Irrigation With Reclaimed Water In Tunisia And In Middle Eas

　English　　Technical-paper

IRRIGATION WITH RECLAIMED WATER
IN TUNISIA AND IN MIDDLE EASTERN 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 semi-arid 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, water 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. Reclaimed water may provide significant additional amounts of water and contribute to the conservation of fresh water resources. It may be considered as a valuable source of water and nutrients in agriculture schemes. Reuse of reclaimed water may alleviate pollution of water resources and sensitive receiving bodies. It may also contribute to desertification control and desert reclamation. 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.

　　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 water reuse policy may be found depending on the socio-economic, 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 practiced.

　　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 water 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-, wastewater-agency, coordination body, or other types.

　　The level of treatment and reuse standards vary 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. Comparison of wastewater collection, treatment,
and reuse in Jordan, Kuwait, and Tunisia.

Jordan Tunisia Kuwait Raw wastewater used in irrigation No No No Coverage by sewerage systems Urban areas: 66%
Total: 51% Urban areas: 78%
Total: 40% Urban areas: 90% Total volume of produced wastewater 232 Mm3/yr. 240 Mm3/yr. 119 Mm3/yr. Total volume of reclaimed water 72 Mm3/yr.
(13% of irrigation water resources) 140 Mm3/yr.
(7% of irrigation water resources) 103 Mm3/yr.
(32% of irrigation water resources) Reuse as % of total reclaimed water 85% 20-30% 10% Treatment level Secondary Secondary Advanced Reused reclaimed water:
irrigation, groundwater recharge, aquaculture, etc. ·Agricultural irrigation: 10 700 ha (18.5% of the irrigated area) ·Agricultural irrigation: 7100 ha
·Landscape irrigation: 600 ha
Total: 7700 ha (2% of the irrigated area) ·Agricultural irrigation
·Landscape irrigation
Total: 1700 ha (25% of the irrigated area) Research and monitoring programs ·Research and pilot operations in the field of agricultural reuse ·Research and pilot operations in the field of agricultural reuse and groundwater recharge ·Pilot and demonstrational applied research in the field of SAT, urban greenery sites, use of treated industrial wastewater Planned/unplanned reuse ·Mainly unplanned reuse ·Planned water reuse projects ·Planned water reuse projects O&M cost recovery ·Partial ($US 0.02/m3 in Jordan Valley; free in other schemes) ·Partial ($US 0.01/m3) ·Partial ($US 0.07/m3) Availability of national legislation for treatment, reuse, and discharge ·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. ·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. ·Quality standards for water reuse require tertiary treatment. Crop selection ·Enforced in restricted areas ·Strongly enforced ·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 66% of urban areas covered by 2000, i.e. about 51% of the total population (Table 1). 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 reclaimed water for irrigation (Tuffaha, 1996). The different treatment processes are mainly stabilization ponds (83% of the treated effluents), activated sludge, trickling filter or extended aeration plus maturation pond. 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 by the 18 existing wastewater treatment plants for the year 2000 was 72 million m3/yr (Mm3). This flow is equivalent to 51% of the population of Jordan. Reclaimed water 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. It is also planned to shift most of the treatment trains to activated sludge processes.

　　The major proportion of reclaimed water is discharged to wadis and reaches reservoirs used for irrigation and groundwater recharge. Blending and storage of reclaimed water (58.8 Mm3) is provided in King Talal, Wadi Shueib, and Kafrein reservoirs for effluents discharged by As-Samra, Baq‘a, Jerash, Abu-Nuseir, Salt, and Wadi Isir plants. 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 10 700 ha of which 667 ha for restricted crops on-site the wastewater treatment plants, 900 ha for restricted crops outside the wastewater treatment plants (155 ha in Aqaba, 63 ha in Madaba, 52 ha in Ramtha, etc.), and 9100 ha located in the Jordan Valley for unrestricted agriculture after blending reclaimed water with surface water. Except the Jordan Valley, the treated effluent is used to irrigate cereals (wheat, barley, etc.), fodder crops (sudangrass, alfalfa, maize, etc.), forest (acacia, casuarina, eucalyptus, etc.) and fruit (olives, citrus, banana, etc.) trees.

　　Reclaimed water 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, 54.6 Mm3, 170 750 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 9100 ha (18% of the actual irrigated area) of which 64% produces vegetables, 7% cereals and fodder and 27.5% fruit trees. The remained area farms forest trees. 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 ($US 0.02/m3) in Jordan Valley; free in other schemes) and not related to the water quality. The Jordan Valley Authority provides free irrigation water to farmers during winter for salt leaching. Farmers cannot sell or lease their water rights.

Table 2. Comparison of reclaimed water quality criteria
and standards for irrigation in Jordan, Kuwait, and Tunisia.

Microbiological parameters Country
Wastewater treatment Type of irrigated crops Parameter
(mg/l) Fecal coliforms
(MPN/100 ml) Intestinal nematodes
(eggs/l)* Amoebae & Giardia
(cysts/l) 约旦



二级处理
Cooked vegetables TDS: 2000
SAR: 9
SS: 200
BOD5: 150x
COD: 500
Nt: 100
Cl2: 0.5 1000 <1 <1 Fruit and forestry trees, crops and industrial products TDS: 2000
SAR: 9
SS: 200
BOD5: 150x
COD: 500
Nt: 100 - - - Fodder crops TDS: 2000
SAR: 9
SS: 250
BOD5: 250x
COD: 700
NO3-N: 50 - <1 - Tunisia

Secondary treatment Cereal crops,
industrial crops,
fodder crops,
and trees EC: 7000
mS/cm
SS: 30
BOD5: 30
COD: 90 - <1 - Kuwait


Advanced
treatment
Fodder & food crops not eaten raw, forestland SS: 10
BOD5: 10
COD: 40
Cl2: 1 10 000 - - Food crops eaten raw** SS: 10
BOD5: 10
COD: 40
Cl2: 1 100 - -

* Intestinal nematodes expressed as the arithmetic mean number of eggs per litre.
** Not including salad crops or strawberries.
x: BOD in effluent from WSP (filtered), and from mechanical treatment plant (not filtered).
Cl2: Chlorine residual (mg/l) after 12 h at 20°C.

　　The Jordanian standard 893/1995 specifies the quality standards required for various wastewater uses such as irrigation of cooked vegetables, fruit and forestry trees, fodder crops, lawns and parks, groundwater recharge, and aquaculture or discharge to streams, wadis, and reservoirs. The general criteria for these standards have also been established.

　　Several institutions are concerned by wastewater treatment and reuse such as the Ministry of Water and Irrigation (Water Authority of Jordan and Jordan Valley Authority), the Royal Scientific Society, the Ministry of Agriculture (National Centre for Agricultural Research and Technology Transfer), the Ministry of Public Health, the Ministry of Environment, the Ministry of Planning, Municipalities, and the potential users.

Planned reuse of secondary treated water - Tunisia

　　Wastewater treatment. Most residents of large urban centres in Tunisia have access to various adequate sanitation systems and the wastewater treatment facilities generally follow conventional designs. The sanitation coverage in the sewered cities is about 78%; this rate, related to the whole urban population (5.8 million), is 61% (Table 1). Concerning industry, compliance with the Tunisian standards (INNORPI, 1989a) to discharge wastewater into the sewerage system is required. So, preliminary treatment plants to fulfil the discharge requirements stated in the regulations must be supplied. Subsidies are given to equip industrial units with pre-treatment processes.

　　Of the 240 Mm3 of wastewater discharged annually, 140 Mm3 (58%) are treated in 61 treatment plants (WWTP) of which around 41 have a daily capacity less than 3500 m3 and 10 above 10 000 m3, Choutrana being the largest with 120 000 m3/d. Five treatment plants are located in the Tunis area, producing about 62 Mm3/yr or 54% of the country‘s treated effluent. Several of the plants are located along the coast to protect coastal resorts and prevent sea pollution. Municipal wastewater is mainly domestic (about 88%) and processed biologically up to a secondary treatment stage. Concerning industry, compliance with the Tunisian standards (INNORPI, 1989a) to discharge wastewater into the sewerage system is required. So, preliminary treatment plants to fulfil the discharge requirements stated in the regulations must be supplied. Subsidies are given to equip industrial units with pre-treatment processes. The treatment processes vary from plant to plant depending on wastewater origin and on local conditions. Out of 61 treatment plants, 44 are based on activated sludge (medium or low rate), 3 on trickling filters, 14 on facultative or aerated ponds. Sanitation master plans have been designed for several towns. The annual volume of reclaimed water is expected to reach 290 Mm3 in the year 2020. The expected amount of reclaimed water will then be approximately equal to 18% of the available groundwater resources and could be used to replace groundwater currently being used for irrigation in areas where excessive groundwater mining is causing salt-water intrusion in coastal aquifers.

　　Wastewater treatment costs. Sanitation charges are included in the drinking water billing. They are graduated upward based on consumption (5 blocks for domestic consumers: 0-20; 21-40; 41-70; 71-150; >150 m3/quarter), usage (domestic < industry < tourism) and degree of water pollution (3 levels for the industrial sector depending on BOD5, COD, and SS concentrations). The tariff structure, similar to the water supply one, is based on social equity; it spares low and medium domestic consumers (<70 m3/quarter) and affects the large ones. Sanitation charges are meant to cover operation and maintenance costs.

　　In the following, treatment costs were estimated for reclamation plants ranging in production capacity from 256 to 43 000 m3/d. Capital costs include facility construction (design life of 45 years, return rate of 7%) and equipment purchase (design life of 15 years, return rate of 7%). Average capital cost is 0.08 $US/m3 (0.003 to 0.49 $/m3, N = 37) (1 DT " 0.67 $US). Capital costs for facultative ponds are the lowest, followed by aerated ponds and extended aeration, the conventional activated sludge and oxidation ditch. Annual O&M costs comprise treatment facility personnel salaries, operating fees (power mainly), and maintenance costs (equipment repairs and replacements). The average O&M costs per treated cubic meter, for the year 1995, was around 0.07 $US (0.01-0.20 $US/m3, N = 37). The least O&M reclamation costs were for facultative ponds, followed by extended aeration, conventional activated sludge, aerated ponds, and finally the oxidation ditch process. Energy fees represent 60% of O&M costs, salaries 30%, and maintenance 10%. The average wastewater treatment cost is then around 0.15 $US/m3, excluding wastewater collection costs but including old wastewater treatment plants with low capital costs. Total treatment costs at the reclamation plant remain the lowest for facultative ponds and extended aeration. Actually, the marginal treatment cost is supposed to be about 0.30 $/m3, investment costs representing 80% of the total marginal cost.

　　Water reuse implementing approaches. Water reuse has been made an integral part of overall environmental pollution control and water management strategy. Water reuse is now a part of Tunisia‘s overall water resources balance. It is actually considered not just as an additional water resource and as a potential source of fertilizing elements (UNDP, 1987) but also as a complementary treatment stage and consequently, as a way of protecting coastal areas, water resources, and sensitive receiving bodies.

　　A gradual approach to expanding reuse since the mid 1960s has been adopted (UNDP et al., 1992). The strategy has consisted of 1) extending wastewater treatment to all urban areas; 2) conducting pilot- and demonstration-scale irrigation operations on agricultural and green areas; 3) establishing large scale irrigation schemes; and 4) implementing a policy calling for an increase in the percentage of treated effluent that is to be reused. Different development phases can then be distinguished.

　　First phase : Reclaimed water to safeguard citrus production. Some of the reclaimed water from Tunis has been used since the early 1960s to irrigate 600 ha of citrus fruit orchards located at La Soukra (8 km North East of Tunis). The reason for using the wastewater was to reduce the impact of salt water intrusion due to excessive pumping of groundwater. The reuse has enabled citrus fruit orchards to be saved. Effluents were thus used, mainly during spring and summer, either exclusively or as a complement to groundwater. Irrigation of vegetables was not allowed.

　　Second phase : Planned reclaimed water reuse. The water reuse policy was launched at the beginning of the 1980s. The main applications of water reuse are agricultural irrigation, and landscape irrigation. Some pilot projects have been launched or are under study for groundwater recharge, irrigation of forests and highways, and wetlands development. Water reuse was implemented after the construction of existing treatment plants. However, for new plants, treatment and reuse are combined from the planning stage up to the implementation studies.

　　About 35 Mm3 of reclaimed water are annually allocated for irrigation. A total flow of about 28 Mm3/yr of treated effluent (approximately 20% of the treated effluent) is being reused. In some areas, irrigation with effluents is well established and most of the volume allocated is being used, while in new areas where irrigation is just beginning, the reclaimed water usage rate is slowly increasing. The use of secondary treated effluents in Tunisia is for a restrictive irrigation from which all vegetable crops are forbidden. The main crops irrigated with reclaimed water are fodder (alfalfa, sorghum, berseem, etc.) (45.3%), fruit trees (citrus, grapes, olives, peaches, pears, apples, grenades, etc.) (28.5%), cereals (22.4%), and industrial crops (sugar beet) (3.8%). Fifty seven percent of the equipped area are sprinkler irrigated and 48% surface irrigated. Some farmers use localized irrigation systems. Cattle (milking cows, calves, sheep, and goats), not grazed on pastures irrigated with reclaimed water, are also fed with forage crops cultivated on the irrigated areas. A water reuse program has been set up and experimental research has been conducted on the subject. The area currently equipped is about 6500 ha, 80% of which are located around Tunis. Main perimeters are Cebala (3200 ha), La Soukra (600 ha), Mornag (1047 ha), Nabeul (350 ha), Hammamet, Sousse, Monastir, Sfax, and Kairouan. Other projects are being implemented extending the area to 9000 ha. The area irrigated with reclaimed water is planned to expand up to 20 000 ha, i.e. 7% of the overall irrigated area, with 14 500 ha located around the Great Tunis. Major crop irrigation projects planned or under implementation are presented in the following.

　　The institutional and legal framework of water reuse in agriculture has been set up to regulate the treatment and the distribution of irrigation with reclaimed water, to supervise the Water Code and other enactments application and to control the sanitary aspects. Water reuse in agriculture is regulated by the 1975 Water Law and by the 1989 decree (Decree No. 89-1047). In separate documents, reclaimed water quality standards for reuse (INNORPI, NT 106.03, 1989b), wastewater disposal standards in receiving waters (INNORPI, NT 106.002, 1989a), a list of crops that can be irrigated as well as the specifications determining the conditions of reclaimed water reuse have also been set up. The reclaimed water quality criteria for agricultural reuse were developed using the FAO guidelines (Ayers and Westcot, 1985), the WHO guideline (1989) for restricted irrigation (< 1 helminth egg per litre), and other Tunisian standards related to irrigation or water supply. Responsibility from wastewater collection to use in agriculture is shared among various ministries: the Ministry of Environment and Land Use Planning (the National Sewerage and Sanitation Agency), the Ministry of Agriculture (the General Directorate for Agricultural Engineering, the Regional Commissariats for Agricultural Development), the Ministry of Public Health, the Ministry of Tourism and Handicrafts. Users‘ associations are also involved in water reuse operations.

　　An adequate estimation of the water price is important for cost recovery and for water use saving. Devising an appropriate water pricing policy is, therefore, an important step in water reuse operations. With the creation of new schemes, water was often distributed free of charge at the beginning of the supply to encourage farmers to use it, then at a fixed price per hectare before evolving towards a price per cubic meter of water used. The price of the reclaimed water sold to farmers use to vary from one scheme to another. The charges were meant to cover some of the O&M costs (operation, maintenance, salaries, and energy). As for schemes irrigated with conventional water, this price was supposed to evolve progressively towards the real cost, remaining, however, lower than conventional water prices. Water services are metered on most of the schemes but there is still a high amount of unaccounted water leading to higher O&M costs. For instance, in the Mornag irrigation scheme, the O&M costs amounted in 1996 to 0.13 $US/m3 (energy fees for pumping representing 68% of O&M costs, salaries 18%, and other costs 10%) and the selling price was 0.04 $/m3. Production cost, including capital costs (for the irrigated schemes), was then about 0.20 $/m3. Water from the Medjerda-Cap Bon canal (conventional water used in the same area), whose O&M costs were 0.07 $/m3, was sold at 0.06 $/m3. In order to promote water reuse, it has been decided, in 1997, to fix the price of the cubic meter at 0.01 $. However, the water reuse rate did not increase as expected and a deficit was generated. New bases should be adopted: a given water quality should be supplied to the farmers for a given price and based on a real water demand.

　　As municipal wastewater discharges at a more or less constant rate throughout the year and as its volume will increase with urban, tourism, and industry development, wastewater will be reused for agricultural purposes -the area irrigated with reclaimed water is planned to expand up to 20-30 000 ha, i.e. 7-10% of the overall irrigated area, with 14 500 ha located around the Great Tunis- and in other activity sectors. A new wastewater treatment plant is planned for the city of Tunis "The Tunis-West project" with a design capacity in the year 2026 of 224 200 m3/d (82 Mm3/yr.). The treatment plant will be operated as a BOT. Interseasonal storage (3 Mm3) in hillside dams is included for water resources protection purposes, and increase of the resource. In a first phase, an irrigation scheme covering 1000 ha is planned. The total irrigated area should cover about 6000 ha. Farmers‘ willingness to reuse reclaimed water is taken into account. Water users‘ associations will manage the irrigation system. The water distribution system at the plot level will be optimised and irrigation saving methods will be encouraged.

　　Third phase : Development of reclaimed water reuse. Actually, there are several other water reuse opportunities when the water quality is in adequacy with the intended end use of the effluent (Asano and Levine, 1996). Diversification of the reuse options by developing non-agricultural uses such as municipal, industrial, and environmental uses is on the way. Based on the on-going reuse projects, a study aimed at developing a strategy to promote water reuse was launched in 1997 (Bechtel and Scet, 1998). The study showed that the strategy should be oriented towards the substitution of conventional water by reclaimed water for the high-rated water activities or the creation of a new demand based on strategic projects. Promotion of reclaimed water reuse should be based on (1) a real water demand, (2) the definition of appropriate water quality standards for the different uses, (3) a relevant regulation, (4) clarified and identified responsibilities for the different interested parties, and (5) an efficient control on all the uses. The legal and institutional framework should be strengthened. Reclaimed water reuse should be more integrated to water resources management. By upgrading the water quality and with more widespread information, reclaimed water reuse should gain wider acceptance in the future. Projects aimed at developing water reuse have been proposed such as the implementation of the water reuse strategy for the District of Tunis, groundwater recharge of some coastal aquifers, and industrial reuse of reclaimed water.

Planned reuse of tertiary treated water - Kuwait

　　In Kuwait, ninety-five percent of potable water comes from desalination (multi-stage flash distillation plants) (Al-Attar et al., 1997). Wastewater is treated in three main municipal treatment plants (Ardhiya, Reqqa, and Jahra) by secondary and tertiary processes (activated sludge, filtration, and disinfection by chlorine) (Table 2) and represents 65-80% of potable water use. The quantity of wastewater produced was 119 million m3 in 1994 of which 103 million m3 were treated. The total irrigated area from reclaimed water was, in 1994, 25% of the total irrigated area (4770 ha) (Sarraf, 1997). Actually, less than 10% of the quantity of reclaimed water currently generated is reused. A share of the industrial wastewaters is also recycled after treatment. However, the national environmental policy of resource conservation is to reuse all wastewater. Therefore, the Kuwait Institute for Scientific Research has established a "Wastewater treatment and utilization program" to develop and accelerate water reuse. Some components of this program are: development of pilot utilization sites for agricultural production, greenery, and aquaculture, pilot artificial recharge of aquifers with reverse osmosis reclaimed water, development of a prototype for use of treated industrial wastewater, and integrated ponding systems for wastewater treatment (facultative ponds and high-rate algal ponds).

　　Initially, chlorinated secondary effluent from the Ardiyah plant was used in restricted areas on experimental farms and in landscape irrigation. Currently, reuse of tertiary treated effluent is also taking place for a variety of trees and greenbelt irrigation. Irrigation of greenbelts is being implemented to reduce mobile sand movement. Application of reclaimed water to crops is made by drip, and sprinkler irrigation. Treated effluent is being supplied to private farms and is charged to farmers at $US 0.07/m3. The areas irrigated with tertiary effluent cover around 1680 ha. Proposals for expanding irrigation include 3300 ha, of which the Kuwait Institute for Scientific Research experimental farm. There is an elaborated system of storage and pumping of chlorinated effluent to the irrigated areas. On some schemes, reclaimed water goes through a second chlorination step before reuse. Storage often occurs in closed tanks. Studies have also been conducted to assess the feasibility of storing reclaimed water in artificial lakes.

　　The ministry of Public Works has established effluent quality standards for water reuse in irrigation. Reclaimed water is only allowed for the irrigation of vegetables that are eaten cooked (potatoes and cauliflower), industrial crops, forage crops (alfalfa, barley, and winter forage crops), and for greening the highways.

　　Water reuse raises, however, some concerns related to different issues such as the pathogens, pollutants and salt content, the need to establish a third piping system for wastewater delivery, and storage facilities and the related costs.

　　The institutions involved in sewerage and reuse are the Ministry of Public Works, the Public Authority for Agricultural Affairs and Fish Resources, a Council for Environmental Policy Setting and Environmental Protection, the Ministry of Health, and the Kuwait Institute for Scientific Research.

CONCLUSION

　　Water reuse is included in the water resources planning of most of the countries of the Southern Mediterranean and Middle East region. Several countries have official policies calling for reuse of all wastewater. However, a wide variety of situations may be found because of the difference in the capacity to implement such policies. Therefore, several challenges have still to be overcome in terms of wastewater treatment and reuse. Technological, scientific, institutional, or legal aspects of collection, treatment, and reuse of urban wastewater are partially mastered and require consequently particular attention. Where uncontrolled direct or indirect reuse of raw wastewater is occurring, the water quality should be improved so as to prevent health hazards and environmental problems. Where crop restriction is applied, upgrading wastewater treatment plants should be promoted for more economical pollution abatements, for unrestricted use with wider crop rotation, and higher valorization and payback of the investments made in the agricultural sector.

　　Concerning the national regulations, there is a wide variety of situations with different regulations and standards that are often independent of the country‘s development state. Experiences gained in different countries will help develop a common approach to wastewater treatment and agricultural reuse based on the documentation and evaluation of existing practices.

　　Institutional strengthening is required for a better planning and coordination among the different involved bodies. Future reuse projects will depend on a better planning and management of reuse operations based on a real water demand. This means a better institutional, regulatory, and organizational setting. Economic and financial feasibility of reclaimed water reuse applications needs to be better assessed. Technical aspects need also further study, along with applied research for specific applications. Education, information, and training of farmers and extension services also play an important role in promoting these practices aiming to achieve higher agricultural production without adverse impacts on the environment.

REFERENCES

　　Al-Attar, M.H., Al-Awadhi, N., Al-Sulaimi, J. and Leitner, G.F. 1997. Water reuse concepts and programs in Kuwait leading to optimum use of all water resources. Desalination & Water Reuse, Feb.-March 1997, (6/4), 46-53.
　　Asano, T. and Levine, A. D. 1996. Wastewater reclamation, recycling and reuse: past, present, and future. Wat. Sci. Tech. 33 (10-11), 1-14.
　　Bechtel International Inc. and Scet-Tunisia. 1998. Development of a strategy to promote reclaimed water reuse in the agricultural sector or others sectors, Water Sector Study, Final Report, December 1998, 112 p. + Appendixes.
　　Institut National de la Normalisation et de la Propriété Industrielle. 1989. Environment Protection - Effluent discharge in the water bodies - Specifications relative to discharges in the marine environment, hydraulic environment and in the sewers (in French), Tunisian standards, INNORPI, NT 106.002.
　　Institut National de la Normalisation et de la Propriété Industrielle. 1989. Environment Protection - Use of reclaimed water for agricultural purposes - Physical, chemical and biological specifications (in French), Tunisian standards, INNORPI, NT 106.03.
　　Official Journal of the Tunisian Republic. 1989. Decree No. 89-1047 issued on July 28, 1989 regulating the use of reclaimed water for agricultural purposes (in French).
　　Sarraf, S. 1997. Trends in water reuse in the Near East Region. Expert consultation on reuse of low-quality water for sustainable agriculture, ACSAD, AOAD, CEDARE, FAO/RNE, ICARDA, UNESCO/ROSTAS, WHO/EMRO/CEHA, Amman, 15-18 December 1997.
　　Tuffaha, A.Sh. 1996. Technologies, practices, and performances of wastewater treatment plants in Jordan, Workshop on Wastewater Treatment and Reuse in Jordan, Water Authority of Jordan, Aqaba, 3-5 December 1996.
　　United Nations Development Program. 1987. "Reclaimed water reuse in agriculture", Technical Report (in French), Vol. 1, 3rd Part, 69 p.+ appendixes, Project RAB/80/011, Water Resources in the North African Countries, Rural Engineering Research Centre (Tunisia) - United Nations Development Program, May 1987.
United Nations Development Program/Food and Agriculture Organization/The World Bank/World Health Organization. 1992. Wastewater Treatment and reuse in the Middle East and North Africa Region - Unlocking the potential, Review Draft, Report of a joint mission to Cyprus, Egypt, Jordan, Kuwait, Morocco, Saudi Arabia, Syria, Tunisia, Turkey, and Yemen, Project RAB/88/009, July 1992.
　　U.S. Environmental Protection Agency. 1992. Guidelines for Water Reuse. EPA/625/r-92/004, U. S. Environmental Protection Agency, Washington D.C. 247 pp.
　　World Health Organization. 1989. Health guidelines for the use of wastewater in agriculture and aquaculture, Tech. Bull. Ser. 77, WHO, Geneva, Switzerland.

close

www.h2o-china.com