Desalination of brackish fish pond effluents - pilot testing and comparative economic evaluation of integrated UF-RO systems vs. conventional systems

Following the recent market penetration of back-washable capillary micro- a nd ultra-filtration membranes, their application for treating polluted fres h water and for pre-treatment of wastewater as well as polluted brackish an d seawater is now widely considered. In 1998 Mekorot initiated a field test ing program to investigate the operation of integrated UF-RO systems to des alt polluted brackish surface water in comparison with a system using conve ntional pre-treatment. The results show that UF pre-treatment yields a perf ormance superior to that obtained by the conventional pre-treatment regardi ng quality and overall system availability. However, at times of very high turbidities, a high load on the UF requires reduction of the filtration rat e, effecting significant water losses. Therefore, a. clarifier is needed to reduce loads of the UF and to improve substantially its performance regard ing filtration rate and water losses. A preliminary economic evaluation mad e for a case study of an integrated UF-RO 20,000m(3)/d desalination plant, indicates a projected cost of about 40-45 US cent/m(3). This cost is signif icantly lower than the projected seawater desalination cost. Therefore, a p riority should be given to this source desalination in the new water source s development plan, especially in inland locations where neither potable no r brackish groundwater sources are available. The paper presents the result s of the ongoing optimization study to improve the performance of the UF an d conventional RO systems, and provides a detailed economics case study.