blowing air through air diffuser located at the bottom of the tanks. The minimum detention period in these tanks is limited at 10 minutes with the application of 0.75 of free air per cubic meter of sewage.
Primary Clarifiers Primary Clarifiers function as sedimentation tanks to remove the greatest part of suspended solids and organic matter in the sewage. It should affect the separation of at least 60% of the total suspended solids. The particles separated in these tanks have a specific gravity close to unity, about 1.07, and the diameter averages 0.1 mm. By applying Stoke's law the terminal velocity of fall of such particles is calculated as:
9.81(0.01) (10) (1.07 − 1) × 10 3 = 0.38 × 10 2 m / sec ond 18 × 0.001 2
U=
4
To ensure the separation of such particles the surface loading in the tanks is limited not to exceed: 0.03 x 10 2 x 3600 = 1.08 m3/m2/hr To avoid turbulence in the tanks it is necessary to have a sufficient weir length so as to limit the overflow rate over the weir not 7.8m/hr/meter length of weir. The capacity of the tanks is determined by the detention period, which equals 1.57 hours at maximum hourly flow rate. The amount of primary sludge plus excess activated sludge (surplus sludge) introduced with the influent to primary clarifiers can be determined from its concentration of solids (4.5% solids by weight). The sludge content of solids can be determined by subtracting from the total amount of suspended solids existing in the raw sewage that part remaining in the final effluent which may be as small as 30 p.p.m. Aeration Tanks These functions for the biological oxidation of organic matter by introducing air at diffusers located at the bottom of the tanks. Air requirements, aeration period, and the quantity of returned sludge are functions of 5-day B.O.D.(8). The air requirements for aeration and reactivation tanks are base on 0.0375m3 free air per each ppm of B.O.D. to be removed per cubic meter of sewage. Aeration period and the quantity of
124
returned sludge can be deter minded from design charts such as that given by Mynhier {7} or Freeze {10}. For example, the amount of returned sludge corresponding to the removal of 600 ppm of the 5-day B.O.D. amounts to 55% of the sewage flow, and the aeration period equals 8.5 hours. The capacity of aeration tanks is determined from the required detention period and the volumetric flow rate of sewage plus the returned sludge. Reactivation Tanks for Returned Sludge: These tanks function for reactivating the sludge returned from secondary clarifiers to aeration tanks. The capacity of the tanks is determined from the volumetric flow rate of the returned sludge determined as mentioned in the previous item and a detention period for reactivation of 8 hours {5,6}. Secondary Clarifiers: Secondary clarifiers function for separating suspended solid which were previously oxidated and settle at higher rate than solids in primary clarifiers. The surface loading is limited not to exceed 1.7 m3/m2/hr {4} to avoid turbulence the maximum overflow rate over the weir equals 7.8 m3/hr/meter {4} to avoid turbulence the maximum overflow rate over the weir equals 7.8 m3/hr/meter length of weir. The minimum detention period shall not be less than 1.75 hr. the greatest part of the separated sludge in these tanks is returned to the reactivation tanks and the remaining part (surplus sludge) is introduced with the raw sewage fed to the primary clarifiers. To affect this, two different sets of pumps are needed, returned sludge to aeration tanks is determined on basis on an average weight percent of suspended solids in the mixed liquor of 0.25% and dry solids concentration in the sludge of 2% by weight Post Chlorination: Post chlorination affects the sterilization of the final effluent. The chlorination equipment should be capable of providing 15 ppm of chlorine at maximum effluent flow rate. The capacity of the chlorine contact chamber is determined on basis of a detention period of 15 minutes. Sludge Digestion Tanks: Sludge digestion tanks function for digesting the sludge separated in primary clarifiers to produce digestion gas rich in methane. The digestion gas is used as fuel in duel engine generating sets providing electric power. It is also used as fuel for sludge drying and to produce the hot water required to hold the digestion temperature at 40ºC
Conclusion The design data presented in this paper is a useful guide for engineers studying projects for sewage treatment works by the activated sludge process. It enable s them to predict the capacity and main dimensions of suitable treatment units. It also helps them to estimate the capacity and power requirements for the different materials handling equipment such as air compressors and different sludge pumping sets. Sludge processing units including digestion tanks, vacuum filters, and flash dryers can be specified by making use of the relevant data mentioned in this paper and the actual analysis of the sewage under treatment.
125
The Omani Regulations for Wastewater Reuse and Discharge - A Critical Review By Dr. Isam M. Abdel-Magid, Dr. Hayder A. Abdel Rahman52 and Dr. Alaa ElZawahry53 Abstract The regulations for wastewater re-use and discharge in the Sultanate of Oman were first introduced in 1986. The combined regulations, for both re-use and discharge, were rather strict and closely followed the drinking water standards. This paper gives a critical review of the existing regulations and makes procedural recommendations. The impact of quality parameters on industrial sectors is manifold. Reuse of hygienically wholesome and potable water would add its merits to both the industrial and agricultural sectors. Likewise proper disposal of industrial, agricultural, domestic and otherwise generated wastes according to predetermined criterion would safeguard the environment. This demands formulation, updating and implementation of guidelines that would properly serve the water sector in the Omani various and varying districts and regions. Relaxed guidelines, rather than standards, are suggested, whereby each and every source of discharge and sink of re-use is given a separate guideline. Industrial wastewaters should be pre-treated, and disposal into surface streams, ocean or ground water should be regulated. Introduction The Sultanate of Oman is known to be one of the few countries in the region, and indeed in the world, which has been environmentally conscious and gave conservation and prevention its utmost attention. The regulations set aside ministerial decision 5/86 for waste-water re-use and discharge complies with the law of Conservation of the Environment and Prevention of Pollution issued by Royal Decree 10/82 and its amendment, to provide health and social welfare for the people and protect the land and water resources of the country. Water quality criteria ask for formulation, adoption and enforcement of standards and regulations. This is necessary and vital to the water and wastewater authorities in the Sultanate of Oman. The benefits to be gained are abundant. Thus, efforts addressing the formulation and implementation of standards, or the evaluation, updating and improvement of existing standards have top priorities.
National standards involving quality control, that need to be implemented for The Sultanate of Oman, need to deal with interacting and overlapping parameters such as: climate, cultural and social habits, diet, Socio-economics, inhabitants’ believes, local customs, methods of treatment and final disposal,agricultural and industrial sectors, and regulations governing disposal. (Abdel-Magid & El-Hassan, 1987; AWWA, 1968; Gorchev & Ozolins, 1982; Ongerth & Dewalle, 1980;WHO, 1970; WHO, 1971, WHO, 1972; WHO, 1984) To be able to implement, evaluate and follow up any adopted standards, ways and means for proper surveillance should be secured. This includes the following: 52 Assistant Professor, College of Engineering, College of Agriculture, Sultan Qaboos University Sultan Qaboos University 53
Assistant Professor, College of Engineering, Sultan Qaboos University
126
optimum required number of well-trained staff and personnel, continuous flow of laboratory supplies and equipment, and proper supervision. Such a task would make use of the competent transportation system in the country. Likewise, it would establish appropriate links between different authorities working in the environmental domain. Abdel-Magid and El-Zawahry, 1992. The aforementioned components to be fulfilled through one standard are hard to fulfill for the entire country. Nonetheless, adoption of guidelines rather than standards would prove the right selection. Formulated guidelines could be read into local regulations or articles or standards in different regions (Wilaiats) whenever practical, bending changing variables. Critical review of the existing regulations Table (1) outlines the limits set for concentrations of elements in waste-water parameters. The standards for drinking water and water used for irrigation purposes, as set by the authorized Omani ministries, are incorporated in table (1) solely for comparison purposes.
It is to be pointed out that the already formed and used Omani standards for drinking water quality resemble greatly the WHO standards (WHO, 1971). In case of wastewater and sludge treatment and disposal the Omani Regulations mainly has been divided into three broad groups. The first group indicates parameters to be considered for wastewater reuse, discharge and sludge disposal (Ministry of Environment, 1986a). Table (1) gives an outline of the Sultanate of Oman Regulations concerning wastewater reuse and discharge. According to article 5 of the regulations: wastewater must meet all the conditions shown which include the maximum limits permitted for its reuse. As outlined in table (1) more emphases were placed on chemical substances. Radioactive materials are covered in a separate article [Article 15], which do not permit reuse of waste-water or sludge containing radioactive material. The discharge of wastewater or sludge containing radioactive material shall in addition to these Regulations be subject to Regulations laid down by the International Atomic Energy Agency or such other regulations that may be issued by the Ministry of Environment and National Resources [now the Ministry of Regional Planning and Environment]. (Ministry of Environment, 1986a). Biological and bacteriological characteristics as laid down by the water standards (Ministry of Commerce, 1978) differentiate between treated water and untreated water. with regard to the former three points are high-lightened: i.e. no sample should contain E. coli in 100 mL; no sample should contain more than 10 coliform organisms per 100 ml; and throughout the year, 95 % of samples should not contain any coliform organism in 100 mL. AS regards the latter two points are indicated namely: no sample should contain E. coli per 100 mL; and no sample should contain more than 10 coliform organisms per 100 mL. Disposal of sludge is limited to treated sludge with characteristics in agreement with that is as indicated in table (2).
127
Table 1 Concentration of Elements in Waste-water Parameter, Drinking Water and Irrigation Water (All units are in mg/l unless otherwise stated)
Wastewater? (ME, 1986a)
Drinking water (WHO, 1972)
Irrigation water (Ayres & Westcot, 1976)
Parameter Max*
MA4W**
HDL+
MPL++
Max-CT#
Max-20##
1500
1000
500
1500
-
-
Turbidity (NTU)
5
2
5
1
-
-
Taste
-
-
unobjectionable
-
-
Odour
-
-
unobjectionable to most of the consumers
-
-
Colour
-
-
Absent
15 TCU
-
-
Turbidity
-
-
Absent
-
-
-
2.0
2.0
-
-
-
-
Al
5
1
-
-
5
20
As
0.2
0.05
0.05
0.1
0.1
2
B
2
1
-
-
0.75
2
Ba
2
1
1
1
-
-
Be
0.3
0.1
-
-
0.1
0.5
BOD5
15
10
-
-
-
-
TOC
50
20
-
-
-
-
0.03
0.01
0.01
0.01
0.01
0.05
0.5
0.5
-
-
-
-
Cl
350
250
200
600
-
-
Co
0.5
0.1
-
-
0.05
5
COD
100
50
-
-
-
-
CN
0.1
0.05
0.05
1.5
0.2
5
Cn
2
2
0.05
0.2
-
-
Cr
0.5
0.1
0.05
0.05
0.1
1
Cu
0.3
0.2
-
-
-
-
2
1
0.8
1.5
1
15
Physical Total Solids
Dissolved Oxygen Chemical:
Cd Chlorine, Free Residual [After 60 min. contact time]
F
128
Fe
5
1
0.1
1
5
20
Hg
0.005
0.01
0.001
0.002
-
-
Li
10
2.5
-
-
2.5
2.5
Mg
150
30
30
150
-
-
Mn
1
0.2
0.05
0.05
0.2
10
Mo
0.05
0.01
-
-
0.01
0.05
N
5
1
-
-
-
-
Kjeldahl N
10
5
-
-
-
-
Total N
50
30
-
-
-
-
Na
200
70
-
-
-
-
Ni
0.5
0.2
-
-
0.2
2
NO3
50
20
45
10
5
30
Oil and grease
5
2
-
-
-
-
Pb
0.5
0.1
0.1
0.05
5
10
pH
6-9
6-9
7-8.5
6.5-9.2
6-8.5
6-8.5
Phenol
1
0.1
0.001
0.002
-
-
-
0.1
0.05
-
-
-
-
Se
0.05
0.02
0.01
0.01
0.02
0.02
SO4
400
200
-
-
-
-
Zn
5
2
5
15
2
10
Vanadium
1
0.1
-
-
-
-
Total Coliforms [MPN/100 ml]
23^
2.2^^
-
10
-
-
Viable Pathogenic Ova & Cysts
None detectable
-
-
-
-
S
Bacteriological
Key ? Parameter Limits not greater than stated values. ^ Not to be exceeded in any sample. ^^ Determined over last 7 days of completed analysis. * Maximum value. ** Monthly average over any four consecutive weeks. + Highest desirable level. ++ Maximum permissible level. # Waters used continuously on all soils. ## Waters used up to 20 years on fine textured soils of pH 6-8.5.
129
Table 2 Limits for disposal of sludge (Ministry of Environment, 1986a) All units are in grams per ton of dry matter Parameter Limit (not greater than) Cadmium 30 Chromium 1000 Cobalt 100 Copper 1000 Lead 1000 Molybdenum 20 Nickel 200 Zinc 1000
The second group of the Omani regulations as related to waste-water and sludge treatment and disposal concerns external building drainage(Ministry of Environment, 1986b). Emphasis has been laid towards surface water drainage system to be disposed from buildings into sewers or otherwise. The regulations forbid discharge of trade waste to surface water drain or channel without prior consent of the municipality for the area. Design parameters were also governed by the regulations e.g. gradient of channels, diameter of pipes, gullies, manholes locations and size, ventilation, testing..etc. Penalties and fines to be paid by persons who do not complying with the regulations are also outlined. The third group of the regulations in filed of waste-water and sludge treatment and disposal has been allocated for regulations concerning septic and holding tanks ( Ministry of Environment, 1986c). The regulations focus on septic tank selection, capacity, effluent discharge to soakaway pit or other underground percolation system, material of construction, maintenance, cleaning. A septic tank design criterion was completely covered in these regulations. The regulations elaborated on the percolation test and soak away pit design. Typical septic tank sanitary engineering drawings were included in appendixes. Holding tanks are dealt with in terms of installation, effluent discharge, construction materials, and their design criteria. In general standards or regulations or guidelines for wastewater and sludge disposal are desirable to be divided in specific divisions that embody relevant areas. Suggested divisions may include: pretreatment, waste disposal in natural bodies of water; industrial waste disposal in sewers; water reuse for agriculture; water use for swimming and recreation; and water use for specific intentions. From the critical review carried herein with respect to the Omani wastewater reuse and disposal standards the following points emerged: General comments: Both the Re-use and Discharge parameters have been given the same standards and limits. Standards required for re-use, according to purpose, are necessarily not the same as those accepted for wastewater discharge. The adoption of guidelines, rather than standards would be a reasonable approach. It is important not to set strict regulations and be confronted with the difficulty of imposing them. Guidelines substantially need to differ according to source of discharge and origin of waste that could mostly be industrial, domestic or agricultural releases. Guidelines significantly ought to vary according to re-use potentials, whether for agricultural, industrial, domestic, recreational, or other objectives. Guidelines require consideration of the socio-cultural habits; water availability, water need; annexation and extension of services, and amenities. The already set Omani limits, closely follow those submitted for drinking water, a comparison of which is given in Table (1). This has great implications on applicability and cost incurred in maintaining established limits, which might drive some industries out of business.
130
Specific technical comments: The limits laid for inorganic substances that are considered hazardous to health such as lead, selenium, cadmium, cyanide, etc., need to be revised. The limits set might be too stringent. The organic list of health significance only mentions phenols. Many constituents need to be included. Examples of these compounds are the organic micropollutants: chlorinated alkanes and alkenes, chlorophenols, benzene compounds, polynuclear aromatic hydrocarbons in plastic and synthetic waste, trihalomethanes, pesticides, insecticides, herbicides in pesticide and agricultural waste, mercaptants in oil refinery waste and fertilizers in agricultural waste. Limits should be set for re-use of wastewater or sludge containing radioactive material. A general mention was pointed to radioactive substances in Article 15 of the Omani regulations. Provision of an appendix summarizing the Regulations laid down by the International Atomic Energy Agency [IAEA] would be of great help to all those concerned. Limits assigned for the aesthetic quality elements such as total dissolved solids, turbidity, hardness, pH, sodium, zinc, aluminum, copper, chloride, zinc..etc., come very close to those limits set for drinking water. The aforementioned pollutants refer to concentrations of substances within effluent. These need to be substituted by total pollutional load discharged to encounter volumes of wastes. Otherwise effluent standards are to be supplemented with a variable ultimate value [ ceiling ] for each particular pollutant from abutting industries. Even though the treated wastewater is now being mostly used for irrigation, yet two of the most important parameters in evaluating irrigation water quality are not specified. The electric conductivity (EC) of the water in milli-siemans/cm [millimohs/cm] is a measure of the salinity [chlorinity] threat to be encountered with continuing use of such waters. The Sodium Absorption Ratio (SAR) calculated as: SAR = Na/[(Ca + Mg)/2]½ is a measure of the sodicity hazard. The adjusted SAR takes into account the precipitating effects of carbonate (CO3) and bicarbonates (HCO3) present in the water. Accordingly, irrigation water is classified from low sodium/salinity hazard to very high sodium/salinity hazard. No limits are set for calcium, which renders calculations of the SAR not possible. High salt concentrations may be avoided by mixing with better quality water from another source and adding gypsum or CaSO4 to the soil can reduce the SAR value. Bacterial contamination of water is normally not serious from the irrigation viewpoint unless severely contaminated water is used on crops, which are eaten uncooked. Some chemicals could be toxic to plants and concentrations of boron above 0.5 mg/liter are deleterious to citruses. Other draw backs resulting from the implementation of the already formulated and used regulations require: a) b) c) d)
Quite a number of skilled technicians and personnel. Reliable and advanced laboratory equipment and materials. High administrative, management and supervision level for monitoring, surveillance and follow-up. Costly financial, technical and administrative resources.
Recommendations 1.
2.
3.
4.
The experience obtained from the past six years [from whence regulations are set] should be evaluated as to pros and cons. The relevance and significance of regular surveillance of achievements, effectiveness, supervision and efficiency of strategies is of paramount importance. The data and relevant information is desired to be stored with a data bank. Such an authority may be formulated basically for this reason. Data could be fruitfully used for justification and checking of mathematical models or as database or for maintenance aspects. Data and information collected over the past years from sewage water treatments plants and ground water recharge monitoring systems should be released, gathered and used for evaluation. Monitoring programs are to embody: sampling techniques, sampling locations, parameters to be measured with selection for individual industries, method of analysis. This is to be incorporated in an ordinance. The adoption and implementation of guidelines and standards need to be preceded by actions such as: Survey and evaluation of the current position of water resources, Enlisting and registration of the different pollution-producing areas with a nationally formed body such as the authorized bodies within the Ministry of Municipalities and Environment. Identification and verification of pollution-producing groups. This is to be followed by portrayal of pollution streams issuing from each providing sector. A sub-committee should be formed in order to formulate and draw laws or guidelines. The committee: a) need to desirably include an environmentalist, a hydro-geologist, a sanitary engineer, an irrigation expert, a microbiologist, a toxicologist, and a legislation and law professional. b) should make use, wherever possible, of regulations and guidelines as set by international organizations such as WHO, FAO, WB, UNDP, UNESCO, etc., regional and neighboring Arab countries, international standards such as those set by the European countries, and the standards as applied by the United States of America. c) is advised to set general guidelines for disposal of wastewater into ground water, surface water, ocean, other water courses [e.g. Afalaj, irrigation canals, agricultural drains and feeders, ponds, khors, public fountains..etc] or sewers, and re-use in agriculture, industry, fishery, recreation and even drinking. Each and every disposal or re-use should have separate guidelines. Guidelines should also be set for disposal of solid wastes from agriculture, domestic and industrial plants especially harmful, toxic and special wastes. The pollutional load discharged need to be stressed upon for different discharge authorities. d. could recommend that all factories undergo a pre-treatment operation or a full treatment frameworks for its wastewater. The pre-treatment plant differs according to the type of industry. Permits should then be issued to factories either to dispose the pre-treated wastewater into the sewage or discharge systems according to the by-laws governing these. The perspective authorities should set financial fees on factories according to wastewater quality or quantity which would require further treatment. e. need to set recommendations in general terms. Specific sanitary engineering design aspects that are research dependent or are debatable should be avoided.
131
5.
The regulations formulated and updated should include the following main group areas: • Physical characteristics, • Biological and bacteriological measures, • Ethically non-attractive elements, • Inorganic health hazardous elements, • Organic health hazardous parameters, • Radio-active substances, • Toxic constituents. • Proper sampling techniques [preparation of sampling containers, sample segregation for particular experiments, sample protection and preservation for analysis, maximum holding time, filed experiments such as temperature, D.O., pH, residual chlorine...etc]. • Standard method of analysis to be followed. This is to enable comparison between different experiments, agreement of results, and to high-lighten the detection limit for each standard procedure. • Environmental impact assessment statement for any newly planned project prior to its construction. 6. A well-equipped, educational, research oriented national laboratory with a training center need to be established. Specialized and medium regional reference laboratories may be formulated within different districts, such as the condition in specific municipalities. The appropriate qualification and training of technical forces would be easily implemented through this establishment. 7. The standards and regulations set by experts need to be updated or improved from time to time. Other standards may be deemed necessary to be formulated. This procedure would dictate setting of a permanent authority for this purpose. Establishment of an Environmental and Public Health Engineering Institute, or a National Academy of Science and Technical Information Agency, or a relevant organization may eventually be the solution. This Organization would be the focal center for many national and international agencies, research centers, laboratories, universities, organizations, and the like. This body would be the agency that assures the government agencies, court of law and accrediting bodies that the national laboratories are generating data of proven and reputable quality. 8. Community education approaches, programs and procedures need to be tackled by a certain authority of jurisdiction. The experienced gained from community education programs would help escalating and expanding the schemes. 9. Harmony and coordination between the separate ministries [e.g.Water Resources, Regional Municipalities and environment, Agricultural and Fish, Electricity and Water, Defence, and Health], municipalities, departments, institutions, organizations, enterprise, establishments and the like is the key factor for successful performance, optimization, better employment of resources, accomplishment of policies and the appreciation of approved guidelines. 10. A minimum quality control procedure need to be established to guarantee precision, correctness, accuracy, completion and typicalness of representative data collected. This could be documented and stored with the formulated data bank. 11. The execution of the ordinance, legislation, decree, rule, and the law is the principal element for the acceptance of guidelines, standards and regulations. Conclusion Land and soil survey studies of Oman indicate the availability of more arable land than could be supported by the present water resources. Water conservation through efficient irrigation, use of modern irrigation system, agronomic management and institutionalization should be coupled with augmentation of resources by desalination, water harvesting and wastewater treatment. To fulfil this objective, to provide the utmost health and social welfare of the people, and to protect land and water resources of the country, it was necessary to put forward the guidelines which would govern the discharge and re-use of wastewater.
References 1. 2. 3. 4. 5. 6.
7.
8.
9. 10. 11. 12. 13. 14.
Abdel-Magid, I. M. and ElHassan, B. M. "Reflections on Drinking Water Quality Guidelines for The Sudan", J. Wat. Intern., 12(1), 1987,33. AWWA "Quality goals for potable water", J. American Water Works Association, 60(12), 1968. Ayres, R.S. and Westcot, D. W. "Water quality for agriculture" ,FAO, Rome, Irrigation and Drainage Paper 29, 1976. Gorchev, H. G. and Ozolins, G "WHO guidelines for drinking water quality" A paper presented at the International Water Supply Association Congress, 6-10 Sept. 1982, Zurich, Switzerland. Ministry of Commerce and Industry "Sultanate of Oman Standards: Drinking water", No. 8, 1978, General Department of Standards and weight, personal communications. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for wastewater reuse and discharge" Ministerial Decision 5/86 dated 17th May, Muscat, 1986a. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for external building drainage" Ministerial Decision 5/86 dated 17th May, Muscat, 1986b. Ministry of Environment and Water Resources "Sultanate of Oman law on the conservation of the environment and prevention of pollution: Regulations for septic tanks and holding tanks" Ministerial Decision 5/86 dated 17th May, Muscat, 1986c. Ongerth, J. E and Dewalle, F. B. "Pretreatment of industrial discharges to publicly owned treatment works" J. Water Pollution Control Federation, 52(8), Aug. 1980, 2246. WHO "European standards for drinking water", World Health Organization, 2nd Edi., Geneva, 1970. WHO "International standards for drinking water", World Health Organization, 3rd Edi., Geneva, 1971. WHO "International standards for drinking water", World Health Organization, 3rd Edi., Geneva, 1972. WHO, "Guidelines for drinking water", World Health Organization, vol. 1,2 and 3,Geneva, 1984. Abdel-Magid, I.M. and El-Zawahry, A. " Formulation of Omani standards for water and wastewater" A paper presented at the seminar on "Transfer of technology" held at the College of Engineering, Sultan Qaboos University, March, 1st, 1992.
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Evaluation of the Updated Omani Regulations for Wastewater Reuse and Discharge54 by Dr. Ahmed Hossam Eldin Hassan55, Dr. Isam Mohammed Abdel-Magid56, and Dr. Alaa Eldin El-Zawahry57
Abstract Guidelines for wastewater re-use quality are based on scientific and epidemiological findings. As such, it provides guidance towards making risk management decisions that are related to the protection of public health and environmental preservation (Hespanol 1992). Over the last thirty years, or so, considerable work has been done to assess risks emerging from wastewater re-use and develop methods that would aid removal or minimization of the risks. For example reports by WHO (WHO 1973, 1989) have contributed greatly in reviewing and summarizing research and experience all over the world with the purpose of establishing sensible guidelines for wastewater re-use. Countries while adopting their national priorities and strategies establish wastewater regulations. Attention is usually paid to technical, economical, social, cultural, hygienic practices, and political characteristics and constraints. The regulations for wastewater re-use and discharge in the Sultanate of Oman were first introduced in 1986. This paper gives a critical review of the updated regulations and makes procedural recommendations.
Introduction The Sultanate of Oman is known to be one of the few countries in the region, and indeed in the world, which has been environmentally conscious and gave conservation and prevention its utmost attention. The regulations set aside ministerial decision 5/86 for wastewater re-use and discharge complies with the law of Conservation of the Environment and Prevention of Pollution issued by Royal Decree 10/82 and its amendment, to provide health and social welfare for the people and protect the land and water resources of the country. It is clear that, at any time regulations can be changed or modified whenever new scientific evidence becomes available, or following changes in national interests and tendencies.
Critical Review of the Existing Regulations National standards involving quality control, which need to be implemented for Oman, need to deal with different interacting and overlapping parameters. Examples of these parameters include: climate, cultural and social habits, diet, socio-economic status, beliefs and taboos, local customs, methods of treatment, and regulations governing final disposal. Limits set for concentrations of elements in wastewater parameters are as outlined in table (1). The standards for drinking water and water used for irrigation purposes, as set by the authorized Omani ministries, are incorporated in table (1) solely for comparison purposes. In case of wastewater and sludge treatment and disposal the Omani Regulations mainly has been divided into three broad groups. The first group indicates parameters to be considered for wastewater re-use, discharge and sludge disposal (Ministry of Environment [MoE] 1986a). More emphases were placed on chemical substances. Radioactive materials are covered in a separate article [Article 15], which do not permit reuse of wastewater or sludge containing radioactive material. 54 Published in the journal of the Egyptian Public Health Association, Vol. LXIX,no. 3,4,1994,pp 185 204 55 Environ. Health Dept., Oman Inst. P. Health, Muscat
56 57
College of Engineering, Sultan Qaboos University, Muscat College of Engineering, Sultan Qaboos University, Muscat
133
Table 1 Concentration of Elements in Wastewater Parameter, Drinking Water and Irrigation Water (All units are in mg/l unless otherwise stated) Drinking water (WHO, 1972) Wastewater(a) (ME, 1986a) Wastewater
Irrigation water (Ayres & Westcot, 76)
(ME, 1993) Parameter HDL
MPL
Max
MA-4W
Max-CT
Max-20
A
B
Total Solids
500
1500(*)
1500
1000
1500
200
-
-
Turbidity (NTU)
5 (+)
5
2
-
-
-
-
-
-
-
-
-
-
Physical
1
Taste
unobjectionable
Odour
unobjectionable to most of the consumers
Colour
Maximum
Perm
Absent
15 TCU
-
-
-
-
-
-
-
-
2
2
-
-
-
-
BOD5
-
-
15
10
15
20
-
-
COD
-
-
100
50
150
200
-
-
TOC
-
-
50
20
-
-
-
-
Al
-
-
5
1
5
5
5
20
As
0.05 (*)
0.1
0.2
0.05
0.1
0.1
0.1
2
B
-
-
2
1
0.5
1
0.75
2
Ba
1
1
2
1
1
2
-
-
Be
-
-
0.3
0.1
0.1
0.3
0.1
0.5
Cd
0.01
0.01
0.03
0.01
0.01
0.01
0.01
0.05
-
-
≥0.5
≥0.5
-
-
-
-
Cl-
200(*)
600
350
250
650
650
-
-
Co
-
-
0.5
0.1
0.05
0.05
0.05
5
CN
0.05(*)
1.5
0.1
0.05
0.05
0.1
0.2
5
Cr
0.05
0.2
2
2
-
-
Cr
0.05
0.05
0.5
0.1
0.05
0.05
0.1
1
Cu
1(+)
1.5
0.3
0.2
0.5
1
-
-
F
0.8(+)
1.5
2
1
1
2
1
15
Fe
0.1
1
5
1
1
5
5
20
Hg
0.001(+)
0.002
0.005
0.001
0.001
0.001
-
-
DO Chemical:
Free Cl2 (after 60 min contact time)
Li
-
-
10
2.5
0.7
0.7
2.5
2.5
Mg
30
150
150
30
150
150
-
-
Mn
0.05
0.05
1
0.2
0.1
0.5
0.2
10
Mo
-
-
0.05
0.01
0.01
0.05
0.01
0.05
N
-
-
5
1
5
10
-
-
Kjeldahl N
-
-
10
5
5
10
-
-
Total N
-
-
50
30
50
50
-
-
Na
200 (+)
-
200
70
200
300
-
-
Ni
-
-
0.5
0.2
0.1
0.1
0.2
2
45
10
50
20
50
50
5
30
NO3
134
Oil and grease Pb
-
-
5
2
0.5
0.52
-
-
0.1
0.15
0.5
0.1
0.1
0.2
5
10
pH
7-8.5
6-9
6-9
6-9
6-9
6-9
6-8.5
6-8.5
Phenol
0.001
0.002
1
0.1
0.001
0.001
-
-
-
-
30
20
30
30
Phosphate -
S
-
-
0.1
0.05
0.01
0.01
-
-
Se
0.01
0.01
0.05
0.02
0.02
0.02
0.02
0.02
SO4
400(+)
-
400
200
400
400
-
-
SAR
-
-
-
-
10
10
-
-
Zn
5(+)
15
5
2
5
5
2
10
V
-
-
1
0.1
0.1
0.1
-
-
10
-
23 (b)
2.2(c)
200
1000
-
-
Ova & Cysts
-
-
N.D.
N.D.
< 1/litre
< 1/litre
-
-
E. coli (per 100 ml)
-
0
-
-
-
-
Bacteriological Coliforms [MPN/100 ml] Viable Pathogenic
Key (a)
Parameter Limits not greater than stated values.
HDL
Highest desirable level
MPL
Maximum permissible level
MAX
Maximum value.
MA-4W
Monthly average over any 4 consecutive weeks.
Perm
Permissible level.
MAX-CT
Water used continuously on all soils.
MAX-20
Waters used up to 20 years on fine textured soils of pH 6-8.5.
(b)
Not to be exceeded in any sample.
©
Determined over last 7 days of completed analysis.
N.D.
Not detectable.
(*)
Effluent standard matches with the WHO Guidelines for drinking water.
(+)
Effluent standard exceeds the WHO Guidelines for drinking water.
Biological and bacteriological characteristics as laid down by the water standards (Ministry of Commerce, 1978) differentiate between treated water and untreated water. With regard to the former three points are high-lightened: i.e. no sample should contain E. coli in 100 mL; no sample should contain more than 10 coliform organisms per 100 mL; and throughout the year, 95 % of samples should not contain any coliform organism in 100 mL. As regards untreated water two points are indicated namely: no sample should contain E. coli per 100 mL; and no sample should contain more than 10 coliform organisms per 100 mL. Disposal of sludge is limited to treated sludge with characteristics in agreement with that one indicated in table (2).
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Table 2 Limits for disposal of sludge ( MoE 1986a, MoE 1993) Parameter Cadmium Chromium Cobalt Copper Lead Molybdenum Nickel Zinc Mercury
Max. Limit (MoE 1986) Max. Limit (MoE 1993) (mg/kg dry solids) 30 20 1000 1000 100 NA 1000 1000 1000 1000 20 20 200 300 1000 3000 NA 10
The second group of the Omani regulations as related to wastewater and sludge treatment and disposal concerns external building drainage (MoE, 1986b). The regulations forbid discharge of trade waste to surface water drain or channel without prior consent of the municipality. Design parameters were also governed by the regulations e.g. gradient of channels, diameter of pipes, gullies, manholes locations and size, ventilation, testing ...etc. Penalties are to be paid by persons who do not comply with the regulations. The third group of the regulations of concern is septic and holding tanks (MoE, 1986c). The regulations focus on septic tank selection, design criteria, effluent discharge to soakaway pit or other underground percolation system, material of construction, maintenance, and cleaning. Typical septic tank and holding tank sanitary engineering drawings were included in appendixes. The above-mentioned regulations have been amended in 1993 to cover limitations of the previous regulations. (MoE, Ministerial Decision 145/1993). Treatment technologies in Oman At present, most sewage treatment plants (STP's) operating in Oman are based on conventional activated sludge treatment technology as the heart of the process. Activated sludge plants have very low pathogen removal efficiencies due to the relatively short retention period (maximum 24 hours). Tertiary treatment, usually sand filtration, as well as chlorination had to be introduced to render the effluent suitable for reuse in irrigation. As an alternative to conventional treatment, waste stabilization pond (WSP's) have been used in warm climates. The lagoons are sized such that retention in each stage is from 5 to 8 days, and overall retention time between 20 and 30 days. Effluents of properly designed and operated WSP's are safe for irrigation even for those vegetables that are consumed raw. This is due to the reliability of the system for high pathogen removal efficiencies. At Muscat WSP process was implemented at Al-Ansab area and continued till December 1989. These lagoons were not sized as per the requirements in accordance with actual load. Thus, it was not considered as an alternative to conventional treatment as was thus abandoned. The BOD, SS, and ammonia after treatment at Al-Ansab WSP were as follows: BOD = 20 to 70 mg/L; SS = 40 to 70 mg/L; and ammonia-nitrogen = 2 to 10 mg/L. Pathogen removal percentages in a typical secondary and tertiary STP (i.e. Darsait) as well as in a 4 stage WSP with 25 days total detention time are as shown in table (3). The table also shows conservative estimates of pathogen survival for both wet and drying sludge. The figures for survival in sludge are derived from experiences elsewhere and from reviewed literature.
136
Table 3 Percentages of Pathogen Removal in Treatment Plants Pathogen Indicator organism
% Removed Secondary treatment
Survival-weeks
Tertiary treatment including chlorination (Cumulative)
WSP
Moist Sludge
Drying Sludge
Helminth Eggs
70 - 90
95 - 99
100
16 - 24
8 - 12
Protozoal Cysts
70 - 95
90 - 98
100
4
1
Bacteria
90 - 99
99.99
99.99
4-8
2-4
Viruses
95 - 99
99.9 (?)
99.99
3-8
2
99
99.999 - 99.9999
99.99
Fecal coliforms
Table (4) gives a comparison between wastewater quality as regulated by the Omani law on the conservation of the environment, and irrigation water quality set by FAO .It can be seen that the wastewater is of high quality and closely follows that of drinking water standards as set by WHO. Table 4 Irrigation Water Quality as Compared to Wastewater Regulated by the Sultanate of Oman for Re-use and Discharge (mg/L) Parameter Aluminum Arsenic Beryllium Boron Cadmium Chromium Cobalt Copper Fluoride Iron Lead Lithium Manganese Molybdenum Nickel Selenium Vanadium Zinc
Irrigation Water Continuous use Use up to 20 yrs1 5.00 2.00 0.10 2.00 0.10 0.50 1.00 2.00 0.01 0.05 0.01 1.00 0.05 5.00 0.20 5.00 1.00 15.00 5.00 20.00 5.00 10.00 2.50 2.50 0.20 10.00 0.01 0.05 0.20 2.00 0.02 0.020 0.10 0.100 2.00 10.00
Maximum 5.00 0.20 0.30 2.00 0.03 0.50 0.50 0.30 2.00 5.00 0.50 10.00 1.00 0.05 0.50 0.05 1.00 5.00
Wastewater Monthly average2 1.00 0.05 0.10 2.00 0.01 0.10 0.10 0.20 1.00 1.00 0.10 2.50 0.20 0.01 0.01 0.02 0.010 2.00
Key: 1 For use up to 20 years on fire textured soils of pH 6 - 8.5. (Ayers and Westcot 1976). 2 Monthly average over any four consecutive weeks. (MoE 1986) Results and discussions From the critical review carried herein with respect to the Omani wastewater re-use and disposal standards the following points emerged: 1. Both the re-use and discharge parameters have been given the same standards
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and limits. Standards required for re-use, according to purpose, are necessarily not the same as those accepted for wastewater discharge. 2. Guidelines substantially need to differ according to the final discharge, origin of waste and re-use which could mostly be industrial, domestic, recreational or agricultural releases. 3. Guidelines require consideration of the socio-cultural habits; water availability, water need; annexation and extension of services, and amenities. 4. The already set Omani limits, closely follow those submitted for drinking water, a comparison of which is given in Table (1). This has great implications on applicability and cost incurred in maintaining established limits, which might drive some industries out of business. 5. The limits laid for inorganic substances that are considered hazardous to health such as lead, selenium, cadmium, cyanide, etc., need to be revised. The limits set might be too stringent. 6. The organic list of health significance only mentions phenols. Many constituents need to be included. Examples of these compounds are the organic micropollutants: chlorinated alkanes and alkenes, chlorophenols, benzene compounds, polynuclear aromatic hydrocarbons in plastic and synthetic waste, trihalomethanes, pesticides, insecticides, herbicides in pesticide and agricultural waste, mercaptants in oil refinery waste and fertilizers in agricultural waste. 7. As clearly shown in table (1) seven of the treated wastewater parameters slightly exceed the WHO standards for drinking water (i.e. turbidity, cyanide, copper, iron, sodium, zinc and sulphates). While, on the other hand, four additional parameters comply with the WHO guidelines for drinking water quality (i.e. arsenic, chloride, mercury and total solids). 8. Limits should be set for re-use of wastewater or sludge containing radio-active material. A general mention was pointed to radioactive substances in Article 15 of the Omani regulations. 9. Limits assigned for the aesthetic quality elements such as total dissolved solids, turbidity, hardness, pH, sodium, zinc, aluminum, copper, chloride..etc., come very close to those limits set for drinking water. 10. The aforementioned pollutants refer to concentrations of substances within effluent. These need to be substituted by total pollutional load discharged to encounter volumes of wastes. 11. Two of the most important parameters in evaluating treated wastewater for use in irrigation are not specified (MoE 1986). Provision was made for Sodium Absorption Rate (SAR), but no limit has been set for calcium. The electric conductivity (EC) of the water in milli-siemans/cm [milli-mohs/cm] is a measure of the salinity [chlorinity] threat to be encountered with continuing use of such waters. The Sodium Absorption Ratio (SAR) calculated as: Na SAR = [(Ca + Mg ) / 2]0.5 is a measure of the sodicity hazard. The adjusted SAR takes into account the precipitating effects of carbonate (CO3) and bicarbonates (HCO3) present in the water. The quality of irrigation water is primarily determined by the EC-SAR combination as to salinity and sodicity hazard. High salt concentrations may be avoided by mixing with better quality water from another source and adding gypsum or CaSO4 to the soil can reduce the SAR value. Bacterial contamination of water is normally not serious from the irrigation viewpoint unless severely contaminated water is used on crops which are eaten uncooked. Some chemicals 138
could be toxic to plants and concentration of boron above 0.5 mg/liter is deleterious to citruses. 12. Based on the conclusion given by Shuval and Feachem (1985) there is no evidence to indicate that there is a high actual risk of disease if the wastewater is sufficiently treated. At this point it is important to compare the proposed microbiological quality guidelines for wastewater use in agriculture with the Omani standards (See table 1 for proposed standard by The International Reference Centre for Waste Disposal (IRCWD) and table (5) for the Omani standards). Comparison reveals two significant differences namely: a) The IRCWD standard allows for intestinal nematode (< 1 viable eggs per litre), while the Omani standard does not allow for any viable counts or ova or cysts. These standards apply to both restricted (irrigation of trees, industrial crops, fruit trees, ..etc) and unrestricted irrigation (irrigation of edible crops, sports field, and public parks). b) The IRCWD standard accepts faecal coliform of less than or equal to 1000 (geometric mean number per 100 mL) for unrestricted irrigation; while this standard is not applicable to restricted irrigation. The Omani standard on the other hand allows for only 2.2 total coliforms for 100 mL for restricted irrigation. Furthermore, this standard is based on a monthly average over four consecutive weeks. Table 5 Omani Regulations for Wastewater Re-use and Discharge Microbiological Standards for Wastewater Parameter Ministerial Decision Ministerial Decision (145/93) (5/86) Max Monthly av. for Restricted Unrestricted 4 consec. wks Irrigation Irrigation * Total coliforms < 23 < 2.2 MPN/100 ml * Faecal coliform -200 1000 per 100 ml *Viable pathogenic N.D N.D. < 1 <1 Ova and Cysts per litre
13)
Table (6) gives the crop quality compared to suggested tolerance levels for heavy metals in Australia to that is suggested by the Omani laws. Green forage samples were collected by Metcalf and Eddy (Metcalf and Eddy 1991) from grasses on non-irrigated (controlled) and in areas irrigated for 60 years with wastewater that had been treated using limited settings. All constituents in the plants, except for nickels, were below the suggested tolerance limits for grasses as suggested by Melsted (Melsted 1973). It was concluded that nickel is poorly absorbed by livestock and is relatively non-toxic and would not pose a health problem to livestock. Omani standards are by far much stringent and wastewater used for irrigation of the grasses in Australia is about 72, 49, 40 and 30 times higher in iron, manganese, copper, and cadmium, respectively. It is obvious that with such waters there would be no problem of pasture raising in Oman.
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Table 6 Suggested Tolerance Levels of Heavy Metals, Crop Quality and Irrigation Wastewater in Oman and Australia (ppm) Constituent Suggested Grasses at Australia Wastewater Tolerance Control Oman Wastewater Cadmium 3 0.77 0.89 0.003 Cobalt 5 < 0.64 0.64 0.5 Copper 150 6.5 12 0.3 Iron 750 970 361 5 Manganese 300 149 49 1 Nickel 3 2.7 4.9 0.5 Lead 10 < 2.5 < 2.5 5 Zinc 300 50 63 5 (Source: Metcalf and Eddy 1991, MoE 1986) Recommendations 1. The experience obtained from the past years (from whence regulations are set) should be evaluated as to pros and cons. The data and relevant information is recommended to be stored with a data bank for fruitful use. 2. Data and information collected over the past years from sewage water treatments plants and ground water recharge monitoring systems should be released, gathered and used for evaluation. Monitoring programs are to embody: sampling techniques, sampling locations, parameters to be measured with selection for individual industries, method of analysis. This is to be incorporated in an ordinance. 3. It remains to be elucidated by more concrete epidemiological studies whether other enteric diseases (e.g. Salmonellosis, Hepatitis, Amoebiasis, Giardiasis..etc) may be transmitted by uncontrolled wastewater reuse. These studies are required for verification and quantification of health risks in defined societies. 4. The adoption and implementation of guidelines and standards need to be preceded by actions such as: a. Survey and evaluation of the current position of water resources, b. Enlisting and registration of the different pollution-producing areas with a nationally authorized body within the Ministry of Municipalities and Environment. c. Identification and verification of pollution-producing groups. This is to be followed by portrayal of pollution streams issuing from each providing sector. 5. A well-equipped, educational, research oriented national laboratory with a training centre need to be established. Establishment of an Environmental and Public Health Engineering Institute, or a National Academy of Science may eventually be the solution. This organization would be the focal centre for many national and international bodies. This body would be the agency that assures the government agencies, court of law and accrediting bodies that the national laboratories are generating data of proven and reputable quality. 6. The standards and regulations set by experts need to be updated or improved from time to time. Other standards may be deemed necessary to be formulated. 7. Community education approaches, programs and procedures need to be tackled by a certain authority of jurisdiction. The experienced gained from community education programs would help escalating and expanding the schemes. 8. Harmony and coordination between the separate ministries (e.g. Water Resources, Regional Municipalities and environment, Health, Agricultural & Fish, Electricity
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& Water, and Defence), institutions, organizations, enterprise, establishments and the like is the key factor for successful performance, optimization, better employment of resources, accomplishment of policies and the appreciation of approved guidelines. 9. A minimum quality control procedure need to be established to guarantee precision, correctness, accuracy, completion and typicalness of representative data collected. This could be documented and stored with the formulated data bank. Conclusion Land and soil survey studies of Oman indicate the availability of more arable land than that the present water resources can support. Water conservation through efficient irrigation, use of modern irrigation system, agronomic management and institutionalization should be coupled with augmentation of resources by desalination, water harvesting and wastewater treatment. To fulfill this objective, to provide the utmost health and social welfare of the people, and to protect land and water resources of the country, it was necessary to put forward the guidelines, which would govern the discharge and re-use of wastewater. For such high quality standards of treated effluent, it may logically be concluded that the degree of protection offered to the public is far in excess. This would defeat the purpose of cost minimization, and would conserve the limited water resources. When comparing both cost and effluent standards against health benefits, one would often detect a point of diminishing returns. This means that after a certain point the cost involved in obtaining a higher effluent standard will continue to rise while actual health risks will remain the same or experience a slight decrease. It merits noting that most of the Gulf States with similar socio-cultural settings are widely using effluent for irrigating edible crops. This includes Kuwait and Saudi Arabia (especially Riyadh). It would therefore be safe to assume that similar practices could be adopted in Oman provided that public awareness is initiated with emphasis on conservation of the limited water resources. References 1. Hespanol and Prost A., "WHO Guideline and National Standards for Water Quality", WHO, Geneva, March 1992. 2. Abdel-Magid, I. M. and ElHassan, B. M. "Reflections on Drinking Water Quality Guidelines for The Sudan", J. Wat. Intern., 12(1), pp. 33, 1987. 3. AWWA "Quality goals for potable water", J. American Water Works Association, 60(12), 1968. 4. Ayres, R.S. and Westcot, D. W. "Water quality for agriculture", FAO, Rome, Irrigation and Drainage Paper 29, 1976. 5. Gorchev, H. G. and Ozolins, G "WHO guidelines for drinking water quality" A paper presented at the International Water Supply Association Congress, 6-10 Sept. 1982, Zurich, Switzerland. 6. Ministry of Commerce and Industry "Drinking water Standards", No. 8, 1978, General Department of Standards and weight, Muscat. 7. Ministry of Environment and Water Resources, Muscat, Sultanate of Oman, Ministerial Decision: • 5/1986a "Regulations for waste-water reuse and discharge" • 5/1986b "Regulations for external building drainage" • 5/1986c "Regulations for septic and holding tanks". 8. WHO "International standards for drinking water", World Health Organization,
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3rd Edi., Geneva, 1972. 9. WHO, "Guidelines for drinking water", World Health Organization, vol. 1,2 and 3,Geneva, 1984. 10. Abdel-Magid, I.M. and El-Zawahry, A. " Formulation of Omani standards for water and wastewater" A paper presented at the seminar on "Transfer of technology" Sultan Qaboos Univ., 1992. 11. Engleberg Report, "Health Aspects of Wastewater and Excreta Use in Agriculture and Aquaculture", IRCWD News 23, pp. 11-19, 1985. 12. Shuval, H. I., et. al., "Wastewater Irrigation in Developing Countries: Health Effects and Technical Solutions", World Bank, TP no. 51, Washington, D.C., 1986. 13. Metcalf and Eddy, Edi., "Wastewater Engineering Treatment, Disposal, Reuse", McGraw Hill, N.Y., 1991. 14. Melsted S. W., "Some Practical Consideration in Waste Management", Proceedings of Conf. on Recycling Municipal Sludges and Effluents on land, p. 121-128, Illinois U., 1973. 15. Abdel-Rahman, H. A., "Appropriate Wastewater Irrigation Practice as Related to Crop Selection in Oman", National Seminar on Wastewater Reuse, Muscat, 1992.
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Recycling of agricultural/ industrial waste: The case of wastewater from sugar factories in the Sudan58 By I M Abdel-Magid59 & Dr. B M El Hassan60 Agricultural industries in general and sugar manufacturing in particular use large quantities of water during the stages of washing and processing. The wastewater so generated is characterized by its high pollution loads in terms of BOD and suspended solids. This is due to the leakage of sucrose during processing and the accumulation of mud during washing. Treatment of this water can be efficiently carried out using waste stabilization ponds (WSP), from which the final effluent can be reused for irrigation in the cane fields. Wastewater produced at Sennar Sugar Factory has been measured, defined and treated biologically. The results so obtained are encouraging for the reuse of effluents from the chosen unit for he treatment of agro-industrial wastes. Introduction The Sugar industry started in the Sudan in the Early 1960s with the commissioning of El Gunied Factory in 1962 followed by Khashm El Birba (1965), Sennar (1976) and lately Kenana and Assalya (1979). The raw material for these factories is sugar cane, These factories have been located near the banks of either the Blue or the White Nile (Fig 1) This siting has solved the problems of obtaining water for irrigation of the cane fields and the processing of the sugar, but unfortunately, lead the sugar industry to believe that the simple way to dispose the untreated effluents was into the Nile. The sugar industry uses large quantities of water for irrigation and processing (i.e cane washing, cleaning water, condensers, boiler water, floor washing and other various cleaning processes). Consequently a large volume of wastewater is produced from the factory (Table 1) The existing particle of disposal of the wastewater endangers the quality of the river Nile water and contradicts the Public Health Act adopted in 1975. Therefore the objective of this study is to quantify the pollution load exerted by the sugar industry on the river Nile and to investigate the possibility of treating the wastewater with the intention of reusing it for irrigation. This will not only protect the Nile but will also save water and energy for the sugar industry. Water conservation through renovation and reuse could provide an economical and logical solution to the problem of sugar wastes where the
water supply is scarce or inadequate, especially in countries such as Sudan Factory El Gunied Kashm Elbirba Sennar Kenana Assalaya Key:
Table 1 Wastewater Production Design Capacity Wastewater m3/h 60000 ND 90000 ND 110000 330000 110000
ND ND ND
ND = Not determined
58
Published in MEW & S Journal, May 1988, pp 98 - 102 Faculty of Engineering and Architecture, University of Khartoum 60 Faculty of Engineering and Architecture, University of Khartoum 59
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Disposal Site Blue Nile Blue Nile Blue Nile White Nile White Nile
In developing countries the choice of treatment units needs to be sound when related to the cost of the units, availability of skilled labour, man power, spare parts, training and the supply of fuel and the necessary chemicals. The units selected must be: 1. simple to install and operate 2. convenient, manageable and easy to maintain 3. of reasonable cost and acceptable both environmentally and socially 4. rugged, robust, reliable and efficient. For these reasons, WSPs have been selected for the treatment of sugar waste. Treatment using WSPs is a low cost technique, as is the operation and maintenance. It requires less energy and highly skilled operators are not essential also the effluent, meet the required standards. Being of simple construction with no mechanical or electrical equipment, WSPs are easy to maintain and cheap to install providing land costs are reasonable which is the case in Sudan Environmental factors such as soil conditions (especially permeability), climate (temperature, light intensity, precipitation, evaporation, wind speed and direction) play leading roles in deciding the design, operation and performance of these biological systems {6,8,11,14) sufficient nutrient are essential to satisfy the high demand carbonaceous BOD to have proper plant performance and efficiency and to avoid troubles that may occur. Domestic sewage may be added to alleviate the problem or perhaps the recommendation of Lund {8} may be used; namely the addition of commercial ammonia and phosphoric acid to meet the required quantities of nitrogen (N) and phosphorous (P) as recommended by Gloyna {5} (BOD: N:P = 100:5:1) but this implies more costs.
Materials and methods This investigation was carried out for the Sennar sugar factory during one processing season. The initiators for this study were the factory and the Ministry of Health. During the study the following tasks were carried out: 1. Wastewater streams originating from the different processing phases were identified, measured and analyzed with the object of separating the contribution made by each stream as well as the final flow discharged to the Blue Nile (Fig 2) 2. A pilot unit consisting of screens, anaerobic facultative and maturation ponds was designed, installed and operated. The performance of the unit has been determined on a weekly basis (Fig 3)
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Table 2 Sennar Sugar Wastewater Characteristics Parameter pH BOD, mg/1 COD, mg/1 TSS, mg/1 Oil & Grease, mg/1 H2S, mg/l Alkalinity. Mg/l Acidity, mg/l Chlorides, mg/l PO4, mg/l Turbidity (NTU) Conductivity (µ mohs)
Discharge points 1 2 3 5.5 4 1200 1800 1650 2160 1867 2400 2080 790 1110 38 40 12 Traces Traces Traces 40 Not done 70 40 200 250 10 20 12 1375 640 390 160 130 90 300 600 870
Results The characteristics of the untreated final effluents were determined through the analysis of three grab samples. These samples were taken from three points on the canal which carries the waste from the factory to the Blue Nile> Results of these analyses are shown in Table 2.
The Pilot Unit The designed unit was to treat 2 litres/min, which is 0.01% of the total final effluent produced by the factory. The specifications of the ponds were as follows: Anaerobic pond: (3.5 x 1.5 x 3 m) with detention time equal to eight days. Facultative pond: (1.5 x 9 x 4.5 m) with detention time equal to three days. Maturation pond: (1 x 4 x 2 m) with detention time equal to three days. It should be noted that the design identified waste, which was strong, mostly biodegradable and mainly industrial. The layout of the pilot unit is shown in Fig 3. Samples were collected weekly from the separated ponds and analyzed for biochemical oxygen demand, total suspended solids, oil and grease and total phosphates with a view to determine the purification capability of the system. Results are shown in Fig 4. Waste stabilization ponds may not meet effluent standards for suspended solids because of the presence of high concentrations of algal cells; but for BOD and bacteria reduction, ponds have little competition {5}. Viruses also were claimed by Ahmed {2} to die off in maturation ponds along with bacteria because the environmental is hostile and unfavourable. Removal or reduction of algal cells content would impose added costs; but if the algal cells are reclaimed, recovered and dried, they may be used as an animal feed supplement. In this investigation the achieved BOD removal amounted to 87%; while for other parameters the removability values amounted to 86% for suspended solids, 94% for oil and grease and 62% for phosphates.
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Discussions and Conclusions Comparing the achieved final effluent quality with recommended quality for reuse of treated effluents for irrigation purposes, it can be concluded that these effluents can safely be reused. In order to increase the efficiency of such treatment plants for sugar industry, it is recommended that good housekeeping should be enforced in the factories. This will minimize the waste produced and useful components such as oil and grease can be recycled. However, these effluents can be mixed with irrigation water in the irrigation canals, where a dilution of more than thirty times can be achieved, thus reducing the possibility of any negative impact on soil and plants. The results of this pilot unit have been used to design a complete large-scale treatment plant with minimum additional units, and is ready for construction. The study and the final design are a model, which is to be implemented by sugar factories. By means of such industrial wastewater treatment plants, the river Nile can be protected against pollution that is taking place due to current practices, and a lot of water and energy can be saved. It is worth mentioning that the possibility of irrigating artificial forests with treated effluent was considered and thought to be an alternative for making use of these treated effluents. Application to land has many advantages: the organic matter is taken care of by the vegetation, bacteria by the soil, nitrogen being absorbed by the plantation, phosphorous gets absorbed into soil particles and exchangeable cations react with soil salts {2}. Nevertheless, any adverse changes in soil characteristics need to be monitored and countered (e.g. reduction in permeability}. When pond effluent is being used for irrigation, there may be objectionable odours resulting from accumulations of algae decaying as the water trickles through the soil or evaporates. Thus public health aspects and implementations of the reuse of effluents must always be kept in mind. Reference: 1. Ahmed, S. M. R., 1980, “Choice and Layout of Various Types of Stabilization Ponds”, WHO/EMRO Tech. Pub. No. 3; WSP Design & Operation Report of a Seminar, Lahore, 133. 2. American Public Health Association (1975), “Standard Methods for the Examination of Water and Wastewater”, 14Th Edition APHA, AWWA, WPCF, New York. 3. California Station Water Resources Cont. Board (July 1984), “Irrigation with Reclaimed Municipal Wastewater”, A Guidance Manual. 4. George, P., Meeda James, CP Chen (1977), “Cane Sugar Handbook”, 10th Edition, Wiley Interscience Publications, London. 5. Gloyna, E. F. (1971), “Waste Stabilization Ponds”, WHO Monograph Series 60, WHO Geneva. 6. Lumbers, P. B. (1979), “Waste Stabilization Ponds: Design Considerations and Methods” J. Instn Pub. Health Engns 7 (21), 70. 7. Lin, P. W. (1980), “Algae in Wastewater Treatment and Upgrading of Stabilization Pond Effluent”, WHO/EMRO Tech. Pub. No. 3; WSP Design & Operation Report of a Seminar, Lahore, 252. 8. Lund, H. G., (1971), “Industrial Pollution Control Handbook”, McGraw-Hill Book Co., New York. 9. Tearle, K., (1973), “Industrial Pollution Control – The Practical Application”, Business Books Ltd, London.
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10. Thirumurthi, O., (1974), “Design Criteria for Waste Stabilization Ponds”, J. Wat,\. Pollut. Confr. Fed. 46 (a) 2094. 11. Widmer, W. J. (1980), “Summer Review of Waste Stabilization Ponds”, WHO/EMRO Tech. Pub. No. 3; WSP Design & Operation Report of a Seminar, Lahore, 73.
Figure 1 The Sudan: Location of Sugar Factories
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Water Treatment Plant
Cane Wash
Sugar Stores
Power Generation Unit
Sugar Processing
Juice Extraction Unit Office Office Office
- Sugar Cane leaves - Traches - Sand - Clay 6m3/min
Store
Irrigation Canal
- Sand - Clay - PO4 0.3m3/min
Molasses 6 m3/min
- Oil & Grease - Lime - Soda -Acids - Sugar 6 5m3/min 18.8 m3/min
Effluent Collecting Channel
To Blue Nile
Figure 2 Plan of Sennar Sugar Factory
Screen
Canal Leading to the Blue Nile
Disposal (by cart)
Maturation Pond Anaerobic Pond
Facultative Pond
Figure 3 The Pilot Unit
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Storage of Treated Effluent
Figure 4 BOD & SS Percentage Removal in the Pilot Unit
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Poultry Wastewater Treatment in Sudan61 By Dr. Isam Mohmed Abdel Magid62 Background Poultry processing is drawing more interest in Sudan for many reason such as amelioration in living standards, prosperity, relatively easy profit and revenue from this sort of investment, increased prices of meat together with relevant environmental, socioeconomic and cultural factors and local impacts. Therefore, old poultry processing centers are expanding and new sectors are emanating to existence. The net result is an augmentation in waste generated creating problems with their handling, treatment and final disposal. This aggravated inconveniences such as occurrence of obnoxious odors, fly nuisance especially the common fly {1}, breeding place for mosquitoes, accumulation of large volumes of wastes annually and presence of unwanted, harmful wild life in the vicinity of the poultry farm as for example the case in the Sudanese-Kuwaiti poultry farm in Khartoum. In that farm there is a large number of wild birds pecking and feeding on the accumulated manure and aiding in spreading it in the neighborhood. The problem of manure is being aggravated by the absence of farm animal and usage of more potent fertilizers than poultry wastes. Source of Poultry Waste and Composition According to Salvato {2} the major source of poultry waste result from battery and feeding rooms, this is followed by wastes from killing, scalding and picking operation. The liquid waste from washing down a poultry house has been reported by Scott and Smith {3} to be high in nitrogen, phosphate and potassium, compared with other live stock wastes. They stated that about 8 hens product the same BOD per day as one human. Johnson and Mountney {4} indicated that the poultry manure is moist and contains nutrients and organic matter and higher fatty acids (butyric, valeric, carponic, and caprylic). The wastewater generated from poultry processing plants is highly versatile in its composition and characteristics. Mead, et.al. {5} stated that the BOD and suspended solids (SS) are high during the processing day, while the BOD, SS, grease and flow rate vary considerable throughout the nightly was down period. During weekends and holidays, wastewater flow may be nil. Furthermore, the type kind and quality of bird being killed has notable substantial influence on the characteristics of the wastewater produced.
Treatment of Poultry Waste Treatment of poultry wastewater necessitates incorporation of: a. Holding tanks to cater for peak flow and they may demand aeration to avoid septic conditions. b. Pretreatment including screens (depending on the type and capacity of the plant) and grease or fat traps to prevent any detrimental effect such materials can supervene on the operation and performance of the treatment on the operation and performance of the treatment plan. The treatment and disposal processes may include trickling filters, activated sludge, extended aeration, waste stabilization ponds, lagooning, oxidation ditches, DAF, ridge 61
Published in Environmental Management for Developing Countries by Envitek A. S., Preprints II, Environmental Technology Research and Development Centre, Istanbul, Turkey 62 B. Sc., DDSE, Ph. D., University of Khartoum, P. O. Box 321, Sudan
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and furrow incineration, dehydration, composting, spray irrigation. etc. The choice of appropriate units for a particular poultry farm depends on the amount and character of waste generated, climotological conditions, socio-economical factors, environmental conditions and impact and technical factors associated with the process. The activated sludge process needs careful handling supervision and precaution against shock loads together with proper maintenance chemical precipitation process is expensive and also demands intelligent supervision. Composting offers a possible way for manure stabilization if the material could be handled efficiently and kept aerobic for aerobic bacterial growth and activity. Chemical coagulation and dissolved air flotation (DAF) treatment were applied to poultry processing wastewater plants. Grives, et.al {7} stated that DAF foam separation is a promising technique for the removal and concentration of colloid-size particles. The methods have been shown to be efficacious by Shannon and Busisson {8}, and the cost of installing and operating a DAF unit has been estimated to be similar to that of conventional sedimentation units of the same capacity {8}. The tremendously large surface area presented by the emerging small air bubbles provides the possibility of extremely efficient collection of dissolved and suspended solids. However, the flotation process alone has been shown by Woodard, et.al. {9} to be incapable of producing a satisfactory effluent, SS removals of 40-50% were reported by Gray {10}. Consideration of the characteristics and nature of solids remaining in the effluent from plain flotation i.e. suspended proteinaceous matter and blood cells, both of which carry a surface charge, suggested that chemical coagulation in connection with DAF could produce the required results. Gray {10} reported SS removals of 90 with chemicals. Also an optimal removal of excess of 90, of SS in the effluent was reported by Levy, et.al. {11} on application of DAF process, Woodard et.al. {9} by using this method, obtaining BOD removals in excess of 05%, and SS removals greater than 90%, while the under flow from the flotation unit was of excellent clarity with no visible grease or blood and very little turbidity, however, this does not agree with Gray’s findings. The advantages offered by the DAF method include: 1. Stability of process efficiency even with large liquid loading rates and influent SS concentration. 2. Rather thick sludge is being removed from the unit {12}. This process was being applied at the Sudanese-Kuwaiti poultry processing center at Khartoum, but the unit performance with neither satisfactory nor beneficial, and after a short period of operation it stopped completely for a number of reasons such as:1. Sophistication of the plant. 2. Lack of the appropriate personnel capable of operating and maintaining the unit. 3. Lack of needed spare parts. 4. Power failure for rather long periods of time. 5. Instability of wastes introduced to it. 6. Chemical needed are not always found, besides the needs requirements and conditions, e.g. doss, pH, etc, are not adhere to. 7. Lack of proper intervention and mastered know-how. 8. Method of effluent disposal from the plant is inadequate. The result is that the unit is now acting simply as a bypass and wastes are finding their way, somehow, to the depressions in the near vicinity of the poultry center. Waste stabilization ponds (WSP) upon proper maintenance and regular supervision would prove a useful means for treatment of poultry waste. The system is a rudimentary and a simple version of biological wastewater purification. It is a low
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cost technique; likewise operation and maintenance costs are low with perhaps only one person is being required to look after a small site. It stipulates less energy, highly skilled operators are not essential and effluent can cope with required standards. Being of simple construction with no mechanical or electrical equipment WSPs are cheap to install, easy to maintain provided land costs are plausible. Poor design and construction and maintenance may end up in: a. Excessive seepage through the bottom, which may contaminate groundwater. b. Eroded embankments. c. Too much waterweed growth. d. Breeding places for mosquitoes and flies with an associated potential health hazard. e. Silting and blockage of inlet and other problems. When deciding to use WSP for treatment of poultry waste primary treatment is needed. It consists of screens and grease or fat trap as emulsified oils can be a special nuisance since they spread over pond surface obstructing the passage of solar radiation and stopping surface adsorption of atmospheric oxygen {13}. Sufficient nutrients are indispensable to satisfy the high demand carbonaceous BOD to have proper plant performance and efficiency and to avoid troubles that easy materializes. Domestic sewage may be added to alleviate the problem or perhaps commercial ammonia and phosphoric acid may be used {14,15} although the latter one implies mere costs. The high degree of purification that could be attained by WSPs in warm and sunny climates, such as in Sudan, makes it possible to use the generated effluents for crop irrigation. WSPs may not meet effluent standards for SS because of the presence of high concentrations of algal blooms, but for BOD and bacteria reduction Glyna {15} states that ponds have little competition. BOD removals of 90% and above are achieved in ponds while for bacterial reduction they are more efficient than the conventional treatment plants (99.5% removal is possible). Viruses also were claimed by Ahmed {16} to die off in maturation ponds along with bacteria because the environment is hostile and unfavorable. Taigaides {1} proposed digestion for poultry wastes to utilize methane gas as a power source and to have an end product that is bore profitable and desirable than the raw manure as a fertilizer, followed with a lagoon. Also Johnson and Mounteny {4} have suggested usable gas production by digestion. Merits to be gained from anaerobic digestion of the poultry waste include: 1. Waste stabilization and reduction of the organic content. 2. Less pollutional and contamination problems. 3. Usage of the end product as a fertilizer. 4. Sludge concentration. 5. Commercial usage of gas produced. 6. Reduction of rodents, mosquitoes and flies problem. Like any other process, digestion, has limitations such as initial capital costs incurred, careful supervision of the feeding of the digester desiderated and care needed to avoid problems such as explosions. In case of scarcity of water, conservation through renovation and reuse could provide an economics and logical solution in a poultry processing plant. Charles {17} concluded that waste titerial can be safely and profitably recycle by feeding without hazard to animal or human health, but this may be questionable Mead…et.al. {5}
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found that some microorganisms such as ……are considerably more resistant to chlorination an E. coli and they recommended a dosage of 5-20 mg/1 of available chlorine in the water used for poultry processing. Saad, et.al {18} found that renovation of reused water by filtration- chlorination may effectively reduce water consumption needed for the washing and chilling process to approximately one-third of the ordinary levels without affecting the bacterial in chemical quantities of the freshly consumed carcasses. However, they reported that application of chlorination may accelerate the rate of free fatty acid release as chlorine may enhance the breakdown of triglyceride into glycerol and the fatty acids.
Recommendations and Conclusions From the aforementioned discussions it could be concluded that when deciding to use a system for poultry wastewater treatment in Sudan it must be: a. Simple to construct and operate utilizing capabilities of unskilled personnel. b. Inexpensive to install. c. Easy to mange and maintain. d. Capable of operation without crating a nuisance at high temperature levels. e. Ruggedly robust and reliable and efficient. f. Coping with social aspects and beliefs and impact on people concerned. g. Does not necessitate usage of chemicals that are not to be found locally. According to Hamm {19} improving techniques and equipments used for killing, scalding and defeathering should prove beneficial in reducing pollution from poultry processing plants. Salvato advocated the following waste reduction measures:a. Separate collection and disposal of the blood, feathers and offal from the killing bench or trough in a proper way in order to reduce volume of waste and cost of treatment and decrease nuisance problem. b. Avoidance of carelessness usage of water in scolding and chilling operations. c. Separate collection of wastes generated from evisceration process. Therefore, one would advocate for the treatment of poultry wastewater in Sudan a system that includes: 1. Screens for separation of feathers, bones, etc. 2. Simple clarifier or sedimentation unit. 3. Passing the effluent from the proceeding unit to a natural biological process for treatment. Examples include: waste stabilization ponds, oxidation ditches or primary and secondary lagoons. 4. Effluent generated from the chosen bit could be used for irrigation purposes or it could be evaporated in a neighboring area in a satisfactory sanitary manner. 5. Solids gathered from the aforementioned units could be: a. dewatered and the product may be rendered to produce an animal feed supplement. b. digested with help of poultry manure and the gas produced could be engineered for power generation, while the end product begetted could be used as a fertilizer.
Summary In Sudan there are many poultry processing centers some of them without any sort of waste treatment, while in others rather sophisticated, unreliable and inefficient methods were used. This situation resulted in many problems and malfunctions. A number of treatment options were discussed in this paper and their merits should be counterpoised against the incurred expense of the selected units, availability of skilled labor and man power with certain prerequisites, spare parts arduousness, training facilities for people involved and supply of power and chemicals. The treatment plant should be located as far as possible from the processing center to avoid contamination, and workers should be aware and careful about what they should wear, how
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they should handle equipments, products and wastes in order to preserve the hygiene of the environment both within the plant and its surrounding.
References 1. E.P. Taiganides, “Aerobic Discussion of Poultry Manure”, World’s Poultry Sci. J. 19(4): 252(1963). 2. J.A. Salvato, “Environmental Engineering and Sanitation”, 2nd ed., Wiley Intersc:., New York (1972). 3. J.S. Scott, and P.G. Smith, “Dictionary of Waste dn Water Treatment”, Butterworths, London (1980). 4. J.H. Johnson, and G.J. Mounteny, “Poultry Manure Production. Utilization and Disposal”, World’s Poultry Sci. J. 25(3) 202. 5. G.C. Mead, H.W.Adams and R.I. Parry, “The Effectiveness of In-plant Chlorination on Poultry Processing”, Br. Poultry Sci., 16:517 (1975). 6. G.S. Mead, “Microbiology the Poultry Carcass and Processing Plant”, Royal Soci. Health, 96(4): 164 (4976). 7. R.B Grieves, D.P. Malone J.L. Bewley, “Dissolved Air Foam Separation to Clarify Turt Waters”, Wat. Resea., 6(2): 145. 8. W.T. Shannon and D.H.Buisson, “Dissolves Flotation in hot Water”, Wat. Resea., 14(7): 759 (1980). 9. F.Ewoodard, MW.Hall, O.J.Sproul and M.M.Onosh, “New Concepts in Treatment of Poultry Process Wastes”, Wat. Mespa., 11(10): 873( ). 10. T.W. Gray, “Introduction to Dissolved Air Flotation”, Institute of Public Health Engin. Year Book: 281 (1982). 11. R.L.Levy, R.I. White and T.G.Shea, “Treatment of Combined and Raw Sewages with the Dissolved Air Flotation Process”, Wat. Res. 6(12): 1487 (1972). 12. C.H. Cleaver, The Development and Application of Dissolved Air Flotation for Water Clarification”, Public Health Engrs. J. 7(2): 84 (1979), 7(4): 154 (1979). 13. K.V.Ellis, “Stabilization Ponds-Water Quality Preliminary Treatment” WHO/EMRO Tech. Pub. No. 3: WSP Design and Operation, Report of a Seminar, Lahore: (8) (1980). 14. H.F. Lund, “Industrial Pollution Control Handbook”, McGraw Hill, New York (1971). 15. E.F. Gloyns, “Waste Stabilization Ponds”, WHO Monograph Seri. 6C, WHO Geneva (1971). 16. S.M.R. Ahmed, “Choice and Layout of Various Types of Stabilization Ponds”, WHO/EMRO Tech. pub. No. 3: WSP and Operation, Report of a Seminar, Labore. 133 (1980). 17. O.w.Charles, “The Economic Feasibility of Processed Animal Waste”, World’s Poultry Sci. J. 31(4): 271 (1975). 18. S.Saad, A. Hamza, and E.Amine, “Water Conservation and innovation in the Poultry Processing Industry in Egypt”, Waste-Water Management in Developing Nation Part2, WHO Wat. Quality Bull. 7(2): 85 (1982). 19. D. Hamm, “Characterisitics of Effluent in Ten Southeastern Poultry Dressing Plants”, Poultry Sci. J. 51(3): 825 (1972).
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Wastewater Reclamation and Reuse Research By Donald R. Rowe63 and Isam Mohammed Abdel-Magid64 Abstract: The introduction to this paper deals with research terminology including research and development as well as operations research. Several sources of research information for wastewater reclamation and reuse is presented, especially regarding access to computer databases. These computer databases make it possible to carry out a literature search that would be impossible to do by hand. Potential sources of research funds are reviewed with emphasis on the most significant research topics and the funding of this research in the wastewater and reclamation area. The scope of the wastewater reclamation and reuse field, both as to technical and societal issues, is categorized and presented in tabular form. The technical issues include: treatment technologies, mode of treatment, physical, chemical, biological, and the specific treatment processes in each of these modes. The scope of the societal issues relating to the use of reclaimed wastewater varying from public opinion to legal issues is also categorized in tabular form. The most pressing research needs in the wastewater reclamation and reuse field including physical, chemical and biological problems are presented. The paper also addresses research needs and priorities in wastewater reclamation and reuse in the Sultanate of Oman. Emphasis is laid on potentiality of reuse and socioeconomic impacts.
INTRODUCTION Research has been defined as a careful, systematic, patient scientific investigation in some field of knowledge aimed at uncovering and applying new facts, principles, techniques, and natural laws (Parker 1984, Neufeldt 1986). A more expanded definition of research indicates that research is the primary activity of science and is a combination of theory and experimentation directed toward finding scientific explanations of phenomena. It is commonly classified into two types: pure research, involving theories with little apparent relevance to human concerns (invention); and applied research, concerned with finding solutions to problems of social importance, for instance in medicine and engineering (innovation). The two types are linked in that theories developed from pure research may eventually be found to be of great value to society. In broad, general terms, scientists carry out basic, pure or fundamental research while applied research includes engineers, technologists, technicians, lawyers, economists and health professionals. Currently, much of the research being, done is by teams of specialists from many disciplines, and is often referred to as research and development (R & D). Another term often used in the research area is operations research/management science (OR/MS). The terms operations research and management science can be used interchangeably as either OR/MS or MS/OR (Chacko 1993, Levin 1989). MS/OR can be defined as the systematic study of a problem involving gathering data, building a mathematical model, experimenting with the model, predicting future operations, and getting the support of management for the use of the model (Levin 1989). Figure 1 presents a flow diagram of these six basic steps (McGraw 1992). OR/MS can be considered to be mainly an operational tool involved in formulating mathematical models used to solve problems, while R & D is mainly involved in industrial research projects to develop and evaluate the economies of the finished product. Ideally, a successful research program includes both the procedures and techniques in operations research/management science and research and development (Rowe and Abdel-Magid 1995).
ACCESS TO COMPUTER DATABASES Following are several informational sources, in the USA, that provide extensive services in almost any scientific or technical research area (Harris 1994). * National Technical Information Service (NTIS) 63
Ph.D., P.E., President, D.R. Rowe Engineering Services, Inc., 1500 Bryant Way, Bowling Green, Kentucky 42103-7121, USA 64 Ph.D., MSES, MIWRA, College of Engineering, Sultan Qaboos University Muscat, Sultanate of Oman
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An NTIS investigative literature search can be made through the following On-line Service Systems provided you have the necessary accession number and have determined the key words for the research topic. Following are only three of these On-line Services. DATA-STAR: (800) 221-7754 DIALOG: (800) 334-2564 STN International: (800) 848-6533 There is a charge for this service. * US Environmental Protection Agency Public Information Center ACCESS EPA is a directory of the US Environmental Protection Agency (EPA) and other public sector environmental information resources (ACCESS EPA 1993). ACCESS EPA is a pathfinder to many major information resources, such as clearinghouses, hotlines, records, databases, models, and documents. This is in addition to providing an overview of more than 300 information resources. On-line Access: ACCESS EPA is available through the EPA Library. On-line Library System (OLS), and the GPO Federal Bulletin Board System (GPO BBS). ACCESS EPA is also available through Internet. Internet is a worldwide network of networks that enables computers of all kinds to share services and communicate directly, as if they were part of one giant, global computing machine. Many universities and institutions with Internet connections have ACCESS EPA available through OLS. EPA's Internet address is: EPAIBM.RTPNC.EPA.GOV. The Internet system lets you connect to government computers, and find information about the most recent research or legislation. It also lets you connect to university computers, and search thousands of different databases. Internet is an electronic highway. The ACCESS EPA publication can be purchased through Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954 ($30 foreign) (EPA 220-B-93-008). A fairly recent EPA database in ACCESS EPA is the Vendor Information System for Innovative Treatment Technologies, VISITT (ACCESS EPA 1993). VISITT contains technology information submitted by developers, manufacturers, and suppliers of innovative treatment technology equipment and services. This database provides a means for innovative technology vendors to make their products and capabilities known to state, federal, and private sector professionals (Fax 703-308-8528). * Federal Research in Progress - FEDRIP (Sullivan 1992) FEDRIP contains descriptions of current and recently completed federally funded research projects in the physical sciences, engineering and life sciences. All 297,828 records contain project title, principal investigator, and the organizations sponsoring and conducting the research. Most records contain a description of the research, although the content of each depends on he sponsoring agency. FEDRIP is updated monthly and available on DIALOG (Sullivan 1992). * American Water Works Association (AWWA) (Waternet 1994) The most comprehensive database on the water industry is now available through a CD-ROM subscription service from the American Water Works Association (AWWA). The CD-ROM service provides access to over 30,000 references of journal articles, books, conference proceedings, government reports, and technical papers from major water publishers throughout the world (Waternet 1994). Some of the topics on the AWWA, Waternet CD-ROM that have application in the wastewater reclamation and reuse field include: * Drinking Water Treatment * Disinfection & Byproducts * Lead & Copper Corrosion * Conservation * Reuse * Appropriate Technology * Ozonation * Alternative Disinfectants * Reverse Osmosis * Desalination * Organics * Operation & Maintenance * Water Quality & Analysis * Waterborne Diseases * Sludge Disposal * Privatization * Regulations & Compliance * Wastewater Treatment
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POTENTIAL RESEARCH FUNDING The United States federal government funds just under half of all research and development (R & D) in the United States but performs only about 10 percent in its own laboratories. Industry conducts nearly 75 percent of the nation's R & D, and academia, about 10 percent (CEQ 1992). Following are some of the major federal agencies involved in the water resources research area (Sullivan 1992). * Environmental Protection Agency (EPA) * Department of Defense (DOD) * Department of Energy (DOE) * Department of Interior (DOI) * Department of Commerce (DOC) * Department of Health and Human Services (DHHS) * Department of Agriculture (USDA) * National Science Foundation (NSF) * National Aeronautics and Space Administration (NASA) The US Congress has been asked to increase the federal research and development budget to $73 billion in Financial Year (FY) 1995. This is a 3 percent or $2 billion increase over the R & D federal budget for FY 1994 (Dinges 1994). While all of the agencies listed above fund some form of water resources research, the EPA being the primary regulator of pollution prevention for the USA is one of the agencies providing the most research funding. EPA engages in a variety of research, monitoring, standard setting and enforcement activities and coordinates and supports research and antipollution activities by state and local governments, private and public groups, individuals and educational institutions (Sullivan 1992). To carry out this mandate, EPA has some 50 to 60 offices, administrations and agencies involved in environmental programs. The budget request for FY 1995 for EPA is up 8 percent over FY 1994 to $6.9 billion (Dinges 1994). Recently, EPA initiated a new program entitled "Environmental Technology Initiative." The focus of this program is long-term research and pollution prevention by EPA, other Federal agencies, and the private sector. The goal is to develop more advanced environmental systems and treatment techniques that can yield environmental benefits and increase exports of " green" technologies. This investment will aid in the transition away from a defense-oriented economy, by stimulating the increased use of private sector R & D resources for environmental quality-related purposes (US EPA 1994). The initiative is funded at $36 million in FY 1994 and, in the President's plan, is to be funded at $80 million in FY 1995, with overall funding projected to be $1.8 billion over nine years (Federal Register 1994). Water Environment Research Foundation (WERF) In 1990, the Water Pollution Control Federation Research Foundation (WPCFRF) was incorporated. When WPCF changed its name, the WPCFRF then became known as the Water Environment Research Foundation (WERF). The Water Environment Research Foundation (WERF) was established to advance science and technology for the benefit of the water quality profession and its customers. Funded through voluntary contributions, WERF manages research under four major Thrust Areas: Collection and Treatment Systems, Integrated Resources Management, Residuals Management, and Human Health and Environmental Effects.
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Table 1 presents the ranking of each topic listed under the four Thrust Areas. Each subject is given a number indicating its rank out of the 51 topics, as well as indicating its priority within each of the four sub groups (WEF 1993a, WEF 1993b). WERF funded twenty-eight research projects during 1991 and 1992. Eight of the Solicited Research projects initiated during this time period continued into 1993. The total value of the 28 research projects was estimated at over $11 million. Over the lifetime of these projects, WERF provided $5,547,000 in funding. The remaining $5,527,000 was contributed as in-kind services (WEF 1993a, WEF 1993b). In 1993, WERF funded $1,954,000 for research in the four Thrust Areas for Solicited Research. The distribution of this research money in the four areas was as follows (WEF 1993a): - Collection and Treatment Systems (CTS) 22 % - Integrated Resources Management (IRM) 3 % - Human Health and Environmental Effects (HHE) 24 % - Residuals Management (REM) 19 % Table 1 Subscriber Priority Rankings of WREF Research Areas (WEF 1993a) (Listed in order of priority within each category, numbers indicate overall ranking) Collection and Treatment Systems Human Health Environmental Effects 1 Water Quality Indicators 2 Transport & Fate of Toxic Contaminants 3 Bioassays & Residual Disposal 5 Effluent & Residuals Disposal 6 Risk Management & Assessments 16 Water Quality & Sediment Relationships 22 Fresh Water Ecosystems 23 Environmental Response & Crisis Management 30 Communicable Diseases 32 Safety 36 Estuarine & Marine Systems 44 Chronic Diseases Integrated Resource Management Residuals Management 9 Watershed Management 15 Land Application 11 Surface Water Quality 18 System Design & Process Optimization 12 Modeling Pollutant Loads 24 Stabilization 13 Air Emissions 26 Biosoils 14 Storm Water Management 31 Bioremediation 17 Water Reclamation & Reuse 33 Thermal Processing 19 Waste Minimization 35 Dewatering 20 Urban Runoff Best Management Practices 43 Conditioning 27 Cross Media Effects 46 Thickening 28 Wetlands & Natural Systems 47 Incineration 29 Non Urban Runoff Best Management Practices 48 Anaerobic Digestion 34 Groundwater Resources & Recharge 49 Conveyance 37 Sampling & Monitoring Protocols 51 Aerobic Digestion 38 Environmental Auditing 40 Non-structural Pollution Controls 4 Advanced Wastewater Treatment Processes 7 Disinfection 8 Pretreatment & Source Control 10 Biological Treatment Processes 21 Instrumentation & Process Controls 25 Laboratory & Analytical methods 39 Planning, Operations & design 41 Industrial Treatment 42 Combined Sewer Overflows 45 Collection Systems 50 Preliminary ^& Primary Treatment
American Water Works Association Research Foundation (AWWARF) The water supply community as its center for cooperative research and development created the AWWA Research Foundation. The foundation functions as a planning and management agency, awarding research contracts to water utilities, universities, engineering firms, and other organizations.
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The foundation's research agenda embraces all aspects of water supply: resources; treatment and operations; distribution and storage; water quality and analysis; health effects; and, economics and management. In 1993, the AWWARF funded 32 new projects with an investment of approximately $11.5 million. More than half this amount represented in-kind contributions from research contractors. The US Congress supplemented this research by channeling $575,000 to the foundation in fiscal year 1993 (Board of Trustees 1994). In January 1994 the AWWARF's Board of Trustees selected 23 projects for 1994 funding. Requests for proposals (RFP's) were issued for 15 of these. The board approved $4 million to sponsor the solicited research projects, and $732,000 was appropriated for projects selected through the foundation's unsolicited project program (AWWA Mainstream 1994) THE SCOPE OF THE WASTEWATER RECLAMATION AND REUSE RESEARCH AREAS The scope of the areas involved in the wastewater reclamation area, both technical and societal are presented in Table 2 (Hass 1992). To evaluate and to try to solve problems associated with these various areas in wastewater reclamation and reuse, will require the skills and knowledge of many disciplines (Lieuwen 1990). Table 2 Scopes of the Wastewater Reclamation and Reuse Field (Hass 1992, Lieuwen 1990) Research Category
Levels of Wastewater Technology Preliminary (Pretreatment)
Technical
Treatment
Primary Secondary
Basic & Applied
*
Advanced Wastewater Treatment *
Tertiary (Polishing Process)
Disinfection
Primary Modes of Treatment Physical Chemical Physical Physical Chemical Biological Physical Chemical Biological Physical Chemical Biological Physical Chemical Biological
* Advanced wastewater treatment and tertiary treatment are often considered synonymous terms, however when in doubt, refer to the definitions given in the publication or regulation.
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Table 2 (Continued) Research
Societal
Sociological & Economical Wastewater Reuse Issues Public Opinion Public Acceptance - User Concerns Public Health Concerns - Health Risks Economic Feasibility - Financing Markets Pricing Structure Taxing Policies (Who pays) Benefits - Cost Effectiveness Safety Industrial Policy Issues Legal Issues
MODES OF WASTEWATER TREATMENT The various modes of treatment involved in treating wastewater can be divided into three broad categories: physical, chemical and biological processes. These three processes can be further categorized. This categorization is presented in Table 3 (Argo 1985, Cook 1985, Odendaal 1991 and Donovan 1980). In many treatment operations, the physical, chemical and biological processes overlap. For instance, in the adsorption process by activated carbon, both physical and chemical phenomena are involved (Rowe and Abdel-Magid 1995).
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Table 3 Physical, Chemical & Biological Categorization of Various Processes in Wastewater Treatment (Argo 1985, Cook 1985, Odendaal 1991, & Donvan 1980) Mode of Treatment Specific Treatment Processes Involved Physical Residual removals Sedimentation Filtration: - Slow sand filters - Rapid sand filters - Upflow filters - Dual-media filters Ultra filtration Microstraining Carbon adsorption Activated Aluminum adsorption Distillation Aeration Centrifugation Reverse osmosis Ion-exchange Ultraviolet Disinfection Chemical Coagulation (Organic/inorganic) Flocculation Clarification Disinfection: - Chlorine - Chlorine dioxide - Ozonation Lime clarification Recarbonation Air-ammonia stripping Biological Trickling filters Activated sludge and modifications Aerated lagoons Stabilization ponds Intermittent sand filters Rotating biological contactors (RBC) WASTEWATER RECLAMATION AND REUSE RESEARCH NEEDS
Physical Problems The most important physical and aggregate properties involved in wastewater treatment include (APHA 1992): * Color * Turbidity * Odor * Acidity * Alkalinity * Hardness * Conductivity * Salinity * Solids (total dissolved solids) * Temperature. For non-potable use of reclaimed wastewater, the physical parameters of primary concern are turbidity/solids, hardness (Ca++, Mg++), alkalinity and conductivity. Many of the physical treatment processes presented in Table 3 can be used to control physical water quality parameters associated with wastewater reclamation and reuse, it is really a matter of cost that generally controls this situation.
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Chemical Problems The chemicals and chemical compounds encountered in the wastewater reclamation and reuse field can be divided into two broad groups, inorganic and organic (Sheikh 1990). In the inorganic category, trace metals that have been given the most attention are arsenic, beryllium, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, selenium, silver and zinc. Metals in this group that have been considered as potential carcinogens in test animals include arsenic, beryllium, cadmium, and nickel (Sheikh 1990, WPCF 1989). Other metals and compounds of concern in reclaimed wastewater include sodium, calcium, magnesium, nitrates, phosphates and chlorides. The sodium, calcium and magnesium concentrations are of particular concern in the wastewater reclamation and reuse field as they relate to determining the Sodium Adsorption Rate (SAR) which is a parameter that indicates the suitability of the reclaimed water for irrigational purposes (Asano 1987). Also, the hardness (Ca++, Mg++) of the reclaimed wastewater is important in urban reuse projects as this water can stain or leave a film on surfaces such as windowpanes or cars (Chansler 1994). In the organic chemical category many, many compounds (over 1,200) are associated with health effects. To obtain information on the carcinogenicity of these chemicals and compounds, the Integrated Risk Information (IRIS) database developed by EPA should be contacted (Fax 202-260-8061 or Fax NTIS, 703-487-4650). (ACCESS EPA 1993, US EPA). The classical methods used to measure organics in wastewater such as BOD5, COD, TOC, organic nitrogen and carbon-chloroform extraction have little or no relevance to the toxicological evaluation or health effects of organics in wastewater reclamation and reuse (WPCF 1989). A special group of organic compounds that are considered to be potential carcinogens for humans include the trihalomethane group (THMs) that can be formed in water disinfected with chlorine (Bauman 1990). These organic compounds must be given special attention if the reclaimed wastewater is intended for potable use.
Biological Problems The biological water quality problems involved in wastewater reclamation and reuse include exposure to pathogenic bacteria, viruses, protozoa and parasitic helminths. These pathogenic organisms can be transmitted by direct contact, ingestion such as consumption of food irrigated with the reclaimed wastewater, drinking contaminated groundwater or by inhaling spray aerosols. Factors that can affect the transmission of these pathogenic microorganisms are the survival time of the pathogens, the minimal effective dose, as well as the susceptibility of the exposed population. Microorganisms of major concern in the wastewater reclamation and reuse field are presented in Tables 4, 5, 6 and 7.
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Table 4. Major Bacterial Pathogens Found In Raw Domestic Wastewater And Also Of Concern In Wastewater Reclamation And Reuse Projects (Hrudey 1992, Moore 1994, Crook 1991, Rowe and Abdel-Magid 1995). Shigella sonnei Shigella dysenterae Salmonella typhimuriumCampylobacter jejuni Eschericha coli (enteropathogenic) Vibrio cholerae Vibrio comma Legionella pneumophilia Table 5. Major Protozoan Pathogens Found In Raw Domestic Wastewater And Also of Concern In Wastewater Wastewater Reclamation And Reuse Projects (Hrudey 1992, AWWA 1994, Rose 1991, Schaefer 1984, Rowe and Abdel-Magid 1995).
Crptosporidum (oocysts) Giardia lamblia (cysts) Entamoeba histolytica Balantidium coli Table 6. Major Viral Pathogens Found In Raw Domestic Wastewater And Also Of Concern In Wastewater Reclamation And Reuse Projects (Kindzierski 1993, Smith 1992, Yanko 1993, WHO 1989, Rowe and Abdel-Magid 1995).
Infectious hepatitis A (HAV) Poliovirus type 1 and 2 Echovirus Coxsackievirus Norwalk virus Human immunodeficiency virus, (HIV) (retrovirus) (AIDS) Rotavirus Reovirus Adenovirus Table 7. Major Parasitic Helminth Pathogens Found In Domestic Wastewater And Also Of Concern In Wastewater Reclamation And Reuse Projects(Schaefer 1984, WHO 1989, Rowe and Abdel-Magid 1995).
Enterobius vermicularis (pinworm or threadworm) Hymenolepis nana (dwarf tapeworm) Ascaris lumbricoides (human roundworm) Ancylostoma dyodenale (hookworrn) Necator americanus (hookworm) Trichuris trichiura (human whipworm) Taenia saginata (tapeworm) Taenia selium (tapeworm) Schistosoma spp. (Bilharziasis)
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SOCIETAL ISSUES In general, the technical research aspect of wastewater reclamation and reuse can be quantified, explained, evaluated, and solutions to the problems developed. The same can be said for some societal aspects of wastewater reclamation and reuse such as economic, taxing, pricing, and cost-benefit issues. However, when it comes to public opinion, user concerns, and public acceptance of the use of reclaimed wastewater, emotional and culture attitudes must be considered. Considerable research work has been done in this area, but more needs to be done in order for governmental agencies to make decisions that involve public acceptance of wastewater reclamation and reuse projects (Bruvold 1985, Bruvold 1988). SULTANATE OF OMAN Following are the main agencies and bodies involved in water and wastewater areas in the Sultanate of Oman: * Ministry of Agriculture and Fisheries (MoAF). * Ministry of Commerce and Industry (MoCI). * Ministry of Communication (MoC). * Ministry of Defense (MoD). * Ministry of Education (MoE). * Ministry of Electricity and Water (MoEW). * Ministry of Health (MoH). * Ministry of Housing and Lands (MoHL). * Ministry of National Heritage and Culture (MoNHC). * Ministry of Petroleum and Minerals (MoPM). * Ministry of Regional Municipalities and Environment (MoRME). * Ministry of Water Resources (MoWR). * Muscat Municipality (MM). * Office of the Advisor of Conservation of the Environment. * Public Authority for Marketing Agricultural Produce. * Royal Oman Police. * Sultan of Oman Armed Forces. * Sultan Qaboos University. * Supreme Committee for Town Planning. * Technical and Educational Colleges. * Vocational and non-governmental Training Authorities and organizations.
Research is being handled by certain departments within some of the aforementioned Ministries, bodies and establishments. Research topics included (MWR 1995, MAF 1995, MERM 1992, Abdel-Magid and AlZawahry 1992, Abdel-Magid and AlZawahry 1993, Abdel-Magid and Abdel-Rahman 1993):
Collection of dew water and harvest of rain water. Exploration of new water sources and resources. Water treatment. Reduction of water wastage.
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Improvement of agricultural irrigation efficiencies especially in Falaj systems. Groundwater recharge. Groundwater contamination (insecticides, fertilizers, traditional excreta disposal techniques). Reuse, recycling, and recreation of wastewater. Use of moderate and brackish water in agriculture for production of crops, pastures and forests. Environmental health control (abatement of water-excreta diseases, epidemiological studies). Forms, sources and causes of pollution. Marine and coastal zone pollution. Identification, impact and abatement of industrial pollution. Appropriate wastewater treatment for rural fringes. Environmental awareness and community education. Environmental impact assessment. Establishment of relevant and workable guidelines, regulations, rules, standards and bylaws.
The Omani National Conservation Strategy, NCS (MERM 1992) recognizes among the main sector projects advocated in field of water and wastewater: agriculture, water resources, industry, environmental protection and conservation of resources, development planning, academic (basic) research, and human health. Particular projects in field of water and wastewater proposed by the NCS incorporated: Field measurement of irrigation water. Extended use of treated sewerage water in crop production. Intensive studies in water harvesting and conservation. Attitudes and behavioral patterns of the Omanis in relation to their environment. Present and potential environmental hazards in urban areas leading to preparation of alternative methods for sustainable healthy communities. The NCS (MERM 1992) proposes establishment of coordination bodies such as national committees for: lands, water resources, coordinating agricultural land uses, coordinating technical cooperation and assistance, public health, and environmental information. The NCS (MERM 1992) pointed the importance of establishing a central scientific analytical laboratory, and setting up of a national integrated Geographic Information System service to record and monitor changes in the environmental and natural resources. The absence of a certain authority responsible for establishing research priorities, research proposals, allocation and distribution of funds is clear. The establishment of a National Research Council would shoulder this responsibility and establish a better link between different sectors. The majority of research carried out is largely influenced by individual interest, availability of resources and cadre. Figure 2 presents a suggested scheme for coordination and cooperation among Omani governmental bodies, institutions, organizations (regional and international) and monitoring agencies in relation to central database and analytical firms, within the domain of resource conservation and environmental protection. Formulation of a body (such as a national Research Council, NRC) that establishes and update needed guidelines, standards and legislation is essential. This body need also to
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find optimum ways for the implementation of formulated criterion (Abdel-Magid and AlZawahry 1992, Abdel-Magid and AlZawahry 1993). It needs pointing out that no certain percentage from the general budget is allocated for research. Each unit conducting research to satisfy its needs seeks funds from its own budget and other approved sources. The MRME and SQU are the primary regulators of pollution prevention for the Sultanate and are the prime agencies initiating research and providing the most research funding. REFERENCES 1. Abdel-Magid, I.M.; and El-Zawahry, A.,1992, "Establishment of water quality guidelines for the Sultanate of Oman", Arab Water World J., Vol. 16 issue 5, Sep-October, 18 - 22. 2. Abdel-Magid, I. M. and Al-Zawahry, A., 1993, "Preconditions and requirements for successful environmental policies in the Sultanate of Oman, the Sudan and Egypt", a paper presented at the conference on preconditions and requirements for successful environmental policies in the Arab World, 3 - 5 May 1993, Yarmouk University, Irbid, Jordan. 3. Abdel-Magid, I. M. and Abdel-Rahman, H. A., 1993, "Water conservation in Oman", Wat. International J, Vol. 18(2) June, 95-102. 4. ACCESS EPA, 1993, US Environmental Protection Agency, EPA/220-B93-008, Washington, D.C. 5. APHA, 1992, "Standard Methods for Examination of Water and Wastewater", 18th Ed., American Public Health Association, Washington, D.C., 2-1. 6. Argo, D. G., 1985, "Water Reuse: Where Are We Headed?," Environ. Sci. Technol, 3, 19, 208. 7. Asano, T. and Pettgrove, G. S., 1987, "Using Reclaimed Municipal Wastewater for Irrigation," California Agriculture", 15, 44. 8. AWWA, 1994, AWWA's New Satellite Teleconference, "Preventing Waterborne Disease Outbreaks," Conference, April 8. 9. AWWA Mainstream, 1994, "Research Foundation Approves $4.7 million for 1994 Projects," AWWA Mainstream, 1, 2, 38. 10. Bauman, L. C., and Stenstrom, M. K., 1990, "Removal Of Organohalogens And Organohalogen Precursors In Reclaimed Wastewater - l," Water Research, 8, 24. 11. Board Of Trustees And Staff, 1994, "AWWA Research Foundation," Mainstream, 3, 10, 38. 12. Bruvold, W. H., 1985, "Obtaining Public Support for Reuse Water," Journal AWWA, 72, July. 13. Bruvold, W.H., 1988, "Public Opinion on Water Reuse Options," Journal WPCF, 1, 45, 60. 14. Chacko, G. K., Operations Research/Management Science, McGrawHill, Inc., New York, NY, 1993, 11, 166. 15. Chansler, J. M., 1994, personal communication. 16. Cook, J., 1985, "Water Reuse in California", Journal AWWA, 60, July. 17. CEQ (Council on Environmental Quality), 1992,: 23rd Annual Report of the Council on Environmental Quality, Washington, D.C., 41, 79, 205, 227. 18. Crook, James, Camp Dressor and McKee Inc., 1991, Water Science and Technology, IAWPC, Great Britain, 9, 24, 109.
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19. Dinges, C., 1994, "Clinton Administration's Investment Budget For FY 1995," Civil Engineering 4, 64, 128. 20. Donovan, J. F., Bates, J. E., 1980, Guidelines For Water Reuse, Camp Dresser and McKee Inc., US E.P.A., Publication No. EPA-600/8-80-936, Municipal Environmental Research Laboratory, Cincinnati, OH, 95. 21. Federal Register, 1994, "EPA's Technology Innovation Strategy," 59-19, Friday 28, 4068. 22. Haas, C. N., 1992, "The State of Water Environment Research," Water Environment Research, 5, 64, 659. 23. Harris, K., 1994, Underground Injection Control Officer, Region IV, E.P.A., Database Information Pathfinder, and EPA National On-line Library, Research Triangle Park, personal communication. 24. Hrudey, S. E., Hrudey, E. J. and Low, N. J., 1992, "Health Effects Associated with Waste Treatment, Disposal and Reuse," 25. Water Environmental Research, 4, 64. 26. Kindzierski, W.B., Rogers, R. E., and Low, N. J., 1993 "Health Effects Associated with Wastewater Treatment, Disposal and Reuse," Water Environment Research, 4, 65, 599. 27. Levin, R.I., et. al., 1989, "Quantitative Approach To Management", 7th Ed., McGraw-Hill Book Co., New York, NY, 21. 28. Lieuwen, A., 1990, "Effluent Use In The Phoenix And Tucson Metropolitan Areas", Arizona Water Resources Research Center, The University of Arizona, Phoenix, AZ. 29. MAF (Ministry of Agriculture and Fisheries), Directorate General of Water Resources and Irrigation, 1995, "Groundwater Recharge Schemes in the Sultanate of Oman ", 1986, 1991, 1995. 30. McGraw, 1992, "McGraw-Hill Encyclopedia Of Science and Technology", 7th Ed., McGraw-Hill Inc., New York, NY, 385. 31. MERM, 1992, "National conservation strategy", Ministry of Regional Municipalities and Environment, The Sultanate of Oman, Vol. I, II,, and III. 32. Moore, A.C. et. al., 1994, "Waterborne Disease in the United States 1991 and 1992," Journal American Water Works Association, Denver, CO, 2, 81, 86. 33. MWR (Ministry of Water Resources), Sultanate of Oman, 1995, "National Water Resources, Master Plan", personal communication. 34. Neufeldt, V., and Guralnik, D. B. Editors, 1986, "Webster's New World Dictionary", 3rd College Ed., New York, NY, 1141. 35. Odendaal, P. E., 1991, "Wastewater Reclamation Technologies And Monitoring Techniques," Water Science and Technology, 9, 24, 173. 36. Parker, S. P., Editor, 1984, "McGraw Hill Dictionary of Scientific And Technical Terms", 3rd Ed., New York, NY, 1362. 37. Rose, J. B., Gerba, C. P., and Jakubowski, W., 1991, "Survey of Potable Water Supplies for Cryptosporidium and Giardia", Environ. Sci. Technol, 25, 1393. 38. Rowe, D. R. and Abdel-Magid, I. M., 1995, "Handbook of Wastewater Reclamation and Reuse", Lewis publishers, Chelsea, Michigan (under publication).
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39. Schaefer, W. J., 1984, "Health Aspects of Reuse of Treated Wastewater For Irrigation," WHO Eastern Mediterranean Region, Intercountry Seminar on Wastewater Reuse, Manama, Bahrain. 40. Sheikh, B., et. al., 1990, "Monterey Wastewater Reclamation Study for Agriculture," Research Journal WPCF, 3, 62, 216. 41. Smith, R. G., Walker, M. R., 1992, "Water Reclamation and Reuse," Water Environment Research, 4, 64,402. 42. Sullivan, T. F. P., Editor, 1992, "Directory of Environmental Information Sources", 4th Ed., Government Institutes, Inc., Rockville, MA, 10, 209. 43. US EPA, 1994, "US -EPA Environmental Technology Initiative: FY 1994 Program Plan", EPA 543-K-93-003, EPA, Washington, D.C. 44. US EPA, "Integrated Risk Information System (IRIS)", US EPA Office of Research and Development, Cincinnati, OH. 45. WATERNET ON CD-ROM, 1994 "Brochure", American Water Works Association, 666 West Quincy Avenue, Denver, CO 80235, USA. 46. WEF, 1993a, "Research Development Plan/1993-1997", Water Environment Foundation, Alexandria, VA. 47. WEF, 1993b, "Research Notes," Water Environment & Technology, Alexandria, VA, 5, 7, 84. 48. WHO, 1989, "Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture", Report of a Scientific Group, Technical Report Series 778, World Health Organization, Geneva, Switzerland. 49. WPCF, 1989, "Water Reuse", (2nd Ed.), Manual of Practice SM-3, Water Pollution Control Federation, Alexandria, VA 201. 50. Yanko, W.A., 1993, "Analysis of 10 Years of Virus Monitoring Data From Los Angeles County Treatment Plants Meeting California Wastewater Reclamation Criteria," Water Environment Research, 3, 22, 65. Figure 1: Operations Research Approach: The Six Basic Rules of Success (McGraw 1992) Available quantative models
Facts
1. Formulate the problem
Possible future changes
Problem Proposed Proposed 3. Solve the solution definition 2. Choose model proposed (a verbal a model model model)
4. Test the solution
Satisfactory 5. Establish solution control
Unsatisfactory solution Education, publicity, technical manuals, etc.
Satisfactory technique 6. Implementation For further or future solutions
Useful technology
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Figure 2 Coordination and Cooperation Ministries MAOF
MOCI
MOC
MOEW
MOD MOHL
MOE
MOH
MONHC
Health Defense Institutions
University
Technical & Educational Colleges
Meteorology
Organizations
PDO
Regional
International
National Research Council Data Bank Key:
National Central Laboratory
MoAF = Ministry of Agriculture and Fisheries. MoCI = Ministry of Commerce and Industry. MoC = Ministry of Communication. MoD = Ministry of Defense. MoE = Ministry of Education. MoEW = Ministry of Electricity and Water. MoH = Ministry of Health. MoHL = Ministry of Housing and Lands. MoNHC = Ministry of National Heritage and Culture. MoPM = Ministry of Petroleum and Minerals. MoRME = Ministry of Regional Municipalities and Environment. MoWR = Ministry of Water Resources. OACE = Office of the Advisor of Conservation of the Environment. PAMAP = Public Authority for Marketing Agricultural Produce. PASYA = Public Authority for Sports and Youth Activities. ROP = Royal Oman Police. Rusail Industrial Estate. SOAF = Sultan of Oman Armed Forces. SQU = Sultan Qaboos University. SCTP = Supreme Committee for Town Planning. TEC = Technical and Educational Colleges. VTA = Vocational Training Authority.
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Wastewater Reclamation and Reuse in Retroleum Refinery at Algeili Area North of Khartoum65 By: Faris Gurashi Faris66 , Isam Mohammed Abdel-Magid67 Abstract This study was conducted at Khartoum Petroleum Refinery at Algeili, North of Khartoum. The study discusses wastewater treatment methods in the refinery as well as final disposal methods applied on reclaimed water. Wastewater reuse in irrigation was presented in the study as well as its effect on plants and crops. The objective of this study is to assess the methods of wastewater treatment adopted in the environment at evaporation ponds near the refinery. After tests and experiment done on the wastewater treatment units and evaporation ponds, the treatment by plant gave good results of water reclamation.99.6 percent of oil was removed during the processes, 99.76 percent of volatile phenol was eliminated, and COD value decreased by 77.4 percent, however, it increased once more at the evaporation ponds due to algae presence and high temperature. PH value had also increased at the ponds for the same reason. Therefore the study recommends adopting wastewater reuse methods for irrigation. Such method preserves the environment and might minimize the effect of groundwater recharge from heavy-flow point source into negligible-flow non-point source and hence causes less contamination. Introduction Oil pollutes water almost in all steps of production, from upstream to downstream. Water is used for drilling purposes, it facilitated and cleans the path of drilling Water is also injected in wells for oil production, as well as large amount of contaminated water is produced during production operation, leaving behind a vast amount of ponds. Several treatment processes should be undertaken before disposal. Refining is an important step in oil production. Water is used here for several purposes at different stages of refining. An appreciable amount of wastewater is left behind. In the process, pollution of water resources and the environment nearby is expected. Literature review In oil refinery, water is usually used in various until operations. In many of these units water or more often steam comes into direct contact with crude oil and products derived from it. Also, chemical reactions take place in certain units and as a result of these reactions by-products will be formed and eventually and up in wastewater streams. In short, one can expect wastewater stream coming out from the refinery to be loaded with different types of pollutants at various concentrations. Usually wastewater is discharged from refinery either to nearby seawater, or river. Alternatively it is discharged to municipal sewage system. In Sudan it is discharged into evaporation ponds. Before the discharged, the wastewater must be treated in the refinery itself especially when the effluent is to be released in the environment.
65
Published in Journal of Science & Technology, Vol. 4, no. 1, Jan. 2003, pp. 38-58. Umdurman Islamic University, Faculty of Engineering 67 Sudan University of Science & Technology 66
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Sources of Oily Water in the Refinery There are two main sources of oily wastewater in refinery (Anas, 1998) • Oily wastewater which comes from the process itself, where water is used in the process at high flow rate for different purposes. • Other sources result from spillage and leakage of oil from tanks and different units, as well as washing water. Treatment Processes in the Refinery The aim of these processes is to control the quality of wastewater effluent according to standards and guidelines. The quality control includes the oil content, toxic materials, color, taste, and odor as well as pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD) and the degree of turbidity. Wastewater treatment processes at petroleum refineries can be divided into three main divisions: 1. Direct petroleum treatment operations processes: These processes include the elimination of hydrogen sulfides gas and extraction of alcoholic sulfates and neutralization using caustic soda. These processes should be included in the design of treatment operators to reduce wastewater effluent problems. 2. Unflocculated oil separation, and sludge removal processes: These processes include oil separation equipment, and oil separation tanks, by using settlement methods, as well as water separation from drain mixture at the top of oil storage tanks (ballast water separators) 3. Special separation processes for the remaining oil, and for the elimination of phenols and sulfates, and all other impurities. Also in this process the BOD and COD are reduced to the acceptable limits to improve the color, taste, and odor of the effluent. Table 1 represents a sample of wastewater standards from a petroleum refinery before discharge (Chalabi, 1986). Table 1: Sample of Wastewater Standards from a Petrol Refinery: Constituent Unit pH 6.5 – 8.5 Total Oil 15 mg/1 Phenols 0.2 mg/1 Sulfates 0.5 mg/1 Alcoholic Sulfates 0.5 mg/1 Wastewater Reuse The use of treated wastewater effluent for irrigated agriculture offers an opportunity to conserve water resources. Water reclamation can also provide and alternative to be disposed in areas where surface waters have a limited capacity to assimilate the contaminants. The sludge that results from wastewater treatment applied to farmland, can improve the physical properties and agricultural productivity of soils, and its agricultural use provides an alternative to disposal options, such as incineration, or land-filling (Rowe & Abdel-Magid, 1995). The application of wastewater effluents to soils may pose some risk of ground water contamination by viruses and bacteria, however, that risk can be minimized (NAS, 1996) by adequate disinfections of reclaimed wastewater and by slow infiltration rates.
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Behavior of Soil and Plants Exposed to Chemical Constitute in Reclaimed Water. Atlas (1981), stated that there are factors which appear to be important in encouraging high decomposition rates of petroleum hydrocarbon (a mixture of aliphatic, aromatic, asphaltic compounds in soil). These factors are temperature, concentrations, adequate supply of essential nutrients, and availability of oxygen. There is a little evidence for significant leaching of petroleum organic compounds from the upper soil layer. Many of the organic compounds are chemically or biologically degraded or volatilized from the soil during the cropping season. Because the fraction of sludge bome-toxic organics that does remaining soil has low bioavailability, absorption by crops is negligible. In some cases, volatile toxic organics may contaminate plant's tissue through absorption of volatilized compounds, however, management practice such as incorporation of sludge with soil and application of sludge before plant sprouting will substantially reduce any plant exposure to volatile organic compounds. (NAS,1996). Available data indicate that potentially harmful toxic organics pollutants do not enter edible portions of plant that are irrigated with treatment municipal wastewater, irrigation of vegetation in test plot with wastewater has shown no accumulation of Poly-nuclear Aromatic hydrocarbon (PAHs), especially. Benzo (a) pyrene (Il'nit skit et al., 1974). In a study of Aldehydes and other organics at agricultural land treatment sites, (Dodolina et al., 1976) found no uptake of Acetaldehyde, Crotonaldehyde, and Benzoaldehyde in the above ground portion of potatoes, and corn. Cyclohexanone, and Cyclohexnol could be found in corn plants four days after irrigation but no later. Dichloromethane was taken up by beets and cereal, but was metabolized and absent within about two weeks after irrigation. Health Concerns about Chemical Constitute in Reclaimed Water There are many chemical constitutes that enter the wastewater streams that are of potential concern for human health. These substances include organic chemicals, inorganic trace elements, and nitrogen. Conventional agricultural practices such as the use of fertilizers also have potential to introduce additional chemical constituents to soil. The degree from which the constituents from wastewater present a risk to human health depends on their concentration in reclaimed water and the fate and transfer of these chemicals from wastewater sources to human receptor via various exposure pathogen (Isam, 2001) {8}. There is a number of environmental processes that, when added to the soil, can interrupt the entry of toxic organic chemicals into food chain (Lessage & Jackson, 1992). Organic chemicals from wastewater may be destroyed after land application by biodegradation and chemical-and-photo-oxidation. Organic compounds may also be volatilized, immobilized into solid particles by sorption processes, or transported (leached) unaltered through the soil column to search the ground water. In more complex mechanisms, sorbed organics may subsequently be chemically or photo chemically degraded, microbialy decomposed or desorbed. Study case: Khartoum refinery: Khartoum refinery is located 70 km north of Khartoum State. It occupies an area of 5.5 km. The refinery is 2.5 km east of the railway lines and is 12.5 km away from the river Nile. The refinery plant is occupying half square kilometer while the remaining 8 km are reserved for buildings and extensions. Another 8 km were reserved for marketing companies and other projects related directly to the work at the refinery including a power station and housing compounds.
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The maximum design capacity of the refinery is 50 thousand barrels/day i.e. 2.5 million tons a year. There are five main units at the Khartoum refinery supported y other utility units. The five main units are: 1. Crude Distillation Unit and its maximum design capacity is 2.5 million tons of crude oil per year. 2. Reforming Unit, with design capacity of 15 thousand tons per year. 3. Diesel Hydro treating Unit, with 400 thousand tons per year designing capacity. 4. Residue Fluid Catalytic Cracking Unit with a design capacity of 1.800.000 tons a year. 5. Sour Water stripper with a design capacity of 400 thousand tons per year. The Utility units at the refinery constitute power generation station 36 megawatt, and water purification and pumping, 1500m3/hr. Water and Wastewater in Khartoum Refinery Wastewater in Khartoum refinery is divided into two main categories, A and B. A-1- Water Contaminated with Oil. 2- Oil Contaminated with Water. B-1- Domestic Wastewater 2-Cooling Water Blow Down. 2-Boiler Water and Boiler Feed Water (BW and BFW ) Blow Down. Water Usage in the Refinery Water is used in the refinery for the following purposes: 1- Cooling purposes. 2- Steam Generation. 3- Oil Washing. 4- Domestic Use. 5- Fire Fighting. Sources of Wastewater Associated with Various Production Units: 1. Crude Tank: Crude oil normally contains traces of water, an average of 0.05% per weight. The crude intake in the refinery is approximately 7500/day. Therefore, the quantity of water per day would be: (0.05/100) x 7500 = 3.75 tons/day 2. Desalting: In this process water is added to dissolve salts in the crude oil then by using electric desalter water is separated from oil. 3. Crude Distilling Unit [CDU]: It is one of the refinery's most active units. It implies the intake of crude oil heated at 360 degrees, accompanied by steam, which will produce a gas usually known as the refinery's gas. Air-cooling and water-cooling will be preceded for cooling down the product. Sour water is then directed to the sour water stripper. 4. Reforming Unit: Reforming unit does not use water in the process. Therefore, there is no wastewater source from this unit. 5. Diesel Hydro Treating Unit [DHT]: Diesel Hydro Treating Unit uses a furnace and a reactor for the removal of Sulfur, Nitrogen, and Olefins from the product. The product will be air-cooled and water cooled, and then it undergoes water wash. Wastewater will be discharged to the drainage system. 6. Residue Fluid Catalytic Cracking: long residue produced from the previous unit is directed to a reactor in the RFCC unit for molecules cracking. Water is discharged similar to CDU. 7. Utility units in Khartoum refinery: a. Cooling water system
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b. Power station c. Boilers 8. Other sources: A. Rain water B. Cleaning "washing" water Materials and Methods: Efficiency of removal was conducted, along with chemical analysis for a period of one month. Each treatment unit in the wastewater treatment plant was thoroughly investigated and analyzed. Investigation also included the final disposal of treated effluent. The treated effluent was disposed into three oxidation ponds 500m from the refinery. Evaporation, dimensions and chemical analysis were worked out, and general environmental observations were remarked. Four samples had been taken from four different units in the treatment plant on daily basis, as will be described later in this article. Three samples were taken from the oxidation pond. An experiment of Broad beans growth was also worked out during the study, to discuss the feasibility of water reuse for agricultural irrigation. The three Oxidation Ponds in Khartoum refinery situated at three decreasing levels. During construction, plastic layer had been installed at the bottom and the sides of the ponds to prevent water seepage. The area of the ponds is 0.78 km2. The flow is evenly distributed to preserve a 1.2m water level. Meteorological experiments of the area, estimated the evaporation rate to be 17.1mm/day. Samples had been arbitrarily taken from the ponds and checked for the following tests: PH, Oil Content, Sulfur Vontent, COD, BOD5, Volatile Phenol, Ammonia-Nitrogen, Sulfur, Suspended Solids, Phosphorous, Total Dissolved Solids, and microbiological tests. Seed-growth experiment of Broad beans had been conducted for all three samples to promote water reuse in specific crops. Remarks on the evaporated water and the size of the ponds water taken during the study.
Results and Discussions: Treatment Units As mentioned previously, the quantity and quality of incoming wastewater to the treatment plant from production units, varies widely according to the stat of production and quality of crude oil in the refinery. Nevertheless, results showed stability in treatment control. At the oily wastewater, oil content had a wide range (i.e. from >1000 to<90 mg/ 1) during chemical analysis tests. Here are the results obtained from the first monitoring point of wastewater in the study. Table 2 Results of wastewater samples taken from oily- water screen basin No Oil, Volatile Cod pH Sulfur mg/l Phenol mg/1 mg/1 mg/1 1 96.89 39.49 341 8.95 0 2 700,23 13.53 443 8.9 0 3 609.38 23.22 577 7.8 3.2 4 1123.86 14.31 378 8.1 1.2 5 1322.8 12.98 317 8.4 0 Average 770.63 20.704 411.2 8.35 0.88
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The importance of these results shown in table 2 is the identification of raw wastewater before treatment. Further treatment is gravity separation of oil. In this process oil was removed and separated for reuse, and wastewater was sent for dissolved air flotation first and second stage. (DAF1 and DAF2). Results of samples tests of wastewater taken from the out take of DAF2 as presented in tale 3 were as follows: Note: Quality Index provided in the study is according to the Chinese National Standards. Table 3 Results of Wastewater Samples taken from DAF2. NO. Oil mg/1 1 53.8 2 285.7 3 121.11 4 179
5 Average
183.7 164.662
The average percentage of removal would be: 800 Removal Percentage of Oil = 78.63 %
600
Oil Content in mg/l 400 200 0
Screen Basin
DAF2
Figure 1 Average Oil Removal Percentage from Intake Point at
The high removal DAF2 percentage was an outcome of the physical method (gravity separation) and Chemo-Physical methods (injection of air and emulsifiers). Oil discharged from is not useful the characteristics of oil deterioration. The third monitoring point was the Bio-Chemical unit in Khartoum Refinery. Samples were taken from the outlet and the results obtained were as follows in table 4. Table 4 Results of Samples Taken from the Biochemical Unit No.
Oil mg/l 1 6.5 2 19.59 3 16.94 4 21.67 Average 16.18
COD mg/l 272 381 117 91.1 215
BOD Phenol Suspended NH3, N Sludge pH mg/l mg/l Solids mg/l mg/l concn. 9.8 0 41 3.2 19 6.13 14.2 0.1 32 1.4 32 7.5 17.2 0 29 15.4 30 6.16 19.1 0.1 18 2.8 29 7.15 15 0.05 30 5.7 27.5 6.74
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After the results of the Bio-chemical unit, the wastewater effluent was by then improved by far. The anaerobic and aerobic units in the bio-chemical unit had extensively reduced chemical constituents of the wastewater, where at this point wastewater discharged clean and odorless to the sedimentation tank. The effluent was discharged afterwards to the filters and hence to the supervision basin. The supervision basin is considered the most important monitoring check point at wastewater treatment plant, and the results of the sample taken from it check the whole previous process. This is due to the fact that the effluent is discharged right way to the environment through the oxidation ponds. If the results were not satisfying, the by-pass pipeline connected to the basin send back the effluent for further treatment by repeating the previous process once again. These processes are repeated according to degree of contamination of the effluent. Sample taken from the supervision basin had results as in table 5 below. Table 5 Results of Samples Taken from the Supervision Basin Oil COD Suspended Sulfide NH3, N pH BOD No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Average Quality Index
mg/l 6.6 6.98 6.23 9.4 13.9 10.9 4.4 15.1 17.2 9.7 8.4 4.2 5.2 3.6 8.7 10
mg/l 124 90 84 171 99 67 83 92 13.3 65 86 44 70 94 9.3 150
Solids mg/l 61 52 68 55 64 42 53 55 100 50 77 70 55 32 64 70
mg/l 0.1 0.2 0.1 0.1 0.1 0.2 0.3 0.3 0.3 0.1 0.2 0.1 0.1 0.1 0.16 0.5
mg/l` 0.2 o.3 0.1 0.0 0.0 0.4 0.5 0.5 0.3 0.1 0.1 0.1 0.6 0.3 0.23 15
mg/l 6.36 6.16 6.95 7.4 7.4 6.0 6.2 6.2 7.0 6.7 6.6 6.0 6.0 5.6 6.45 6.9
15
23
7
15 260
As shown from the previous results, the oil content has been enormously reduced from DAF2 to supervision basin. Figure 2 shows the removal percentage of oil at these stages.
Figure 2 Oil Removal Percentages from Bio-chemical Unit to Supervision Basin
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The volatile phenol removal from oily water screen basin and the biochemical unit was as follows:
Figure 3 Volatile Phenol Removal from Only-Water Screen to Biochemical Unit
Oxidation Ponds The Oxidation Ponds at Khartoum Refinery are the final disposal terminals of treated wastewater effluent discharged from the treatment plant. The ponds are about 1100 m in length and 625 m wide. The effluent is odorless and greenish in color. No traces of oil (i. e. oil films) could be seen. The total area of the ponds is about 687500 m2. A level of 1.2 m is always maintained through even distribution of wastewater effluent into the ponds, y using control valves. There are embankments 3 m wide around the three ponds, which would make the total surface area of the effluent to be: [625 x 1100] – [(3 x 4 x 625) + (3 x 21100)] = 673400 m2 Multiplied by the depth (i. e. 1.2 m), the volume of the treated effluent would be: 673400 x 1.2 = 825000 m3 The peak evaporation index of the area is 17.1 mm/day. Therefore the daily evaporated water from ponds would approximately be 673400 x 17.1 x 10-1 = 11515.14 m3/day This result varies at different times of the year, making peak values at very hot dry weathers. The index drops in cold and humid weather to 16mm/day 10774.4 m3/day. Therefore, the average daily-evaporated volume of effluent would be approximately equal to 11144m3/day. Sources of daily discharged wastewater to the ponds were: 1- Production wastewater discharged from the treatment plant. 2- Blow-Down "circulating" water. The daily amount of production water (Q1) discharged to the ponds is calculated approximately as follows: Q1 = Wav x Q1av = 30 x 170 = 5100 m3/day Where, Wav: The average working hours of production pumps per day. Q1av: The average discharge of production wastewater per (m1/day) While the daily amount of blow-down wastewater (Q2) is approximately: Q2 = Wav2 x Q2av
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= 47 x 130= 6110 m3/day. Where, Wav2: The average working hours of blow-down pumps per day, Q2av: The average discharge of blow-down wastewater per (m3/day) Therefore the total daily average discharge of wastewater effluent to the oxidation ponds (Q) would be: Q = Q1+ Q2 = 5100 + 6110 = 11210 m3/day. The results showed that there had been a slight increase of incoming wastewater to that of evaporated one, which implied a continuous increase of wastewater onto the ponds. Water quality of the oxidation ponds had tested through samples taken from the ponds. These samples were chemically analyzed for different chemical constitutents that were suspected to be present at the ponds. Table 6 shows tests conducted and results that had been obtained: Table 6 : Tests and results of the first sample taken from the pond. No. Test Result Unit 1 PH 9.2 No 2 Oil 2.18 mg/1 3 Sulfur 0 mg/1 4 COD 351 mg/1 5 BOD5 23 mg/1 6 V.Phenol 0.04 mg/1 7 NH3-N 0.701 mg/1 8 S.Solids 93 mg/1 9 P 1.02 mg/1 10 TDS 1103 mg/1 The previous sample was taken from the first pond, which is situated at the lowest level of the three ponds. Results obtained on this sample were all acceptable ones, only the PH, and COD seemed to be slightly raised from the standard index. This is due to the presence of algae. A filtered sample tested for COD obtained acceptable results. Microscopic test that had been conducted on this sample indicated the dense presence of algae on the sample. The second sample had been taken from the second pond (The middle one); it is elevated 2m approximately above the first pond. The treated effluent looks greener than the first pond. No odor or oil films can be detected by human senses. Table 7: Showing the tests conducted and results obtained for the sample: No. Test Result Unit 1 PH 10.2 No 2 Oil 3.5 mg/1 3 Sulfur 0.8 mg/1 4 COD 377 mg/1 5 BOD5 39 mg/1 6 V.Phenol 0.08 mg/1 7 NH3-N 7.40 mg/1 8 S.Solids 325 mg/1 9 P 0.34 mg/1 10 TDS 1166 mg/1
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Microscopically, algae presence on this sample was denser than the previous one. That is why more COD and pH value were received during testing. Temperature, and sunlight also affect the value of COD and PH (i.e. the results vary during the day). Other results were acceptable according to the quality index. The third pond had the most algae presence between other ponds. It is also elevated 2m above the previous pond. The water at this pond was odorless and green in color. Tests and results are described at table 8:
Table (8) Tests and results of the third sample taken from the third pond No. 1 2 3 4 5 6 7 8 9 10
Test pH Oil Sulfur COD BOD5 V. Phenol NH3 - N S. Solids P TDS
Result 10.3 3.54 0.8 340 14 0.005 3.7 4.31 0 897
Unit No Mg/l Mg/l Mg/l Mg/l Mg/l Mg/l Mg/l Mg/l Mg/l
Birds swimming on the ponds and plants growing at the sites of the ponds were observed during testing. Microorganisms were found along with dense presence of algae at microscopic test conducted for the three ponds. There were slight differences on the effluent quality of each pond, as well as in color (i. E. algae presence). The average results of the effluent of the three ponds together would be shown in Table 9. Results from the treatment plant showed that there was no sulfur content on the wastewater coming from it. However, one does that sulfur content on the samples taken from the ponds were coming from the blow-down water. Nevertheless the result was acceptable to quality index guidelines. Oil content and volatile phenol values were acceptable for discharge standards, and can be discharged into waterways. The algae presence at the ponds increased the COD, pH and suspended solids values. On the other hand algae presence is an indication of good quality wastewater effluent. To translate the results into real-time experience and to open doors for effluent reuse for agricultural purposes or artificial groundwater recharge, and depending on the previous results, an experiment of broad beans growth was conducted.
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Table (9) Average Results of the Three Samples Taken from the Ponds No. 1 2 3 4 5 6 7 8 9 10
Test pH Oil Sulfur COD BOD5 V. Phenol NH3 - N S. Solids P TDS
Result 9.9 3.07 0.53 356 25 0.042 3.93 2.83 0.45 1055.3
Unit No mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l
Broad Beans-Growth Experiment and Results The first sample was tap water referred to as blank sample (sample 0) kept on a pity dish. Broad beans were dumped at sample 0. The second sample was from the first oxidation pond, referred to as sample 1. The third and the forth samples were from the second and the third ponds, referred to as sample 2 and sample 3 respectively. Small equal broad beans had been dumped n these samples, where all samples held the broad beans on pity dishes for the same period of time. All samples from the ponds had been taken randomly. Time of the experiment before removing the samples for photography was three days.
Figure (4) Roots Growth on Broad Beans for Four Samples As shown in figure (4), the results of the experiment were very encouraging. Some samples from the ponds showed even better results than tap water itself. This is clearly seen at the growing roots and the healthy textures of the broad beans.
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Conclusion and Recommendations The study of petroleum wastewater effluent management in Khartoum refinery had investigated the various wastewater treatment plants in the refinery, as well as terminal disposal point of reclaimed wastewater at oxidation ponds. Based on the results, reclaimed water reuse for agricultural irrigation would be considered. Conclusions drawn from this study can be summarized as follows:
Preliminary Physical Treatment Units: In this process an average of 78 percent of content had been removed with minimum losses policy. The useful removed oil had been sent to the crude oil tank. Biochemical Treatment Units: At the end of this process volatile phenol content in wastewater was removed to as high as 99.76 percent, and oil content was reduced. Other chemical constituents such as COD, BOD, SS, NH3-N, had all been quite acceptable according to known guidelines. Secondary Physical Treatment: These units are the sedimentation tanks and the mechanical filters.
Oxidation Ponds The chemical tests results on the oxidation ponds had shown some improvement on the reclaimed water quality due to dilution with blow-down water. The oil content had been reduced by 52 percent and volatile phenols by 16 percent from the results obtained previously on the supervision basin. Nevertheless, some deterioration had occurred on the quality of the effluent. Suspended solids, COD, and pH values had increased due to the dense presence of algae and photosynthesis, which in itself is an indication of reduction of inorganic compounds in the effluent. Seed Growth Experiment: To enhance the credibility of the previous results, broad beans growth experiment had been conducted, and the results obtained had showed that the reclaimed water at the oxidation ponds had satisfied good quality water of irrigational characteristics, which could be reused for some agricultural purposes.
Recommendations For optimum results concerning the core of the study the writers recommend the following: 1. The installation of monitoring wells at different distances scattered at downstream areas to record the groundwater quality of the underlying groundwater basin. 2. Reuse of reclaimed water at oxidation ponds for forestry irrigation. Camphor trees at eastside of the refinery are recommended. 3. Installation of several flow meters for each unit at the wastewater treatment plant for better monitoring of the quantities and quality at each unit. 4. Expanding the varieties of chemical tests to include more trace elements and organic compounds.
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Suggestions for Further Study 1. Studying the types of algae and bacteria present on the oxidation ponds and trying to genetically modify it so as to reduce the organic compounds through degradation or ingestion. 2. Analysis of more organic compounds such as Poly-nuclear Aromatic Hydrocarbon (PAH). Aldehydes and other organics might be done to study their effect on different crops. 3. Study to increase the efficiency of the biochemical unit at the refinery is recommended. 4. A statistical model to monitor and predict the contamination of groundwater upstream to downstream through observation wells records, are highly recommended for further studies at the Khartoum Refinery.
References 1. Anas M. Younis (1998), “Thermodynamics Study of Super Critical Carbon Dioxide Extraction of Refinery Wastewater, Unpublished M. Sc. Thesis, University of Malaya. 2. Atlas R. M. (1981), “Microbial Degradation of Petroleum Hydrocarbons”, An Environmental Perspective, Microbial Rev. 45: 180-209 3. Dodolina V. T., Kutepov L. Y. and Zhirnov B. F (1976): “Permissible Quantities of Organic Substances in Wastewater used for Irrigation” Vest. S-K Nauki, Moscow 6: 110-113. 4. IPNitskii A. P., Solenova L. G. and Ignatova V. V. (1974): “Sanitary and Oncological Assessment of Agricultural Use of Sewage containing Carcinogenic Hydrocarbons”, ORNL-2959 Kazanskiimed, Zh. 2: 80-81. 5. Lessage L. and Jackson R. (1992): “Groundwater Contamination Analysis at Hazardous Waste sites”, Marel Decker inc. New York. 6. NAS (1996): National Academy of Science, Water Science and Technology Board, “Use of Reclaimed Water and Sludge in Food Crop Production”, National Academy Press, 1996. 7. Rowe, D. R. and I. M. Abdel-Magid: “Handbook of Wastewater Reclamation and Reuse” CRC Press Lewis Publications, Boca Raton. ﺁﻓﺎق ﻟﻠﻄﺒﺎﻋﺔ، اﻟﻄﺒﻌﺔ اﻟﺜﺎﻧﻴﺔ،" "اﻟﻤﺎء،(2001) ﻋﺼﺎﻡ ﻤﺤﻤﺩ ﻋﺒﺩ ﺍﻟﻤﺎﺠﺩ واﻟﻄﺎهﺮ ﻣﺤﻤﺪ اﻟﺪردﻳﺮي.8 .واﻟﻨﺸﺮ ﻋﺼﺎﻡ ﻤﺤﻤﺩ ﻋﺒﺩ ﺍﻟﻤﺎﺠﺩ واﻟﻄﺎهﺮ ﻣﺤﻤﺪ اﻟﺪردﻳﺮي وﻋﺒﺪ اﻟﺮﺣﻤﻦ أﺣﻤﺪ اﻟﻌﺎﻗﺐ واﻟﺘﻴﺠﺎﻧﻲ إﺳﻤﺎﻋﻴﻞ.9 . دار ﺟﺎﻣﻌﺔ اﻟﺴﻮدان ﻟﻠﻄﺒﺎﻋﺔ واﻟﻨﺸﺮ واﻟﺘﻮزﻳﻊ،" "اﻟﻔﻀﻼن اﻟﺴﺎﺋﻠﺔ،(2000) اﻟﺠﺰوﻟﻲ
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The Effects of Industrial Pollutants on Water Resources in the Sudan by Dr. Isam Mohammed Abdel-Magid* & Dr. Bashir Mohammed El-Hassan**
Introduction It is truly assumed for long that the surface and ground water sources in the Sudan were not exposed to contamination. Nevertheless, and due to intensification of human settlement, industrial expansions, agricultural growth and communal development projects and schemes, the picture is nowadays changing. In certain circumstances there is confirmed contamination (industrial) and in others it is suspected (agricultural and domestic). If this trend is to continue, then the availability of sufficiently wholesome drinking water supply would be endangered. More than half of the Sudan area (2.5 million square kilometers, see Figure 1) is not riverain. Therefore, the country is exposed to water shortages especially during the dry season. This is confirmed by the drought, famine and desertification that struck the country during early and mid eighties. It is known that more than 70 percent of the Sudan inhabitants live in these none riverain parts, this is in addition to more than sixty million domestic and wild animals; thus making them liable to hazards of drought in prone areas.
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Figure 1. The Sudan
Historically, the domestic water supply and management has been the responsibility of two distinct sectors working at different levels namely: A. The Urban Sector: This sector is used to be the responsibility of the Water and Electricity Company (WEC), then the Water and Electricity Administration (WEA), and lately the different Regional Ministries of Services; and B. The Rural Sector: This is used to be the responsibility of the Land Use Board and Rural Water Development Department (LUBRWD), then the Rural Water Development Corporation (RWD), then the National Administration for Water (NAW) & lately the National Water Corporation (NWC) at the governmental level with delegated responsibilities to concerned regional ministries. It merits pointing out that these sectors continue to undergo changes and revision. This condition resulted in creation of a level of instability, which led to a negative impact on the overall performance of the water sector. The status of water quality at the source suffered tremendously due to many factors such as: Lack of coordination between concerned bodies having activities that are related to water consumption.
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The none existence of an authority of jurisdiction that would look after the welfare of the water resources in spite of bylaws and regulations such as the 1975 Environmental and Public Health Act. Increased water use by the industrial and agricultural sectors. The none awareness and/or none consciousness of some of the concerned bodies related to water and the community making use of the facility; with the consequences of indiscriminate use of water and disposal of effluents.
Results and methods: Generally, the water sources in the Sudan are exposed to contamination through domestic, industrial and/or agricultural activities. Lately, the industrial contamination has assumed a serious dimension. This is so because many industrial units and factories are using the so far wholesome river for dumping and disposing off their wastes.
Most of the factories are located along the banks of the river Nile and its tributaries, for ease of process water abstraction, cooling water supply, and, unfortunately, the ultimate disposal of treated effluents. This opened the door for misuse of water bodies, since it is used mainly as a dumping site rather than for the intended reasons. It can be forecasted that before long the nation will be facing an unsolved problem that will not only endanger the fresh water sources, but also will exhaust them and reduce possibilities in taking appropriate remedial actions. Table (1) shows the location and type of the major factories and industrial sectors that are liable to contaminate water resource bodies. Table (2) and Figures 2 and 3 summarizes the strength of waste
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Table 1 Type and Location of Major Industries Type of Location Industry Sugar El_Geneid factories El-Girba Kenana Sennar Asalaia Tannery Khartoum (2) Wad-Madani Port Sudan Textile Khartoum Port Sudan El-Hasahisa, Wad-ElHadad Tyre Port Sudan Factory Refinery Port Sudan Soap & Oil Khartoum Mills Port Sudan (Kemeir) Power Khartoum, Plants Sennar, Shendi Port Sudan Poultry Khartoum Dairy Khartoum Slaughter All over the House country Food Khartoum Port Sudan
Flow rate, Waste Treatment m3/d None None 22440 None 27072 None None Partial AS* AS* 71 None 40 None None OP** None 5828 None
Disposal Site Blue Nile Atbarah river Khor-White Nile Blue Nile White Nile El-Goz STP~ Blue Nile Red Sea ElHaj Yousif STP On site, Red Sea On site, Blue Nile On site, Blue Nile Red Sea
1050
None None
On site ElHaj Yousif STP + El-Goz STP
10 2100
None EB*** None None None S#,DAF## None None
On site, Red Sea Blue Nile Blue Nile On site, Nile On site, Red Sea On site, Blue Nile On site On site
None None
On site STP, On site
Key: AS* = Treatment plant incorporating Activated Sludge. OP** = Treatment plant incorporating oxidation ponds (Evaporation beds). EB*** = Equalization basins. S# = Soakaway. Khor = Native name for a seasonal stream. DAF## = Treatment plant incorporating dissolved-air flotation unit. STP~ = Sewage Treatment Plant.
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Figure. 2. Strength of Wastes from Factories
Table 2 Strength of Wastes Disposed from some Factories
Figure (2) outlines the strength of waste in terms of minimum and maximum values of the 5-day Biochemical Oxygen Demand (BOD20) as generated from the Sugar Factory (SF) at Sennar, the Red Sea Tannery (RST), the Kameir and Sons Soap Factory (KSF), the Power Station at Port Sudan (PS), the International Spinning and Weaving Factory (SWF), the El-Shiek Mustafa Oil Mill (EMO), the Petroleum Refinery at Port Sudan (PR), the International Tyre Factory at Port Sudan (TF), and a selected Slaughter House (SH) situated at Port Sudan. Figure (3) indicates both minimum and maximum concentrations of suspended solids (SS) of the wastes generated from the aforementioned factories and industrial units.
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Figure. 3. SS of Factory Wastes Discussions and Conclusions It is evident that the industrial pollution is assuming increasing dimensions as shown in the previous tables and figures. From Figure (3) it is clearly shown that the major pollutants are conveyed from the slaughterhouse, the sugar factory, the soap industry, and the tannery, respectively. Figure (3) also reveals that the soap factory ranked first in terms of the high level of suspended solids generated, yet to be followed by the slaughter house, tannery and the power station, respectively. Previously it has been safe to use raw water almost from any of the various water courses. Unfortunately, this is no longer the case, even at the remotest fringes of rural areas of the Sudan. For instance the evaluation of the UNICEF4 water supply project in South Kordofan, a province in the western part of the country, revealed that almost all Hafeers are contaminated. The hafeer is a large surface rainwater storage reservoir to be utilized during the summer (dry) season. Usually natural depressions in the area are modified and used by the inhabitants or the regional government. Hafeers range in their depths from 2 to 8 metres. An amount of up to 0.5 million cubic meter of water may be stored in these basins. Nevertheless, the average evaporation rate is estimated to reach 37 percent bending depth of reservoir, shape and type of reservoir, climatic conditions, topography of land and other related parameters. Water related diseases inveterate almost all the country. Examples of these diseases include: Dysentery, Gastroenteritis and diarrheal diseases, Giardiasis, Hepatitis, Typhoid, Malaria, Schistosomiasis, Trypanosomiasis, Trachoma and Eye diseases. The degree of incidence of a particular disease and distribution vary widely from a region to another. The general effect of
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these diseases, if not fatal, is to sap and bate the strength and productivity of their victims with varying degrees of debility and sequel. Even the supplied drinking water in towns and villages is liable to contamination due to the embodied irregularities. For example, though Khartoum town is supplied with treated surface water, nonetheless, where there is an increasing dependence on groundwater. This trend is likely to continue for years to come, the reason being the insufficiency of the existing five treatment plants. The outcome of this insufficiency is an overall shortage of the supplied water with low pressure in the network, which led to the non-authorized installation of private small pumps (in many cases) in the network, at the expense of the efficiency of the system and the quality of the supplied water. This picture takes an alarming dimension during the summer season. This allows for greater dependence on groundwater during that period, with the consequence that the consumer is supplied alternating with potable surface water or untreated groundwater. The effect of such practices on consumer’s health needs to be investigated; likewise any effects on the network. Some of the industrial factories as well as the inhabitants are practicing underground disposal methods through systems such as soakaways. This endangers the quality of ground water in view of the town's increasing dependence on this water source. The absence of an effectively authorized body or agency to look after the quality and characteristics of industrial effluents is, annoyingly, noted. The felt negative attitude of the industrialists and the concerned official public personnel could be attributed to either negligence or non-awareness with respect to environmental hazards associated with the ill practices and malfunctions of waste disposal systems. For example, the sugar factories (such as El-Geneid sugar factory) used to dispose large amounts of molasses, hot and muddy effluents, into the rivers. This practice will not only deplete the dissolved oxygen, but it will also increase the temperature, augment the suspended solids concentration, and alleviate the level of oil and greases with the eventual danger to the aquatic life and other related problems. Likewise, the steam power station in Khartoum town is disposing a lot of excessive heat to the river. Some factories, such as the Friendship textile factory at El-Hasahisa was commissioned without any facilities for industrial waste treatment and disposal. It seems that the designer took it for granted that the effluents will find their way to the Blue Nile, as the installed evaporation beds were a late solution. The tyre factory at Port Sudan disposes off its untreated effluent to the coast with possibilities of marine pollution problems. Likewise, the soap and detergent factory at Omdurman generates a strong waste that would augment the degree of pollution in the surrounding area. In many cases factories are installed and commissioned without the prior knowledge of the environmental protection agencies. Lack of awareness of concerned bodies led to what is prevailing at ElHaj Yousif sewage treatment plant (STP). This STP is originally designed to accept both the industrial and domestic waste of Khartoum North town. Due to the lack of a sewerage network in the area, the waste of certain factories from the neighboring industrial area is connected to the STP. The characteristics of the wastes interfered with the action and treatment process of the waste stabilization ponds constituting the biological treatment units. Therefore, the STP is serving as a bypass to untreated sewage rather than operating to meet design objectives. Hence the fear for the country's water resources is justifiable. The overall problem facing management of industrial waste sector could mainly be attributed to lack of awareness, lack of coordination, managerial and budgetary problems.
Recommendations: 1. -
-
Formulation of a national environmental ministry (as shown in figure (4)) in order to: develop and implement a comprehensive environmental strategy that would shoulder within its chapters the problem of water resources pollution abatement. The proposed strategy may be built on the part addressed by the Comprehensive National Strategy8. coordinate between all bodies concerned with industrial waste (ministries, institutions & societies), develop standards, bylaws and realistic legislation system for the protection of the environment, as well as reuse of wastewater, encourage industrialists, as much as possible, to reuse the generated wastes from their
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-
-
utilities. Address possibilities of wastewater reclamation and reuse, and propose work that would initiate expansion and improvement of experience and avoidance of mishaps of the Green Belt area in Khartoum, which is irrigated by a wastewater effluent. Establish an environmentally oriented data bank with emphasis on the protection of water resources Ministry of Environment
Water Department
Waste Department
Air Pollution Department
Reuse & Reclamation
Law & Legislation National Environmental Laboratory
Data & Information Centre
Regional Laboratories International Organization
Local Institutions
Related Ministries
Water, Air & Waste Authorities
Figure 4 the Proposed Ministry of Environment and Interaction between Related Environmental Bodies
2. 3. 4. 5.
- coordinate and cooperate between proposed regional laboratories, and to act as a focal point for water quality, and the existing national laboratory, - improve operation and maintenance and repair systems and funding. Encouragement of existing individual factories to have pretreatment units or treatment units to produce effluents in agreement with the adopted standards. Introduction of community education at national levels in order to mobilize the people for environmental protection and water resources safe guard. Initiation of research programs and epidemiological studies in industrial wastes collection, transportation, treatment disposal, and recycle or reuse. Integration of the development planning and administration with environmental planning and management.
References 1. El Haj, K.O.H., "A Technical Study of Industrial Waste in Port Sudan," M.Sc. thesis, IES, University of Khartoum, 1984. 2. Ahmed, E.E.O., "Environmental Assessment of Industrial Waste of Khartoum North Industrial Area," M.Sc. thesis, Institute of Environmental Studies (IES), University of Khartoum, 1982. 3. Shargawi, F., "A Report on the Industrial Waste in the Sudan," WHO/EMRO Publications, 1976. 4. UNICEF, "Report on South Kordofan Water Supply - an Evaluation Study," Khartoum, 1982. 5. Abbo, G. M. H., "Phiso-chemical Treatment of Tannery Wastes," M.Sc., thesis, Civil Engineering Department, University of Khartoum, 1985.
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6. El-Hassan, B.M. and Abdel-Magid, I.M., "Industry and the Environment: Industrial Waste Treatment", IES, Khartoum University, 1986 (in Arabic). 7. Abdel-Magid, I.M. and El-Hassan, B.M., "Water Supply in the Sudan", Khartoum University Press, KUP, Khartoum, Sudan, 1986. 8. Comprehensive National Strategy 1992 - 2002, Vol. I and II, Strategic Studies Centre, Khartoum University Press, Khartoum, Sudan, September 1992.
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Vulnerability of Groundwater to Pollution Risk from On-site Wastewater Disposal Systems with Emphasis on Khartoum Area68 By Abu Obeida Babiker Ahmed ElTayeb69 and Isam Mohamed Abdel-Magid70 Background In the past the purity and wholesomeness quality of groundwater was assumed, and even when groundwater resources were used for drinking purposes, little or no treatment was thought to be required. But in recent years, it has become obvious that groundwater may not always be safe to drink without adequate treatment {1}. The groundwater aquifer in Khartoum area is being threatened by a serious source of pollution, (i.e. septic tanks and their on-site wastewater disposal systems). In the last few years, many studies conducted regarding this aspect revealed that there is strong possibility for groundwater to be contaminated from urbanization activities. This is because the geological and hydrological formations of the area are not protective enough to prevent such pollution. The International Hydrology Programme, HIP, National Committee of the Sudanese National Commission For Education, Science and Culture {2} mentioned, that the common belief among some of the top water authority officials that groundwater in Khartoum State is safe from contamination, is proved to be wrong and Khartoum city mainly is classified to be extremely vulnerable to pollution risk due to high density of septic tanks existing there. In addition, the belief that there is a complete separation between the two levels of groundwater was also proved to be fault. The On-site Sanitation Department of Khartoum State estimates the number of septic tanks licensed annually, by 2,600, 45% of which are actually constructed (i.e.1200 per year) and 90% of Khartoum city inhabitants use septic tanks and their on-site disposal systems as means of disposing household wastewater. The vulnerable zones include: Riyadh, Manshia, Arckwit, Shagara, and Sahafa. In the light of these facts, a very alarming picture is drawn now concerning the quality and safety of this vital resource. Objectives This study was directed to investigate the following objective: Review of bacteriological quality of water wells through testing of total coliform, thermo tolerant (faecal) coliform and E.coli. Review of chemical quality for certain chemical pollutants (e.g. Nitrate, nitrite, ammonia, chloride, and phosphorous) . Investigation of many sanitary conditions around these boreholes. Review of different regulations, legislation, and environmental health procedures devoted to protect groundwater from pollution and the integrated management aspects concerning groundwater protection programmes. Outline appropriate integrated water resources management scheme to abate groundwater pollution.
68
Industrial Research Journal, Vol 1, No. 1, Dec. 2003, PP.10-30 ElImam ElMahdi University, ElGezira Aba 70 Industrial Research and Consultancy Centre, IRCC, P.O.Box 268, Khartoum 69
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Materials and Methods
Study Area The study area is Khartoum province with emphasis on those districts that are classified by Groundwater officials as highly susceptible for getting pollution (the area lies between the two Niles) because of rapidly growing urbanization. The area is bordered by the railway lines from the south and Sikka Hadid area from the north and by White Nile from the west and by Blue Nile from the east.This area is also characterized by high densities of septic tanks that are connected to on-site disposal wells as a sole system for disposing domestic wastewater. Geology and Hydrology of Study Area: According to Abdelraheem, {3} and Sudan Hydrological Map of Groundwater and Wadies Directorate, four distinct units in the study area have been distinguished: 1. Surface soils of recent age, consisting of unconsolidated clays and frosted sands, which do not contain groundwater. 2. Alluvial deposits of Quaternary age, consisting of sequence of unconsolidated clays and silts together with sands and gravel. The thickness of this unit extends up to 80m. The deposits are recharged either from rainfall or from water from the two branches of the Nile. 3. Tertiary Volcanic, consisting of olivine basalt emplaced in the Nubian Sandstone, and non-water bearing. 4. Nubian Sandstone Formation of possibly Mesozoic age, consisting of coarse, poorly cemented, cross-bedded sands with conglomerates. The material is alluvial continental deposit, which forms a large aquifer system. Water occurs in the jointed sandstone and conglomerates. The storage capacity is 77billion m3 and the saline content is 370to 1500 mg/l. the groundwater level near the Blue Nile is higher than that in the rest area. The aquifers systems are confined to nonconfined and can be divided in many layers. Some of them are partly confining layers, which are represented in pockets of clay and clay stone. The upper part of the aquifer is mainly clay and sand with some pockets of gravel and recent alluvial deposition. This layer lies above the level of abstraction. The lower and most thicker layer is a sandstone with some formations of sand and the thickness varies from 100 to 400 m covered by some pockets of clay (5-15m) and the lateral out flow is mainly directed to the North direction, following the river Nile direction in a very few amount out of the area. Khartoum sewerage system was established in 1954 and started to operate in 19581959 serving only about 80,000 populations of Khartoum and Khartoum North. The final treatment at that time was Algows Station, which receives about 3.2 million gallon of wastewater/day (40 gallon/person/day) and the length of the system is 146 km. In 1992, the project was extended to cross a distance of length of 200 Km and the capacity of the station was increased to 9 to 10million gallon/day. The final treatment station was transferred to Suba. With this capacity the project serves only about 10% of the population of Khartoum city and Khartoum north, the rest area uses on-site sanitation means (septic tanks, aqua privies, pit latrines…etc).
Materials and Methods To assess the quality of drinking water abstracted from different boreholes in Khartoum area, bacteriological and chemical quality of water wells were investigated 193
through tests of total coliform bacteria, thermotolerant (faecal) coliform bacteria, and E.coli for bacteriological quality and tests of nitrate, nitrite, ammonia, chloride, and phosphorus for chemical quality of water wells {4, 5}. Nitrate, nitrite, ammonia, phosphorus, and chloride were tested because these parameters if detected in water wells, they are mostly related to on-site disposal wells. Nitrate and its further transformation to nitrite may induce a major public health problem presented by methaemoglobinaemia or blue – baby syndrome {6}. Chloride may pass from disposal well unchanged to groundwater and is implicated in hypertension problems, Phosphorus is a nutrient and can cause eutrification {7}. Presence of ammonia indicates fresh pollution by sewage {8}. The sample size is amounted to 14 wells (30%) {9} out of 34 (in operation) distributed all over the area and include Shagara, Lamab, Dium, Sahafa, Arckwit, Riyadh, Maamura, Manshia, Burri, Taief, Geraif west, and Alfirdows. This area was characterized by high density of septic tanks not connected to the sewerage system of Khartoum State but the effluent is disposed off directly into the aquifer of Khartoum through the use of on-site disposal soakaways. Many observations were taken from the field to obtain an informative data concerning the sanitary conditions around the boreholes in addition to the investigation of opinions of parties concerned with groundwater pollution protection (i.e. local health authorities at Khartoum municipality, Al-Shuhada and Suba locality, and Khartoum east locality; On-site Sanitation Department- Ministry of Physical Planning and Public Utilities; and Groundwater and Wadies Directorate- Ministry of Irrigation & Water Resources). All bacteriological and chemical tests were held at the National Health Laboratory, after collecting samples from the production wells (pump outlet). Membrane Filtration (MF) method was used to identify and enumerate total coliform bacteria and thermotolerant (faecal) coliform bacteria and E.coli was detected through the use of EMB agar. Standard procedures of the American Public Health Association for Examination of Water and Wastewater 1998 were followed for testing bacteriological and chemical parameters of water wells.
Discussions The bacteriological quality of water wells in Khartoum area seems to be deteriorated as indicated by the presence of coliform bacteria in more than 78% of boreholes tested in the area with number of colonies ranging between 2 - 35 per 100ml of sample and more than 9% of boreholes that showed positive total coliform are also positive “contaminated” thermotolerant (faecal) coliform with number of colonies equal to 27 per 100 ml of sample. The presence of faecal (thermo tolerant) coliform is a clear indication of contamination due to faecal matter. In addition, the presence of coliform, bacteria (total coliform) is also an indication of pollution. The same case holds at Khartoum area in which water abstracted from boreholes is directly pumped and injected in the distribution system without prior appropriate treatment. Abdelraheem, {3}, referred to the presence of bacterial contamination in Alriyadh, Burri and Imtidad Nasir with total coliform count ranging between 10 and 37colonies per 100ml sample. These findings are justified when considering the results of cross section studies developed by IHP National Committee of the Sudanese National Commission for the Education, Science and Culture, {2, 10}, which revealed that the aquifer supplies the area is
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highly vulnerable to pollution risk as a result of intentional use of septic tanks that are not sewered but use on-site disposal soakaways as means of disposing household wastewater. The zones that are at risk include the rapidly developed districts in southeast of Khartoum town, namely: Riyadh, Sahafa, Arckwit, and Manshia. A significant association was found between the presence of bacterial contamination in water wells and the existence of boreholes in a distance less than 50 m from the neighboring on-site wastewater disposal well. In this aspect, the boreholes tested and showed positive bacterial result and at the same time they were at the distance of <50 m from the disposal well are equal to 90.91% while those of ≥50 m and positive coliform are only 33.33%, p value = 0.03 According to Khartoum Water Corporation records, the boreholes in the area when tested initially for ammonia they showed negative results. Nevertheless, as a result of laboratory analysis performed, a considerable level of ammonia pollution is found in Sahafa, Riyadh, Al Firdows, Dium east, Lamab and Shagara Mudraat. These levels of ammonia, although they are less than WHO and National guideline values (1.5 mg/l), but as UNESCO, {11}, WHO, {12}, and Salvato, {8}, they indicate fresh pollution by organic matter (i.e. sewage pollution). The indication of sewage pollution is identical with the results of bacteriological quality, which confirm the presence of faecal (thermotolerant) coliform. The values of nitrite (NO-2) and nitrate (NO-3) in water wells do not exceed the WHO (3 mg/l and 50 mg/l respectively) or National (2 mg/l and 50 mg/l respectively) recommended values. This may be related to the presence of nitrification process of nitrogen cycle in which ammonia is oxidized to nitrate and nitrite by Nitrosomonas bacteria, which oxidizes ammonia to nitrite and subsequently, Nitrobacter, oxidizes the nitrite to nitrate {13}. The only borehole that showed high level of nitrate above the WHO and national recommended value is Dium east (about 98 mg/l). This level of nitrate pollution is of great health importance since this water if infants (under six months old) and pregnant women consume it, a risk of methaemoglobinaemia and other health problems may prevail there. A noticeable association between nitrate/nitrite presence and bacterial contamination is found as indicated by those boreholes of positive coliform (positive NO-2) which represent 100% while those of positive coliform (negative NO2) are 75% and those boreholes with positive coliform bacteria (positive NO-3) were found to be 83% where as those with positive bacteria (negative NO-3) are 75%. The presence of nitrification process may contribute to the reduction in percentage of positive bacteria (positive ammonia) referred to in the results when compared to the positive bacteria (negative ammonia). The sanitary conditions around boreholes, as this work showed, are to some extent unsatisfactory and need to be improved against risks of pollution from many sources that may threaten the quality of well’s water. All boreholes in the area (100%) were located at the same level with neighboring dwellings and buildings and not higher than the sites of possible sources of pollution. This when taken with those results which indicate that 79% of boreholes are in less than the recommended distance (i.e. 50m) from the neighboring on-site sanitation systems, reflect the poor location of supply wells and reveal lack of coordination between concerned parties. These results are supported by those, which indicate that more than 90% of boreholes were found to have positive coliform bacterial test, and located at a distance of less than 50 m from neighboring on-site disposal system. More than 9% of these boreholes were found to have positive thermo tolerant (faecal) coliform test. The existence of such condition may create a conducive environment for both bacterial and chemical contamination to be dominant in this aquifer as WHO,
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{13} indicated that the travel of bacteria is found to be about 30m over the period of 33 hours if the borehole is in the range of less than 50m from the sanitation system. The travel of chemical pollution is found to be twice as fast. Both, Local Health authorities and On-site Sanitation Department mentioned that they are responsible for licensing septic tanks and their final disposal systems but in spite of that, they have no plans or activities for monitoring the requirements demanded by the law for construction or operation of septic tanks to check any violations that may occur. Complete lack of coordination between these concerned parties and other governmental bodies (i.e. Groundwater & Wadies Directorate) are evident during this study. Lack of coordination is reflected in absence of participation of local health authorities in planning and management of water supply programmes although they are delegated to conduct periodical examination of water supply wells to check their physical, chemical and bacteriological quality according to Environmental Health Act 1975. Such task is done only when there are outbreaks of diarrhea diseases. An independent authority as recommended by WHO, {14} should be involved in the planning, supervision and certification of new boreholes especially for chemical and bacteriological quality as well as the task of surveillance and monitoring to guarantee the management of drinking water program. Chemical and bacteriological results of tested water wells confirm that the situation is going to be deteriorated especially in the light of lack of integration between concerned parties. Both, Environmental Health Act 1975 and Groundwater of Sudan Regulation 1999 cover the subject of water pollution including pollution of underground waters by wastewater emanating from septic tanks (treated or not treated) and discharged directly or indirectly into the aquifer of the area. The results obtained from district councils (Local Health Authorities) revealed that they do not perform any sort of surveillance, monitoring and inspection activities for groundwater resources although the 1975 act requires this as a principal task of these districts. The two Acts require continuous monitoring and sampling of water wells and consider all the sanitary measures needed to ensure better quality of water intended for drinking purposes. The deficiency is the integration needed between them and others concerned. Joint technical committee concerned with aspects of where to locate boreholes with regard to pollution sources such as on-site disposal wells, depths of these disposal wells and boreholes and other necessary sanitary measures need to be formed. The fine or imprisonments imposed by these laws are not adequate when compared to the resultant condition (i.e. pollution of aquifer). The problem is that the Environmental Health Act 1975 and Local Orders of Khartoum Municipality 1960 were repealed. There are many reasons that make the aquifer of Khartoum area more vulnerable to pollution risk from on-site disposal wells. These can be summarized in: The belief that there are two zones of groundwater in Khartoum city is not true {3}. The cross section studies developed by Abdullah, {10}and the IHP National Committee of the Sudanese National Commission for the Education, Science and Culture, {2} revealed that the two levels of groundwater are separated with a very thin layer that consists of clay in some zones and sandy materials in others such as Shagara, Sahafa, and Arckwit (see bacteriological results of Sahafa {38}. Further, on-site disposal wells are placed at the same depth from in some boreholes were placed. The depths of boreholes according to the Groundwater and Wadies
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Directorate ranges between 98 to 498 ft. This range covers the two not separated zones of groundwater (i.e. Gezira formation and Nubian Sandstone). According to Abdallah, {10} and the On-site Sanitation Department, about 90% of households in Khartoum town use ill-designed soakaway as means of disposing off household wastewater. Hence a very alarming picture is now emerging regarding groundwater quality in Khartoum area when considering data which revealed that new techniques have been involved in the field of drilling of disposal wells with maximum time not exceeding 48 hours using a machine instead of manual drilling.
Conclusions and Recommendations 1. This study confirm that septic tanks and their final on-site disposal units may impose a great threat to Khartoum area aquifer, the ultimate solution of such problem is to construct a complete sewerage system to serve the whole area under consideration. 2. Establishment of effective groundwater protection programmes which include enactment of effective legislation and laws for groundwater, and clear definition for the extent of private property rights, and national and state implementing agencies. 3. Enforcement of existing Environmental Health and Groundwater legislation and regulations to control septic tanks effluent disposal, well licensing and drilling. 4. Closed supervision and effective monitoring to design & construction of septic tanks and disposal wells is therefore, highly needed for ground-water protection programmes. 5. Existence of different programmes with different conflicting goals and interacted jurisdictions may lead to serious managerial complications regarding groundwater quality management. Many conflicting interests were evident during this study. Therefore, delegation of licensing activities and monitoring of septic tanks and supply wells to the same authority is the favor. 6. Increasing public awareness and community participation in groundwater protection programmes is a necessity. 7. A detailed study on groundwater pollution should be conducted in future concentrating on those factors and conditions, which pose pollution of such aquifer or enhance its induction. References 1. Driscoll, F., G. (1986), Groundwater and Wells.Minne-sota: Johnson Division. 2. IHP National Committee of the Sudanese National Commission for the Education, Science and Culture (2000), Vulnerability of Groundwater Resources of Sudan to Pollution Risks. Khartoum, IHP National Committee of the Sudanese National Commission for Education, Science and Culture. 3. Abd Alraheem, M.A (1995), Pollution in the water Supply Wells of Khartoum, Sudan, Khartoum: Springer-Verlag. 4. Lanfax Laboratories. (2001), Water Sample Collection. Polk City: Lanfax Laboratories. 5. APHA; AWWA and WPCF. (1998), Standard Methods For Examination of Water And Wastewater, Washington: American Public Health Association; American Water Work Association and Water Pollution Control Federation. 6. Haller, L.; McCarthy, P.; O’Brien, T.; Riehle, J. and Stuhldrenher, T. (2002), Nitrate Pollution of Groundwater. Montague, Alpha Water Systems Inc.
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7. Rowe, D. R. and Abdel-Magid, I. M. (1995), Handbook of Wastewater Reclamation and Ruse, Boca Raton, Florida, CRC Press.Lewis Publishers Inc.. 8. Salvato, J. A. (1982), Environmental Engineering and Sanitation, 2nd Ed. Toronto: John Willey & Sons, INC. ﻭﻋﺒﺩ. ﻉ. ﻉ،؛ ﻤﺤﻤﺩ. ﻉ. ﻉ،؛ ﺍﻟﺤﺎﻜﻡ. ﻉ. ﻉ، ؛ ﻤﺤﻤﺩ. ﻱ. ﺱ،؛ ﻤﺤﻤﺩ. ﺵ. ﺃ،؛ ﺤﻤﺩ. ﻉ. ﺃ، ﺼﺎﻟﺢ.9 ﺴﻠﺴﻠﺔ ﺍﻷﻭﺭﺍﻕ ﺍﻟﻌﻠﻤﻴﺔ ﺭﻗﻡ، ﺍﻟﻤﺭﺸﺩ ﻓﻲ ﺇﻋﺩﺍﺩ ﺍﻟﺒﺤﻭﺙ ﻭﺍﻟﺩﺭﺍﺴﺎﺕ ﺍﻟﻌﻠﻤﻴﺔ.(2001) . ﻡ. ﻉ،ﺍﻟﻤﺎﺠﺩ
. ﻤﺭﻜﺯ ﺍﻟﺒﺤﺙ ﺍﻟﻌﻠﻤﻲ ﻭﺍﻟﻌﻼﻗﺎﺕ ﺍﻟﺨﺎﺭﺠﻴﺔ_ ﺠﺎﻤﻌﺔ ﺍﻟﺴﻭﺩﺍﻥ ﻟﻠﻌﻠﻭﻡ ﻭﺍﻟﺘﻜﻨﻭﻟﻭﺠﻴﺎ: ﺍﻟﺨﺭﻁﻭﻡ،(11) 10. Abdallah, A. (2001), Assessment of Groundwater Pollution from Domestic Wastewater in Khartoum Area, Dellft: International Institute for Infrastructural, Hydraulic and Environ-mental Engineering. 11. UNESCO (1992), Environment and Development Briefs, Groundwater. Paris: UNESCO. 12. Center for AI Application in Water Quality, the Pennsylvania State University – Agricultural and Biological Engineering Department. (2002), Water Shedds, Nitrate – Nitrite. Carolina: Center for AI Application in Water Quality. 13. WHO. (1993), Guidelines for Drinking - Water Quality, 2nd ed. Vol. 1, Recommendations, Geneva: WHO. 14. WHO. (1997), Guidelines for Drinking - Water Quality. 2nd ed. Vol. 3, Surveillance and Control of Community Supplies. Geneva: WHO.
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Identification and Assessment of Pollutional Aspects in Vegetable Oil Manufacturing in Sudan71 By Tagelsir Mustafa Abdelsalam72, Abdel Aziz Abdel Mageed Abdel Aziz73 and Isam Mohammed Abdel-Magid74
Abstract Vegetable oil manufacturing is an old and widespread industry in Sudan. The sources of pollution in oil manufacturing are partly attributed to the intrinsic properties of oil seeds and partly to techniques of processing. This study is an attempt to identify the sources of pollution in oil processing and assess the significance of their impact in environmental pollution. A statistical procedure based on Randomized Blocks and Factorial models of experimental design was adopted. The percent loss in processing, which goes into wastewater or disposed with refuse in the ground, was used as a measure to qualify the effect of the process on pollution. The study has established a model for assessment of effects on environmental pollution. However, the numerical results and the obtained quantification of pollution require further confirmation through more elaborate and proper selection of samples using random techniques.
Introduction The economy of Sudan is mainly dependent upon agriculture and agro-industries. Vegetable oil manufacturing is one of the first agro-industries established in Sudan. The manufacturing of vegetable oils and allied processes are industrial activities that have fairly gone Up-to-date development in Sudan. It started in the middle of the 19th century by the camel driven presses, then developed into the mechanical screw presses and recently applied modern techniques of solvent extraction. Also, the processes of oil refining and soap making have been greatly improved during the last two decades. Vegetable oil production and soap making are industrial processes which may compound pollution of the environment {9}. Due to this fact, intensive studies on pollutional characteristics potential in oilseeds and on waste resulting from the vegetable oil processing are of great importance. In Sudan this area is still virgin and needs more work to investigate the pollution qualitatively and quantitatively. Moreover, other studies are required to minimize the loss of resources resulting from the wastes in oil processing and soap making operations and hence improve the efficiency of production. 71
Published in The Sudan Engineering Society Journal, Issue No. 30, June 1988, pp 30-36 Lecturer, Chemical Eng. Dept. Faculty of Engineering, University of Khartoum 73 Private Engineer, Khartoum North, Sudan 74 Lecturer, Civil Eng. Dept. Faculty of Engineering, University of Khartoum 72
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One of the objectives of this work is to identify the types, sources and content of pollution caused by the vegetable oil industry as practiced in Sudan, then assess their significance on the pollution of the environment. Hence, the study is an attempt to develop a model for identification, quantification and assessment of pollutional aspects of vegetable oil industry in Sudan.
Vegetable Oils in Sudan Generally, many oilseeds are used for production of edible oil, and the most widely used is soyabean. In Sudan, the main oilseeds which are used to produce edible oils are cotton seeds, groundnuts and sesame. All of these seeds have intrinsic pollutional constituents which introduce some limitations on the use of their products in food making {4}. Typical examples are the secretion of toxic polyphenol gossypol and some pigembryo cells in cotton seeds. Also if aspirglius flavus infect groundnuts, highly toxic Alfatoxins will be initiated. Some of these pollutants are partially removed by processing, e.g. gossypol can be reduced by cooking. Hence, food products like edible oil and cakes have been made from these seeds. On the other hand, storage aspects may subject the oil seeds to some attacks and/ or bacteria, fungi and spoilage organisms {4}. These attacks are dependent upon physical and chemical properties of the media such as nutrients, moisture content, relative humidity, pH and temperature. The control of seed deterioration may be governed by controlling the concentration of dissolved oxygen.
Vegetable Oils Processing Before starting processing, the oilseeds must undergo some preparations {14}. The seeds are cleaned to remove foreign matter, then dehulled or decorticated to improve the yield, as the case may be. Prior to extraction, by mechanical expression or solvent extraction, the seeds undergo size reduction so as to facilitate the extraction process. In the case of mechanical expression, cooking by heat treatment is believed to improve the yield via coagulating or destroying of proteinous matter, unraveling of natural structure and breakage of some cross linking bonds, decreasing the oil affinity for solid surface attachment, giving the seeds proper plasticity, detoxicating gossypol, increasing fluidity of the oil, destructing bacteria and spoilage organisms {14}. The solvent extraction achieves high yield with less heat treatment. However, the relatively mild heat processing may result in products containing toxic matters which are not removed or inactivated and thus require further treatment to minimize the toxicity. The oil refining process may include neutralization, bleaching, deodorization and hydrogenation {1}. These processes involve the reaction of oil with chemical materials like caustic soda and bleaching agents which contain halogenated compounds. Some of these chemicals remain in wastewater and when discharged with water, they act as source of pollution in form of B.O.D., suspended solids, oils and grease and impurities {11}. These contribute to deoxygenation, toxic pollutants and alkalinity or acidity build-up. Typical characteristics of waste water from oil processing are shown in table 1, {5}. 202
For comparison between wastewater characteristics and the composition of industrial effluents, tolerable limits of these industrial effluents in Khartoum North are shown in table 2, {8}. There are considerable amounts of solid waste from spent bleaching materials, spent catalysts, seed residues, sludge from settling basins, off-quality raw materials and waste from packing materials {13}. In the case of solvent extraction, air may be polluted by vapor of hexane and odourferroussubstances, but these are found to be insignificant.
Table 1 Industrial process
Volume, liter per 1000 kg raw oil
BOD, kg per 1000 kg raw oil
SS matter, kg per 1000 kg raw oil
CIL, kg per 1000 kg raw oil
Solvent extraction & 148 0.06 0.04 degumming, Nuetralization, 1084 4.67 1.69 1.62 bleaching & deodorization 1542 9.36 3.35 2.82 Nuetralization, bleaching, deodorization& dehydrogenation Tank, car cleaning 225 0.49 0.19 0.2 Margrine from 1501 1.93 1.34 2.96 refined oil For comparison between the above characteristics and the composition of industrial effluents, the tolerable limits of these industrial effluents in Khartoum North are shown in table 2.
Table 2 Tolerable Limits of Industrial Effluents Discharge into Public Sewers Parameter PH Temperature Grease and Oils Suspended solids &BOD Petroleum products Sulphates & sulphides Iron &magnesium Chromium Calcium Copper Zinc Nickel
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Limits 5.5 – 10.0 60 C 15 mg /litre 800 mg /litre Flas point 85 C 10mg /litre 5.0 mg /litre 1.0 mg /litre 0.2 mg /litre o.1 mg /litre o.3 mg /litre 2.0 mg /litre
Investigation Procedure To carry out this study, existing factories of vegetable oil are classified according to the technological processes, operation and techniques of pollutional control applied in these factories. The criteria of technical practice have revealed different levels of processing technology i.e the operations of oil extraction from seeds varies from early camel-driven method to the most advanced solvent extraction. Also different levels of refinery processes are identified in different oil mills while some factories do not practice any refining operations. The main processing criteria adopted for the classification of factories are the following: a. Full refining processes: neutralization, bleaching and deoderization b. Semi-refinery process i.e. neutralization only c. No refining at all. From the view- point of pollution control, the following criteria were considered: 1. In-site or off-site pretreatment of waste materials 2. Recycling, recovery and reuse of suitable materials 3. No pretreatment and direct discharge of waste into the available disposal facilities. According to the above classifications, five categories of the factories have been designated as shown in table 3.
Table 3 Categories of Oil Factories Refining Category Extraction Batch Continuous Bleach& Pollution by screw neutralization neutralization Deodorization control pressing I * NA * * * II * NA * * NA III * * NA * NA IV * * Na Na Na V * NA NA NA NA * : Designates that the process is applied in the category. NA: Designates that the process is not applied in the category.
Analysis and Discussions For proper investigation, random selection of a sample of factories is necessary. In this study, the sample selection was governed by practical considerations. The main restrictions are availability of technical information, ease of accessibility to information if available and cooperation of the factory management to release the information. Due to lack of proper randomization, the data used in this work was just enough for the purpose of identification and qualification of pollution as well as the assessment of the process effect on the environment. In fact, the data obtained for this study is fairly useful for establishing a model for assessment of pollution which can be used with any reliable data to quantify more accurately, the pollutional aspects in oil industry. The investigation techniques adopted in this work are based on the design of experiments for study of variation between the categories of factories as well as variation within the same factory at different conditions. The Randomized Block 204
Model was used to test the significance of variation, in terms of percent waste, between the categories of factories (treatments) during one year over two-months intervals considered as (blocks) as shown in table 4, {7}.
Table 4 Randomized Blocks Table Treatments Blocks 1 2 3 4 5 6 Mean
II 7.8 8.3 7.9 8.6 8.8 9.4 8.5
Mean IV 10.1 10.0 11.0 11.1 10.5 9.7 10.4
III 8.8 9.5 9.3 8.9 9.1 8.7 9.1
V 7.5 6.8 6.7 6.9 7.1 7.3 7.1
8.6 8.7 8.7 8.9 8.9 8.8 8.8
For the investigation of each category of factories, the Factorial Design model was adopted. The factors were considered as the following ones: a. Pretreatment of wastewater to recover fatty acids. b. Bleaching and deodorization processes Batch or continuous neutralization. c. Batch or continuous neutralization. Each of these factors was tested at two levels and a model of 2 {3} was developed as depicted in table 5.
Table 5 Two Factorial Design Table Ao
A1
Process
Mean (Bo) (B1) (Bo) (B1) (Co) 6.0 8.7 5.0 7.9 6.9 (C1) 7.3 10.4 6.4 9.4 8.4 Average 6.7 9.6 5.7 8.7 7.7 Ao : The category uses no pretreatment of wastes A1 : The category makes treatment of wastes Bo : The category uses no bleaching & no deodorization B1 : The category uses bleaching only Co : The category uses continuous neutralization C1 : The category uses batch neutralization Statistical manipulation of the data in table 5 was carried out and the analysis of variance reflected the following findings There is no significant variation between periods of time during the year The pretreatment of wastewater is fairly significant at 95% level of confidence The effects of bleaching and deodorization and that of batch or continuous neutralization are only significant at a level of 99% of confidence.
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6. Findings and conclusions The following general findings and conclusions have emerged from the results of this study: a. In the analysis, the measure “percent waste” designates the percent of pollutants that are lost from the manufacturing processes and entered the wastewaters, evolved in the atmospheric air and dumped in the ground. b. In general terms, the study revealed the fact that the different processes in oil mills have significant effects on the pollution problem in the sub sector of industry. Bleaching, deodorization and neutralization seem to have similar effects. The average percent waste was found as follows: 133 kg/ton crude oil in the case of mechanical pressing with no refining processes. 71 kg/ton crude oil in the case of extraction with neutralization but no bleaching nor deodorization. 33 kg/ton crude oil in the case of extraction with all refining processes. c. Pretreatment of wastewater to recover fatty acids before final disposal has a fairly significant role in minimizing pollution. d. The best combination of processes is the full refining with continuous neutralization and pretreatment of wastewater to recover fatty acids. e. Despite the fact that the results agree with the local norms, they are found unaccepted when compared with international standards. This may be due to the fact that most of the factories discharge their wastewaters in sewers without pretreatment. f. The last mentioned result reflects the need for some preventive measures based on legal grounds so as to control; the disposal of wastewater from oil industries. g. Because all numerical data were obtained from production logbooks of he investigated factories, whose selection was not strictly random, the numerical results may need further confirmation. h. Despite the need for confirmation of the results, the application model of experimental design and statistical procedures for the qualification assessment of pollutional aspects in oil industry is valid and can be used with any reliable data. References 1) Anderson, A. J. C., Refining of oils and fats for edible purposes, 2nd Revised Edi., Pergamon Press, 1962. 2) Austin, J. E., Agro industrial project analysis, The Johns Hopkins University Press, London, 1981. 3) Cocks, L.V., and Van Rede, C., Laboratory handbook for oil and fat analysis, Academic Press, London and New York, 1966. 4) Duffs, C. M., and Slaughters, J.C., Seeds and their uses, John Wiley and Sons, New York, 1980. 5) El Zein, E. O., Environmental assessment of the industrial wastes, M. Sc. thesis, Inst. Of Environmental Studies, U. of K., 1982. 6) Environmental health act, the Gazette of Republic of the Sudan, 1975. 7) George, E.P., et al, The design and analysis on industrial experiments, 2nd Edi., Longman Group Ltd., London, 1956. 8) Industrial waste local order for the local council of Khartoum North, 1971.
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9) Lund, H. F., Industrial pollution control handbook, McGraw Hill Book Co., London, 1971. 10) O’Riordan, Timonthy, Tumer and Kerry, Progress in resources management and environmentl planning, Vol. 3, John Wiley and Sons, New York, 1981. 11) Ouano, E. and Lohnni, A. R., Water pollution and control in developing countries, Proceedings of international conference at Bangkok, Thailand, 1978. 12) Pirie, N. W., Food protein sources, International biological program 4, Cambridge University Press, 1975. 13) Royston, and Michael, Pollution prevention, Pays Pergamon Press, London, 1979. 14) World conference on oil seeds and vegetable oil processing technology, The American oil chemists society, Amsterdam, the Netherlands, March, 1-5, 1976. 15) WHO, Compendium of environmental guidelines and standards for industrial discharges, EFP/83.49, WHO, Geneva, 1983. 16) Personal communication with production managers of oil factories in Khartoum.
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The Effect of Retention Time and Length To Width (L/W) Ratio on the Removal Efficiency of BOD5, SS, and TS in Septic Tanks75 By Dr. Bashir Mohammed El Hassan76, Dr. Ahmed Hossam Eldin Hassan77, Dr. Mohammed Ali ElHag Alloba78, Dr. Isam Mohammed Abdel-Magid79 Abstract In this study the effect of retention time and length to width ratio on septic tank efficiency was investigated through a laboratory model. The model was designed based on dimensional analysis. The model was operated by using municipal wastewater from the inlet to Soba Sewage Treatment Plant (which incorporates stabilization ponds). The removal efficiency of BOD5, SS, and TS in the Septic tank Model was found to increase with the increase of retention time up to two days beyond which the increase was not substantial. Introduction Septic Tanks are increasingly used for the disposal of domestic waste for isolated communities, squatter urban areas, and rural fringes of developing countries. This is because of the nonexistence of municipal sewerage disposal facilities, and the doubts of ensuring complete sewerage coverage in the near future due to economical technical and social factors. Besides small communities ask for robust and compact sewage treatment works that require little maintenance and can be installed and operated with unskilled labour (Abdel-Magid et. al. 1995). The design features of septic tanks are mostly not standardized which is reflected in usage of a wide range of geometrical features (L/W ratio) as well as on low effectiveness regarding tank cost. this paper attempts to find the most effective tank volume based on the required retention time as well as the appropriate geometrical features in case of rectangular tanks. Material and Methods
Model Description A laboratory model of two compartmental septic tank as shown in figure (1) was built of pyrespex, and in order to avoid the effect of light and to help in establishing anaerobic conditions, the model was covered with black plastic sheets. The dimensions of the model were chosen through dimensional analysis. The model is having a length of 90 cm, width of 40 cm, overall depth of 400 cm, and an effective depth of 31.5 cm. The horizontal and vertical scale factor is 4. The dimensions of the large scale septic tank are 3.6m*1.6m*1.3m for length, width and effective depth, respectively. The dimensions were chosen to conform to common design relationships.
75
Published in the Bulletin of High Institute of Public Health. Vol. 25 No. 4, Oct. 1995, pp. 941-946.
76
Dean, Faculty of Public and Environmental Health, University of Khartoum 77 High Institute of Public Health, University of Alexandria 78 Department of Environmental Health, Faculty of Public and Environmental Health, University of Khartoum 79 Department of Civil Engineering, College of Engineering, Sultan Qaboos University
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Operation of the Laboratory Model To study the effect of variation in retention time and length to width (L/W) ratio on septic tank efficiency, the model was operated by using municipal wastewater from Soba Waste water Treatment Plant. The model was put on operation by filling it with drinking water, and then pouring into it a digested sludge from a working septic tank. The volume of the digested sludge poured into the tank was about 50 percent (by volume) of the model capacity. By this seeding method bacteria can be established within 24 hours, rather than waiting for about three weeks for bacteria to develop. (Impey 1959, and Pickford 1980). The model was dosed with wastewater taken from the grit chamber of the Soba wastewater treatment plant. The volume of the dosed wastewater was adjusted to give the required retention time based on the model capacity. Retention times, studied were 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 days. The model was operated at varying length to width ratios to study their effects on septic tank efficiency.
Parameters Investigated The following parameters were tested to evaluate the quality of the final effluent from the model, with different retention times and varying length to width ratios: 1. Biochemical Oxygen Demand (BOD520) 2. Total Solids ITS). 3. Suspended Solids ASS). 4. pH. 5. Temperature.
Experimental Procedure Samples of effluent from the model were collected and analyzed for the parameters described in section 2.3 above. The tests were carried out according to the standard Methods for the Examination of water and Wastewater (ALPHA 1992). Results and Discussion Figures 2, 4, and 6 show effect of retention time on efficiency of model. It was found that TS, SS, and BOD5 removal percentages achieved for two days retention time were 73.4%, 89.7% and 86% respectively, while those for three days retention time were found to be 77%, 94% and 86.4% respectively. This shows that the efficiency increased at a slower rate as the retention time increased from two days to three days. The obtained results demonstrated that a reasonable retention time to be aimed at in designing a septic tank is about two days rather that the commonly adopted retention times. The design of a septic tank on basis of two days retention time makes it cheaper due to reduction in construction material needed. Figures 8, 10 and 12 show the effect of the length to width ratio on the efficiency of the model. It was clearly seen that as the ratio of length to width increased better effluent was obtained. this is most probably due to the increase of settling efficiency, which in turn is due to minimization of short - circuiting and possible turbulence. From the least square analysis of BOD data obtained from the experimental results, the value of the rate constant for BUD removal K1 was found to be equaling 2-ld-1 and the
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value of Lo (the initial amount of BOD) was found to be 689 mg/l. Therefore, it can be concluded that the removal of BOD from septic tanks is governed by the following rate equation: BODt = 689 x (1- e-2.1t) Where: t = retention time in days BOD = biochemical oxygen demand in mg/L.
Conclusion 1. The removal efficiency of BOD5, SS and TS, for the septic tank model was found to increase with the increase in retention time up to two days, beyond which the increase is not substantial. Therefore a reasonable retention time to be aimed at in septic tank design is two days. 2. The behavior of BOD removal in the septic tank ( under the conditions prevailing in the study area) is governed by the following equation: 3. BODt = 689 x (1- e-2.1t) Where: t = retention time in days BOD = biochemical oxygen demand in mg/L.
References 1. Abdel-Magid, I.M., Hago, A. and Rowe, D.R., Modeling methods for environmental engineers, CRC Press/Lewis Publishers, Boca Raton, 1995 (Under publication). 2. Alloba, M.A.E. Alternative On-site wastewater management systems in Khartoum, Ph.D. Thesis, University of Khartoum, 1993. 3. ALPHA, AWWA, WPCF "Standard methods for the examination of water and wastewater" 18th edition, ALPHA Washington, D.C., 1992. 4. Dees, P.L., On-site Alternative for treatment, and Disposal, J. WPCF, Vol. 56, No. 6, pp 558, 1984. 5. Engle hardt, J.D and Ward, R.C., Operation and maintenance requirements for small flow treatment systems, J. WPCF, Vol. 58, pp 967,1986. 6. Hwang, N.H.C., Fundmental of hydraulic engineering systems, Prentice Hall, Englewood Cliffs, 1987. 7. Imply, L.H., The Development and use of the septic tanks, J. Ins. Sewage Purification, Part 3, 1959. 8. Otis, R.J. and Boyle, W.C., Performance of single household units, J. Env. Eng. Div., Vol. 102, No. EE1, pp 175, 1979. 9. Pickford, J. "The design of septic tanks and aqua prives" Overseas Div. of the Building Research, England, pp 1-10, 1980. 10. Schroder, E. D., Water and waste water treatment, McGraw Hill Inc. New York, 1977.
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The Effect of Natural Soil Characteristics on the Disposal of Septic Tanks Final Effluent80 By Dr. Bashir Mohammed El-Hassan81, Dr. Mohammed Ali ElHag Alloba82,Dr. Isam Mohammed Abdel-Magid83 and Dr. Ahmed Hossam Eldin Hassan84
Abstract In this study the leaching capacity of the soil to absorb the final effluent from septic tanks was investigated through percolation rate tests conducted on three locations of different soil types. The results revealed that the infiltration or percolation capacity of the investigated soil system was essentially controlled by the nature and rate of the solids accumulation at or near the soil surface and not of the soil structure. Introduction The utilization of soil for household waste treatment and disposal is an accepted practice for either individuals or small-scale wastewater treatment plants in developing countries (Salvato, 1992). These systems are generally easy to use, require normal, unskilled and low-cost technologies and show a high efficiency in relation to water resources safety. Thus, these devices form a sanitation alternative that can be applied in developing countries under some conditions and within certain limits that must be specified. These conditions are related to relevance of soil nature and its permeability. Materials and Methods
Percolation Rate Test
Objectives of the Test Current design practice for individual on-site Systems involves the use of a percolation test to determine the needed area of the required absorption system, and to assess whether the soil is sufficiently permeable to accept wastewater (Schroeder, 1977). Thus, percolation test in fact determines the acceptability of the site and establishes the area for the subsurface disposal System. It also determines the factors governing the percolation of the waste into soil formations and the steady-state percolation rates which could be expected under continual inundation. Experimental Procedure Three locations were selected for the purpose of this study. These were Shambat, Sahafa and ElMogran sites. The test was conducted according to the standard method adopted by Tchobanoglous (l982). Figure l shows the definition sketch for the conduction of the percolation test. 80 Published in the Bulletin of High Institute of Public Health. Vol. 25 No. 4, Oct. 1995, pp. 947-952. 81 Dean, Faculty of Public and Environmental Health, University of Khartoum 82 Department of Environmental Health, Faculty of Public and Environmental Health, University of Khartoum 83 Department of Civil Engineering, College of Engineering, Sultan Qaboos University 84 High Institute of Public Health, University of Alexandria
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The test was continued for 22 days through continuous inundation by septic tank effluents to determine the percolation capacity as a function of time.
Results and Discussions Figures 3 and 4 illustrate the percolation rates of septic tank effluent through different types of soils of varying initial permeabilities. The most significant finding from this study was that regardless of the initial soil permeability, under continual inundation all the soils studied reached, after varying periods of time, a steady-state of equilibrium percolation rate of about 0.04 m/day, as shown in figure 4. From these results it can be concluded that the ultimate infiltration or percolation capacity of a soil system is essentially controlled by the nature of the solids accumulations at or near the soil surface, and not of the soil structure. This finding is in agreement with Tchobanoglous (1982) and supports his conclusions that suspended solids are filtered out by the soil at interface or are deposited in the soil pore space in the immediate vicinity of the interface. Under anaerobic conditions, decomposition of both suspended and dissolved organic matter also results in the production of polysaccharides (slimes) and ferrous sulfide, a black insoluble precipitate, both of which tend to fill the soil pore space. The net results of the accumulation of effluent solids, bacterial growth and bacterial decomposition products on and near the liquid soil interface are a reduction of the infiltration capacity of the soil system. The practical implications of these experimental findings are the following: 1. The results of the standard percolation test are of little value in establishing loading rates because most soils will achieve the same equilibrium-loading rate when completely inundated with an effluent of poor quality. 2. More effective treatment of the wastewater will prolong the useful life of the disposal system and will allow the use of a higher equilibriumloading rate. References 1. Alloba, M.A.E., Alternative On-site Wastewater Management System in Khartoum, Ph.D Thesis, University of Khartoum, 1993. 2. Brands, M., Accumulation Rate and Characteristics of Sludge and Septage, J. WPCF, Vow. 51, No. 5 pp 936-943 1948. 3. Lambe, T.W., Soil Testing for Engineering, John Wiley, New York 1967. 4. Kovacs, G., Seepage Hydraulic, A Kademiai Kiado, Budapest, 1981. 5. Osman, M. A., Report on Soil Investigation for Arab Company for Livestock Development Headquarter Building at El Mogran, BRRI, University,v of Khartoum, 1987. 6. Osman, M. A and Zein, A. M., Report on Soil Investigation for the proposed Building of the EPI site, Sahafa, Khartoum, BRRI, University of Khartoum, 1987. 7. Salvato, J.A.P., Environmental Engineering and Sanitation, 4th Edi., John Wiley and Sons, New York, 1992. 8. Tchobangolous, G., A Review of On-site Waste water Management Alternatives for Kalamth River Country Estates, Leisure Industries Inc. California, 1982.
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Tchabonoglous, G., Wilson, G. E Huany, J.Y.C. and Wheeler, G., Managed On-site Disposal in Unsewered Areas, J. Environ. Erg. Div., Vol. 150, No. 3 pp 583 - 586, 1979. 10. Wilson, E. M., Engineering Hydrology, Macmillan Press Ltd., London, 1990.
9.
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Effect of Additives on Dewatering of Sludge85 By Dr Isam Mohammed Abdel-Magid and Dr Allaa ElDin M. El-Zawahry86 Abstract: The paper tackles research undertaken to determine the effect of addition of filter aids and additives to sewage sludge with the aim of improving its dewatering characteristics. The filtration features of a synthetic sewage sludge were studied prior and after the addition of additives and filter aids. The additives and filter aids used in this research work included various types of synthetic and natural substances such as: Acacia nilotica (Garad), Fenugreek or Trigonella foenum (Helba), and Vicia faba (horse beans). The basis for the selection of adopted additives included their relevance, adsorptive properties, incurred costs and availability. The selected additives improved the filtration properties of the sludge with varying results bending the type of additive used, the dose applied, and characteristics such as size, porosity and adsorptive capacity. Adsorption is illustrated to be the dominant mechanism controlling dewatering of the mixture of sludge and additives through the removal of sludge fine particles.
Background Dewatering of sludge that are produced in the course of wastewater treatment signifies a difficult problem. The cost of sludge treatment and ultimate disposal can approach around fifty percent of the capital and running cost of a sewage treatment plant {1}. The process of water withdrawal from sludge is important for the ultimate disposal of the sludge. This process not only reduces the volume of sludge requiring final disposal but also it slows down the biological decomposition reactions. As such research is needed to solve the sludge-dewatering problem via appropriate choice and use of suitable additives and filter aids. The factors that influence the sludge dewatering process are many in fold. Amongst essential and influential parameters are: sludge solids concentration, particle size and distribution, amount of available fine particles, proteinaceous matter content, hydrogen ion concentration and particle charge, moisture content, viscosity, shearing strength, oil and grease, method of sludge digestion, and used additives and filter aids. Many researchers {1, 2, 3, 4 and 6} have described the deterioration of sludge filtration properties through the existence of fine particles. Therefore, the presence of fine particles is regarded to be the critical factor that establishes the troubles practiced during dewatering of sludge. This condition asks for the removal of fine particles in order to gain any notable improvement in dewatering and filtration properties of sewage sludge. The general objectives of the work carried on were: (i) to gain more information and knowledge of the dewatering aspects of sewage sludge, (ii) to demonstrate the effect of additives and their fractions in expediting the easy egress of water from sludge, (iii) to describe the parameters that play a significant role in sludge dewatering practice, and (iv) to demonstrate the possible use of local and natural filter aids that are able to enhance dewatering efficiency.
85 86
Published in Dirasat Hundasia, Vol 7, No. 1, 1994, pp. 22-37. Assistant Professor, Civil Engineering Department, College of Engineering, P. O. Box 33, Postal code 123, Sultan Qaboos University, Muscat/Al-Khod, Sultanate of Oman
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Materials and Methods Due to problems faced with collection of sludge from the nearest treatment plant, and due to difficulties in using sludge within the premises of the laboratory, a synthetic sample has been used throughout this investigation. The value of the specific resistance of prepared sample was comparable to actual sludge collected during the early stages of the work. Synthetic sludge were prepared by adding to a volume of 1 litre of water 80 percent, by weight, of Bentonite soil, 10 percent of margarine and 10 percent of a fine soil composed of a clayey soil obtained from Nakhal area (a place in the Sultanate of Oman about 100 kilometers south-west of the capital Muscat). This mixture resembled greatly digested sewage sludge which is one of the common sludge found in practice, besides it is one of the most difficult to dewater due to its complex physical and chemical properties {1, 4}. The series of experiments conducted were to fulfill the previously outlined objectives. The selected filter aids included the following: a. Acacia: acacias are robust, wide ranging plants, which grow and coppice relatively rapidly yielding a source of protein in forest ecosystems {7}. Acacia species used included those species found in abundance locally including A. nilotica and A. senegal which is known locally as "Garad". b. Fenugreek: fenugreek (Trigonella foenumgraecum) is a slender herb used as a food, a flavouring, and a medicine [8] and is known locally as "Helba". c. Horse beans (Vicia faba): Vicia faba are flowering plants belonging to the class of dicotyledon. The selection of additives has been conducted according to their adsorptive properties, accessibility, convenience and inexpensive price. The concept used for determining the filtration property of the sludge is the specific resistance to filtration. The specific resistance has been defined to be the resistance to filtrate flow caused by a cake of unit weight of dry solids per unit filter area {1, 4}. The specific resistance is as given by the Carman-Coackley {9} equation which is presented in equation (1): P × A2 dV = (1) dt µ (r × C × V + Rm × A) Where: V = Volume of filtrate, m3, t = Time, s, P = Applied vacuum, Pa, A = Area of filtration (taken to be equal to the filter paper area, {2}), m2, µ = Viscosity of filtrate (found from tables, {10}), N*s/m2, r = Specific resistance to filtration, m/kg, C = Total solids content (to be determined following standard methods, {11}), kg/m3. Rm = Resistance of filter medium, m-1, When an additive dose of C1 is added to a sludge dose of C2, the mixture will have a solids concentration of (C1 + C2). For constant pressure, integration of equation (1) with respect to time yields:
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t ⎡⎛ µ × r × c = ⎢⎜ V ⎣⎜⎝ 2 × P × A 2
⎤ µ Rm ⎞ ⎟⎟ × V ⎥ + ⎠ ⎦ P× A
{2}
Equation (2) may be put in the form t/V = b*V + a
(3)
Where: b=
µ ×r ×c
(4)
2 × P × A2 µ Rm a= P× A
(5)
Then by plotting t/V versus V a straight line of gradient b is obtained and r is found from equation (4) as: 2 × b × P × A2 (6) r= µ ×c Where: b = Slope of the straight line of the plot of t/V versus V, s/m6. The apparatus employed in this investigation for finding the specific resistance {1,9} is the ordinary Buchner Funnel (see Figure 1). The apparatus was capable of giving a pressure range of 66 up to 199.6 kN/m2. The vacuum pressure used was 68.95 kN/m2.
The effect of different fractions of additives on the filterability of sewage sludge was also investigated. A sample of a particular additive under investigation was sieved into different size fractions according to the British Standard Methods {12}. While conducting specific resistance experiments it was observed that the clarity of the sludge supernatant increased upon introduction of certain species of filter aids. The incorporated changes differ according to the type of filter aid used. A set of experiments was designed and run to study this phenomenon more accurately. The apparatus used for
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the analysis consists of 500 mL graduated cylinders. The optical density was used as the criterion for determining the clarity of the supernatant of the mixtures left stagnant for 24 hours. Measurements were conducted by a spectrophotometer type Phillips, PU 8625, UV/VIS at a wavelength of 925 nm, which corresponds to the optimum wavelength for the supernatant for a blank sludge sample. Adsorption capacities of different additives were evaluated to represent the degree of adsorption of sludge colloidal and particulate matter by added additives and filter aids. The method used for this purpose is the dye solution method. This method was selected for its simplicity and rapidness {5}. The dye solution being chosen as adsorbate was Methylene Blue dye from BDH chemicals of a molecular weight of 319.859. In the isothermal curve plots, the amount of dye, which was adsorbed, Ym, was found from the empirical formula presented in equation (7). Ym =
(Ci
− Ce ) × V W
(7)
where: Ym = The amount of dye adsorbed at the plateau of the isotherms, mole/g adsorbent, Ci = Initial concentration, mole/L, Ce = Equilibrium concentration, mole/L, V = Volume of dye solution added to the sample, L, W = Weight of sample, g.
Results and Discussion Filterability analysis indicated that the selected materials varied in improving the filtering characteristics of the tested sludge (Figures 2 to 5). This may be ascribed to adsorption of sludge fines on the surface of the filter aid. This finding is in agreement with Coackley {1}. Addition of Fenugreek to the sludge sample resulted in a decrease in specific resistance with an increased additive dosage. The reduction achieved reached an optimum value of 72 percent, corresponding to a dose of 40 percent by weight, after which addition of more additives resulted in an increase in the specific resistance due to the increase of fine particles. This may be attributed to the high content of proteinaceous matter contained in the seeds. Kolousek and Coulson {13} found that the protein nitrogen and alkali-insoluble nitrogen are quite high in the seeds of fenugreek. Fenugreek addition resulted in a slight change in the pH value of the mixture of sludge and additive (see Figure 2). A similar result has been noticed for the mixture of sludge and Vicia faba but with a lower reduction in specific resistance (see Figure 3). Activated carbon has been employed for comparison purposes and its effect on filterability is as presented in Figure 4.
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It was noticed that the smaller the additive size, the better the passage of filtrate since the larger will be the surface area. This is shown in Figures 5, 6 and 7 for Acacia, Fenugreek, and activated carbon respectively.
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221
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The optical density measurements revealed that, the optical density decreased with the addition of more doses of filter aids as displayed in Figure 8.
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The figure reveals that the clarity of the supernatant improved greatly upon addition of more doses of the additives yet yielding different filterability efficiencies. In the case of Fenugreek the clarity of the supernatant decreased greatly due to the color induced by the seeds themselves. Usually, Fenugreek contains pigments such as carotenes and flavonoid aglycone which add a yellow color to the supernatant {14}. The addition of Vicia faba to the sludge demonstrated a reduction of optical density upon more addition of the filter aid up to an optimum dose of 60 percent. Further increase of Vicia faba resulted in an increase in the optical density denoting deterioration in dewaterability beyond this dose. Adsorption of solids by these filter aids is apparent and has been demonstrated to be of significance in the adsorption of methylene blue dye solution. The adsorption isotherms for acacia, fenugreek, and Vicia faba signified that these materials have a substantial adsorptive capacity as shown in Figure 9.
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Conclusions From the investigation carried out in this study it could be concluded that: 1. Addition of selected natural and locally found additives to sludge improved its filtration properties with varying results. 2. More reduction in specific resistance of the checked sludge samples was detected upon the usage of more dosage of filter aid. 3. Better deawatering properties were obtained when a smaller additive size has been used. This is demonstrated via the reduction in the specific resistance of the sludge. 4. The rate of adsorption of fine particles from the sludge, on surface of the filter aid, increases with a decrease in the size of the filter aid. Accordingly, and for improved dewatering characteristics of the sludge, the filter aid that ought to be added is required to be: i. of a high permeability and porosity value. ii. with a considerable adsorptive capability. iii. of a particle size approaches that of the fines present in the sludge. Lastly, but not least these findings are to be confirmed using actual sewage sludge from a sewage treatment plant.
References 1) Coackley, P. (1975) Development in our knowledge of sludge dewatering behavior 8th Public Health Engineering Conference held in the Department Civil Engineering, Loughbourough University of Technology, 5. 2) Gale, R.S. (1971) Recent research on sludge dewatering, Water Pollution Research Laboratory, Stevenage, Herts, 531. 3) Karr, P.R., and Keinath, T.M. (1978) Influence of particle size on sludge 225
dewaterability, J. WPCF, 1911. 4) Abdel-Magid, I. M. (1986) The influence of lime and grease on dewaterability of sewage sludge, The Sudan Engineering Society J., No. 29, 26. 5) Hang, P.T. and Brindley, C.W. (1970) Methylene Blue adsorption by clay minerals: Determination of surface areas and cation exchange capacities, Clays and Clay Minerals 18, 1970, 203. 6) Al-Rashdi, S. K. G. (1992) The effect of local Filter aids on sludge dewatering, B.Sc, Project, Civil Engineering Department, College of Engineering, Sultan Qaboos University. 7) Doran, J. C., Jurabull, T. W., Boland, D. I. and Gunn, B. V. (1983), Handbook on seed of dry-zone acacias, FAO, United Nations, Rome. 8) Nour, A.A.M., and Magboul, B.I. (1986), Chemical and amino acid composition of Fenugreek seeds grown in Sudan, Food Chemistry, J., 21(1), 1. 9) Coackley, P. (1953) The dewatering treatment, Ph.D. thesis, London University. 10) Shames, I. H. (1992), Mechanics of fluids, McGraw-Hill International Editions, 3rd Ed., New York. 11) APHA, AWWA, WPCF. (1985) Standard methods for the examination of water and wastewater, 16th ed., APHA, Washington, DC. 12) British Standard Institution (1975) Methods of testing soils for civil engineers, B.S. 1377. 13) Kolousek, J. and Coulson, C.B. (1955), Amino acid content of the seed protein of Trionella foenum graecum L., and of the seed protein and thallus protein of Galega officianalis L., J. Sci. Food Agric., 6, 203. 14) Abu-Al-Futuh, I.M. (1975) Studies on Trigonella foenum, Graecum L., and its 4hydroxyisolucine, Ph.D. thesis, University of Bath.
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The Impact of Irrigation and Drainage on Environmental Health along the Nile Introduction The establishment of the many agricultural irrigation canalization schemes and the subsequent drains along the river Nile and its tributaries and in the valley and the Delta of the Nile has intrigued Egyptian and Neolithic farmers, in different localities, to settle close to and around canals` banks. In this way settlers are able to satisfy their household water needs for the purposes of drinking, washing, cooking, etc; together with the relative food resources in terms of fish, aquatic animals and plants. The basic and essential water requirements by farmers address the adequacy, convenience aspects, and continuity of the supply to its planed intentions. The farmer's dependence on the canals copouled with ignorance and poor environmental awareness lead to canal misuse, introduction of pollutants to these surface water resources, and the progressive deterioration of the aquatic environs. In addition, the compound effect of population increase and poor personal hygiene aggravated the contamination situation. The establishment of the canal and drain network has influenced the social, economical and health environment in various ways with the consequent evolution of expected merits and demerits. Although, irrigation canals are constructed primarily to transmit and distribute water to agricultural land, they always go through or close to villages and are used by people frequently. Typical uses include: • Supply of water for domestic purposes especially drinking and cooking in absence of a wholesome water supply source or when the existing source has an unacceptable quality. Examples of deterioration in quality include the problems of salinity in the northern part of the Delta of the Nile, Iron, Manganese and Nitrates at some other localities. • Washing utensils, containers and clothes inside the canal. This activity seems to establish itself as an ordinary habit of settlers in vicinity of canals even in areas where a wholesome drinking water facility is found. This may be attributed to female social gathering, or due to intension of settlers to avoid overloading their sewage collection tanks. • Watering and cleaning of livestock. • Usage of the canal as a disposal site for the discharge of urine and human faeces. • Disposal of households’ refuse (garbage) or dead animals or birds into the canal. The state of health of the inhabitants has varied from one region along the Nile to another. Also, settlers located in different areas along the Nile interact and influence the water pattern in a manner distinct from those adjacent to a Rayah, a Hawasha, a main canal, a distributary canal, a secondary canal, or an Abu Ishreen. Environmental perception and awareness, personal hygiene, existence of a potable and palatable water supply, and establishment of appropriate waste disposal facilities would affect significantly the social and health environmental situation in the Nile communities. Irrigation canals also witnessed the reception of industrial wastes from illegal connections. Also, the Egyptian Ministry of Public Works and Water Resources plans to reuse agricultural drainage water and many canals are receiving or scheduled to be augmented with drainage water in the future. Consequently, water quality of those canals downstream the mixing points shall reflect quality of both waters. Similarly, agricultural drains are constructed primarily to collect and transport drainage water reaching surface drains or spilled from irrigation canals and Mesqas. They are intended to either dispose the collected drainage water or reuse it by pumping to
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canals. In Upper Egypt, and Central Sudan drains discharge to the Nile, and in lower Egypt they dispose their water into the sea or the Northern Lakes. However, as with canals, drains are also misused. In most cases, they receive wastewater from individuals, houses and industrial sources. In addition, subsurface drainage water reaching drains usually includes a large fraction of the fertilizers, pesticides, insecticides, and other chemicals applied on the field during the agricultural activities. In summary, the construction of the irrigation and drainage (I & D) systems affects adversely the health environment of the Egyptian and Sudanese farmers due to the chemical and biological pollution of their water. The following sections discuss the impact of the chemical and biological pollution of canal and drain water on health environment. Impact of Biological Pollution of the I & D System The health environment in rural areas has been affected by the biological pollution of the water of the I & D system. Two aspects are important in this regard. First, when people use biologically infected. Second, in the absence of environmental awareness and due to other factors they themselves re-introduce the pathogens into the systems with an accelerated cycle. Fortunately, the recent progress in medical care slows down this alarming cycle. The supply of wholesome water is basic in the management and control of many water related infections. Approximately about 80 percent of all diseases in the world are considered to be connected with the use of unsafe water. This water-disease linkage may be found in separate patterns and forms. Therefore, the classification and arrangement of diseases may be initiated in accord with theses patterns and forms. The human health may also be affected by the chemical quality of the water. For example, a high Fluoride content in a groundwater source may introduce an adverse effect on the growth of bones. Nevertheless, the chemical health risks to be induced are, normally, not as high as the risks that are brought about from microbial contamination of the water in specific localities. Generally, the diseases that are associated with water and/or reclaimed wastewater may be grouped in five main groups. These suggested groups include: Water-borne diseases, water-washed diseases, water-based diseases, water-related insect vectors, and infections primarily of defective sanitation. These groups are briefly summarized herein. Water related diseases can be classified into three main categories: (a) water-borne diseases, (b) water-hygiene diseases, and (c) water-habitat diseases. Water-Borne Diseases Water-borne diseases are those infections that may be spread through a water supply system. Water acts exclusively as a passive vehicle for the pathogen that causes the disease. Examples of these diseases include: Typhoid fever, Cholera, Giardiasis, Dysentery, Leptospirosis, Tularemia, Paratyphoid, Infective hepatitis, and some Enterviruses, etc. Typhoid and Cholera are both due to relatively fragile microbes whose sole reservoir is man. Typhoid causes a severely high fever. The Typhoid victim may recover clinically but continue passing pathogens in the feces for a period of time that may extend to some months or years. The Typhoid carriers are regarded as the principal source of the infection. A toxin produced by the bacterial agent Vibrio cholerae in the human small intestine causes cholera. The ability of the bacteria to stick to the intestinal lining and establish themselves in this area (bound organisms) is regarded as an important feature in producing the disease.{11}
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Giardiasis is usually brought about by the infection of the cysts or trophozoites of Giardia lamblia. The parasite lives in the upper small intestine and trophozoites may also be found in jejunal juice or lying alongside the jejunal mucosa in a jejunal biopsy. Giardiasis is responsible for gastrointestinal disturbances, flatulence, diarrhea, and discomfort. Likewise, Giardiasis is emerging as a major waterborne disease.{5d} Bacillary Dysentery is usually due to Shigella flexneri and Shigella sonnei. The protozoan Entamoeba histolytica is figured responsible for Amoebic dysentery and Amoebic Hepatitis. Amoebic dysentery is normally present with a bloody diarrhoea stool, lower abdominal pain and mild fever. Usually, the disease often exhibits a subacute or a chronic sickness. Water-borne diseases include enteric diseases (diarrhea, dysentery,...etc.) due to pathogens in drinking water which are of faecal origin. These pathogens may be bacteria such as salmonella, shigella, coli, vibrio, cholera, or entero viruses such as polio, or protozoa such as Entamoeba histolitica, or helminthes such as guinea worm, and hook worm. The occurrence of water-borne diseases depends on the existence or non-existence of a water supply system. With the government policy of supplying the Egyptian villages with potable water, these diseases are reduced. Water-washed diseases: Water-washed diseases are those diseases that eventuate due to a shortage of water for personal hygiene, i.e. lack of an adequate quantity of water. The main group of these infections is those that affect the body exterior surface, the eyes, and the skin. Examples of the water-washed diseases include: Bacillary dysentery, Skin Sepsis and Ulcers, Conjunctivitis, Trachoma, Scabies, Yaws, Leprosy, Tinea, Louse-borne fevers, Diarrhoeal diseases, Ascariasis, etc. The eyes infections are of special concern in arid and semi-arid zones. This is because the eye conjectiva is negatively influenced by availability of factors such as: dry atmosphere in the area, dusty winds, sand storms and deficiency of water in the region. Trachoma may cause inflammation of the eye, rotation of the eyelashes and the resulting opacity of the cornea. These conditions may lead to partial or complete blindness. Salmonella pathogens are usually found in municipal wastewaters. The Salmonella group includes a great number of species that may initiate infections in man and his domestic pets. Salmonellosis in man may be classified as: Enteric fevers [e.g. typhoid fever], Septicemia, and acute Gastroenteritis. Diarrhea is a condition that produces watery or bloody stools that leads to a loss in child weight. The infection usually includes one or more of the following symptoms: fever, vomiting, cramping, loss of appetite, and malabsorption of nutrients. Diarrhea is usually due to the ingestion of many enteric organisms that cause disease. Diarrhea may also be caused by other non-enteric infections such as Measles or even be caused by intestinal abnormalities not related to infection such as lactose intolerance. These enteric organisms are usually transmitted through excreta (human and animal) and may be ingested through contaminated drinking water, food, hands, or other objects. The organisms can go directly from person-to-person, person-objectperson, or person-water-person. In some instances self reinfection may continue in an individual such as in the case with Giardia.73 The pathogenic organisms that may cause diarrhea may be bacteria, viruses, or parasites. Some of the major organisms are Campulobacter jejune, E. coli, Shigella spp., V. cholerae, rotavirus, Cryptosporidium, Entamoeba hystolitica, and Giardia lamblia.The transmission for the diarrhea-causing pathogens may be reduced by improving excreta disposal and sanitation, increasing the amount of water for personal and domestic hygiene, improving drinking and cooking water, promoting breast-feeding in mothers, better weaning practices, reduction of food contamination, and vaccine development are all expected to reduce diarrhea rates.{73} Diarrhea is considered the main cause for the high morbidity and mortality rates among children less than five years old. Diarrhea may lead to death in severe cases and in a child
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with malnutrition. The annual incidence of diarrhea per child in developing countries is estimated at 3.5 cases. Some children suffer more than others, and they may have 10 or more episodes of diarrhea per annum. Several million children die each year from diarrhea {73}. Water-hygiene diseases are the consequence of the inadequate use of eater to maintain personal cleanliness. Enteric diseases, eye (trachoma) and skin (scabies) diseases as well as louse-borne diseases (typhus) diseases are the results. Water quantities appear to be of higher priority than quality in this category. It appears that the existence of the irrigation canals may have had a positive impact in this category. Obviously, personal hygiene still governs the spread of these diseases. Water-based diseases: Water-based diseases are considered as infections transmitted through an aquatic invertebrate host, usually an animal. It is to be noted that an essential part of the life cycle of the infecting organism takes place in this aquatic animal. Examples of the water-based diseases include: Schistosomiasis, Guinea worm, Filariosis, etc. Schistosomiasis, or Bilharziasis, or swimmers itch, is a disease that is caused by the infection of the venous system by trematodes of the genus Schistosoma. The disease is transmitted through the skin and it may be accompanied by inflammation and itching. Hematuria or bloody urine among children is the classical clinical sign of urinary schistosomiasis.{74} Urinary infection is caused by S. haematobium, which inhibits veins around the bladder. Intestinal infection is caused by S. japonicum and S. mansoni in the portal venous system that transports blood from the intestines to the liver. S. intercalatum also causes intestinal infection which has a localized distribution in West Africa.12 In most endemic communities the prevalence of the infection is highest in 10 to 14 year old children. In many communities of Africa, over 70 % of village school children can be infected.{74} Schistosoma mansoni infection is gained by contact with contaminated fresh water in rivers, lakes, streams, ponds and very frequently irrigation canals. Drinking contaminated water rarely infects people. Any contact with contaminated waters can result in infection. This involves the following: water collection for home use, hand and utensils washing, clothes cleaning, washing animals, washing after defection, bathing, swimming by children, and occupations that require human-water contact such as: irrigation, irrigation canal and drainage construction, canal cleaning and fishing. {74} The infection is not spread directly from person to person but rather through the snails. If the snails are not present, schistosomiasis transmission will not occur {74}. The adult worms produce eggs or ova. When the eggs come in contact with fresh water they hatch and release another form of larvae denoted miracidium, which search for and contaminate snails. Consequently, the snail releases the cercaria larvae. Many of the schistosomiasis victims start having lethargy, abdominal pain and intermittent diarrhea after some months of being infected. The vast daily laid amounts of microscopic eggs impair the body tissues with a resulting loss of blood into the urine or feces. The eggs are usually kept in the bladder wall, or are transferred to the liver, which is ruined greatly. The eggs that are deposited in the bladder wall may die and become calcified. Damage to the liver, spleen, kidneys, bladder (including bladder cancer) and to the central nervous system occur to those patients who are highly infected. Much of the chronic damage to these organ systems is irreversible and in severe cases the individual may die from internal bleeding {74}. Generally, the disease has a negative impact on the self-productivity and socio-economic growth. Schistosoma mansoni infection is endemic to many areas of Africa, Caribbean, the Middle East, Northeast and South America. The escalated land usage through the development of irrigation projects may result in an increasing incidence of S. haematobium transmission through Bulinus snails breeding in the irrigation canals. S. haematobium is widespread in Africa and the Middle East and in certain places in Europe and Southeast Asia. The main genera of snails that act as hosts besides Bulinus are Biomphalaria for S. mansoni, Oncomelania for S. japonicum {10} and Tricula for S. mekongi {12}. The three common parasites of Schistosomiasis in man, S. haematobium, S. japonicum and S. mansoni, have a similar life cycle. The parasitic eggs are passed in the urine in case of S. haematobium or faeces in the cases of S. japonicum, and S. mansoni. After their release the eggs
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hatch in aggregations of water such as ponds, lake edges, streams and canals. From the eggs the miracidia hatch into the water where they invade suitable snails. In the snails the miracidia develop two generations of sporocysts the second of which manifests the fork-tailed cercariae, a macroscopic larval form released by certain species of fresh water snails. The cercariae enter the skin of a new host which approaches the infected water. When the cercariae penetrate the skin they discard their tails and become schistosomulae. The Schistosomulae move through the tissues approaching the portal venous system of the liver. In the liver the males and females copulate and reside in pairs. From the liver they migrate to the venous plexus of the bladder or rectum, where they lay spiny eggs. These enter into the bladder or rectum yet to reach the exterior. Most of the eggs are transferred via the wall of the rectum and colon with the lateral spine guiding them in an opposite direction to that of the blood stream in the mesenteric venous radicals, to which the adult worms are adhered. The snails will not become infected and the disease will not be transmitted if urine and feces from infected persons do not go into surface waters. This suggests sanitary disposal of human excreta, which would halt the release of cercaria and stop transmission of infection. Thus, improved sanitation may reduce the prevalence of schistosomiasis. Therefore, preventing contact with contaminated surface waters and obstructing eggs from reaching water supplies are two approaches for reducing schistosomiasis transmission. It follows that by improving water supplies and sanitation in endemic communities, transmission of schistosomiasis may be prevented or at least reduced {74}. Guinea worm, or dracunculiasis, is found in regions of Africa, Brazil, India, Pakistan, the Middle East or other localities where water is extracted from shallow ponds, unhygienic wells, etc. The disease is only transmitted by drinking water infected with the microscopic immature stage of the parasite. The disease has no natural reservoir other than the human population. The worm larvae are ingested by a tiny cyclopoid copepod, commonly known as a water flea, when un-boiled or not disinfected water is swallowed. The larvae emerge in the intestine from where they migrate to, and grow in the subcutaneous tissues. In humans the larvae mature and mate in about three or four months, after which the males die. About several months later the mature adult female worm, which measures up to a meter in length, secrets a toxin. The toxin causes a severe local burning feeling below the skin and raises a blister, through which the female inevitably appears. The appearance of the female is to enable it to discharge her hundred of thousands of larvae into a body of stagnant fresh water. Dracunculiasis is a debilitating disease, victims of which are crippled for weeks or months by the emergence of the long worms through their skins. The worms are inclined to emerge on the lower legs, ankles or feet, but they may show through the skin or mucosa anywhere on the body. As the worms commonly emerge during the harvest or planting season, the infection has a disproportionate adverse effect on agriculture as well as health in endemic communities {75}. The adults of the hookworms Necator americanus and Ankylostoma duodenale are attached to the walls of the jejunum by the buccal capsule. The females lay an enormous amount of eggs, which are discharged with the faeces. The eggs mature to larvae, which hatch in the soil grazing on bacteria. The larvae grow and manifest the filariform or the infective larvae. Usually, the larvae enter the skin of a new host through the feet. From whence they travel into the venule and consequently invade the right heart and the lungs. Within them they multiply and penetrate the capillaries to the alveoli, trachea, pharynx, and then they are ingested and transferred to the small intestine. In the small intestine they develop into adults. One of the methods used for the extraction of the adult female worm is by gradually winding it round a match stick as it appears from the subcutaneous tissues. The introduction of chemotherapy eased the process and decreased the incurred health risks. Ascariasis is a disease that is introduced by Ascaris lumbricoides adult worms. The worms survive in the small intestine where they lay an immense number of eggs that are discharged with the faeces of the infected person. The eggs may infect vegetables and crops found in the soil especially when sludge or night soil is used as a fertilizer or a soil conditioner. If raw vegetables and crops are consumed the infection is transferred to the victim. Then the eggs penetrate the jejunum where the larvae hatch, enter the mucosa, and pass through the hepatic circulation to the heart and the lungs of the sufferer. Within the heart and lungs the worm larvae develop, and pass
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on to the alveoli. They further invade the stomach via the trachea and oesophagus, and proceed to the small intestine. In the small intestine the larvae grow to the maturity stage. The mosquitoes Culex pipens complex are the vectors of the nematode worm Bancroftian filariasis (Wuchereria bancroftii) especially in Asia. In other places the vector for the disease may be Anopheles or Aedes mosquitoes. The mosquitoes breed mostly in highly polluted water such as: stagnant open drains, poorly maintained ponds, pit latrines, septic tanks, soakaway pits {10}. Filariasis is an infection that is conveyed by nematode worms, which have different forms. The worms survive in the lymphatic ducts of man, and the disease in an infected victim may block the lymphatic vessels. This condition ultimately leads to swelling of the arms, legs or genitalia, leading to deformity or elephantiasis.
Water-Habitat Diseases Water-habitat diseases are vector-borne and are the most important group of diseases related to the introduction of irrigation. Three different types of vectors are involved in disease transmission: - snail vectors are the essential link in transmitting schistosomiasis (bilharzia), - Mosquito vectors are responsible for the widespread occurrence of malaria, filariasis and arboviruses. The malaria parasite is transmitted by a mosquito which depends on the aquatic environment for breeding. - fly vectors transmit onchocerciasis (river blindness) and trypanosomiasis (sleeping sickness).
Water-related insect vectors: Water-related insect vectors are the infections that are spread by insects, which rely on or live near to a water system. Normally, these vectors are dynamic and hostile around a still and an open water system. - Examples of the water-related-insect vector diseases include: Trypanosomiasis (Sleeping Sickness), Yellow fever, Dengue, Onchocerciasis, Malaria, etc. - Trypanosomiasis is a disease caused by parasites of the genus Trypanosms. It includes sleeping sickness in Africa and chagas disease in Central and South America. African trypanosomiasis is known as sleeping sickness in humans and nagana in livestock. Cattle Trypanosomiasis is a main source of economic loss in endemic areas. Trypanosomiasis is detected in all tropical areas of Africa where tsetse flies are found. The disease is due to many Trypanosome species that attack humans, cattle, and a variety of other domestic as well as wild animals. Typical symptoms of the disease include a decrease in the number of red blood cells (anemia), fever, and irritation of the inner lining of the eyelid (conjunctivitis), nervous symptoms, paralysis, and death. Many tsetse fly groups transfer the parasitic protozoa from animals that serve as reservoirs of the disease agents to humans and domestic animals. The males and females of the tsetse fly feed exclusively on the larger vertebrates, hunting their prey over extensive areas to take a blood meal every few days. This regular supply of protein-rich food fits well with the reproductive strategy of tsetse, which is distinct from that of most insects and somewhat like that of mammals. The female matures one egg every nine days, retaining it in her uterus where it develops into a fullygrown larva by feeding on a milk-like secretion from the mother. The larva is then deposited in a sandy place where it burrows into the soil to pupate. It emerges as an adult about a month later. This method of reproduction guarantees the abundance and stability of generation of the fly {49}. The total flying range of tsetse flies includes 37 countries and extends over 10 million square kilometers. Gambiense trypanosomiasis is transmitted by riverain species of Glossina requiring optimum shade and humidity. Shady trees near lakes, river and pools of water are ideal habitats. Man-fly contact is close when many people assemble around the pools for collecting water, washing, bathing, playing, etc. Glossina tachinoides is second in importance to G. palpalis as a vector of sleeping sickness. Rhodesiense trypanosomiasis can occur in scrub savannah country because the Glossina vectors are less dependent on moisture. Moreover, in such terrain wild animals and domestic cattle provide alternative feeding opportunities for the fly. Trypanosomiasis is a serious disease of domestic animals, causing great economic loss and depriving man of the required
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protein. Normally, T. vivax and T. congolense are the normal pathogens. The common vectors of T. b. gambiense are Glossina palpalis and G. tachinoides in West Africa. T. b. rhodesiense is associated with G. morsitans, G. swynnertoni and G. pallidipes. Other, secondary vectors are to be found in certain localities. A reservoir of T. rhodes may be found in wild animals such as the bush-buck (Tragelaphus scriptus). In the lack of treatment, the patient with gambiense infection becomes gradually unconscious and comatose and sleeping insensibly. Frequently, the Rhodesiense sickness results in death. Onchocerciasis, or river blindness, is a disease caused by the parasitic filarial nematode Onchocerca volvulus. The disease is endemic throughout the sub-Sahara, Central, West and East Africa, Yemen and Central America where it is the chief reason of blindness. The vector of the disease is the blackfly, or the Simuliid. Simuliid is a family of biting flies including the important genus Simulium. The crucial ecological environment for the vector is provided in fast moving, highly oxygenated waters in streams, rivers, waterfalls, etc. With Onchocerciasis there is intense itching, which usually starts in one limb, shoulder or buttock, and continues gradually over the remainder of the body. Itching is normally accompanied by papular urticaria, which differs eminently in its severity. Sometimes the rash consists of minute livid red papules. Prolonged exposure to the disease causes the skin to get thickened, rough (patchy-derma), inelastic, sags down, and excoriated from endless scratching. Impairment is caused to the skin after the death of the microfilaria which induce an intense inflammatory impact upon their death. Yellow fever is an acute, often fatal, disease caused by an arbovirus. The disease is described by severe headaches, aches in the bones, fever followed by a deep Jaundice, internal hemorrhages and vomiting. Aedes aegypti is the vector of yellow fever, dengue, and dengue hemorrhagic fever viruses. The vector breeds in domestic water vessels, deserted containers, in clean water stored in pots and cisterns, in tree holes, plant axil, cut bamboo, and other similar areas. Malaria is a disease of humans caused by blood parasites of the species Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale or Plasmodium malariae. The typical symptoms of the disease involve fever, rigors, headache and myalgia. The symptoms are unsteady during the first stage of the disease but once the infection develops they tend to result in a tertian pattern. In Cerebral malaria the first symptoms are unstable but may include severe headache, drowsiness and confusion. If an appropriate treatment is not prescribed at an early stage, sufferers may quickly enter into coma and die. Figure 4.2 {1} illustrates the possible interactions that may develop between man, water, vector and parasite within a particular environment. The outcome of this interaction would be the unwelcomed vector-related parasitic diseases. Infections primarily of defective sanitation:
Infections primarily of defective sanitation are those infections that spread within a community usually due to the absence of suitable sanitation facilities. Examples of these diseases include: Hookworm, Round worm (Ascaris), etc. Human hookworm penetrates the skin from a damp and contaminated soil, or through ingestion of water or through the consumption of food. The hookworm live in the small intestines where it results in major blood loses. This situation may initiates anemia, especially for those people with a diet low in iron or where their bodies poorly absorb the iron. Enteric pathogens, i.e. disease-causing microorganisms, are able to live, for long periods of time, on crops or in the water or the ground when they find the relevant environmental conditions. The factors that govern and control the survival of these pathogens include: number and type of the pathogen; conditions affecting the rate of growth of microorganisms such as: temperature, humidity, pH, nutrients, etc.; soil organic matter content; amount, intensity and duration of precipitation; sunlight; protection granted by foliage; availability of other competitive microorganisms, etc.
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Table 4.1 shows examples of the survival times of some disease-causing microorganisms and the related media in which the particular organism grows and multiplies. Table 4.2 illustrates a general summary of the classification of aforementioned groups of infective diseases in relation to the water supply systems. The incubation period of diseases are related to their specific microbial agent and the resulting disease are as highlighted in table 4.3. Table 4.1 Survival Times of Organisms {2} Organism Ascaris ova
Media
Survival Time [day]
Vegetables Soil
27 - 35 730 - 2010
Vegetables Soil Water
3 6-8 60
Vegetables Soil Pasture Grass
3 - 40+ 15 - 280 200+ 100+
Vegetables Lettuce Soil Water
10 - 53 18 - 21 2 - 120 87 - 104
Vegetables Grass Soil Vegetables Water Water
7 42 26 - 77 532 20
Entamoeba histolitica
Salmonella(species)
Salmonella typhi
Shigella (spp.)
Streptococcus faecalis Vibrio cholera Vibrio comma Poliovirus
The common transmission routes of disease by pathogenic microorganism from one person to another occur in many different ways. Examples of these routes include: direct contact between one person and another; by ingestion, by the exposure to contaminated objects, by intermediate vectors, by animals and birds that harbor some disease-causing organisms, or through drinking, eating, using or entering a contaminated water supply system; or by inhalation of infectious agents in reclaimed wastewater, air, etc. Table 4.4 and figures 4.3 and 4.4 give a summary of the transmission routes and paths of diseases. Generally, the disease transmission routes may be grouped broadly as: a) Mechanical transmission: Mechanical transmission is the simple transport of pathogens on the feet, body, surface, and proboscis of the vector. A further route is through the gastrointestinal tract, the pathogen being in the food intake of the vector and leaving in its feces or by regurgitation by some flies {72}. There is no biological cycle of development of the pathogen in or on the vector. Diseases transmitted via this route include: Trachoma, Yaws, Conjunctivitis, etc.
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Table 4.4 Common Transmission Routes of Certain Diseases {74} Diarrhoea
{74} Salmonella spp., Shigella spp Escherichia coli Viruses, etc Vibrio cholerae
{74} man-feces-- flies, food, water--man Cholera man--feces, water, food-man. Typhoid or Salmonella typhi man--food, water--man. Leptospirosis Leptospira spp. enteric animal--oral, skin, eye-fever man Infectious Hepatitis Hepatitis virus A man--feces, water, food-man Yellow fever Yellow fever virus man--mosquito--man Amoebic dysentery Entamoeba histolytica man--feces, flies, food, water--man Bacillary Shigella dysentery man--feces, flies, food, water--man. Giardiasis Giardia lamblia man--feces, food, water-man Trypanosomiasis Trypanosoma gambiense man--tsetse fly--man. Ascariasis Ascaris lumbricoides man--soil, food, water, vegetables, dust, etc--man Schistosomiasis Schistosoma mansoni, S. man--snail--man haematobium, S., japonicum b) Biological transmission: Biological transmission route signifies the transmission of diseases by bloodsucking vectors. Examples of the diseases transmitted via this route include: Sleeping sickness, Malaria, Sandfly fever by the bites of the Phlebotomus fly, Yellow fever, etc. c) Transmission from an Animal Host: Examples of diseases transmitted from animals to man by vectors include: Plague, Typhus fever, etc. The rats of significance in disease transmission include Rattus norvegicus (also known as the brown, sewer, Norway rat) and Rattus rattus (also known as roof, ship, grey, black, Alexandrian, English rat) which lives in close to man. The house mouse, Mus musculus has no great role in disease transmission, but it may still transmit diseases such as Rickettsia alkari which causes rickettsial pox in humans with symptoms like chicken pox.72 Table 4.5 outlines some diseases that are transmitted from an animal host to man by vectors.
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Table 4.5 Selected Diseases Transmitted from Animals to Man by Insects72 Disease Animals Insect and its action Plague: Bubonic Rat: roof, Norway Flea regurgitates on biting Sylvatic Squirrel, bandicoot prairie Flea regurgitates on biting dog, other wild rodents Typhus: Endemic, Rat: roof, Norway Flea defecates during murine biting. Encephalitis: Equine Horse, cow, rabbit, Mosquito bite. ground squirrel St. Louis Wild birds, domestic hen Mosquito bite. Wester Wild birds, domestic hen Mosquito bite. horse, deer, squirrel Eastern Small wild birds, duck, Mosquito bite. turkey, pheasant Hemorrhagic fevers: Wild rodents Tick bite. Some types Leishmaniasis: Three Dog, other canines wild Sand fly bite. types rodents Rickettsial pox House mouse, wild Mite bite rodents Tick fevers: Several Small wild rodents Tick bite types Trypanosomiasis: African Cow, sheep, horse, Tsetse fly bite. hog, antelope American or Chagas Dog, cat, monkey, bat, Fecal material of disease opossum armadillo, triatomid bug squirrel other rodents Tsutsugamushi, or scrub Field rats and mice,. Mite bite typhus voles, swamp birds parrot, monkey, bush hen
Health concerns are related to the degree of human contact with wastewater, effluent quality, and the reliability of the treatment system {5a}. For a person to develop sickness the following conditions must prevail: a) the infectious agent [disease-causing organism] must be present in the community that produces wastewater. Likewise the microbe must be present in the wastewater emerging from that community; b) the disease agents must survive all the wastewater treatment processes to which they are exposed; c) the person must either directly or indirectly come in contact with the wastewater effluent; and d) the disease agents must be present in sufficient numbers at the time of contact to cause illness. {5d}. The factors that influence the occurrence and spread of a certain disease include: pathogenic dose, infective dose or number of pathogens needed to initiate the disease, pathogenicity or the potential of the pathogen for infection, virulence or the ability of the pathogen to infect a host, the relative degree of susceptibility of the host, etc.
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It is estimated that about 25000 persons per day, or the equivalent of 9.1 million persons per year, die of preventable, waterborne diseases, alone and in combination with malnutrition.6 Bilharzia along the Nile No doubt that the existence of irrigation canals has created favorable conditions for the life cycle of bilharzia. However, with the recent concentrated efforts of the government along with changing social behavior, bilharzia seems to be decreased. Bilharzia is a water-habitat disease, which depends on an intermediate aquatic host for the completion of its life cycle. The adult worm lays eggs, which are passed in human faeces or urine to water, where they hatch into larvae (miracidia), which hunt for aquatic snail, but they die if they do not enter one within a day. Inside the snail cercarial larvae are produced and released into the water. These cercariae penetrate unbroken skin of human beings who come in contact with the infected water. A sample of 16,295 persons was selected and tested for bilharziasample from Aswan, Kom Imbo, Beni Suef, and Kafr El-Sheikh. In addition, a sample of 6,024 persons was selected from Quena. The results of the examination of urine and stool of sample members for schistosomiasis are shown in Tables (4.1) to (4.3). The obtained results can be summarized as follows: 1. The disease rates tend to decrease from north to south. 2. The peak infection is usually in the young adolescent age group 15 to 19 years of age. 3. For any specific age group the prevalence is higher in males than females. 4. Contrary to the original speculations there is a general declining trend in the prevalence of schistosomiasis in rural Egypt which has not been reversed by the construction of the Aswan High Dam.
This may be primarily due to: a. a.Effect of programs in environmental health including b. protected water supplies and construction of latrines c. in villages. d. bImproved services by treatment of cases and health e. education. f. cSnail control programs. g. dPopulation shift from rural to urban areas.
Impact of Agriculture Related Chemical Pollution Pesticides Pesticides have a negative ecological impact on food chain organisms, including aquatic communities. A large variety of chemicals have been used, among them most commonly being DDT, aldrin, dieldrin, benzene ... etc. DDT has a slow rate of degradation and a possibility of accumulation in plant and animal tissues. There are no harmless pesticides, they can cause poisoning to millions of people. Besides the favorable effects on plant crops of pesticides, damage to agricultural production caused by perticians is diversified: • by hampering biological activity of soil, they prevent restoration of natural soil fertility; • changes plant content, complicates storing of agricultural produce; 237
•
Pesticides create favorable conditions for mass over growth of some varieties that caused no damage prior to the application of pesticides.
Despite the ever-growing use of agricultural chemicals for plants protection, there is an increase in crop losses observed for the last decade. In the Conclusions References 1. McJunkin, F. E., Water, Engineers, Development and Disease in the Tropics, Agency for International Development Department of State-Washington, D.C., 1975. 2. Crook, J., Water Reuse in California, J. American Water Works Association, 77(7), 1985, 60. 3. WHO Expert Committee on Vector Biology and Control, Environmental Management for Vector Control, 4th Report, WHO, Technical Paper Series 649, Geneva, 1980. 4. Salvato, J. A., Environmental Engineering and Sanitation, Wiley-Interscience, New York, 3rd Edi., 1982. 5. a. Pettygrove, G.S. and Asano, T., edi., Irrigation With Reclaimed Municipal Wastewater: A Guidance Manual. Lewis Publishers, Inc., Chelsea, 1985. b. Asano, T., Smith, R.G. and Tchobanglous, G., Chapter 2: Municipal
Wastewater: Treatment and Reclaimed Water Characteristics. pp. 2.1 2.26. c. Westcot, P.W. and Ayers, R.S., Chapter 3: Irrigation Water Quality Criteria, pp. 3.1 - 3.37. d. Crook, J., Chapter 10: Health and Regulatory Considerations, 10.1 - 10.49. e. Broadbent, F.E. and Reisenauer, H.M., Chapter 12: Fate of Wastewater Constituents in Soil and Groundwater: Nitrogen and Phosphorous. 6. Dale, J.T., World Bank Shifts Focus on Third World Sanitation Projects, J. Water Pollution Control Federation, 51, 1979, 662-665. 7. a. Pescod, M.B., and Alka, U., Urban Effluent Reuse for Agriculture in Arid and Semi-arid Zones, 93-106. b. Cowan, J.P., and Johnson, P.R., Reuse of effluent for Agriculture in the Middle East, 107-145. c. Feachem, R.G, Blum, D., Health Aspects of Wastewater Reuse. 237-247. Reuse of Sewage Effluents, Proceedings of the International Symposium Organized by the Institution of Civil Engineers, and held in London on 30 31 October 1984, Thomas Telford, London, 1985. 8. WB/UNDP/WHO/IRCWD, Health Aspects of Wastewater and Excreta Use in Agriculture and Aquaculture: The Engelberg Report, International Reference
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Center for Waste Disposal, WHO Collaboration Center for Waste Disposal, Switzerland, IRCWD News Number 23, Dec. 1985, 11-18. 9. Strauss, M, Survival of Excreted Pathogens in Excrete and faecal Sludges, Part II, International Reference Center for Waste Disposal, WHO Collaboration Center for Waste Disposal, Switzerland, International Reference Center for Waste Disposal, WHO Collaboration Center for Waste Disposal, Switzerland, IRCWD News Number 23, Dec. 1985, 4-9. 10. Feachem, R.G., Bradley, D.J., Garelick, H. and Mara, D.D., Sanitation and disease: Health aspects of excreta and wastewater management, Published for the World Bank by John Wiley and sons, Chichester, 1983. 11. Alabaster, J.S. and Lloyd, R., Water Quality Criteria for Freshwater Fish, Butterworths, London, 1980. 12. Edwards, P., Reuse of Human Wastes in Aquaculture: A Technical Review, UNDP/World Bank Water and Sanitation Program, The World Bank, Washington, 1992. 13. Shuval, H.I., Adin, A., Fattal, B., Rawitz, E. and Yekutiel, P., Integrated Resource Recovery: Wastewater Irrigation in Developing Countries: Health Effects and Technical Solutions, World Bank Technical Paper Series Number 51, UNDP Project Management Report Number 6, World Bank, Washington, 1986. 14. a. Pescod, M.B. and Arar, A. Edi., Treatment and Use of Sewage Effluent for Irrigation. b.Pescod, M.B. and Alka, U., Guidelines for wastewater reuse in agriculture. c. Hillman, P.J., Health Aspects of Reuse of Treated Wastewater for Irrigation, pp. 52-63. d. Morishita, T., Environmental Hazards of Sewage and Industrial Effluents on Irrigated Farmlands in Japan, in Treatment and Use of Sewage Effluent for Irrigation Edited by Pescod, M.B. and Arar, A., Proceedings of the FAO Regional Seminar on the Treatment and Use of Sewage Effluent for Irrigation held in Nicosia, Cyprus, 7-9 October 1985, Butterworths, London 1988, pp. 64-73.
15. Sorber, C.A., Bausum, H.T., Schaub, S.A., and Small, M.J., A Study of Bacterial Aerosols at a Wastewater Irrigation Site, J. Water Pollution Control Federation, 48(10), 1976, 2367-2379. 16. Bausum, H.T., Schaub, S.A., Bates, R.E., McKim, H.L., Schumacher, P.W., and Brockett, B.E., Microbiological Aerosols from a Field-source Wastewater Irrigation System, J. Water Pollution Control Federation, 55(1), 1983, 65-75. 17. Wistereich, G.A. and Lechtman, M.D., Microbiology, McMillan Pub. Co., New York, 1988. 18. Grant, W.D. and Long, P.E., Environmental Microbiology, Blackie and Son Ltd., Glasgow, 1981. 19. Hejkal, L.,J.B., Keswick,B., LaBelle, R.L., Gerba, C.P., Sanchez, Y., Dressman, G., Hafkin, B., and Melnick, J.L., Viruses in a Community Water Supply Associated with an Outbreak of Gastroenteritis and Infectious Hepatitis, J. American Water Works Association, 74(6), 1982, 318-321. 20. IAWPRC, Study Group on Water Virology: The Health Significance of Viruses in Water, J. Water Research, 17(2), 1983, 121-132. 21. WHO Scientific Group, Human Viruses in Water, Wastewater and Soil, World Health Organization Technical Report Series Number 639, Geneva, 1979. 22. American Society of Civil Engineers, Committee on Environmental Quality Management of the Sanitary Engineering Division, Engineering Evaluation of Virus Hazard in Water, ASCE Sanitary Engineering Division, 96(SA1), 1970, 111-161.
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23. Clarke, N.A., Stevenson, R.E.,Chang, S.L., and Kobler, P.W., Removal of Enteric Viruses from Sewage by Activated Sludge Treatment, J. American Public Health, 51(8), 1961, 1118-1129. 24. Mack, W.N., Frey, J.R., Riegle, B.J., and Mallman, W.L., Enterovirus Removal by Activated Sludge Treatment, J. Water Pollution Control Federation, 34(11), 1962, 1133-1139. 25. Kelly, S. and Sanderson, W.W., The Effects of Sewage Treatment on Viruses, J. Sewage Industrial Wastes, 31(6), 1959,683-689. 26. Lund, E., Hedstorm, C.E., and Jantzen, N., Occurrence of Enteric Viruses in Wastewater after Activated Sludge Treatment, J. Water Pollution Control Federation, 41(2), 1969, 169-174. 27. Hickey, J.L.S., and Reist, P.C., Health Significance of Airborne Microorganisms from Wastewater Treatment Processes, Part II: Health Significance and Alternatives for Action, J. Water Pollution Control Federation, 47(12), 1975, 2758-2773. 28. Drinking Water Health Effects Task Force, Health Effects of Drinking Water Treatment Technologies, Lewis Publishers, Chelsea, 1989. 29. Rose, J., Editor, Trace Elements in Health: A Review of Current Issues, Butterworths, London, 1983. 30. Ince, M, Water and Disease, in the book, Developing World Water, edited by WEDC, Grosvenor Press International, Hong Kong, 19-22. 31. Fair, G.M. Geyer, J.C., and Okun, D.A., Water and Wastewater Engineering, Volumes 1 and 2, John Wiely and Sons, Inc., New York, N.Y., 1968. 32. Mara, D., and Cairncross, S. Guidelines for the Safe Use of Wastewater and Excreta in Agriculture and Aquaculture:Methods for Public Health Protection, Published by the World Health Organization in Collaboration with the United Nations Environment Program, WHO, Geneva, 1989; and the IRCWD News Number 24/25, May 1988, 4 - 12. 33. WHO Meeting of Experts, Reuse of Effluents: Methods of Wastewater Treatment and Health Safeguards, WHO, Technical Report Series Number 517, WHO, Geneva, 1973. 34. Tate, C.H. and Trussel, R.R., Developing Drinking Water Standards, J. American Water Works Association, 69, 1977, 486. 35. WHO, Guidelines for Drinking Water Quality, Volume 1: Recommendations, Volume 2: Health Criteria and Other Supporting Information. Volume 3: Drinking Water Quality Control in Small-community Supplies, WHO, Geneva, 1984. 36. Eaton, F.M., Deficiency, Toxicity and Accumulation of Boron in Plants, J. Agricultural Research, 69, 1944, 237-277. 37. Chen, K.Y., Young, C.S., Jan, T.K., and Rohatgi, N., Trace Metals in Wastewater Effluents, J. Water Pollution Control Federation, 45, 1974, 26632675. 38. Walker, R., Water Supply, Treatment and Distribution, Prentice Hall, Inc., Englewood Cliffs, New Jersy, 1978. 39. Eisenbud, M., Environmental Radioactivity: From Natural, Industrial and Military Sources, Academic Press, Inc. Harcourt Brace Jovanovich, Publishers, Orlando, Florida 1987. 40. Eckenfelder, W.W., Industrial Water Pollution Control, McGraw-Hill Series in Water Resources and Environmental Engineering, New York, 1989.
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41. WHO Study Group, Technology for Water Supply and Sanitation in Developing Countries, Technical Report Series 742, Geneva 1987. 42. Rajagopalan, S. and Shiffman, M.A., Guide to Simple Sanitary Measures for the Control of Enteric Diseases, WHO, Geneva 1974. 43. White, G.F., Bradley, D.J., and White, A.W., Drawers of Water, Domestic Water Use in East Africa, University Chicago Press, Chicago, 1972. 44. WHO Expert Committee, Environmental Pollution Control in Relation to Development, A Report of a WHO Expert Committee, Technical Report Series Number 718, Geneva, 1985. 45. Peavy, H.S., Rowe, D.R. and Tchobanoglous, G., Environmental engineering, McGraw-Hill Book Co., New York, 1985. 46. Hammer, M., Water and Wastewater Technology, Prentice Hall, Inc., Englewood Cliffs, New Jersy, 1986. 47. Burns,R.W. and Sproul, O.J., Virucidal Effects of Chlorine in Wastewater, J. Water Pollution Control Federation, 39(11), 1967, 1834-1839. 48. Budde,P.E., Nehm, P., and Boyle, W.C, Alternatives to Wastewater Disinfection, J. Water Pollution Control Federation, 49(10), 1977, 2144-2156. 49. Curtis, C.F., editor, Appropriate Technology in Vector Control, CRC Press, Inc. Boca Raton, Florida, 1990. 50. Service, M.W., Blood Sucking Insects: Vectors of Disease, The Institute of Biology`s, Studies in Biology Number 167, Edward Arnold, London, 1986. 51. WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control, Guidelines for Forecasting the Vector-borne Disease Implications in the Development of a Water Resource Project, VBC/86.3, Geneva 1987. 52. Burgess, N.R.H., Public Health Pests: A Guide to Identification, Biology and Control, Chapman and Hall, London, 1990. 53. IPCS, International Program on Chemical Safety: a. Environmental Health Criteria 63: Organophosphorus Insecticides: A General Introduction, WHO, Geneva 1986. b. Environmental Health Criteria 64: Carbamate Pesticides: A General Introduction, WHO, Geneva, 1986. 54. Stanng, W. D. E, Pesticides: Data Collection Systems and Supply, Distribution and Use in Selected Countries of the Asia-Pacific Region, UN, Bangkok, 1984. 55. WHO Study Group Report, Recommended Health-based Limits in Occupational Exposure to Pesticides, Technical Report Series 677, WHO, Geneva, 1982. 56. WHO, Public Health Impact of Pesticides Used in Agriculture, Published by the World Health Organization in Collaboration with the United Nation Environment Program, WHO, Geneva, 1990. 57. WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control, Report of the 5th Meeting, Bangkok, 7-11 Oct., 1985, VBC/85.5, Geneva 1985. 58. WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control, Report of the 6th Meeting, Geneva, 8-12 Sept., 1986, Part I: Technical Discussion, and Part II: General Program and Policy, VBC/86.2, Geneva 1986. 59. WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control, Report of the 7th Meeting, Rome, 7-11 Sept., 1987, VBC/87.2, Geneva 1987. 60. FAO, Environmental Management for Vector Control in Rice Fields, Rome, 1984.
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61. Jobin, W. R, Environmental Management of Disease Vectors, Case Studies on Disease Vector Control through Environmental Management in Water Resource Development Projects, Sections A and B, VBC/TRV/SEM/ENV/VCT/87.9/1. 62. WHO, Manual on Environmental Management for Mosquito Control, WHO Offset Publication number 66, Geneva, 1982. 63. WHO, Dengue Hemorrhagic fever Control Program in Singapore: A Case Study on the Successful Control of Aedes aegypti and Aedesalbopictus Using Mainly Environmental Measures as a Part of Integrated Vector Control, WHO/VBC/86.928. 64. WHO Scientific Group, Vector Control in Primary Health Care, WHO, Technical Report Series 755, Geneva, 1987. 65. WHO Expert Committee on Vector Biology and Control, Integrated Vector Control, WHO, 7th Report, Technical Report Series 688, Geneva, 1983. 66. FAO, Effects of Agricultural Development on Vector-borne Diseases, Edited Versions of the Working Papers Presented to the 7th Annual Meeting of the Joint WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control 7-11 Sept. 1987, Food and Agriculture Organization of the United Nations, Rome, 1987. 67. IRCWD, Health Aspects of Nightsoil and Sludge Use in Agriculture and Aquaculture, International Reference Center for Waste Disposal, WHO Collaboration Center for Waste Disposal, Switzerland, IRCWD News Number 23, Dec. 1985, 1-2. 68. Cross, P., Existing Practices and Benefits in the Use of Human Excreta, International Reference Center for Waste Disposal, WHO Collaboration Center for Waste Disposal, Switzerland, IRCWD News Number 23, Dec. 1985, 2-4. 69. Kott,Y., Ben-Ari, H., and Betzer, N., Lagooned Secondary Effluents as Water Source of Extended Agricultural Purposes, J. Water Research, 12(12), 1978, 1101-1106. 70. Douglas, J.F., Gasiorek, J.M., and Swaffield, J.A., Fluid Mechanics, Pitman, London, 1981. 71. Jordan, A.M., Trypanosomiasis Control and African Rural Development, Longman, London, 1986. 72. Chanlett, E.T., Environmental Protection, McGraw-Hill Book Co., New York, 1979. 73. Esrey, S.A., Report on International Drinking Water Supply and Sanitation Decade (IDWSSD) Impact on Diarrheal Disease, IDWSSD Steering Committee for Cooperative Action, Document prepared for WHO with Support from United Nations Development Program on behalf of IDWSSD, July 1990. 74. Miller, F.D., Report on International Drinking Water Supply and Sanitation Decade (IDWSSD) Impact on Schistosomiasis, IDWSSD Steering Committee for Cooperative Action, Document prepared for WHO with Support from United Nations Development Program on behalf of IDWSSD, July 1990. 75. Hopkins, D.R., Report on International Drinking Water Supply and Sanitation Decade (IDWSSD) Impact on Dracunculiasis, IDWSSD Steering Committee for Cooperative Action, Document prepared for WHO with Support from United Nations Development Program on behalf of IDWSSD, July 1990. 76. Kathren, R.L., Radioactivity in the Environment: Sources, Distribution, and Surveillance, Harwood Academic Publishers GmbH, Chur, 3rd Printing, 1991.
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Table Most Common Diseases in the Sudan Disease Malaria Dysentery Bilharzia Typhoid Infectious hepatitis Tracoma Eye infections Diarrohea
1971 713392 420150 76010 957 3574 32634 564223 8320960
Year 1979 2830931 1090943 98143 42474 70578 1261601 2794628
198 2925404 1177938 120917 50338 140458 1192889 2871513
Table The Rate of Occurrence of the Most Common Diseases in the Sudan Disease Occurence rate for every 1000 person 1971 1979 1981 Malaria 63.8 167.1 205.0 Dysentery 37.0 64.4 83.0 Bilharzia 6.7 5.8 8.0 Typhoid 0.08 Infectious 0.3 2.5 4.0 hepatitis Tracoma 2.9 4.1 10.0 Eye 39.7 74.5 84.0 infections Diarrohea 732.4 165.4 202.0
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Chapter Three: Water Management Integrated Water Resources Management and Global Water Partnership87 By Isam M. Abdel-Magid88 and Siddig E. Ahmed89 Abstract This paper gives highlight on inter\grated water resources management (IWRN) and global water partnership (GWR) that seeks to balance human, industrial, agricultural and environmental needs. Global water partnership is a working partnership among all those involved in water management-government agencies, public institutions, private companies, professionals' organizations, multilateral development agencies and others committed to Dublin-Rio principles. In this paper attention has been given to areas of concern for IWRM and liaisons to Sudan or local water resources issues as well as the importance of GWP and launching of the Regional Water Partnership, East Africa Region.
What is integrated Water Resources Management (IWRM)? Compare to traditional approaches to tackling water resources problems. IWRM takes a broader view, examines a more complete range of solutions, and considers how different actions affect, and can reinforce, each other. IWRM places novel demands on the policy maker, operator and water – user, but offers more comprehensive, efficient and powerful approaches than those tried hitherto. It offers greater hope of addressing water resources problems at all levels and in all their variety and complexity. IWRM looks outside the narrow water sector for policies and activities, to achieve sustainable water resources development .IWRM can assist countries as they try to deal with increasingly challenging water issue a with due consideration of equity, efficiency and sustainability. IWRM has attracted particular attention since the1992 international conferences on water and environmental issues in Dublin and Rio GWP defines IWR Mas follows: “IWRM is a process which promotes the coordinated development and management of water, land and related resources in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems” IWRM deals with water resources in the broadest possible manner. It has to look at water resources in the context of the entire economic -, social- and eco-systems of the nation or region. Operationally this means that policies and programs in other resource areas have to be carefully analyzed see how they will influence demands placed upon the water sector. For example, when considering non–point pollution due to agricultural land use practices the analysis should consider agricultural policies on 87
Presented at the Global and National Water Partnership Workshop, 13 August 2002, Khartoum Sudan University for Science & Technology, Khartoum 89 Ministry of Irrigation & Water Resources, P.O. Box 318, Wad Medani, Sudan 88
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crop support and fertilizer pricing. It may turn out to be more effective to change the policies in the agricultural sector instead of attempting expensive control of non-point source of the nutrient contaminates themselves. Other examples can be drawn from energy sector pricing and regulation policies that may influence the demand for water use for hydropower or cooling uses. Because water is pervasive throughout the economy, almost all national economic and social policies could have major impacts on water use. IWRM is a process, a process of change from unsustainable to sustainable resource management. It will take time and will need to be implemented in small pieces to allow incremental reform. In the meantime sectoral developments will continue and it is imperative that they are compatible with IWRM. IWRM demands certain requirements (clear laws and institutional roles for example) that cannot to avoided. They may require –up difficult trade-offs and choices have to be made. The local circumstances and the political will for change and progress need to be taken into account. Why IWRM? Failure of Traditional water policies
Supply orientation Water policies have been dominated by a supply–oriented and compartmentalized sector mentality. Moreover, important distinction between managing water as a common property natural resource and providing services for water users has not been fully recognized, leading to a confusion of responsibilities. Demand was usually taken as given, often extrapolated from past trends and driven by notions of requirements or entitlements. Any current or projected shortage of water would be addressed by investments in the creation of new capacity, funded largely by the public sector, with a very limited ambition for cost recovery. Expansion of the system would take precedence over attempts to influence demand, improvements in the efficiency of delivery (e. g. adjusting pressure, reducing leakage) or refo rm of the supplying authority. Advantages and disadvantages of the traditional policies An advantage of supply oriented policies was that they often led to the creation of Sound And technical efficient systems which, for some, provided good service the limitations of policies are revealed, however, when change is required, perhaps because of a growth in demand, competition for sources, rising environmental or large financial deficits. Infrastructure solutions also run into difficulties in many places. Often, financial difficulties result from high operation and maintenance costs in combination with inadequate cost recovery. Expansion of the supply system may run into hydrological limits, entailing rising financial costs and environmental impacts to which the public is increasingly sensitive. Governments are becoming less willing or able to finance the growing deficits from free or under-priced water, and many cannot fund the escalating cost of new infrastructure . Indicators of failure At the Millennium general assembly of the UN September 2000, target was agreed to halve, by 2015, the number of people without access to affordable and safe drinking water. It was further agreed that unsustainable use of the water resources must stop. Achieving these targets will require a major change of approach, it is impossible to
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imagine that “Business as usual” policies could fill the gaps and generate the required funding levels Agriculture and sectoral approaches Agricultural water use makes up to 70% of water withdrawals on average and this increases to 90% in some water–scare regions. Irrigation systems are often scattered across vast rural areas, often with poor managerial control and service levels. Water resource mangers are concerned, for while improvements in domestic service have started, for agricultural water use the process of modernization has hardly begum. The supply–oriented approach still dominates in agriculture, driven by fears of food insecurity. But other water stakeholders, not fully regarded in acompartmentalized water sector, are now making a growing claim on water resources. These include stakeholders concerned with the vital ecosystem, fisheries, tourism and recreation. Experience teaches that conflicts among agriculture, industries and cities, and ecosystem champions can only increase if the wider and integrative approach of IWRM is not used to manage the resource more sustainably. Integrated Water Resources Management –the Main Ideas? IWRM is a balancing process IWRM processes, among other things, co-ordinate the development and management of water and other related resources, with the objective of attaining water security and sustainability. It is political procedures with long-term gains are vital to the sustainability of the resource base. It does, however, require trade–offs in which there may be some short –term losers especially among those with vested interest in the status quo. IWRM is an interactive method, in which implementing one policy or management tool may result in the need to modify others. It requires vision and political will to introduce, but with careful consultation and preparation can bring rich rewards. IWRM Principles As noted above, IWRM draws its inspiration from the Dublin principles: water as a finite and vulnerable resource, the importance of a participatory approach involving users, planners and policymakers, recognition of the special role of women as water users, and water as an economic good with economic value in competing uses and as having key social and environmental roles. Overriding criteria are economic efficiency in water use, equity and access for all, and sustainability of vital ecosystems. IWRM promotes a holistic view IWRM looks at the entire hydrological cycle and the interaction of water with other natural and socio-economic systems. The same water can serve many different purposes, in different places. It is even possible for the same water to fulfill different purposes at the same time or sequentially, if proper planning takes place. However, the planning and operation of water systems is usually fragmented, causing a lack of co-ordination, waste and conflict, Moreover, water is frequently neglected when decisions are made about crop patterns, trade and energy policies, urban design and planning, all of which are critically determinants of water demand. The sustainable use of the resource calls for the creation of institutions and systems that can transcend these traditional boundaries and involve a variety of users and other stakeholders. Keynotes are integration, participation, consultation, gender awareness and consensus.
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Integration Integration implies a concern with upstream–downstream relation, including land use, coastal zone management, a unified management of surface– and groundwater, a shift to management at a catchment or river basin level, and harmonizing water management with other sectoral policies with a collateral impact (trade, housing, energy, agriculture, etc.). Quantity and quality concerns need to be reviewed in conjunction. Economic value The concept of water as an economic good distinguishes clearly between the value of water, assisting allocation processes, and pricing, being part of the cost recovery issue .the economic value of water is highlighted within IWRM through a greater stress on demand management rather than supply–side actions, a recognition (and estimation, where possible) of the economic value of water in different uses, acceptance of the notion of opportunity cost (what is lost to other uses from taking it for a particular purpose) and attention to cost recovery, though with concern for affordability and securing access for the poor. Global water–local I issues or concerns Water issues vary drastically Different geographical areas have widely differing water problems and challenges. Although problems around the resource availability are normally prominent, the issue of quality of water is gaining recognition, and is already a major problem in many regions. The greater fluctuation in resource availability associated with presumed climatic changes is causing concern, as many regions experience increasingly sever flooding and /or droughts. The solutions to some of these concerns can be sought locally, whilst other depend on international co-operation (e. g sharing an international river, tackling pollution of regional water body, transferring water from one country to another). Water quality is deteriorating Water quality is deteriorating worldwide. Many countries have difficulties protecting their surface– and groundwater resources (as e. g. evident in the difficulties in Europe of complying with the EU framework Directive) and in many locations around the world discharges of untreated domestic and industrial wastewater threatening ecosystems and human health. Competition for a scarce resource Conflicts and competition for water is a problem encountered in countries at very different levels of development (e. g. Southern India, Western USA, China). Similar conflicts arise in multipurpose river schemes (USA, China), where stakeholders have difficulty in reconciling the needs of bio–diversity, amenity and other kinds of in– stream benefits with other uses. Water and poverty An estimated 80 percent of diseases in developing countries are related to contaminated water, and the death toll is as 10 million people every year. Because the slums in which many poor people live have no piped water, they have to buy water at a price that is as much as 10 times greater than the rich pay. People whose poverty
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forces them to live in the low–lying floodplains along river banks risk losing everything they have, including their lives, whenever a flood occurs. Funding though necessary is not a sufficient condition to break this vicious circle of water and poverty. That requires clarifying causal relationship between water and poverty. Water for peace The signs of a looming water crisis are evident. Because water is essential to every aspect of life, the water crisis affects everything and cannot be dealt with in isolation. And because water defies political boundaries and classification, the water crisis is beyond the scope of any individual country or sector. For this reason, trans-boundary water management of river basins that are shared by two or more states is needed to reach integrated and co-operative solutions. The United Nation Education, Scientific, and Cultural Organization (UNESCO) and Green Cross International (GCI) are jointly examining the potential for shared water resources to become a catalyst for regional peace and development through water resources to become a catalyst for regional peace and development through dialogue, co–operation, and participatory management of river basins. They are currently implementing a water for peace project called “From Potential Conflict to Co-operation Potential”. The idea of establishing an international fund to prevent and resolve water–related was initiated at the 2nd World Water Forum by Mikhail Gorbachev, president of GCI and former president of the soviet Union. Water and cities More than half the world’s population is concentrated in urban areas covering just 4 percent of the world’s surface. Such dense concentrations can lead to high rates of water–related illnesses from lack of safe drinking water or adequate sanitation. Urban water issues are intertwined with issues of poverty, groundwater, floods, and land use. Because the number of people potentially affected is high, solving urban water issues in cities, especially mega cities, deserves increased public attention. Water, Nature and Environment A “Vision for Water and Nature” was presented at 2nd World Water Forum through discussions from environmental, social, and economic perspectives seeking the harmonious coexistence of water needs and nature. The vision noted that the ecosystem was in crisis, as evidenced by the loss of fresh water diversity, and that integrated planning and management of land use and water use in river basins were needed to regain ecosystem balance. Achieving that requires resolving many intertwined environmental, social, and economic issues – from developing practical methods for ecosystem conservation to ensuring participation of stakeholders in decision–making and establishing legal and economic frameworks for sustainable water management. Water Extremes are Growing (Flood and Drought) Floods are the most devastating of natural disasters. Rapid population growth, excessive concentration of population and food–prone areas, and a reduction in the earth’s water–retaining capacity as a result of deforestation are some of the major causes of floods. Flood threats are projected to increase as a result of rising sea levels and abnormal climatic conditions accompanying global warming. Counter–measures to reduce flood threats and damage must reflect each region’s geographic features, climate conditions and social parameters, and must include both
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structural and non-structural measures. To advance knowledge about what works, and where, information on flood prevention and mitigation measures that have been successfully applied in various parts of the world needs to be collected and shared widely. On the other hand many countries, including Sudan, faced severe episodes of droughts. Drought affects food security, social life, the environment and factors of sustainability. The result is that many countries face water scarcity and have insufficient water for the expansion of food security. . Water and Energy As we move into the 21st century, global economic prosperity is driving energy consumption to record levels. Electricity use is increasing at faster rate than the energy supply. Almost 80 percent of energy comes from thermal sources, coal gas and oil, with growing concerns about the lack of sustainability of such forms of energy, greater emphasisis being placed on sustainable energy, including renewable energy sources. Water and Culture Management of water resources is one of humanity’s oldest activities. It has left tangible and intangible traces in virtually all cultures. To create sustainable solutions to water–related problems and account for the needs of people, societies and nature, information, action and techniques have to be adapted to the cultural (emotional, intellectual, moral and spiritual) dimensions of people’s interactions with water. Water and Information How will information technology, including the Internet, influence the world water situation? As the use of information technology spread, information technology– driven research and development activities are being promoted in water-related fields. But many areas especially in developing countries do not have the basic infrastructure and data collection system in place to make use of this technology in water management. They need, foremost appropriate technology to precise data on water. A growing number of conferences and workshops are being held across the world to share research results and promote the new technologies. Water and Gender The “World Water Vision” declared that every woman, man and child must have access to safe and adequate water, sanitation and food while and also being responsible for ensuring maintenance of the ecosystem. Governments were urged to involve interest groups in all levels of decision and policy-making and to establish and strengthen mechanisms at national regional and international levels to facilitate participation by all stakeholders. Optimizing development implies recognizing that women and men have different requirement and often unequal opportunities for domestic and productive uses of water and the use of catchments areas. Women and poor people generally have fewer opportunities to share in and benefit from development and management. More effective mobilization of human resources and institutional capacities is needed to achieve more logical and equitable sharing of burdens, benefits and responsibilities between women and men.
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Public Private Partnership Some countries have turned to privatization of water services to boost efficiency, reduce costs and improve water treatment and sewage services .In many developing countries, this has resulted in a decline in water quality and a sharp rise in water rates. Some civic groups have intensified their activities against privatization and have opened a new debate on the pricing of water and the spread of privatization. Consensus has been lacking on the notion of full–cost pricing and user payment for water expenses, as proposed in the “World Water Vision”. Many believe that this approach places too heavy burden on the poor. Capacity Building There is now a strong consensus that institutional weaknesses and malfunctions are major causes of many national water services being ineffective. There is an urgent requirement in many countries for attention to be given to building and developing institutional capacities. Capacities have to be built in order to address the needs relevant to all water sector activities, including water resources assessment and water planning and management. Capacities must be built to allow individual countries to look after their own affairs. Capacities at all levels of government, from national through provincial or regional to local levels of government, must be developed in order that total needs be met. Capacity building is a cross–sectoral activity, being needed within both the urban and the rural areas, being needed to address environmental and health concerns and being needed in order to implement effective policies for sustainable food production and so on. Implementation or Basis for Action Demand Management Abundance or scarcity of water can mean prosperity or poverty, life or death. It can even be a cause of conflict. Most countries have serious problems concerning the quantity and quality of their fresh water resources. Constraints on the supply of fresh water are increasingly aggravated by droughts; depletion of aquifers, pollution and degradation, while demand for water is rising rapidly for food production, industry and domestic consumption. A constraint of a different kind is the absence of detailed knowledge of the volumes of water ‘used’ by the different customers that would be obtained from the effective metering and measurement of supplies. Pursuant to the recognition of water as a social and economic good, the various available options for charging water users (including domestic, urban, industrial and agricultural water–user groups) have to be further evaluated and field–tested, (see UN-DTCD, 1991a). Institutional Arrangements Sustainable water development is contingent on appropriate institutional arrangements. Such arrangements should ensure an unbiased and independent approach in policy-making, planning, allocation, development, conservation, protection and in the monitoring and assessment of the water resources on which the other activities depend. They should also bring about optimum technical efficiency, and ensure effectiveness in the provision of water–related services.
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Legal Frameworks Policy decisions cannot be implemented successfully unless there is adequate water legislation. Based upon the agreed strategy to develop water resources, water legislations provides part of the enabling environment, ensuring as far as possible the most equitable, economic and sustainable use of available water resources. Such legislation is a complex endeavour since it has to take account of several simultaneous, and sometimes conflicting objectives: development objectives, including related public and private investments, environmental and conservation goals, requiring effective public control, but also demanding private sector cooperation and involvement, and social objectives, consisting mainly of water–related services and the social impact of development components. Public Participation No matter how efficiently the water resources planning and implementation process is carried out, its long–term impact and sustainability will depend on the effectiveness of public participation. This applies particularly to the full implementation of demand management, the establishment of a legal framework for water resources management and cost-recovery in developing countries, the role of women in water resources management must be enhanced since they and their families are the prime users and beneficiaries of water development programmes and since they are often more concerned than men with protection of the quality of surface –and ground water (cf. Rodda, 1991). The delegation of water resources management to the lowest appropriate level necessitates educating and training water management staff at all levels and ensuring that women participate equally in the education and training programmes. Particular emphasis has to be placed on the introduction of public participatory enhancement of the role of women, youth, indigenous people and local communities. Effective Technologies To bring about the more effective integration of water resources development end management activities, a wide variety of technological options are available. These range from improved methods of data collection and handling, which enable the water resources planner to review different ways of developing a resource, to so–called “non–conventional” methods of increasing the resource base, such as desalination and inter–basin transfer. The dissemination of knowledge of these techniques and options and the technology transfer needed to make them operational in developing countries is priority area for action. The development of interactive data bases, forecasting methods and economic planning models appropriate to the task of managing water resources in an efficient and sustainable manner will require the application of techniques such as geographical information systems and expert systems to gather, assimilitate, analyze and display multisectoral information and to optimize decision making. Global Water Partnership General Global water partnership (GWP) established in 1996, is an international network open to all organizations involved in water resources management developed and developing country government institutions, agencies of the United Nations, bi– and multilateral development banks, professional associations, research institutions and non-governmental organizations and the private sector. GWP was created to foster
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Integrated Water Resources Management (IWRM), which aims to ensure the coordinated development and management of water, land, and related resources by maximizing economic and social welfare without compromising the sustainability of vital environmental systems {1}. GWP responds to the wide recognition that water – a finite natural resource essential for human survival, economic development and maintenance of ecosystems – is under increasing demand, which is making the management and allocation of water one of the vital issues for the 21st century. GWP promotes lWRM by creating flora at global, regional, and levels, designed to support stakeholders in the practical implementation of IWRM {l}. Worldwide adoption and application of IWRM requires changing the way business is conducted by the international water resources community, particularly the way investments are made. To effect changes of this nature and scope, new ways to address the global, regional, and conceptual aspects and agenda of implementing actions are required {l}. GWP facilitates exchange of knowledge experiences and the practice of IWRM through worldwide network of partners, GWP identifies critical knowledge needs at both global and regional levels, helps design programs for meeting these needs, and serves as marketplace for providers and financiers of the required knowledge service {2}. The GWP was created as a mechanism to follow up the water management principles agreed at the 1992 Dublin conference and chapter 18 of Agenda 21on fresh water Resources, the United Nations Conference on Environmental and Development, Rio de Janeiro, June 1992. GWP Objectives {2} The mission of GWP to support countries in the sustainable management of their
resources –is accomplished through: 1. establishing the principles of sustainable water resources management 2. stimulating partners to identify gaps and meet critical needs within their available human and financial resources 3. supporting action at local , national regional or river basin level which follows the principles sustainable water resources management 4. helping match needs to available resources 5. strengthening mechanism for exchanging information and experience. GWP Regional Partnerships In seeking to achieve these objectives, the GWP has established embryonic regional, sub regional and country water partnership that provide for members, platforms for cross–sectional, multi stakeholder dialogue on IWRM at country and regional levels. To date, regional partnerships have initiated in: Southeast Asia, South Asia, South Africa, West Africa, The Mediterranean, Central and Eastern Europe, South America, Central America and China. Admission to Membership GWP Membership is open to organizations involved with issues related to integrated water resources management that recognizes the Dublin- Rio principles: - fresh water is a finite and vulnerable resource, essential to sustain life ,development and the environment .
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- water development and management should be based on aparticipatory approach involving users planners and policy –makers at all levels . - women play a central part in the provision , management and safeguarding of water . - water has an economic value in all its competing uses and should be recognized as economic good. It commits itself to putting these principles into practice through : sharing knowledge and experience on integrated water resources management freely with other GWP partners. providing advice and professional inputs GWP partners . coordinating its integrated water resources management activities with those of other organizations. In turn, the GWP is committed to assisting Members with : identifying critical needs, assessing demands , and arranging strategic assistance . mounting programmers and partnerships to address critical global and regional needs in integrated water resources management . GWP Governance The Consultative Partnership, CP The consultative partnership sets the strategic directions and policies of the GWP. The partnership consists of partner representatives that met once a year in Stockholm, Sweden to review reports from the Steering and Technical Advisory Committees, appoint the Chair of Partnership, and elect and appoint members of the Steering Committee. As far as possible, policy decisions are taken by consensus. These meetings are open to observers for information exchange and discussions. Steering Committee, SC The steering committee acts as a Board of Directors and meets several times a year. The committee is empowered to decisions and run the partnership in accordance with the strategic directions and policies set by the Consultative Partnership. Committee Members are elected by the Consultative Partnership and initially appointed for three years. There are 22 Committee Members including ex officio members and representatives from the GWP’s partners. Gender balance on the Committee, and throughout the Partnership, is given high priority The Chair The GWP chair, initially appointed by the Consultative Partnership for years, is the leading spokes person for the Partnership. The incumbent chairs both the Consultative Partnership and the Steering Committee. The Executive Secretary The Executive Secretary, as chief executive of the GWP and head of the GWP secretariat, is responsible for the implementation of the GWP’s work plans and decisions approved by the steering committee. Hosted by the Swedish International Development Agency (Sida), Stockholm, the secretariat provides support to the Executive secretary, the Technical Advisory Committee and other GWP committees in the areas of governance, finance, communications, planning, operational management of GWP programs and administration. The Technical Advisory Committee The Technical Advisory Committee consists of 12 internationally recognized professionals selected for their experience in different disciplines relating to
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integrated water resources management .The Technical Advisory Committee ensures quality control of GWP programs by : performing analyses of strategic issues impacting water management . facilitating and supporting the development of GWP programs. performing analyses of strategic issues impacting water managements . facilitating and supporting the development of GWP programs . providing guidance on the priorities and quality assurance of proposals submitted to the GWP financial support group . Monitoring the implementation of GWP programs. Ensuring consistency and quality of technical advice throughout the partnership. Financial Support External support agencies interested in water resources management and members of GWP provide financial support to the partnership through a Financial Support Group. The task of this group is to: Stimulate the donor community to provide financial support to the international priority programs - the Associated Programs – for water resources management identified by the Technical Advisory Committee and Regional Water Partnerships Provide a forum for debate among funding agencies on the criteria for support to, and provide advice on, the global priorities for integrated water resources management. Assess the financial viability of GWP’s activities and provide financial for the partnership. The current donors to GWP are the governments of Canada, Denmark, Finland, France, Germany, Luxembourg, The Netherlands, Norway, Sweden, Switzerland, the United Kingdom, the Ford Foundation, the United nation Development Program and the World Bank. GWP Programmes {2,4} The Regional Partnerships work with the GWP Technical Advisory Committee to
identify, prioritize and provide quality assurance to the GWP’s global and regional programs, the Associated programs. These programs are designed to provide strategic assistance to members by filling knowledge gaps that have been identified in the regions. These gaps are filled by pooling the best knowledge available within the partnership and packaging it into services to meet these demands. Program proposals – designed to fill the identified knowledge gaps – are reviewed by the Technical Advisory Committee for relevance and quality. Once approved they are submitted to the GWP financial Support Group for funding.
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An associated program is a network of organizations that supports stakeholders to develop and manage water resources in a sustainable and integrated way. An AP is independent, self –sustaining program, hosted within different organizations. An AP contributes to the golas of GWP by supporting countries in the sustainable management of their water resources. All AP’s promote the concept of IWRM. However, some APs have their center of gravity within a particular sub–sector, such as water supply and sanitation, irrigation and drainage, fisheries, etc. APs support the process of decision-making in the development and implementation of IWRM as defined in the country’s framework for action. The GWP TAC and the GWP Regional TACs assess needs for strategic assistance through consultation with all relevant stakeholders. These committees constitute a pool of eminent water professionals around the globe. Results of the identification process are regularly presented to the donors that support water resources assistance in the GWP Financial Support Group meetings. This guarantees the fanciers are informed and involved in development of associated programs from an early stage. The central and regional TACs provide a quality label for new and on-going AP’s. The GWP endorsement focuses on the strategic relevance and overall quality of the programs, and their conformity with sound principles, approaches and methodologies for IWRM. A network of existing global, national or local institutions implement an AP.AP’s bring together institutions working in similar fields in various regions of the world. These institutions can benefit from each other’s experience, and learn from each others mistakes. AP’s have different organizational structures and lifetimes depending on the type of services they provide and their geographical scope. CAPNET : The economies of scales The global capacity building network CAPENT fosters human resources development for integrated water resources management through the strengthening or establishment of a number of regional IWRM networks able to deliver education and training CAPNET and its regional nodes will be in a position to add value to all APs dealing with the business of capacity building. The first regional node of CAPNET that is operational is WaterNet in Southern Africa Why East Africa Regional Water Partnership? o Bring water management under one roof and strengthen water institutions. o Ensure water security for all people of the region for all water demands (food, drink, sanitation, health, industry, power and the environment). o Promote public water awareness campaigns for government, water professionals and civil society o Generate political commitment and mobilize political will from governments for effective water governance. o Encouraging private sector to be involved in water security issues o Adapting and adopting policies for best practices for sharing common waters and developing agreements, between riparian countries seeking win –win gains o Coordinate water resources research. o Knowledge and information sharing, and appropriate technology transfer. o Capacity building and human development in IWRM o Train more women professional in water resources management and water related cares and safeguard their rights in managing water
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o Target poverty eradication and promote economic integration o Establish and launch an East African vision to action for shared view of appropriate strategies, mechanisms for immediate action and investment for sustainable water management in the new millennium. Global Water Partnership Contacts Executive secretary: khalid Mohtadullah (khalid
[email protected]) GWP secretariat: Sida, SE -105 25 Stockholm, Sweden (
[email protected]) Technical Advisory committee (TAC) chair: Torkil J nch –clausen (
[email protected]) Central America: tempis @sol.racsa.co.cr Central and Eastern Europe:
[email protected] Mediterranean:
[email protected] South Asia:sastac @bom4.vsnl.net .in Southeast Asia:angel @nhrc .engg.upd.edu.ph South America: gwpsamtac @eclac.cl Southern Africa: tmc@samara .co.zw West Africa:
[email protected] Bibliography 1. GWP TAC Integrated Water Resources Management, TAC Background Paper No.4, Stockholm, Sweden, 2000 2. Global Water Partnership, membership, pamphlet. 3. e>mail:
[email protected], web site: http :??www.gwpforum.org 4. GWP secretariat, Associated programs, Portfolio, March 2000
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Oman Water Resources: Management, Problems and Policy Alternatives90 By Dr. Mohamed Ahmed Osman Ibnouf91 and Dr. Isam Mohammed Abdel-Magid92
Abstract Oman is an arid country. Water abstraction exceeds annual recharge. Limited possibilities for new water sources exist. The government is working on augmenting water supplies, adopting conservation and improved management policies. This paper advocates flexible water policies responding to changing supply and demand. Involvement of communities is necessary for successful water management. Food security is recommended rather than a food-self sufficiency. Dependence on imported food may be resorted to in the short and/or medium term to alleviate pressures on strained water resources. Community education and awareness, administrative and pricing of irrigation water approaches are suggested as alternative integrated policies for water management. Introduction Land and water resources are basic capital for mankind. They are largely location specific. Although, water is transferable to some degree, yet its transferability is governed by physical, economic, social, political and legal constraints. Proper use of limited water resources calls for a complex judgment on water resources supply and use planning, involving engineering, agricultural, economic, institutional and social factors that need to be integrated to reach optimum water resources use. Each year, increased demands are being placed upon Oman's scarce water resources. Agricultural, commercial, recreational, domestic, and growing industrial use are facing increasing problems of water quantity and quality. In response to the challenges posed by ground water overdraft in the major populated and crop producing region of the country, the "Batinah Area" (See Figure 1) and parts of other regions, the government started after mid-1970's extensive ground water studies, and took policy actions to increase supply, rationalize water consumption and to call for water conservation. The purpose of this paper is to describe Oman's water resources, their exploitation and problems that are emerging due to water resource use and scarcity. Government policies and programs in the area of water management and conservation are also discussed. Alternative policies to manage scarce water resources are suggested. Water Resources and their Exploitation Oman is a country that has almost total arid climatic conditions. The country is highly dependent on rainfall for its fresh water supply and groundwater recharge. The main source of water is groundwater. Almost all fresh water in Oman, apart from domestic water supplies obtained from desalination plants, is from rainfall. Unreplenished fossil 90
The second Gulf water conference, Bahrain, 5-9 November 1994, Water in the Gulf region toward integrated management, Water Sciences and Technology Association, Manama, Conference Proceedings Vol 1, pp. 19-31 91 Lecturer, Agricultural Economics and Rural Studies Department, College of Agriculture, Sultan Qaboos University, Muscat, Sultanate of Oman 92Assistant Professor, Civil Engineering Department, College of Engineering, Sultan Qaboos University, Muscat, Sultanate of Oman.
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water aquifers are found in certain localities such as Al-Najd area in Dhofar region. Rainfall is limited and varies considerably throughout the country. Generally, it is described as sporadic and unreliable. A regular rainy season (monsoon) is experienced only on limited scale on Dhofar mountains. Frequent rains fall on Al-Hajar mountain range of Northern Oman (See Figure 1). The mean annual precipitation is estimated at 5,178 million cubic metres (MCM) of which 28 percent is lost as run-off. The hot climate causes 48 percent of total precipitation to evaporate, leaving 24 percent to recharge under ground water aquifers (equivalent to 1,240 MCM) {1}. Desalination plants were constructed to supplement domestic water supply in Greater Muscat Area and some other municipalities and villages. Recent discoveries of fossil water aquifers in Al-Najd area suggest that the estimated stock of water amounts to 5,000 MCM. The Ministry of Water Resources (MWR) estimates annual withdrawal of 100 MCM can be used annually to irrigate an area of approximately 2,500 feddans {2}. Figure 2 shows the annual use and supply of water in different regions of the Sultanate. Agricultural use amounts to 92 percent of the total water use. Most of the water used is in irrigation of crops, 94 percent, is consumed during the hot summer season (May to August) {3}. The consumption of water in agriculture has continuously grown since the 1970's, due to extensive and intensive increase in agricultural production. The area under crops was continuously growing as shown in Figure 3. The intensification of agricultural production is clearly demonstrated by the jump in total production by 328 percent between 1970 and 1993 {4}. During this period the Ministry of Agriculture and Fisheries (MOAF) estimated that the productivity per feddan tripled. Livestock numbers increased from 214,000 head to 1.4 million head, representing an increase of seven fold {5}.
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Water used for domestic purposes increased tremendously over the last two decades. Piped water, which was not available before the 1970's, is now in common use in most urban areas. Net potable water use is now estimated at 70 MCM and expected to grow to 263 MCM by 2010 {6}, this being a result of the rising standard of living for the rapidly increasing population. Two main systems of irrigation are used in Oman, Falaj (plural Afalaj) and well systems. Falaj system is an old system of channeling irrigation water by gravity, sub-surface or in canals from springs and/or surface wells to farms. The village(s) community in a very strict and well-organized fashion controls the use of irrigation water. Water allocation is based on acquired rights, which can be passed through inheritance or rarely through purchase. It is estimated that approximately 70 percent of irrigation water in the Sultanate is delivered by Aflaj, which irrigate 55 percent of the cropped land {7}. Current Policies The government awareness of the importance of sustaining water for agricultural and domestic use was clearly evident. A number of policies and programs were initiated over the last two decades to increase water supply, improve its use and conservation. These programs were mainly of institutional and technical nature. Technical work on improved water management practices included reduction of water loss in different uses, improvement of ground water supplies (through construction of many
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groundwater recharge dams, see Table 1), water harvest, and building of desalinization units. Institutional building has been one of the concerns of the government to deal with growing water problems. Before 1975 a number of government ministries and agencies were supervising water resources management and use based on location and type of use. The MOAF supervised irrigation water, the Ministry of Electricity and Water dealt with potable water, the Minister of State for Dhofar worked with water projects in the Southern Region, and Musandam Development Committee worked with water projects in Musandam. In September 1975 the Water Resource Council was established under the chairmanship of His Majesty, the Sultan of Oman, to decide, as a central body, on policies and programs in the water sector (to be implemented by concerned ministries and government agencies). The council's main function was to coordinate exploitation of water resources to ensure a balance between supply. The Public Authority for Water Resources was established in December 1979 under the chairmanship of the Minister of Electricity and Water, to assist the Council for Water Resources in carrying out its duties. The Ministry of Environment and Water Resources was established in 1985 to reorganize water management activities. The Department of Water Resources of the MOAF was transferred to the newly formed ministry. The alarming decrease in water availability for different uses and deterioration of water quality led to the Royal Decree of November, 1988 which considered water as a national wealth. This decree was considered necessary in the face of the continuous depletion of ground water aquifers and decrease in water quality. Batinah coastal area was the most affected zone, because of seepage of seawater into ground water aquifers as a result of ground water depletion {9}. In 1989 the National Committee for Guidance of Water Use on the Batinah Coast was established by a royal decree. Before 1989 was over, the MWR was established to shoulder all the responsibilities of the previous councils and agencies dealing with water resources management.
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261 Figure 2 Annual Supply & Use of Water in Oman (2)
Figure 3 Area Under Crops in Oman (3) Table 1 Groundwater Recharge Dams in the Sultanate of Oman {7} Dam W. Al-Khod W. Khilts/Salahi* W.Quryat* W.Al-Jizzi* Tanuf# W. Al-Ghul# W. Kabeer* Al-Maawil* W.Al-Fieleij* W. Sahnut*
a 1985 1986
b 110 126
c 1674 554
d 14.0 8.8
e 5100 9062
f 8.0 4.5
g 5.0 3.0
h 54.0 27.0
I 2.6 2.5
j 11.55 0.5
1986 1989 1989 1989 1991 1991 1991 1991
131 128 160 164 148 120 141 150
427 812 157 173 753 566 680 258
8.5 6.6 5.0 4.8 8.3 7.5 2.2 6.5
1630 1234 135 415 2635 7500 530 2355
5.3 20.4 14.8 7.6 5.9 8.3 7.0 22.8
3.0 6.0 3.0 4.0 6.0 6.0 4.0 -
32.0 129 36.0 45.0 59.0 38.0 29.5 -
0.18 1.25 0.12 0.16 0.7 2.5 0.19 1.1
0.125 5.4 0.7 0.45 0.5 10 0.7 6.4
Key: a. Year of construction of dam. h. Maximum bottom width (m). b. Average yearly rainfall (mm). i. Dam lake area (km2). c. Dam water surface area ( km2). j. Dam year's storage capacity, (million m3). d. Length of dam (m). * f. Height of dam (m). Earth dam. # g. Top width of dam (m). Rock Fill dam. A number of projects and programs were initiated by the MWR. These projects have three main objectives: 1) to assess available water, 2) to increase water supply and 3) to decrease water demand through conservation. To achieve the first objective, water resources assessment, a number of leading international consulting firms were invited
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to do water inventory and management studies {10,11}. Expatriate water experts were employed by different water authorities to help in studying water resources and develop alternative policies for proper water management. Starting 1990 a detailed survey of wells throughout the Sultanate was carried out by the MWR. More than 167,000 wells were registered and technical data have been collected on their depth, groundwater table, aquifer characteristics, quantity and quality of water extracted and other relevant information {12}. The strategies to increase supply of water in the Sultanate concentrate on three areas, water harvesting, desalinization and wastewater reclamation and reuse. Water harvesting potentials were recognized from the fact that intense `wadi' flows following cyclonic storms can be restrained to increase the seepage of water into the underlying aquifers. The annual amount of surface water lost to the sea is about 120 MCM {13}. Water desalination started in the Sultanate in 1976, when a unit was built to meet rapid increase in demand for domestic water in the capital area. Presently, about 80 percent of fresh water requirements of the capital area is supplied from desalination units. Smaller capacity desalination units have been also built in other parts of the country. The third source of water now is from wastewater reclamation and reuse. Wastewater treatment works are mainly in the capital area with a total capacity of 28,400 cubic metres per day. Table 2 gives details regarding the existing wastewater treatment plants (WWTP's) in the Sultanate as well as the volume of the treated wastewater used for irrigation purposes. The table also illustrates the locations of the WWTP's, their design capacity, the actual flow rates in 1993, and the average effluent quality for Biological Oxygen Demand (BOD520), suspended solids (SS), and ammonia-nitrogen (NH3-N) {14, 15, 16}. Reuse of this water is restricted to the irrigation of landscape areas and parks, recreational activities and in fountains in the capital area. Sludge within each plant is subjected to digestion and dewatering. The stabilized sludge is used as a fertilizer or soil conditioners. The strategies to conserve water use are based on two approaches {18}. The first is to decrease water loss due to water delivery system, and the second is to restrict well drilling. As mentioned earlier, the two major irrigation systems in Oman are the Falaj and well-irrigation systems. The Falaj irrigation system is an old practice dating over eight centuries. Relatively, the falaj community spends very little on water distribution system to/or within the fields. Based on research work on modernizing falaj irrigation systems, the government embarked on an extensive construction program to maintain and repair falaj systems {19}. The major objectives of the program are to preserve this efficient system of underground water tapping and decrease water losses through seepage or cracks in the delivery channels. The government through a subsidy program promoted the use of modern irrigation systems to save water losses from pump irrigation using traditional open channels to convey water to the fields, and basin irrigation of crops. Modern irrigation is a description of a system based on sprinkler, drip or bubble irrigation. Farmers willing to adopt modern irrigation systems are subsidized between 25 to 75 percent of the costs of the systems, depending on their farm size. For farms of 10 feddans (4.2 ha) or less the subsidy is 75 percent of system cost. For farms between 10 and 50 feddans (4.2 to 21 ha.) the subsidy is 50 percent. The subsidy is 25 percent of the cost for farms over an area of 50 feddans. Estimates of water savings, using modern irrigation systems, as compared to traditional irrigation go up to 50 percent {20}. The policy to restrict well drilling was initiated in early 1990's. Restrictions are now imposed on drilling of new wells unless a stringent set of rules is met. Increasing the depth of any existing well is not allowed unless the MWR issues a permit. However, permission is 263
only granted if the well is used for domestic consumption. Also, a restriction on drilling wells within a diameter of 3.5 km from a falaj is prohibited {21}. The MWR is installing flow-measuring devices on wells to determine quantities of water pumped. At a later stage there may be a limitation on the quantity of water that to be pumped based on recommendations of the MOAF. The Ministry will base its recommendations on crops to be grown and their water needs. As an integrated approach for water conservation and management, the MWR is engaged on a public awareness campaign. Table 2 Wastewater Treatment Plants (WTP) in Muscat Area [6,9,10,11] WTP Name
Al-Amerat Al-Ansab Al-Aynt Al-Kod Bowshar Darsait Jibroo Mabella Al-Qurum Total
Design, m3/d
Actual flow, m3/d
600 1200 60 1200 400 10800 70 1920 1350 28400
600 5400 100 700 400 11500 100 700 800 20300
Standard+ , mg/L BOD 20 10 10 20 10 10 10 10 10
SS 30 10 10 30 10 10 10 10 10
NH3(N) 1 1 1 1 1 1 1 10850-17350
Reuse* , (m3/d)
2000-5000 8000-11500 50 800
Key: Design standards for BOD520, suspended solids (SS), and ammoniacal nitrogen. (All measurements are in mg/L). * Reclaimed wastewater used for irrigation processes. Mass media, billboards, posters, lectures, seminars, and school syllabi are all used to convey water conservation messages. Religious beliefs, moral and environmental codes and themes were used in these messages. Projections for Water Demand The current imbalance between water supply and demand is clearly manifested in water shortages, groundwater depletion, deterioration of water quality and intrusion of seawater. Estimates of water demand by the year 2010 expect supply and demand for agricultural use will balance but that of potable water uses will increase by more than three fold (See Table 3). Table 3 Estimated Present and Projected Demand for Water in Oman {4} +
Region Batinah & Capital area A'Dhahira A'Dakhaliya A'Sharqiya Musandam Dhofar Total
Agriculture(MCM/year) 1990 2010 697 (To 116 match 198 supply) 224 23 38 1278
Potable use, (MCM/year) 1990 2010 55.8 167.9 3.7 12.0 3.2 14.6 4.3 29.0 0.6 5.8 10.4 34.6 78.0 263.9
The demand on limited water resources for agriculture, domestic, commercial and industrial uses is expected to increase continuously. A number of factors will increase water demand augmenting the problems of scarcity of water resources in the Sultanate. Agricultural needs for irrigation water are projected to increase. This will be a consequence of increased demand for agricultural products for human
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consumption and livestock feed. Factors leading to increased demand for agricultural products include an increase in Oman population, a greater per capita use of crops grown for food and livestock. The 1993 census results indicated that the total population of Oman was 2,017,591 with 74 percent being Omani nationals and 26 percent being non-Omanis. Table 4 shows the population and number of families as per region. A general observation suggest that with growing per capita income and more chances for better education levels, consumption of food crops will continuously increase. Expansion of agricultural production to new frontiers, like "Al- Najd" area, will also lead to increase in water demand for irrigation. Table 4 Population Estimates {12} Region Number of families Total number of people Muscat 92298 622506 Batinah 68373 538763 Musandam 4027 27669 Dhahira 21170 169710 Dakhaliya 27311 220403 Sharqiya 35943 247551 Central 2384 16101 Dhofar 22851 174888 Total 274357 2017591 Nature of Water Problems Shortage of water, falling water table and increasing salinity are problems that lead to increased costs of irrigated crops because of the energy needed for lifting and distributing water. Heavy pumping of fresh ground water may allow intrusion of salt water from sea, in coastal areas, resulting in saltwater contamination of fresh water aquifers. Fresh water being less dense, overlays salt water in aquifers. The condition can be aggravated when the soil is already salt affected. Along the Batinah coast, the phenomenon is highly manifested. In certain areas encroaching salt water made well water unsuitable for domestic use, and ultimately agricultural use. Monitoring of 270 wells on the Batinah coast indicated that the salinity increased by 38 percent. Use of fertilizers, pesticides and other chemical substances can cause ground water contamination. Use of chemical fertilizers grew from almost nil before 1970's to an average of 15 thousands tons by 1990 {25}. Contamination from certain nutrients, like nitrate (which may cause methemoglobinemia in infants), can be a serious human health hazard. The use of pesticides and insecticides has increased over the last two decades. Government subsidies on fertilizers, pesticides and insecticides amounts to 50 percent of their market price {26}. Some Alternative Policies To Deal With Water Problems Water availability could be increased through different technical options. The major concern is how can the society use and allocate water resources among its members. The uncontrolled use of a resource, in the case of a common property resource, leads to the social trap of each user maximizing his own use without recognizing society needs as a whole. Incentives for water conservation in agriculture, the major user, are few. It may even be claimed that water pricing and opportunity costs of water are not enough incentives to encourage users to invest in technology or gain management expertise needed to conserve water. The low cost of water in agriculture coupled with the lack of opportunity cost, and traditional market failures are apparent disincentives to water conservation.
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There are certain facts that can be taken as background for any water policy. First is the fact that over 90 percent of fresh water use in the Sultanate is in agriculture, and that the major bulk of water use is during summer period (May to August) amounting to over 90 percent. The second fact is that water extraction systems are mainly of two types; Afalaj system and pumps. The third fact is that over drafting already occurred in major water use areas (Batinah). Based on these facts the current government policies of resource augmentation, conservation and monitoring are encouraged to continue as long as they prove to be economically sound. A major concern is how to raise particular community's involvement. The drive should not only be community participation, but stronger emphasis on their management of water resources. The falaj system of irrigation is based on community management. There is no community management when pump irrigation system is practiced. Water over drafting is actually happening in areas where pumps are extensively employed. The suggested role of the government is to provide community enabling environment, which would provide information, know-how, set legal framework, enable users to organize, and would oversee the major improvement works which are subsidized by the government. Expatriate consulting firms carried out previous studies done on water resource assessment and management. Oman needs to build a national cadre of water resource specialists to conduct research, manage and monitor activities on continuous longterm basis. Minimizing dependence on expatriate labour coming from water rich areas, sometimes with no background in farming, should be advocated. Even passing extension messages to this labour force is difficult, due to language barriers and/or low levels of education. A strategy of food self-sufficiency needs not be advocated if it means putting more demand on the already stressed water resources. Food security strategy do not put increasing demand on water and can provide the populous with adequate food supplies from domestic sources or from world market-using oil revenue. More dependency on imported food supplies may be needed, at least as a short or a medium term policy. This is to alleviate the pressure on already over drafted water resources to regain aquifers water levels that can improve quality and counteract seawater intrusion. This policy can be supported by available oil revenue hoping that in future technological developments can provide cheaper methods of desalination of sea water, improve plants tolerance to salts and develop more efficient methods of irrigation. Available desalination techniques cost 30 to 40 times extracting water from wells {27}. The approach endorsed is a holistic and integrated one that recognizes no single solution to solve the problem. Such an approach recognizes both the supply and demand side of water resources management. Water availability could be relatively increased through different technical options, some of which are being practiced or there is planning to practice them in the Sultanate as indicated in section 3 of this paper. Water use can be altered through better water conservation, changing cropping patterns, and shifting use of water from low to high economic value uses. Kenneth Boulding wrote in 1980 that three major mechanisms organize utilization of natural resources, price, policemen, and preachments {28}. Preachments and extending the message to all concerned about water scarcity and its conservation is practiced in the Sultanate. Religious and moral and nationalistic messages need to be stressed more. Emphasis on community involvement and responsibility in water management needs to be increased. Mass media, schools, mosques, and all public forums can be used as means to deliver messages in different forms and kinds.
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Administrative procedures to control water use require political will and clear vision, which is not lacking in Oman. Restrictions of water use to irrigate low value crops, banning of irrigation of seasonal crops during summer, and limit growing particular crops to certain localities are possible actions that can be taken. These policies can be implemented in the context of regarding user's acquired rights and their dependence on agriculture for their livelihood. Government incentives could be used as a support to administrative actions to decrease growing of tree crops or the number of trees. Horizontal expansion of crop production on soils, of marginal productivity, should be discouraged. Control on quantity of water extracted can be a possibility of restricting water use, especially with the MWR installs measuring devices to estimate well yields. Compensating payments for follow practice can also be used as a mean to conserve water. Water is almost universally treated as a free resource and no charge is imposed for its withdrawal from its natural supplies. As an additional pillar in water use management, policy pricing of water is suggested. The use of price signals as a mean for water allocation can be tried. Water is considered as a public good, and as such pricing of water needs certain considerations. In the case of the Sultanate, a system of water tariffs and pricing could be effective way to decrease and economize water use in agriculture. The suggestion is to practice pricing system in well irrigation areas only on the natural flow of falaj make it self-regulating. In order to device a pricing system information needs to be collected on an estimated demand curve for water use in different regions and localities. From the demand curve, estimates of marginal value of resource use can be made. Cost of least expensive alternative for providing water can be used as a proxy for the value users willing to pay. A theoretical framework needs to be established before the system can actually be implemented. A minimum quantity of water can be given free of charge before a progressive price is charged against its use. The money generated could be used for increasing the supply of water or developing more efficient water use and distribution. For these suggested policy alternatives to work certain conditions need to be satisfied. Adequate information about water supply and potential uses need to be established. Clearly defined policies, methods of implementation and control procedures need to be set. It is better to take drastic measures to use the scarce water resources now before they can be damaged irreversibly. Conclusions and Recommendations Oman is an arid country highly dependent on rainfall for its fresh water supply and groundwater recharge. Rapidly increasing population, improved living standards and use of modern technological machinery in agriculture contributed towards straining and over drafting of the country's water resources in certain areas. Sea water intrusion, increased salinity, depletion of aquifers are all being experienced. The government is keen on improving the deteriorating water conditions. Institutional reforms are continuously being implemented for the last two decades. The MWR acts as the government body responsible for control of water resources. The government strategies to increase water supply concentrate on water harvesting, desalinization and wastewater reclamation and reuse. On the demand side, the policies advocate water conservation through use of modern irrigation systems and wastewater reuse and community education. The paper stresses the importance of an integrated water policy, that respond to changing conditions of supply and demand. The suggested strategy not only calls for local community participation in water management programs, but active involvement
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in devising and implementing these policies. Building a national Omani cadre of water research and management experts is seen as an important facet in the strategy. A food security strategy that does not put an increasing demand on already strained water resources is seen as a better alternative than striving for food self-sufficiency. The domestic food production can be augmented with imports, using oil revenues. Administrative procedures to control water use restrict it to high value crops and decrease areas of summer crops is recommended. Use of marginal land need to be restricted to conserve available water for more productive land. A policy of putting a price on irrigation water is suggested. Water, extracted over a certain amount, can be charged a progressive rate. The price system is suggested for pump-extracted water. The price system makes use of MWR decision to install flowmeasuring devices on wells. The changing conditions of water supply and demand call for continuous research and monitoring of resources. The information available about water resources, their use and problems can be made accessible by researchers, policy makers and the public at large for a better understanding and devising alternative management policies. References 1. Japan International Co-operation Agency, The Study on a Master Plan for Agricultural Development, Muscat, Sultanate of Oman, November 1990. 2. Al-Watan Daily Newspaper, H.E. Minister of Water Resources Address to AlShura Council, Al-Watan, Muscat, March 28, 1994. 3. Al-Watan Daily Newspaper: Op. Cit. [2]. 4. Ministry of Agriculture and Fisheries, Summary of H.E. Minister of Agriculture and Fisheries Address to Al-Shura Council on March First 1994, Ministry of Agriculture and Fisheries, Muscat, Sultanate of Oman. 5. Ministry of Agriculture and Fisheries: Op. Cit. [4]. 6. Ministry of Regional Municipalities and Environment, National conservation strategy: Environmental protection and natural resources conservation for sustainable development, Ministry of Regional Municipalities and Environment, Muscat, Sultanate of Oman, 1992. 7. Dulton, R.W., Modernizing Falaj Irrigation Systems, A Proposal for Dhahira Action Research Centre 1986 - 1990, Centre for Overseas Research and Development University of Durham, U.K., September 1984. 8. Abdel-Magid, I.M. and Abdel-Rahman, H.A., "Water conservation in Oman", Water International J,Vol 18(2), June 1993, pp 95-102. 9. Ministry of Information, Oman'90, Ministry of Information, Sultanate of Oman, Muscat, 1990. 10. Ministry of Information, Oman'92, Ministry of Information, Sultanate of Oman, Muscat, 1992. 11. Hunting Technical Services, Pre-feasibility Study to Investigate Alternative Means of Establishing Commercial Farming in Interior of Oman, A Report Submitted to the Ministry of Agriculture, Sultanate of Oman, Muscat, October 1976. 12. Ministry of Information: Op. Cit. [9]. 13. Abdel Magid, et. al.: [8]. 14. Ministry of Health, Papers presented at the National seminar on wastewater reuse, held in Muscat, during the period 26-29 April 1992, organized by the Ministry of Health, Muscat, Sultanate of Oman.
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15. Muscat Municipality, Directorate General of Technical Affairs, personal communication, Oman, 1993. 16. Rowe, D. R., and Abdel-Magid, Wastewater Reclamation and Reuse, Lewis Publishers, INC., Chelsea, 1994 (Under publication). 17. Abdel Magid, et. al.: [8], Papers presented at the National seminar on wastewater reuse: [14], Muscat Municipality: [15], and Rowe: [16]. 18. Japan International Co-operation Agency: Op. Cit. [1]. 19. Dulton: Op. Cit. [7]. 20. Abdel-Magid, et. al.: Op. Cit. [12]. 21. Ministry of Information: Op. Cit. [7]. 22. Ministry of Regional Municipalities and Environment: [6]. 23. Al-Watan Daily Newspaper, Results of the Census, Tuesday 28 December 1993, Al-Watan, Muscat, Sultanate of Oman. 24. Al-Watan Daily Newspaper: Op. Cit. [2]. 25. Japan International Co-operation Agency: Op. Cit. [1]. 26. Ministry of Agriculture and Fisheries: Op. Cit. [4]. 27. Ministry of Agriculture and Fisheries, Agricultural Sector Plan, Ministry of Agriculture and Fisheries, Muscat, Sultanate of Oman, Muscat, Undated. 28. Oman Daily Observer, Middle East Water Talks, Oman Newspaper House, Muscat, April 20, 1994. 29. Boulding, K. E., The Implication of Improved Water Allocation Policy, in Western Water Resources: Coming Problems and Policy Alternatives, Compiler Marvin ncan, Westview Press, 1980.
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Along the Way Towards an Environmental Strategy for the Arab World By Dr. Isam Mohammed Abdel-Magid93, Dr. Alaa Eldin Al-Zawahry94, & Dr. Hyder Abdel-Shafi95
Abstract The paper focuses on the possibility of formulating an environmental strategy for the Arab countries with emphasis on the preconditions and requirements for the implementation of a sound and successful strategy. To accomplish this the general framework of the environmental strategy and policies for three of the Arab countries has been proposed as a model that can be utilized and generalized for the rest of the Arab world. The three countries selected were the Sultanate of Oman the Sudan, and the Arab Republic of Egypt. The paper generally deals with the status-quo analyses of the named countries with stress on environmental issues, suggested remedial strategies, regulations and legislation, pollution avoidance features, function of environmental organizations within the countries and expected collaboration and stable coordination. Background In each of the three countries environmental an strategy has been formed and initiated. The Sultanate of Oman has already launched several suitable initiatives with the aim of coupling the existing notable socio-economic development with the neat and well planned environmental protection together with the available natural resources. However, the speedy pattern of development, combined with the apparent demand for using foreign new technological methods and patterns of production and services, have resulted in an increase in levels of environmental contamination and pollution {1,2,5,6,7,8,9,10} Ministry of Regional Municipalities and Environment has prepared The Omani National Conservation Strategy of Oman (NCS) {1}. The NCS has tackled the synthesis and policy framework of the country’s natural and human resources, economy development policies and performance and utilization. Likewise, the NCS has initiated projects and program profiles that are geared towards its implementation to the different regions within an integrated development and an environmental protection framework. From an economic point of view the Sudan is lead to the furnishing of the basic needs and essential requirements that would enable the upkeep of a reasonable stage of growth, development and productivity. The supply of fundamental requirements, food securities, construction of the crucial infra structure and trials for accomplishing a relevant environmental equilibrium attracted the greatest attention. Several natural resources that are available within the Sudan (e.g. crude oil and minerals) have not greatly been utilized. This may be owing to financial drawbacks, shortage of experiences and advanced technology. The countries economy counts immensely on the export of certain agricultural outputs, some industrial commodities, taxes and resources from workers in the Gulf countries. The Comprehensive National Strategy (CNS) {9} of the country has been formulated, and discussed with different parties. 93
Assistant Professor, College of Engineering, Sultan Qaboos University, Muscat, Sultanate of Oman Assistant Professor, College of Engineering, Sultan Qaboos University, Muscat, Sultanate of Oman 95 Assistant Professor, College of Agriculture, Sultan Qaboos University, Muscat, Sultanate of Oman 94
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Likewise, the CNS addressed the general and different strategies and the ten-year plan for each sector with emphasis on general programs, priorities and stages of implementation. Egypt has the largest population among the Arab countries. Many of the existing environmental problems in Egypt deserve and need immediate and future actions and solutions. The Environmental Action Plan of Egypt (EAP) has summarized the magnitude of the environmental problems as related to pollution and degradation of the country’s natural resources of land, water and air. The EAP proposed relevant plan of actions to stop the on-going environmental deterioration {11}. Many studies were carried out to investigate such problems in all environmental fields. The council of environmental affairs, which is affiliated to the council of ministers is the highest environmental authority in the country. Usually essential data and information is needed to enable the preparation of the NCS. This condition proved to be difficult to sustain while formulating the strategies for the three named countries. Nevertheless, the formulated policies have managed to utilize the readily available information, data, results and findings of local studies and research work. Thus, the strategies have contained data of natural resources and data of renewable resources (including land, water, rangelands, forests and fisheries) with focus on present and future status of requirements and demand. This is besides presentation of data and information on non-renewable resources (such as: petroleum, natural gas, and minerals). General basic data as related to the three countries is summarized in Table (1). Main Environmental Problems and Issues The national environmental and conservation strategies for the three named countries has outlined the following main environmental problems {1,8,11}. - Problems related to natural elements: such problems emerge from the presence, distribution and use of natural resources examples may include: drought, desertification (due to scarcity of rainfall, changes in plantations and green cover, unauthorized cutting of forests and wood, utilization of wood as a source of energy, etc.), desert-locust attacks, depletion of fresh water resources in certain districts, prevalence of such diseases as related to water and sanitation (for example the average death rate due to water-based diseases in the Sudan is estimated to fall around 40 percent of the officially registered death cases). - Problems related to exposure to technology and modern methods of production: such problems are apt to occur due to the choice and employment of unsuitable technological designs that may ease occurrence of environmental pollution in agricultural and industrial sectors. - Problems related to mismanagement of resources: these problems arise from misuse of resources or mismanagement in the agricultural, industrial, tourism, commercial and service sectors: examples may include: overgrazing (such as the case along the Southern Region of the Sultanate of Oman), unauthorized cutting of natural trees, over extraction of groundwater, over fishing, over use of agricultural chemical substances and fertilizers.
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Table 1 General Data Regarding Oman, Sudan and Egypt {4,5,6,7,8,9} Item
Oman 308000
Sudan 2505813
Egypt 995450
Population million) Annual growth rate (%) Male/female ratio Birth rate/1000 Infant mortality rate/1000 Death rate/1000 Literacy rate (%) Main economic resources
2 3.5 51:49 44.9 29
25 2.7 50:50 50 20
54.706 2.9
20 12.7 Crop fodder
Livestock resources
Goats, sheep, cattle, camels, fisheries,
Metallic minerals
Copper, chrome, gold silver
Major exports
Petroleum, fish, dates, dry lime, copper, light manufactures& consumer goods Cotton, Wheat, rice, sugar, vegetable oils metal dairy products, vehicles, building materials& intermediate agricultural& industrial production goods
31 45 15.8 8.6 Crops (millet, wheat, Crops (rice, wheat, oats), cane sugar, maize), cotton, fruits cotton, sesame, peanut, and vegetables gum Arabic, yam Goats, sheep, cattle, Cattle, horses, camels, fisheries buffaloes, goats, sheep, camels and fisheries Iron, copper, chrome, Crude petroleum, iron zinc manganese, ore, salt (unrefined), uranium, phosphate, phosphate, rock, gypsum, marble natural gas Cotton, cattle, gum Raw cotton, cruedand arabic refined petroleum, cotton yarn, textiles
Land area (km2)
Major imports
Health facilities Hospitals Hospitalbeds
Health centres Physicians/ capita Education Primary schools Secondary schools Universities
47 3431
production,
37.5 90
Machineries, vehicles, industrial products, petroleum products, food stuff, textiles, chemicals, medicines
160 17328
Food stuff, machinery & equipment, fertilizers wood products, durable consumer goods,
491 population/b ed
90 2/ 10000 persons 703 76 1
6707 2265 16
- Problems related to marine and coastal zone pollution for instance in the vicinity of the Gulf of Oman, the Red sea and the Mediterranean coast. This is due to industrial waste disposal from adjacent and concerned establishments, and the utilized methods of solid and liquid waste ultimate disposal. - Problems related to air pollution due to the escalated increase in traffic, heavy use of leaded gasoline, and industrial and oil development (for example in Helwan, an industrial suburb of Cairo Egypt, 29 % of school
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children suffer from lung diseases compared to 9 % in rural areas of Egypt {11}). - Problems related to generous subsidies to users of natural resources: for instance such as subsidies in meat prices that has aggravated overgrazing problems of Dhofar highlands in Oman {1}. Likewise, subsidies in groundwater development resulted in over abstraction and salination problems in Batinah region in Oman {1}. - Problems related to contaminated imported foodstuffs. - Problems related to water pollution: groundwater pollution is detected in certain localities in the named countries and there are signs for surface water pollution. Generally, the quantity of water treated usually is not fulfilling the water-demand. This may be attributed to limitation in financial, technical, and technological aspects or due to deficiency in the supply. - Problems related to shortages of wholesome water in shanty and scattering areas in towns and in villages. Likewise, suitable methods of excreta disposal are not introduced in these surroundings. - Problems related to disposal of solid and hazardous wastes. - Problems attributed to air pollution especially in great cities with industrial plants, factories and traffic. - Problems related to wastewater disposal especially in absence of treatment facilities (for example the sewerage network covers only 15 % in Khartoum, 5 % in Khartoum North, and 0 % in Omdurman in the Sudan). - Problems related to refugees, in the Sudan, along the western, eastern and southern boundaries. - Problems of accelerated deterioration of antiquities in Egypt.
Environmental Law and Means of Implementation The number of national environmental standards in the Sultanate of Oman amount to over 28 regulations. They cover items of wastewater discharge, air pollution control, solid waste disposal, marine pollution control, open protected areas, protection of fish resources, life stock, veterinary, and agriculture quarantine, water resources development, protection of crops from pests and diseases, national parks. Different regulations cover specific localities of environmental concern. In the Sudan the number of national standards found are very few if any. They are in the form of articles that address public health and hygiene within homes, restaurants and certain local sectors. These regulations are formulated by certain ministries such as the Ministry of Housing, or Ministry of Health. Usually, the implementation of the regulations and bylaws or the environmental law, depends on the local authorities and councils. These regulatory agencies and/or bodies include: * The Ministry of Industry: relates to standards and quality control of the industrial sector. * The Ministry of Health: different departments shoulder the responsibilities of formulating and implementing regulations: - Health commissioner: the unit relates to hospitals, dispensaries and affiliated health facilities. The disposal of waste from the concerned units follows regulations emerging from this unit.
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- section of food and water covering the national central laboratory, which analyzes the water and food samples. Likewise, the section aids in formulating bylaws and standards. - section of occupational health and air pollution which addresses pollutants emanating from industrial enterprises. - section of environmental health which deals with environmental problems and related health impacts. - section of pharmacology and toxic substances where laws concerning medications are prepared. - section of primary health care unit, it concerns the divisions normally established in rural areas. * Ministry of Housing: The section of sanitary engineering helps in framing regulations for governmental organizations. * Ministry of Energy and Natural Resources (or Ministry of Electricity and Water): the sections of rural and urban water corporations addresses the water sector. * Ministry of Irrigation / Public works/Water Resources: attention is paid to agricultural and water aspects. * Ministry of Regional Municipalities and Environment, in Oman, it addresses land, water, pastures, forests and other natural resources. * Ministry of Communication which tackles environmental aspects of land, marine, resources, and air. * Ministry of Petroleum and Minerals, in Oman, dealing with land and water. * Ministry of Agriculture and Fish Resources, in Oman, dealing with land, water, pastures and forests. * Ministry of Commerce and Industry (land, water and industry). * Diwan of Royal Court, in Oman, (wild life and land). * National Council for Environment and Natural resources: initiated towards establishing regulations of environmental criteria. * District and Regional Municipalities (land). * National Research Council/Council: this body was formulated to organize the research aspects within the country yet with limited authorities. * Educational institutions help in advice and research work in the environmental field whenever consulted. * Public Authority for Conservation of Environment and Prevention of Pollution. * Water Resources Council. * Public Authority for Water Resources. * Council for Conservation of Environment and Prevention of Pollution, CCEPP. * Drainage Research Institute.
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* Research Institute for Groundwater. Environmental law is enforced by the appropriate sector via one of the previously named ministries, agencies and/or bodies.
International Conventions and Directions of Enforcement In Oman the number of binding international conventions signed amount to around 18 agreement and protocol3 covering marine environment protection, regulation of Whaling, desert locust, oil pollution, world culture and natural heritage, and safety of navigation. In the Sudan the signing of the international agreements and protocols follows the office of the president or who represents him. This may be carried by the advice of the Minster of Justice. The international agreements signed by the Sudan amount to around ten covering plant protection, nuclear weapons, desert locust, conservation of nature and natural resources, protection of world culture and natural heritage, wild fauna and flora, Red Sea and Gulf of Aden environment, oil pollution, and protection of plant and animal life. In Egypt the number of signed international agreements, conventions and protocols amounts to over 35. They cover regulation of Whaling, Mediterranean environment, plant protection, oil pollution, protection of workers against ionizing radiations, nuclear weapons, desert locust, exploration and use of outer space, phyto-sanitary, conservation of nature and natural resources, wild fauna and flora, pollution from ships, occupational hazards, military and hostile use of environment, protection of workers, migration of wild animals, Red Sea and Gulf of Aden environment, tropical timber, Ozone layer depletion, and nuclear accident. Along the regional status the Sudan and Egypt has signed the agreements relating to the Nile water and its tributaries, and conservation of lakes water quality.
Pollution Avoidance Considerations The existing pollution prevention and cleaning mechanisms include the following: i] Water and wastewater pollution: water treatment for different types of sources. wastewater treatment, disposal and reuse whenever and wherever appropriate (examples may include: irrigation of plantations and public parks and lawns). recycle of used water within some industrial factories. development of a continuous surveillance and monitoring system for measurement of pollution levels and trends. reuse of drainage water in suitable projects. regulation of well drilling operations and activities. establishment of relevant and workable guidelines, regulations, rules, standards and bylaws. ii] Environmental health: Preventive measures are to be utilized to reduce the incidence of occurrence of certain water-sanitation-related diseases. iii] Marine pollution supervision and control of any pollutants emerging from ships, steamers, vessels, etc., at ports and harbors. prevention of the discharge of liquid and solid waste into the marine environs. imposing certain relevant regulations and laws. 275
iv] Air pollution monitoring the level of air pollutants at particular sites, industrial companies and vehicles. forcing new industrial sectors to acquire a No Environmental Objection Certificate (NEOC). v] Soil pollution control and supervision of fertilizers and chemical substances usage to irrigated crop areas. development and introduction of appropriate methods for the disposal of wastewater in rural areas. adoption of systems to avoid eutrophication problems. introduction of efficient methods to stop problems of desertification and sand encroachment. vi] Solid waste appropriate and efficient collection, transportation, treatment and disposal of solid waste. vii] Food pollution: application of efficient quality control criteria on imported stuff. health control over communal establishments. introduction and monitoring of appropriate plant and animal quarantines. Normally, the acceptance of environmental measures maintains an extended monitoring and remedial measures rather than adoption of parameters of preventive quality. The lacking pollution prevention and cleaning mechanisms and measures merit the following considerations: 9. initiation of work on pollution abatement from existing industrial, commercial and related units. 10. introduction of research work on soil and water pollution by agricultural chemical substances. 11. conduct of epidemiological studies and research work to evaluate any reduction on the occurrence of incidents of water-sanitation-related diseases. 12. initiation of research work on relevant techniques for combating oil spills and pollution along coastal and marine shores, regions and zones. 13. carrying out investigations to evaluate influence and degree of acceptance of wastewater reuse and recycle within various societies. 14. development of relevant methods for solid waste reuse and recycle. 15. realistic legislation system for waste collection, transportation and disposal. 16. improvement of operation and maintenance funding. Function of Environmental Non-governmental Organizations
In Oman the number of non-governmental agencies working in the environmental aspects are very few, if any. A great role may be played by the Public Authorities for Sports and Youth Activities, and the Vocational Training Authorities. This is together with any existing non-governmental sectors scattered within the different regions. In the Sudan and Egypt the number of non-governmental agencies working in the environmental aspects are very few. An important part may be shouldered by the Environmental Protection Societies and agencies (usually public groups of voluntary nature), the Medical and Engineering Societies and any other existing groups or organization.
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Community Environmental Education In the Sultanate of Oman the Ministry of Regional Municipalities and Environment has made good efforts in arising public awareness towards the protection of the environment. Environmental consciousness and awareness programs are being executed by different ministries and municipalities within the local mass media e.g. press TV, radio, and through the usage of booklets, periodicals and leaflets, etc. The efforts has been complemented and supported by valuable attempts from the Ministry of Agriculture and Fish Resources, Ministry of Water Resources, Ministry of Education, and Ministry of Commerce and Industry. This has been done by each ministry within its own framework, responsibility and competence. The national conservation strategy, NCS {1}, proposed project and program profiles that addresses a national campaign of environmental awareness. The project emphasizes on schools, youth, women, farmers, industrialists, and different groups of workers in services sector. The shortcomings of these efforts are reflected by their separate and persuasive nature. Established efforts lack an educative criteria and taste. More emphasis need to be stressed on adequate programs to enhance community education and awareness through publishing and distributing well planned and prepared booklets, leaflets, posters guidelines..etc, and through better use of available resources. In the Sudan and Egypt there is no organized and well-established environmental education policy that addresses the public through a regular media. Individuals and certain agencies have initiated programs in this field. Examples of meritable trials has been conducted by the Health Education Section of the Ministry of Health, Community Medicine Departments of the Faculties of Medicine at different Universities. Examples of organized programs within this context include diseases such as Bilharziosis and diarrhea through the national press. National, Regional and International Environmental Cooperation In the sultanate of Oman environmental planning has not been directly associated with the economic and social planning. Nonetheless, some limited efforts have been initiated by different sectors working in pollution control aspects. The environmental protection framework has constituted a basic component in the objectives of the national conservation strategy. In the Sudan and Egypt environmental planning has not been directly associated with the economic and social planning. Nonetheless, some limited efforts have been initiated by different sectors working in pollution control aspects. The environmental protection framework has constituted a basic component in the objectives of the national conservation strategy in the Sudan. The Egyptian Environmental Affairs Council is regarded as the highest environmental authority within the country.
Implementation of National Environmental Strategies The strategies and policies that are aught to be proposed to shoulder the outlined problems has been tackled by the environmental strategies in different chapters and they include the following recommendations {1,8,11}: 9. Enclosure of sound environmental considerations at all planning stages. 10. Furnishing resource accounts and environmental costs in national income estimates and feasibility studies of development projects and programs. 11. Improving the resource use in terms of management efficiency particularly in the renewable resources field. 12. Sustaining the renewable resources to avoid the over-exploitation of water and rangelands and fisheries.
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13. Usage of better irrigation systems and methods of water use (domestic, industrial, etc.). 14. Establishing better land reclamation methodologies. 15. Exploring the possibility of finding new water resources and sources in places of scarcity of water. 16. Improving and rationalizing management of fisheries sectors. 17. Utilizing, in an optimum way, energy to ensure development sustainability and nature conservation. 18. Integrating development planning and administration with environmental planning and management. 19. Initiation of better coordination and cooperation with regional and international organizations working in the field of resource conservation and environmental protection policies. 20. Planning and implementation of a comprehensive national program for arousing community consciousness and awareness towards better levels of public education. 21. Formulation of a body that establishes needed guidelines, standards and legislation. This body needs also to find optimum ways for the implementation of formulated criterion. The decentralization principal aught to be considered within this framework. 22. Formulation of an organization that identifies research objectives, proposals and research priorities. 23. Formulation of a data bank. 24. Introduction of the primary health care to the different sectors and regions wherever appropriate. 25. Getting rid of epidemic, endemic diseases and malnutrition, through the usage of integrated control methods such as: wholesome water, environmental sanitation, vector control, primary health care, food hygiene, etc. 26. Introduction of better and appropriate sanitation measures to the locals. 27. Appropriate reuse of wastes (in industrial sectors for instance). 28. Initiation of rehabilitation projects in drought, desertified areas, and in localities where there are environmental degradation problems. (Community participation ought to be considered). 29. Preservation of wild life and the establishment of protected regions. To be able to implement the aforementioned proposed strategies and policies to shoulder the environmental problems the following restrictions facing the different countries merit attention: a. Difficulties of communication and limitations of paved roads in certain member estates. b. Geographic and natural barriers such as deserts, suds and swamps, etc. c. Drought and desertification problems within some particular countries and in neighboring estates as well. d. Limitations within the industrial sector in some member estates in terms of spare parts, petroleum products, energy resources, skilled labor, foreign currency and needed finance. e. Unavailability of the required infra structure in majority of estates. f. Weaknesses and shortcomings in formulated plans, evaluation and maintenance aspects. g. Immigration of skilled labor and technical experts from countries without their proper use in other estates.
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h. Poor coordination between the different units. i. The high rate of illiteracy between inhabitants.
Summary (1) The study has described and reviewed the primary environmental problems confronting three of the Arab countries namely the Sultanate of Oman, the Republic of the Sudan and the Arab Republic of Egypt. (2) The study has been carried out in order to demonstrate a working model for initiating a comprehensive Environmental Strategy for the three countries. A general Complete Arab Environmental Strategy may be founded and built along these guidelines. (3) The study revealed the importance of formulating a comprehensive, well planned and complete national conservation strategy in each member country. (4) The study focused on the analysis of existing environmental problems and offered some appropriate solutions. (5) The work undertaken illustrated the importance of formulating a regional data bank system, a coordination unit between member estates, and an Arab non-governmental body for environmental protection.
References i. ii. iii. iv. (2) (3) (4)
(5) (6) (7)
(8)
"National conservation strategy", Ministry of Environment and Regional Municipalities, The Sultanate of Oman, Vol. I, II,, and III, 1992. Regulations and guidelines from Different Governmental Agencies, and Environmental Organizations in the Sultanate of Oman. United Nations Environmental Program, Resistor of International Conventions and Other conventions in the Environmental Field. Annual report of the World Bank. Annual report of the Arab Bank for African Financial Development. Annual Report of the Arab Agricultural Development Association, Khartoum, Sudan. Official Reports and issues from the Government of Sudan, relating to: a. Economical plan. b. Programs of Maintenance and Development. c. Health. d. Agricultural status and the Future. Comprehensive National Strategy 1992-2002, Vol. I and II, Strategic Studies Centre, Khartoum University Press, Khartoum, Sudan, Sep. 1992. Regulations and guidelines from Different Governmental Agencies, and Environmental Organizations in Egypt. Abdel-Magid, I.M. and Al-Zawahry, A. "Preconditions and requirements for successful environmental policies in the Sultanate of Oman, the Sudan and Egypt", a paper presented at the conference on preconditions and requirements for successful environmental policies in the Arab World, 3-5 May 1993, Yarmouk University, Irbid, Jordan. Egyptian Environmental Affairs Agency "Environmental Action Plan of Egypt", EEAA, 1992.
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Reflections on Drinking Water Quality Guidelines for The Sudan96 By Isam Mohammed Abdel-Magid97 and Bashir M. ElHassan98. Background Adoption and enforcement of standards and regulations for drinking water quality is of paramount importance to the water sector in Sudan. The benefits gained are unaccountable. Therefore, any efforts towards the formulation and implementation of such a valuable tool should be encouraged by all concerned. The adopted national standards for The Sudan need to address the following peculiarities: • The varying climatic conditions within the Sudan, • The culture and habits in the different regions of the country, • The type of diet and available water, • Socio-economic status, • Beliefs, taboos and local traditions, • Reliability and availability of the required quantities of water (majority of inhabited area in Sudan is non-riverain), • Availability of efficient and properly operated treatment plants ...etc Since the above mentioned points are difficult to satisfy for the whole Sudan through one standard, adoption of guidelines rather than standards is therefore the realistic approach. The adopted guidelines need to be translated into local standards in different regions whenever applicable, bearing in mind that flexibility should prevail and also the ever changing socioeconomic parameters. Shortages of water along with economic, technological and political constraints have compelled water authorities to sacrifice water quality against quantity in so many places in the Sudan; since the problem is of quantity. Quite a number of towns of the country are bound to face a gloomy future if the current trend of drought continues. Examples of these are reflected in towns of Northern Kordofan and Darfour regions. The upgrading of the quality of the treated water to that recommended by the adopted standards, in many situations, does not mean the satisfaction of the consumer as deemed necessary. Hence, the fate of treated water after leaving any authorized water processing facility should be seriously reconsidered. Generally, water in Sudan is greatly misused with consequent deterioration through any or all of the following: System used for water distribution and metering (It should be noted that more than 80% of the installed meters are not functioning. Therefore, a flat rate has been assumed, amounting to 5 Sudanese pounds/ plot/month. This is unfair to consumers in squatter and shanty areas; since water is bought there from contractors according to an actual meter reading. Having in mind the greater differences in per capita income and actual water consumption, the degree of deprivation is clear. This unfairness would continue if this system of charging is to prevail. Not only that but water purchased in squatter areas, through contractors and vendors, is inferior in quality when compared to that available in high-class areas.) 96 Presented at a Seminar on Drinking Water Quality Standards, Khartoum, Sudan, March 8-13 1986, and published in the Water International J., 12 (1987), pp 33-35 97 Department of Civil Engineering
98
School of Hygiene, University of Khartoum, P. O. Box 321, Khartoum, Sudan
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• • •
Water vendors, sellers and contractors, Water collection systems and methods, Water storage facilities at homes (zeers, roof-storage tanks, girbas, barrels.... etc) • Lack of awareness with respect to hazards associated with polluted and contaminated water, • Traditions regarding water handling, • Belief and social values, • Tariffs and charging systems adopted for consumers...etc. To be able to implement, evaluate and follow up any adopted standards, ways and means for proper surveillance should be secured. This includes the following: • Efficient transport, • Optimum required number of trained staff, • Continuous flow of laboratory supplies and equipment, • Proper supervision. Unfortunately, what is asked for is currently lacking. Nevertheless, what has been achieved nowadays is more than that is anticipated, bearing in mind the constraints and problems. Thus what is reflected is due to mere devotion and dedication. Recommendations: The adoption and implementation of standards need to be preceded by certain activities such as: Evaluation of the current status of water resources. Registration of the different pollution-producing sectors with a nationally formed body (The National Environmental Council), Identification of pollution producing bodies and characterization of pollution streams emanating from each contributor, Advice on adoption of appropriate pretreatment or treatment methodologies, Securing of well equipped national and regional reference laboratories, Training of relevant personnel to satisfy needed demand, Community education. The enforcement of the law is the key factor for the adoption of these standards and regulations, likewise, the regular surveillance of performance and efficiency. The formulated National Environmental Council should act as a focal point at the national and international levels. One of the major responsibilities of the National Environmental Council is the coordination between authorities, donors, institutions and the like (Fig. 2). This coordination is the yardstick to the success of programs and the adopted standards. Bibliography 1. International standards for drinking water, 3rd Edi., World Health Organization, Geneva, Switzerland, 1972. 2. Guidelines for drinking water, World Health Organization, vol. 1,2 and 3,Geneva, Switzerland, 1984. 3. National interim primary drinking water regulations, US Environmental Protection Agency, Federal Register, Washington, DC, 1975. 4. Quality goals for potable water, J. American Water Works Association,, 60 (12), 1968.
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Survey of potential existing water sources (Quantity & Quality)
agreeable
Data Bank not agreeable Investigated possibility of treatment
Resort to another source
Adopted guidelines
yes
Distribution
not possible
possible & affordable
Treatment
Figure 1. Sources selection in agreement with guidelines
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Monitoring, Evaluation, Coordination, Research
Chapter Four: Water Computer Applications WESNET: An Important Utility in Water Distribution Network Design99 by Eng. N.B. Abdeljabar100, Prof. I.M. Abdelmagid101, Eng. A.S. Altahir 102, Dr. A.H. Hassan103, Eng. O.B. Ibrahim104, Eng. F.G. Faris105, and Eng. M.A. Saad106 Abstract
This paper discusses the designing of water distribution network system by introducing HI-TECH software, WESNET. The program is designed to ease and hasten design procedures. A comparison has been made between traditional methods of design and by WESNET. An anonymous difference in time has been spotted between both methods. This program supplies all information about the network; and it gives an account every fifteen minutes of the situation of the network, the pump, and the reservoir. The software is easy to use; it works in such a way that a person with good basic knowledge of hydraulics, little training on software operation and needed parameters, can easily design a huge water distribution network. The software is characterized by the precision of design, operation, and control. Using this method, it is easy to design a complicated network in a noticeably short time. The designed network area has been chosen to be in the northern rural district of the Sudan. This locality suffered from water scarcity for quite a long time, which on the other hand helped on the retardation of the surrounding villages. The water supply project of this area is considered to be an important one, especially after the installation of the new petrol refinery, and the new duty free zone. Literature Review
Water plays a great role in the development of life and humanity. The individuals’ daily needs show the importance of water purification and distribution, as it has a good effect on those who use it. On the other hand there is a great negative effect for those who use unclean water that is reflected in one’s health, attitude and performance. The problem that faces the Sudan is water transportation and distribution, despite its richness in water resources. There are over 60% of the inhabitants who use unsafe water, and 80% of known diseases come as a result of unsafe water usage. Many women and children spend most of their day in bringing or selling water for their families. Only 3% of the population has access to wholesome tap water in the country. These annoying data hint the tragedy that is faced by the local inhabitants.
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First published in the Sudan Engineering Society Journal, vol. 47, no. 38, July 2000, pp17 - 27 Faculty of Engineering Sciences, Omdurman Islamic University 101 Faculty of Engineering Sciences, Omdurman Islamic University 102 Faculty of Engineering Sciences, Omdurman Islamic University 103 Environmental Higher Institute, Alexandria, Eygpt 104 Faculty of Engineering Sciences, Omdurman Islamic University 105 Faculty of Engineering Sciences, Omdurman Islamic University 106 Faculty of Engineering Sciences, Omdurman Islamic University 100
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The traditional methods of designing distribution networks that have been used all the way in the past are time consuming methods, and the expenses in executing the project are usually more expensive due to trial and error methods that are used in such networks. The water supply procedure of a certain area passes through different stages that include collection, treatment, storage, and distribution (see figure 1). The treatment of water must fulfill prevailing guidelines, and standards. Figure 1 Water treatment & distribdiution Source
Treatment
Storage
Distribution
Transportation
Figure 2 Water distribution pattern Secondary main pipeline
Individual s’
Distribution pipeline
bl
Design of water distribution network: Network design is calculated by any of the following methods: a) Hardy-cross method: this method calculates looped networks and it depends on the two basic laws of Kirchoff. The algebraic summation for inflows and outflows is equals to zero. The algebraic summation of head loss in one loop is equals to zero n n ∑ Qi = 0 ∑ ∆Mj= 0 i=1 j=1
Where: Q = flow of water (m³/s), (variable, i, values from 1 to n). ∆M = difference in head loss (m) There are two ways in which network iteration and correction is carried out: Flow equilibrium method:
δH
=
n 2 ∑ q j j =1 ⎛
n ⎜⎜ 1 ∑ ⎜ ⎜ R * ∆h j = 1 ⎜⎝ j j
(1)
⎞ ⎟ ⎟ ⎟ ⎟ ⎟ ⎠
Head equilibrium method:
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δql =
n ∑ dm j j =1 ⎛
n ⎜⎜ ∆h j 2 ∑ ⎜ ⎜ q j = 1 ⎜⎝ j
(2)
⎞ ⎟ ⎟ ⎟ ⎟ ⎟ ⎠
Nodes: demand, ground level and center coordinate (at least one) must be known to the designer. Likewise, pipe’s length, diameter, roughness, and secondary loss factor must be known. b) Linear theory: The development that has occurred on computers lately limited the use of traditional methods of design. This theory depends on the swift mathematical transformation, iteration, error handling and correctness that the computer provides. The method has been invented by Mcllory in 1949 and modified it until 1972. In designing, the following must be fulfilled: Reservoirs are designed as nodes. Pumps are designed as pipes with flows. Valves are designed as minor loss factors. As a result of the technological development, a reliable designing software package (WESNET) has been brought to existence. WESNET is a new PC-based software package; it is fully interactive, and especially designed for the operational management of real supply and distribution systems. WESNET program is used for: Operational Management of existing water supply systems, Design and analysis of existing & /or future water supply systems, Analysis of the system’s actual operation, Verification of current control policy, Optimizing pump scheduling, Selection of post-chlorinating sites, Selection of the most favorable electricity tariff, Analysis and control of data collected by telemetry, Planning and design of new facilities, Design of enlargements and reconstruction of the system, Design of a new control/telemetry system, and Training of new operators Design Area: (Arrif Ash’shamali Province) The design area lies in Arrif Ash’shamali of Khartoum State which starts from Algaily town that is located about 54 km North of Khartoum and it is connected to Khartoum by an asphalt road until the borders of Khartoum State with River Nile State (Willayat Nahr Alnil). (See map). The population of Algaily town and the surrounding villages is estimated to be about 54000 inhabitants {7}. The main water supply sources are: Algaily Town: three wells were drilled inside the town, only two are in operation, recently two more wells were drilled east of the village at Elnia well field.
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Water supply for the village: Elnia, AbuTelieh, and army forces camp to the south east of Algaily town. (See map). All water sources for the above villages are situated at Elnia well field. The water supply for Algaily town and the surrounding villages was considered according to an agreement signed between The Non Nile Water Resources & The Khartoum Company for constructing and housing {7}. The objectives of the hydrogeophysical studies were to: Evaluate the water resources of the study area, Determine the water demand for the population of the area for the coming 15 years, where a growth rate of population of 3% was considered, Conclude specific recommendations for the water supply demand with respect to the findings of the study. The hydrogeophysical studies indicated the following {7}: An Aquifer of dimension 1.3 x 3 km was defined. All wells drilled at Elnia well field are discharging water from this aquifer. The Aquifer test with it’s limitation to the existing wells revealed that there is quick recovery and there was no effect on the observation wells during the pumping with discharge Q = 62 m³/hr). The water at Elnia well field is of acceptable quality, TDS not exceeding 320 ppm, whereas the water quality at Algaily town is also very good and a maximum 598 ppm is recorded. Analysis showed the increase of ions of (SO4 & Na) which is attributed to the irrigation return otherwise all water are of good quality according to the WHO guidelines & Sudanese water quality standards. Water demand of the study area is estimated, with 80L/c/d for the population of the area, which was considered to be 54,000 inhabitants & 83,000 animals, to be 5300m³/d. The discharge of the existing wells with the design rate of discharge and with hours of operation adopted now is estimated to be 2500m³/d for Elnia well field. If the existing wells in Elnia field all work with 10 hr/day with the same current discharge, a total of 3650m³/day can be obtained; there will be water demand deficit of 1650m³/day. To support the existing water wells it is recommended to drill three wells to the west of the railway line. A system of operation can be put forward when the well field wells are completed. The groundwater at storage with annual recharge exceeding the discharge of Elnia wells field against the demand is quite sufficient for the current and future demand of the area. Design Methodology
Previously for the design of the water supply network of Arrif Ash’shamali was evaluated by using WESNET software. The total water demand of the area was 5300m³/day, with an estimated growth rate of 3% for 15 years, estimated by equation (3) for water demand. n Q t = Q i × ⎛⎜1 + a ⎞⎟ = 5300 × (1 + 3 )15 = 5351m 3 / d 100 ⎝ 100 ⎠
(3)
Where: Qt = estimated water demand after 15 years with growth percentage of 3% (m³/day) 286
Qi = present water demand, (m³/day). n = number of years. a = population growth percentage % The same formula was used to calculate the expected water demand for every village individually. Every village consists of four (x, y) coordinates and the demand on each node has been distributed fairly. The lengths of pipes have been calculated by the formula presented in equation (4). Li =
( x 2 − x1) 2 + ( y 2 − y1) 2
(4)
Where L1 = length of the pipe. (x1,x2, y1,y2) = coordinates of two points (nodes). The diameter of the pipe may be computed by using equation (5) Q=Axv and A = π D2 4 Where: Q = discharge, m³/day A = pipe’s cross-sectional area, m² V = velocity (estimated to be 0.6 m/s) D = diameter of the pipe, m (Every unit will be in the appropriate form by the use of the Unit Conversion System of the software). The ground level of the area is almost flat according to the topographic survey that has been made previously. (b) The software is now ready for feed-in of the information, in which designing, analysis, iteration, and correction will take place. In designing, three different models of water supply networks were made, and saved in WESNET directory. Afterwards the software listed the main activities that will be used by the user. The main activities of the software include: Model Building and Update: this activity contains a list of options for input data to build the model. The ground level, the reservoir, nodes coordinates, working pressure, head loss, friction coefficient, and node’s water demand where among the basic information that is needed to build up the model, as well as the adequate information of the pump station. From the information available the node’s name, elevation, and the vertical and horizontal coordinates were entered. Leakage was taken 20%; the working pressure 12 m as it is a rural area. Then information about the pipes followed this procedure, a friction factor for the pipe to be 120. These information were put in the three designs bearing in mind the slight changes that have been made in the connections that will make the difference between each model. The reservoir’s level, coordinates, and shape were put as the software allows division of the reservoir’s depth into five units gradually with each volume of water respectively, by this method; the shape of the reservoir will be determined. Then the pumps were connected according to its demand (m³/day), pumping pressure (m), and rotation
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velocity (rpm). Two pumps were chosen to be connected to the network with the specifications mentioned above bearing in mind the power (w), and the efficiency of the pumps used. Demand Diagram, this is to obtain a graphic preview of the consumption on the network. This option allows filling the Peak Factor tables. The Peak Factor is obtained by dividing the year, month, week, or day into equal segments, then dividing the total demand of the node between them equally. Then results were compared with the actual consumption of the node; afterwards a factor to match the difference between the theoretical and actual consumption. The peak factors for the three models are the same. These factors consider the yearly, monthly, weekly, and daily consumption of the network. From the results for the peak factors, the software calculated the average consumption of the network to be 327.1m³/hr Control & Operation: The network is created using the Model Building activity described above. The result is a mathematical model of the system, suitable for simulation of many different normal, emergency and/or catastrophic situations, which can occur, in real life. Each situation must start from a known Initial State and must define a control policy: how you run the file facilities (pumping station, control valves, zone valves, etc.,). This also includes eventual trade-off: transfer of water to and from the system, excessive demands (such as fire extinguishing) and correction to demand (factoring) for a single run. All this data define the state of the system. One of the most important options that the software supports is the Run Network Model. These options guarantee a flood of information about the network at any moment; this includes the pressure inside the pipes and the flow velocity, as well as the quantity of the flowing water. This is the option where the iteration procedure takes place, some errors may appear in the design, but it is very easy to correct. (c) The first design we introduced a main pipeline 150 mm in diameter supplying the Branched connection of the villages with water by pipes of diameter 100 mm (see figure 4). The second design consists of a main pipeline that goes until the middle of the network only, then it is connected by a combined connection, with diameter of the pipes that vary from 100 mm to 250 mm (see figure 5). The third connection is a connection without a main pipeline. It consists of a branched and combined connection ideals for rural areas, diameter in this model are from 100 mm to 250 mm (see figure 6).
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(d) Through use of program activities, information is yielded: 1. WESNET Net Graph, 2. WESNET Pump Station Information (flow L/s), head (m), speed (rpm), Number of Stages, power (kW), efficiency), 3. WESNET Demand Category Graph (total demand), 4. WESNET Demand Category Graph (demand factor), 5. WESNET Net Graph in details (node: pressure, reservoir: depth, pipe: flow, flows (L/s), 6. WESNET reservoir (time versus outflow) Graph, 7. WESNET System Flows (demand, source pumping, reservoir volume, boosting, raw pumping), 8. WESNET System Flows II (total demand, consumption, transfer out, transfer in, expected demand, losses), 9. WESNET Snap Shot for Links Pipes Information (length, type, flow,
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diameter, friction coefficient, head loss, velocity), 10. WESNET Active Pump Station Summary (energy, pumping, consumption, energy cost, loss, max. power). … and many more valuable information about the network Results and Discussions
The software gave full account of the network. The tables, graphs, and the net graphs have been revised and checked for precision of functioning. The three models are now ready to function, each with its characterized design. To choose the best model, a comparison between all three models had to be done, with concentration on the economical factor, as well as the future network’s extension and maintenance. Economical feasibility: PVC (polyvinyl chloride) pipes were used in all the three models according to its properties that suit the country, as well as its accessibility, and its low price. The prices of pipes with different diameters that have been used in the models were as shown in table 1. Table 1 Cost of PVC pipes Diameter of pipe (mm) 100 150 200 250 300
Cost of pipe per metre (SD) 183 375 658 1008 1375
The price of energy as given by The National Electricity Cooperation was 1.5 Sudanese Dinars SD for kWh/m³ * The primary cost of the First Model (material, energy costs) is as presented in table 2: Table 2 Cost of PVC pipes for the first model. Diameter (mm) Total length (m) Cost (SD) 100 148,282 27,185,033 150 33,600 12,600,000 200 0 0
Total pipe’s cost is 39,785,033 SD WESNET active pump station activity will calculate the energy consumption, and according to equation 6 the energy cost may be calculated. C = Se x Dav x Y x M x N
(6)
C = 0.35 x 90.1 x 365 x 15 x 1.5 = 258,981 SD Where C = total cost of energy, Se = specific energy consumption,
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Dav = average demand, Y = number of days in a year = 365, M = energy cost every kWh/m³ N = number of years = 15 years. Therefore the total cost for the first model is estimated to be 40,044,014 SD * The primary cost for the Second Model is as shown on table 3 Table 3 Cost of pipes for the second model Diameter (mm) Length (m) 100 82310 150 13500 200 32840 250 25650 300 1212
Cost (SD) 15,090,167 5,062,500 21,619,667 25,863,750 1,666,500
The total cost of energy is 0.282 x 90.1 x 365 x 15 x 1.5 = 208,665. The total cost for the second model is estimated to be 69,511,249 SD. * Primary costs of the third model is as shown in table 4 Table 4 Cost of pipes for the third model Diameter (mm) Length (m) 100 95413 150 31973 200 28840 250 9710
Cost (SD) 17,492,750 11,989,875 18,986,333 9,790,917
The total cost of energy is 0.438 x 90.1 x 365 x 15 x 1.5 = 324,096 SD. The total cost for the 3rd model is estimated to be 58,583,971 SD. Network’s future, maintenance and extension: The first model is designed to meet future’s needs of the area. The main pipeline is introduced here along the whole network; there are branched connections from the main pipeline that supply the villages with water. As the largest diameter is the main pipeline it is very easy to maintain future extension on the network as well as regular maintenance. See figure (4). The second model has a main pipeline that passes until the middle of the network, followed by combined connections to ensure water flow to whole system all the time, different diameters can be seen in this model, will induce losses in the network. Some part of the network can be extended, and the system can afford regular maintenance. See figure (5). The last model was designed with the ideal connection that is used for rural areas. It consists of combined connections starting from large diameters and the diameters are decreasing along the network. Very remote chances here of extension in the future, but maintenance could be done regularly. See figure (6).
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Conclusions and Recommendations
From the work carried out the following conclusions and recommendation emerged: The first model is the most appropriate one, it is recommended for execution as it is the cheapest, and supports modification, extension, and maintenance. Water will be supplied for the villagers for multiple purposes continuously. The network is characterized by precision of functioning. Drilling of other wells is recommended due to the development of the area, a large duty free zone is expected to be executed there as well as the petrol refinery and its supplements. WESNET proved to be a powerful software, as such, it is strongly recommended to train engineers and technicians to use its capabilities in design, analysis, and operation. It is also advisable to buy new versions of the software to meet the world up-to-date technology. Acknowledgements
The authors acknowledge help received while conducting this work from the sponsor of the project Assalaam for Housing and Construction Company, and Omdurman Islamic University, Military Surveying Department, Arrif Ash’shamali Locality Council, and The Non Nile Water Resources Department & Underground Water Researches. References
1. Ibrahim, A.S. Altahir, F.G. Faris, N.B. Mohammed, Final year project thesis, Civil Engineering Department Collage of Engineering Science, Omdurman Islamic University, 1997 2. M.S. Aladawi “Engineering Methods of Water Planning and Sanitation”, Dar Alratib 1988. 3. Renaldig-Gayells “Hydraulics and Fluid Mechanics” International Home for Publishing and Distribution 1992. 4. Trifunovic “Water Supply and Distribution” Holland 1994. 5. Nvazirani-S.P. Chandole, Water Supply & Sanitary Engineering. 6. WESNET User Guide, version 5, third edition, Wessex Water B.L.C Poole, Dorset 1993. 7. E.A. Adam, M.K. Salih, R. Eltereifi, and M.M.A/Magid, Report on Elgaily Town Water Supply, Khartoum, February 1998. (By agreement with NWRDGR, and The Khartoum Company for Housing and Construction).
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Development of data-base program for Management of Water Supply Systems107 By: Dr. Ahmed Mohammed Tahir Mohammed108 and Prof., Dr. Isam Mohammed Abdel Magid109,
Abstract Suitable areas in the field of water supply system that are requiring a database to be developed have been selected under priority basis. A database named WelldataBaseSudan has been developed and linked to the web application developed within this research. Web application with title WWW.WATERDATA.ORG have been developed and hosted on the remote server of Discount.Com Company at USA, which by now running in the Internet 24 hours a day, 7 days a week the whole year. This dynamic web application was developed utilizing recent state-of-art technologies. Where important information related to water supply systems in Sudan have been published in this web, also included abstracts of valuable papers related to domestic water supply conference that held at Khartoum on 21 to 22 of October 2002. In addition, included abstracts of very important papers that were prepared on conference of Sediment Transport and Nile Watershed Management that held at Khartoum on November 2001. Noting that, this later subject is a hot issue that is getting more attention from irrigation ministries of Sudan, Egypt and Ethiopia and remaining riparian countries, and the UNESCO Chair in Water Resources of Omdurman Islamic University. Through work in this research, recent database languages, programs, software, tools, have been linked together, and resulted in a newly established scalable database driven web application, with approximately no cost and ready for buildability for future clients. The research, set strong infrastructure, and gave a very good example, into how the recent revolution in Information Technology has been utilized successfully in management of water supply systems, and it can be considered as a good basis from which researchers can benefit. Introduction: Fresh water is a finite and vulnerable resource essential to sustain life, development and the environment. The water development and management should be based on a participatory approach, involving users planners and policy makers. Urban populations are growing as never before and this level of urbanization is presenting profound challenges to urban water management 7 (Global Water, 2000). And in many regional and national conferences it has been concluded that in order to improve domestic rural and urban water supplies, data collection, processing, analysis, retrieval comprising surface water and ground water sources with the use of databases in desktop environment, client server environment, the World Wide Web (Internet) In integration with AutoCAD and Geographical Information systems should be intensified {18}. 107
Industrial Research J., Vol. 5 No (1), June 2007, pp. 81 -110
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Qatar General Electricity & Water Corporation (Kahramaa), Doha, Qatar 109 Industrial Research & Consultancy Centre (IRCC), P. O. Box 268, Khartoum, Sudan
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The work prepared here is a contribution towards filling the gab in the field of managing water supply systems by utilizing databases, web applications and software. It compromises of three {3} main parts, the first part, covered literature review and site visits in field of water supply systems {2}, second part addressed the topic of database development {3,8,9,10, 20} and related languages & software third part which’s most important and exciting part, is the development and utilization of web applications in management of water supply systems. This paper concentrated on this third part {5, 8, 12, 14, 15, 21, and 22}.
Research Objectives Development of a scalable database driven web application, by linking programs, databases, and information related to water supply systems, and water resources utilizing state-of-art tools and technologies with optimum cost. Contribution to improvement of water supply levels in both quantity & quality. To identify operation & management of a number of selected water supply systems and present water related institutes, such practice shall help in better understanding of problems facing the water sector and leads to proper practical solutions. To spread and strengthen the knowledge in the field of water resources and to make possible related staff to share ideas, make their valuable publications available to a wider range of interested staff, professionals, scientists and students. Development & introduction of web application shall contribute to improvement and encourage research environment in the field of water resources. Development of such web application shall assist and pave the road to development of specific similar web applications.
First Part: Literature Review and Site Visits Study, of selected water supply systems, site visits, interviews, literature review and data collection starting from the water source, and the distribution system, as well visits to related research centers and water institutes. The literature review covered study of water supply systems in general, selected water supply systems mainly in Sudan {16, 18, 19}. In addition some of water supply databases that have been developed internationally and in Sudan {3}.
Databases A database is a collection of all Tables and other objects such as forms and reports that are used to manage Data. A database is a complex object for storing structured information, which are organized and stored in a way that allows its quick and efficient retrieval .The information is broken into Tables. Microsoft (MS) Access Database: Since its original introduction in 1992, (MS) has sold more than 120 million copies within MS office; MS Access is a relational database that allows linking related information easily {9}. Nearly all-modern database management systems store and handle information using the relational database management model. The term relational stems from the fact
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that each record in the database contains information related to a single subject and only that subject. Selected Water Supply Databases: Khartoum Ground Water and Wadi’s Corporation Database: Initially, a database to manage, ground wells information, have been started in 1983, and then continued and completed in 1992 in co-ordination between Sudan and the Netherlands Governments. Its main function is to store, retrieve and manage information pertaining to ground water sources in Sudan (Wells), as well assists in setting out necessary strategies. Sudan National Water Corporation Data Base: The archive of the National Water Corporation (NWC), previously Urban Water Corporation, has been established, since 1960, in coordination with the Unicif (Mohmed Kheir Saleh, verbal discussion). The present NWC is responsible for planning, monitoring, and managing of water supply systems in Sudan, for both rural and urban areas. Its function is to provide technical consultations and support. The existing database, that is established approximately in 1997, in co-ordination with the United Nations Children Fund (UNICF), have been developed with Dbase 5.5. ( Foud Yassa, verbal Discussion ),.This software is running into a client server environment network using Windows NT for the network, and Windows 95 for the client. The database here, noticed to be well developed, organized and managed. And in addition to its main function of managing the data pertaining to the water supply (Ground + surface), it has been used as a training centre WellDataBaseSudan (MS Access Database) Development: From literature review stated above, suitable areas that are requiring a database to be developed have been selected on priority basis, and a database with title WelldataBaseSudan, developed in MS Access and linked with the web application that developed in this research with title: www.waterdata.org. The WellDataBaseSudan covered information related to Wells, Voluntary Agencies acting at Sudan in the field of water supply, Wells Water Quality, Sudan Western Provinces water supply information. Where both the database and the application have been hosted at DISCOUNT.NET Service provider ( hosting company) as shown in Figure ( 1, 3 ). This database which is accessible at WWW.WaterData.Org web site, 24 hours a day, 7 days a week, the whole year is comprised of 5 separate tables, as shown in Figure (1, 4)
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Figure(1, 3) Discount.Com Hosting Company (Service Provider) FTP server. The database developed here using MS Access and it is straightforward, just necessary steps to design, develop tables with required relationships followed as shown in figure (1, 4) and Figure (1,5).
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Figure(1, 4) Stating WelldataBaseSudan database with its 6 No. tables: agency, Chemical, TblProvince, Welldata, Welldata1, wetsprovinces.
Figure(1,5) Stating tables in WellDataBaseSudan database, together with correspond. fields in each table. And Relationship between two of the tables. 300
The Web Applications, Introduction A combination of most advantage tools have been reviewed, this included, Active Server Pages Dot Net (ASP.NET) language that used to develop the web application. FrontPage 2002 to develop static part of the web. Axtive-X Data Objects.Net (ADO.NET) to access the database, Notepad editor utilized to write the ASP.NET code, where all these softwares integrated in DotNet Framework. As it will be seen later, ASP.NET is a combination of HTML, Visual Basic.Net and ADO.NET classes. In addition Adobe Photoshop software used in preparation of required images and pictures also considered. It can be said that all tools stated above are Microsoft (MS) tools with exception of Adobe Photoshop. The candidate in the research concentrated on MS tools, because of their flexibility, popularity, availability, i.e most of MS softwares either freely downloadable through the Internet or free trial versions that accompanying related books are obtainable for limited period of time. In this work, brief historical background about the Internet has been made (AppendixA), the famous Internet Information Services (IIS) software that used to host the web application discussed in details. Also, it has been shown that how the web application thus developed, tested on the local computer through Internet Information Services (IIS), as well how hosted on the remote service provider company’s server. Furthermore the subjects that have been included in the web, i.e the web page’s contents highlighted: As it is clear from research title: Utilization of Databases and the Web in management of water supply systems, the web application is inclined and concentrated on database driven web pages, as well static web pages, on the field of water resources and water supply systems. And in order to make the paper more useful and meaningful, abstracts of all papers that presented on the conference of domestic water supply, that held at Khartoum, Sudan on 21-22, October, 2002 were included. These papers nearly covered all provinces of Sudan.
Internet Background Undoubtedly it is clear that the Internet is becoming a major part of the way that the world works. With each passing day, the Internet is having more and more of an impact on the daily lives of countless people. The amount of information available to anyone, anywhere, at any time is overwhelming, and this trend is only going to continue to grow in the future. Originally, computer networking started by USA Department Of Defense (DoD), to hook up computers at different military sites. {11, 12} Web Applications Development Tools Active Server Pages (ASP): ASP is one of the most popular languages for building scalable, interactive web sites. Several of the highest traffic web sites on the internet employ Active Server Pages.
Active Server Pages.Net (ASP.NET): ASP.NET, is latest version of Active Server Pages, is Microsoft ‘s Technology for building dynamic, database-driven Web sites. It is one of the most popular languages for building scalable, interactive web sites.
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ASP.NET, is more robust and contains many performance enhancements over original ASP (21), as well ASP.Net is enhanced by very large No. of components, if for example in case of classical ASP access has been made to 5 (five) classes, in contrast ASP.NET, provides with access to over 3,400 classes!. Several of the highest traffic Web sites on the Internet employs Active Sever Pages. Examples include Dell Online, Barnes and Noble, and the Microsoft site itself. It has been adopted as one of the main tools, used for development of our research web site. In this research candidate started developing with Visual Studio.Net, since original software is relatively expensive, approximately 1,800$, a 60 days trial edition has been used. Although good progress made, however the period expired before completing planned works. As a result the candidate moved to an excellent alternative i.e Asp.Net by direct coding which’s available and free downloadable through the Internet coming within the .Net Framework software. Although a pit difficult than using Visual Studio.Net, however it did the job satisfactory and more. This .NET FRAMEWORK shall be explained in coming sections. Macromedia-Dreamweaver (www.macromedia.com/software/dreamweaver): Is available for both the Macintosh and the PC. It offers benefits such as customizable features and automated production. Adobe Photoshop/ ImageReady: Adobe is the world leader in graphics and imaging software. When designers started being asked to create graphics for the web, Photoshop was used mostly because it was what every one had. Photoshop is a bitmap program, best known for image manipulation, using layers to allow for virtually limitless flexibility in design.{22}. It has been adopted as one of the tools, used for development of our research web site. A Text Editor Alternatively, web pages can be created with any text editor, such as Notepad, by typing in the HTML tags, saving the file, and then opening it in a web browser. This product can save and open web file format {22}. It has been adopted as one of the tools, used for development of our research web site. Extensible Markup language (XML) While HTML was created for primary purpose of marking up and linking text documents, the Extensible Markup language (XML) is specifically designed with the purpose of communicating page content {22}. XML is a markup language for document containing structured information, such as words, pictures, etc... It draws relationships between page content, it does not format or style content to the browser, in other words it does not say (make this bold and make that red). Therefore the formatting is left to cascading style sheets. Microsoft Data Access Components (MDAC): Tools for accessing databases are very important. This is because they are the links between the web application on one hand and the database on the other hand. Microsoft has developed a tool named Microsoft Data Access Components (MDAC) taking care of such job. Web Site Application Development and Necessary Code:
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Figure (1,1) shows 5 controls: Home, Unesco, Data, Supply, Friend. Details of contented pages. The complete web application www.waterdata.org can be browsed through using user name & password as Isam, here only subjects related to design shall be briefed. All these controls except for the Data control, containing ordinary pages that are developed using plain simple FrontPage 2002 language, with 2 pages linked to Home, 2 pages linked to Unesco, 7 pages linked to Supply and 9 linked to Friend. As a result and due to similarity of these pages, developments details in FrontPage and associated code for only one of these pages shall be shown. However, better return back to the Data control, most important one, and then resume, where it contains 5 pages, each of these pages are linked to a database, therefore here both FrontPage and ASP.NET are used. And due to limitation of space, only one of these pages shall be stated in details, that is the water Quality Data page. Here, as first step, the water quality page is developed in FrontPage as shown in Figure (3 , 1) below:
Figure (3, 1) Khartoum Water Quality Data web page is developed in FrontPage 2002. The area is divided into suitable tables and cells. Starting from above the title: Utilization Of Databases & The Web In Management Of Water Supply Systems, is placed in the cell that is colored black as background, and this title that is planned to be sliding and moving between the two ends is developed as follows: first click on Insert (forth item on the top, main menu). Then select Dynamic Effects and marquee, and follow steps provided by dialogue box. Same sliding effects can be developed by
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JavaScript code, however, development of this step is more easier by FrontPage 2002 as explained. Next, in second row, 5 No. of hyperlinked controls are placed, these are achieved by directly typing each control name on suitable rectangle and then linking to the suitable hyperlink by selecting Insert, then Hyperlink and following necessary steps. In first column of third row an image is placed on a rectangle. The image with its required size is prepared in Adobe PhotoShop and stored on a folder named images that usually placed on the root of web site. In next step, corresponding cell where intended to place this image is selected and the right hand mouse is clicked., at once a dialogue box titled cell properties pops up. In the bottom left side text enclosing the following can be noticed: use background picture, select it and refer to proper path of image. Each of the above 10 hyperlinked controls, are referring to a web page that is linked to corresponding control, once any one of these controls is clicked, it will open a new web page. Now since static page already prepared using FrontPage as shown above, next step is to see how ASP.NET code and ActiveX Data Objects (ADO.NET) were used in order to manage, access and presents the out put of necessary database. In chapter 2, page27, it has been shown how to access a database through ASP.NET and ADO.Net tools. Figure (3, 2), shows HTML code corresponding to static page that developed in FrontPage. In Appendix-B, complete code including code to access and manage database through ASP.NET language is shown, where its main features shall be discussed in brief: The overall code consists of 9 pages, 5 out of 9 pages generated automatically by FrontPage, therefore no need to explain, as this code generated automatically when developing the page in MS FrontPage, what you see is what you get tool. In Listing (1.1), ASP.NET code is shown in blue bold, where it has started with the ASP.NET namespace classes that designed to access Microsoft Access database. In first paragraph of this code the IsPostBack property is used with the load event in order to execute the enclosed code only once when a page is first loaded. i.e to initialize necessary variables and controls on a page only the first time the page is loaded, not every time the page is submitted. Therefore, the cmdSelectChem class below shall be ordered (sorted) by the initial “WeLLName” parameter that is given in BinddataGrid together with IsPostBack property. Therefore the data page shall be shown sorted by “WellName” parameter refer to Figure ( 3 ,3 ). Next time the page shall be sorted according to any of selected above underlined hyperlinked column headers, for example if WellNo is selected the page shall be populated and sorted according to Well Number Order, that is to say in this case it starts from 1, 2, 3 and upward. In general sorting can be enabled for all columns or for only particular columns. To enable sorting for all the columns in a DataGrid, required to set the Allowsorting property to true and associate a subroutine with the SortCommand event. In our case only particular columns have been set for sorting, as shown in above code written in red bold color. To achieve sorting on particular columns, the sortexpression property is used as shown in above red color code. First the AutoGenerateColumns property is set to false. And AllowSorting property is set to true. Then in the code related to each column the sortexpression property is introduced. The value of this property will be assigned to corresponding field name in the database, by which the Grid shall be sorted.
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Once the hyperlinked title is selected the dgrdChemical_SortCommand , retrieves the name of column selected, for example WellNo and passes it to BindDataGrid(strSortField As String) Subroutine. The actual sorting is performed in the BindDataGrid subroutine. The records are sorted with the help of a SQL order by clause, and populated as shown in Figure (3, 3).
Figure (3 , 2) When the HTML button at the lower left corner is clicked; corresponding HTML code is generated as shown. Detailed full code is shown in Appendix-
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Figure (3, 3) Presnts how the Water Quality data are populated to grid. Note that in first time it is sorted by the Wellname that is included within IsPostBack property and explained in above code. Next time the page shall be sorted according to any of above underlined hyperlinked column headers. Development Of The Sudan Wells Data Page: Development of this page is nearly similar to previous page, as shown in Figure Figure (3, 4) presenting the Login page, where the user has to submit a valid user name and a password in order to access the web application.
Uploading web page files to the hosting server Once, development of the Web site completed and tested in the local Internet Information Services (IIS) in local computer. Then the second step is to find out a suitable hosting company in order to start and host the web site. To find a suitable hosting company through the internet: Actually in the Internet there are hundreds of Web Hosting Companies. Regarding hosting prices, it can be said that the prices are reasonable & difference among companies is relatively small. .That means, to find a company that meets and supports one’s web site’s requirements is not easy as it seems, actually it needs a considerable effort. 306
In brief, at last a suitable Hosting Company titled WWW.DISCOUNTASP.NET selected. Most important hosting features provided by this company are: It supports ASP.NET language, it supports Windows 2000 hosting, new domains can be registered through this company, or domains that are existing elsewhere can be transferred to this hosting company for free. It provides minimum of 75 MB disc space, 2 GB/ month data transfer, web based E-Mail. FrontPage Support, it supports MS Access database, it supports MS SQL Server 2000 database, it supports .Net Framework, it Supports Microsoft Data Access Components (MDAC) including ADO.NET tools. Hosting prices and domain name: Domain Registration is 15$ for one year. Hosting fees per month are about 10$.
Figure (3, 5) What Discount companies are saying about them-selves.
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Figure (3, 6) stating the FTP server space that allocated by the DISCOUNTASP hosting company to the Candidate. All ASP.NET files, WellDatabaseSudan MS Access database file, the Web.config file, the bin directory, the images directory, i.e all files that are necessary to develop the web site are placed on this server. Discussions and Conclusions: Through work in this research the candidate has been identified to operation and management of a number of water supply systems in Sudan, this included Khartoum Capital of Sudan, and Kassala Town, and covered overall system starting from water sources, water stations and water distribution network. In this stage, some of main problems facing water supply system have been identified and as well areas requiring a database to be developed considered under priority basis, as well importance of developing a web application and utilizing it in management of water resources, has been realized. A database developed with title WellDataBaseSudan, using MS Access and linked to the web application titled WWW.WATERDATA.ORG that is developed during the course of this research. This database covered information related to Wells, Khartoum Wells water quality, voluntary agencies acting at Sudan in the field of water supply at present, Sudan western provinces water supply information. The database completed and hosted together with accompanying web application on the Server of Discount.Com companies at USA, and by now working successfully and interested staff can access it at any time. The web application is utilizing state-of-art tools including Active Server Pages Dot Net (ASP.NET), MS FrontPage 2002, Active-X Data Objects.Net (ADO.Net), Notepad, HTML, XML, Visual Basic.Net, Adobe PhotoShop in addition to MS 308
Access database. The beauty with these powerful tools, that they are easily obtainable: either can be freely downloadable through the Internet, or free academic version licensee that accompanying textbooks are available for limited period of time. Therefore interested researchers and students can utilize same tools. The web application comprised of two parts the development part, which’s explained above, and web contents part. The contents parts included three subjects: databases related to domestic water supply systems in Sudan, abstracts of papers of a very important conference that held at Khartoum on 21-22, October, 2002, under title: domestic water supply crises and possible solutions in Sudan. As well the web included abstracts of papers related to sediment transport and watershed management in Nile Basin Countries, related to the conference held at Khartoum, on November, 2001. Such papers shall enrich the web application, and as a result the site is expected to meet its targeted goals: that is to spread and strengthen the knowledge in the filed of water resources and to make possible related staff to share ideas, and make their publications available to a wider range of interested staff and students. The importance of documentation have been well understood, therefore all stages of database and application developments have been documented. As well a comprehensive user manual developed in order the web application to be operated easily.
Recommendations For Future Study Development of database driven web applications, for specific needs of FRIEND/NILE Project and National Water Corporation in Sudan: The plan of FRIEND/NILE Project Under UNESCO CHAIR in Water Resources Of Omdurman Islamic University is to develop a Web application to assist in sharing information among riparian countries, specially when their on going research works in fields of Sediment Transport and Watershed Management are completed on 2005, these are expected to yield into considerable amount of data, which require to be properly secured, managed and published through the web, for use by wider audience. The web application www.waterdata.org that is developed in this research is an excellent example, and same function can be achieved by further upgrading this web application to meet specific goals of Friend/Nile Project. As well the Sudan National Water Corporation, has already prepared an excellent database in desktop & client server environment, its function is to store & retrieve information related to water supply facilities in both rural areas & urban areas of Sudan including water yards, bore hole information, hand pumps, water ponds (hafiers), dug wells, and urban water stations. It is further recommended to develop similar web application, so that concerned staff at the different Provinces of Sudan can be able to retrieve and as an additional option to add and update information related to their specific locality remotely through the Internet. Water Supply For Horticulture & Environment: The practice of horticultural farms has been witnessed around many Towns of Sudan. The, phenomena require attention, because it affects a number of fields, among which are: domestic water supply, food security, environment & landscaping,
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housing, Population distribution, animal grazing, proper land use and productivity, new job chances, recreation & tourism, etc…. Such Towns have been attractive and given more value, because of many reasons, among which is most important is proper utilization of water. Appendix-A References ﺍﻟﻘﺭﺁﻥ ﺍﻟﻜﺭﻴﻡ.1 ﺍﻷﺴﺘﺎﺫ ﺍﻟﺩﻜﺘﻭﺭ ﻋﺼﺎﻡ ﻤﺤﻤﺩ ﻋﺒﺩ ﺍﻟﻤﺎﺠﺩ ﺃﺤﻤﺩ – ﺍﻟﻬﻨﺩﺴﺔ ﺍﻟﺒﻴﺌﻴﺔ – ﺠﺎﻤﻌﺔ ﺍﻟﺴﻠﻁﺎﻥ ﻗﺎﺒﻭﺱ –ﻜﻠﻴﺔ.2 – ﺘﻠﻔﺎﻜﺱ184248 ﺍﻷﺭﺩﻥ – ﺹ ﺏ11118 ﺩﺍﺭ ﺍﻟﻤﺴﺘﻘﺒل ﻟﻠﻨﺸﺭ ﻭﺍﻟﺘﻭﺯﻴﻊ – ﻋﻤﺎﻥ،ﺍﻟﻬﻨﺩﺴﺔ 658263 ﻡ – ﺩﻟﻴل ﺍﺴﺘﺨﺩﺍﻡ ﻨﻅﺎﻡ ﺒﻨﻙ ﺍﻟﻤﻌﻠﻭﻤﺎﺕ ﺍﻟﻤﺎﺌﻴﺔ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻲ ﺍﻟﺠﻤﺎﻫﻴﺭﻴﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﻠﻴﺒﻴﺔ1999 ، ﺃﻜﺴﺎﺩ.3 ﺃﻜﺴﺎﺩ-)ﺍﻟﻤﺭﻜﺯ ﺍﻟﻌﺭﺒﻲ ﻟﺩﺭﺍﺴﺎﺕ ﺍﻟﻤﻨﺎﻁﻕ ﺍﻟﺠﺎﻓﺔ ﻭﺍﻷﺭﺍﻀﻲ ﺍﻟﻘﺎﺤﻠﺔ ﺩﻤﺸﻕ.ﺍﻟﺸﻌﺒﻴﺔ ﺍﻻﺸﺘﺭﺍﻜﻴﺔ ﺍﻟﻌﻅﻤﻰ
.124 ﺕ/ﻡ.– ﺩ
ﺘﺤﺕ ﺭﻋﺎﻴﺔ-ﻗﺎﻋﺔ ﺍﻟﺘﻨﻤﻴﺔ ﺍﻟﺯﺭﺍﻋﻴﺔ ﺍﻟﺘﺎﺒﻊ ﻟﻠﻤﻨﻅﻤﺔ ﺍﻟﻌﺭﺒﻴﺔ- ﻤﺅﺘﻤﺭ ﻤﻴﺎﻩ ﺍﻟﺸﺭﺏ ﺍﻟﻤﺨﺎﻁﺭ ﻭﺍﻟﺤﻠﻭل.4
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ReadChemicalDataBase.aspx | Jan; 2003, Ph.D., Research, WaterData, Inc., Doha, Qatar, Khartoum, Sudan. Contact Us |
