EFFLUENTS QUALITY ALONG A MULTIPLE-STAGE WASTE-WATER RECLAMATION SYSTEM FOR AGRICULTURAL REUSE

A multiple stage wastewater reclamation system in northern Isreal is described and analyzed for effluents quality along its components. The reclamation system uses Haifa's treated wastewater to irrigate cotton fields and other crops in the Valley of Jezreel. During five years of operation it was found that each stage of the reclamation system, after the treatment plant, has some impact over effluents quality. Degradation of organic matter and bacterial regrowth take place at the effluents conduit which connects the treatment plant and the irrigated area along 30 km. This is mainly due to relatively long retention time of the effluents within the conduit because of operational restrictions. The stabilization reservoir that stores effluents during winter time, improves their quality to a great extent. The effluents that enter the operational reservoir at the irrigation season, are mixed with fresh water from the Sea of Galilee, and may cause rapid growth of phytoplankton and zooplankton populations. The reclamation system successfully replaces large amounts of fresh water otherwise used for cotton irrigation.