wastewater reuse in agriculture has been set up to regulate the treatment and the distribution of irrigation with reclaimed water. This paper attempts to present ...
IRRIGATION WITH RECLAIMED MUNICIPAL WASTEWATER IN SOUTHERN MEDITERRANEAN AND MIDDLE EAST COUNTRIES
Akissa Bahri National Institute for Research on Agricultural Engineering, Water, and Forestry, B.P. 10, Ariana 2080, Tunisia
ABSTRACT Most of the countries of the Southern Mediterranean and Middle East region are arid to semiarid and are facing increasingly more serious water shortage problems. In order to overcome these constraints, wastewater is being reused at different extents. There are, however, important differences in approaches to wastewater reuse policy in the Southern Mediterranean and Middle East countries. A large range of situations may be found depending on the socioeconomic, institutional, and technological conditions. Differences between countries occur in environmental and public health policies. They also occur in existing wastewater collection, treatment and disposal facilities, in human resources, in equipment and material resources, and in financial resources. Five groups of countries may be distinguished. A first group where often untreated wastewater is discharged in the environment and direct reuse of wastewater is occurring with serious health hazards and environmental problems. In the second group, uncontrolled reuse by farmers is taking place as well as research and pilot programs to study the environmental and health aspects of wastewater reuse applications. In such situations, regulations and standards related to discharge and reuse may be available but often not enforced. A third group where mainly indirect use of treated wastewater is practised. In the fourth group of countries, wastewater reuse has been made an integral part of overall environmental pollution control and water management strategy with planned wastewater treatment and reuse projects. Direct use of treated effluent is then practised to restricted irrigation. In the last group, only tertiary treatment of wastewater is practised and the treated wastewater is used for crop production and landscape irrigation. The availability of capital, in this case, has made this option possible. In the three last groups of countries, the institutional and legal framework of wastewater reuse in agriculture has been set up to regulate the treatment and the distribution of irrigation with reclaimed water. This paper attempts to present different situations and relies on 3 country case studies that illustrate diversity of physical, technical and environmental conditions, institutional setting, implementation approaches, and regulatory aspects.
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IRRIGATION WITH RECLAIMED MUNICIPAL WASTEWATER IN SOUTHERN MEDITERRANEAN AND MIDDLE EAST COUNTRIES
Akissa Bahri National Institute for Research on Agricultural Engineering, Water, and Forestry, B.P. 10, Ariana 2080, Tunisia
INTRODUCTION Most of the countries of the Southern Mediterranean and Middle East region are arid to semiarid and are facing increasingly more serious water shortage problems. In some countries, actual water consumption already exceeds the renewable conventional water resources and it is estimated that no more known water resources can be developed. Some countries of the Middle East and Gulf region have few naturally available fresh water resources and rely mainly on groundwater and desalinated seawater. Problems of water scarcity will intensify because of population growth, rise in living standards, and accelerated urbanization which threaten the water supply in general and agriculture in particular and lead to both an increase in water consumption and pollution of water resources. Continuing increase in demand by the urban sector has led to increased utilization of fresh water for domestic purposes, on the one hand, and production of greater volumes of wastewater, on the other. Agriculture in competition with other sectors will face increasing problems of water quantity and quality considering increasingly limited conventional water resources and growing future requirements and a decrease in the volume of fresh water available for agriculture. Around the cities of the region, competition with other sectors often makes water the main factor that limits agricultural development. Policy makers have then been compelled to develop additional water resources as well as to preserve the existing ones. Reclaiming water is among various measures designed to encourage integrated and efficient management and use of water resources and should therefore be an important component of the national resources policy. When integrated to water resources management, wastewater reuse may be considered as an integral part of the environmental pollution control and water management strategy. It may present benefits to public health, the environment, and economic development. Reuse of reclaimed water may alleviate pollution of water resources and sensitive receiving bodies. It may provide significant additional amounts of water. Reclaimed water may also be considered as a potential source of nutrients in agriculture schemes. Other social and economic benefits may result from such schemes such as employment and products for export markets. It is, however, essential that the development of reuse prevents negative effects on environment and public health since wastewater content in mineral and organic trace substances and pathogens represents a risk for human health. Adequate treatment has therefore to be provided for the intended reuse.
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This paper attempts to present different situations and relies on 3 country case studies, Jordan, Tunisia, and Kuwait, that illustrate diversity of physical, technical and environmental conditions, institutional setting, implementation approaches, and regulatory aspects. THE REUSE CONDITIONS A large range of approaches to wastewater reuse policy may be found depending on the socioeconomic, institutional, and technological conditions. Differences between countries occur in environmental and public health policies. They also occur in existing wastewater collection, treatment and disposal facilities, in human resources, in equipment and material resources, and in financial resources (USEPA, 1992). Many cities in the Southern Mediterranean and Middle East region are still unsewered; when sewers are available, they often discharge untreated effluents in the environment. There is a potential for reuse when water constraints reach critical levels and when pollution may become a threat to water resources and to public health. The need to develop additional water resources becomes then important and collection systems and wastewater treatment plants have therefore been built. However, in several cases, these plants are often not functioning or overloaded and thus discharge effluents not suitable for reuse applications. In some other situations where conditions for reuse are met, reuse policies have been set up and treated effluents are being reused for different purposes. The main applications of reclaimed water reuse in the region are agricultural irrigation, landscape irrigation, and groundwater recharge. Industrial reuse is very seldom practised. Several research and pilot studies have been conducted in the region. The information gained from such studies has allowed the development of treatment and reuse for the specific conditions of the region. The implementation of large-scale reuse schemes has resulted in significant technical and operational experience in reclaimed water reuse. Implementation of wastewater reuse operations is still a big challenge because of the specificities of the reclaimed water market and of the different issues that have to be taken into account. Planning and management of agricultural reuse operations imply institutional, organizational, legal, regulatory, socio-economic, financial, environmental, and technical constraints. Reuse projects are also complex and expensive operations with economic and financial uncertainties, which may be critical: some costs and benefits are difficult to quantify (public health protection, economic development, etc.). A large diversity in planning approaches can therefore be found among the countries of the region and different management structures are set up depending on the type of agency: water-, wastewateragency, coordination body, or other types. The level of treatment and reuse standards varies from country to country. In most of the cases, conventional technology has been adopted for treating wastewater independently of the type of reuse. The general approach adopted up to now is based on producing an effluent in compliance with water quality discharge requirements. Concerning the national regulations, schematically, the bases are either the WHO guidelines (1989) or the California’s Title 22 wastewater reclamation criteria. Countries where reuse is developing on a rational basis, within an organised institutional setting, have elaborated and implemented their own regulations and precise standards. In other countries, it is just referred to health standards. Table 1 summarizes wastewater collection, treatment, and reuse in Jordan, Kuwait, and Tunisia.
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Table 1. Comparison of wastewater collection, treatment, and reuse in Jordan, Kuwait, and Tunisia. Jordan Tunisia Raw wastewater used in No No irrigation Coverage by sewerage Urban areas: 80% Urban areas: 78% systems Total: 55% Total: 40% Total volume of produced 232 Mm3/yr. 240 Mm3/yr. wastewater Total volume of treated 69 Mm3/yr. 140 Mm3/yr. wastewater (8% of irrigation water resources) (7% of irrigation water resources) Reuse as % of total treated 85% 20-30% wastewater Treatment level Secondary Secondary • Agricultural irrigation: 6500 ha Reused treated wastewater: • Agricultural irrigation: 13 300 ha (18.5% of the irrigated area) • Landscape irrigation: 600 ha irrigation, groundwater Total: 7100 ha (2% of the irrigated area) recharge, aquaculture, etc. Research and monitoring • Research and pilot operations in the • Research and pilot operations in the programs field of agricultural reuse field of agricultural reuse and groundwater recharge Planned/unplanned reuse O&M cost recovery Availability of national legislation for treatment, reuse, and discharge
Crop selection
• Mainly unplanned reuse • Partial • Water quality requirements for reuse of treated domestic wastewater for agricultural purposes, groundwater recharge, and aquaculture: Jordanian standards 893/1995. • Water quality discharge requirements: Jordanian regulation 893/1995. • Enforced
• Planned reuse wastewater projects • Partial ($US 0.02/m3) • Decree No. 89-1047 regulating the use of reclaimed water for agricultural purposes and water quality requirements for agricultural reuse: Tunisian standards, NT 106.03/1989. • Water quality discharge requirements: Tunisian standards, NT 106.002/1989. • Strongly enforced 3
Kuwait No Urban areas: 90% 119 Mm3/yr. 103 Mm3/yr. (32% of irrigation water resources) 10% Advanced • Agricultural irrigation • Landscape irrigation Total: 1700 ha (25% of the irrigated area)
• Pilot and demonstrational applied research in the field of SAT, urban greenery sites, use of treated industrial wastewater • Planned reuse wastewater projects • Partial ($US 0.07/m3) • Quality standards for wastewater reuse require tertiary treatment.
• Strongly enforced
CASE STUDIES Unplanned reuse of reclaimed water - Jordan In Jordan, the government's policy in the 1980s was to achieve the provision of improved wastewater collection, conveyance, treatment, disposal, and reuse systems. Therefore, urban sanitation coverage, including piped sewerage, was developed at a fast rate, with 80% of urban areas covered by 1996, i.e. about 55% of the total population (Table 2). Most of the cities of Jordan were then equipped with wastewater treatment plants and it was decided to treat wastewater up to the secondary level and meet the WHO guidelines for the use of treated wastewater for irrigation (Tuffaha, 1996). The different treatment processes are stabilization ponds (88% of the treated effluents), trickling filters, rotating biological contactors, activated sludge, or conventional or extended aeration. Pre-treatment of industrial wastes was also implemented and it has reduced discharges of organic and mineral elements since regulations were issued in 1991. The estimated total wastewater flow discharged to the 14 existing wastewater treatment plants for the year 1996 was 69 million m3/yr (Mm3). This flow is equivalent to 50% of the population of Jordan. Treated wastewater has long been recognised as a valuable resource for use in irrigation (UNDP, et al. 1992) and is considered as an important water resource in the Jordan Water Strategy (1997). The contribution from wastewater for irrigation is expected to grow to over 100 Mm3/yr. by 2005. The major proportion of reclaimed water is discharged to wadis and reaches reservoirs used for irrigation. Most reuse is then indirect. Planned direct use of treated effluent is, actually, limited (2%) but on increase since 1985. In order to encourage reuse, the government made it mandatory to include for all new wastewater treatment projects a fully designed and feasible reuse component. The treated effluent is then mainly reused for agricultural production. The irrigated area is around 13 300 ha of which 13 000 ha located in the Jordan Valley, 150 ha in Aqaba (the stabilization pond effluent of 7500 m3/d. is being used to irrigate palm trees and forests), 50 ha in Ramtha, 40 ha in Madaba, etc. Except the Jordan Valley, the treated effluent is used to irrigate fodder crops, forest and fruit trees. Treated wastewater from Amman has been used for irrigation in the Jordan River Valley (JRV) since the completion of its first activated sludge treatment plant (Ain Ghezal) in 1968. As the springs feeding the Zarqa River have been used to supply the water needs of Amman, the Amman wastewater has partially compensated for the reduction in base flow of that river. The flow of effluent from the stabilization ponds of the Al Samra treatment plant (181 ha, Vol.: 2.8 Mm3, 120 000 m3/d.) is blended with water from the King Talal Reservoir (KTR) and used for unrestricted irrigation downstream in the JRV. The treated effluent provides 15 to 80% of the annual inflow to KTR. Reuse of the effluent from the KTR permits the winter flow in the JRV to grow one winter crop, and contributes to the irrigation of perennial crops. The area irrigated partially or completely by KTR water is, at present, approximately 13 000 ha (18% of the actual irrigated area) of which 75% produces vegetables, 15% cereals and 10% trees. The remained area farms fruit trees or field crops (wheat, barley, berseem, etc.). In the future, there could be potentially about 43 100 ha irrigated with treated effluent if all the water was to be used for irrigation purposes. In the central Jordan Valley, 56% of the farms use drip irrigation (70% efficiency on average), the remainder use surface irrigation methods (76% efficiency on average). The cost of the water is low (15 fils/m3) and not related to the water quality. The Jordan Valley Authority provides free irrigation water to farmers during winter for salt leaching. Farmers can not sell or lease their water rights.
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Table 2. Comparison of reclaimed water quality criteria and standards for irrigation in Jordan, Kuwait, and Tunisia.
Country Wastewater treatment
Type of irrigated crops
Cooked vegetables Jordan
Secondary treatment
Fruit and forestry trees, crops and industrial products
Fodder crops
Tunisia Secondary treatment Kuwait
Advanced treatment
Cereal crops, industrial crops, fodder crops, and trees
Parameter (mg/l) TDS: 2000 SAR: 9 SS: 200 BOD5: 150ξ COD: 500 Nt: 100 Cl2: 0.5 TDS: 2000 SAR: 9 SS: 200 BOD5: 150ξ COD: 500 Nt: 100 TDS: 2000 SAR: 9 SS: 250 BOD5: 250ξ COD: 700 NO3-N: 50 EC: 7000 µS/cm SS: 30 BOD5: 30 COD: 90
Fodder & food crops not eaten raw, forestland
SS: 10 BOD5: 10 COD: 40 Cl2: 1
Food crops eaten raw**
SS: 10 BOD5: 10 COD: 40 Cl2: 1
Microbiological parameters Fecal coliforms Intestinal Amoebae & (MPN/100 ml) nematodes Giardia (eggs/l)* (cysts/l)
1000
