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Effluent Management Concept It is by now well established that treated effluent must play a key role in re-establishing a water balance in the Coastal Aquifer to aid sustainable development in the Gaza Strip. This will require farmers to substitute effluents for groundwater as the principal irrigation source, wherever feasible, and require effluent that is surplus to agricultural demand to be recharged to the aquifer. Such a strategy is recognized as optimal and could be implemented in an integrated and flexible manner, according to strategic water management decisions and demands for water. Irrigation of agricultural crops is the only feasible option for the direct reuse of treated effluent and will also reduce the reliance of farmers on wells. Existing irrigated crops that are currently suffering yield reductions due to the high salinity of the groundwater, particularly citrus in the area, should recover some of their yield potential and return to more economic levels. In addition, aquifer recharge by strategically located infiltration ponds is clearly identified as a crucial component of effluent reuse strategies in Gaza. The major advantages with regard to the local water resources are the recovery of declining groundwater levels and reduction of salinization of the aquifer from seawater intrusion and upconing of saline water. For recharge purposes, the hydrogeological conditions in Gaza Strip will provide effective filtering of any pathogens within the surface layer. Nonetheless, additional treatment of effluent at the WWTP would be advisable to minimize the loading of solids on the filtration surface. It is also clear that discharge of treated effluent to Wadi Gaza has the potential to improve the environmental conditions and recreational potential of the area. But for this and other initiatives to be implemented, there needs to be an expressed willingness to use and pay for reclaimed water. One of the main concerns is willingness of farmers to use treated wastewater for agriculture. A number of surveys have been conducted in the context of studies on the reuse of reclaimed water which dispel concerns about cultural barriers to wastewater recycling. In the northern area, 86.1% of all interviewed farmers accepted the use of reclaimed water for irrigation (Tubail et al. 2004). The general acceptance level for using reclaimed water for irrigation in Gaza and the middle area is also very high (89.9% of all farmers). The most important reason for wanting to use reclaimed water as an alternative to groundwater is related to anticipated higher incomes, either due to irrigation cost reductions or improved yields. On average, farmers would be willing to pay 0.36 shekels/m3 . Farmers expressed a number of concerns about reclaimed water regardless of their acceptance or refusal to use it for irrigation. Their principal concern is that customers might refuse to buy their products if they become aware about the source of irrigation water. Strategic Assumptions and Implications Future Palestinian sewage policy relies on several assumptions: that farmers are willing to use and pay for effluent; that the quality of the effluent is suitable for the intended outlets and in compliance with appropriate standards; that the cropping Sewage Treatment in Gaza 179 practices of farmers can be controlled to ensure that specific crops (mainly vegetables ) are not grown where restricted reuse is necessary; and that the Coastal Aquifer can accept large quantities of effluent by artificial recharge at appropriate locations that will benefit groundwater levels and reduce saline intrusion. Potential Impacts The main implications of the current Palestinian effluent reuse standards are that some parameters are significantly more stringent than the well-established WHO and FAO guidelines. For example, the limit values set for salinity and chloride concentrations according to the Palestinian standards would prevent any reuse of effluent in agriculture or aquifer recharge. The standards would also set a limit for effluent recharge of 25mg N/l and an equivalent concentration of 110mg NO3/l. At this level, the effect would be to increase, or at least maintain, the currently high concentrations of nitrates in groundwater. Exclusion of all vegetable crops from effluent irrigation, however, is considered unnecessarily restrictive since the hygienic standards for effluent are appropriate for unrestricted reuse and meet the WHO guidelines. The area in Gaza in which vegetables are grown has increased from 26% of the agricultural land to 44% during the last years. A fecal coliform limit of less than 200 MPN/100 ml should be...

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