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

The cost of potable water production from brackish or saline water is substantially greater over treating fresh water, where adequate fresh water is not available [1]. Development of desalination techniques is predicted to reduce cost in levels comparable to fresh water treatment. Using ion exchanger through hydrogen and hydroxyl-base resins systems are simple to operate in moderate capital cost with few operating problems. However, they require costly regenerant and produce troublesome waste streams [2]. A number of novel industrial systems reducing regenerant requirement have been developed. The effluent from the two-stage process is comparable to distilled water quality, which costs approximately one-fourth to one-fifth of those distillation processes. ETRAS Thermal Desalination System was observed during the roughing stage in treatment of brackish and low saline water with 500 to 4000ppm/TDS as effluent. In this application, the feed water is first passed through a thermal resin plant yielding soft low salinity of 50 to 100TDS, product water. After the thermal resins are exhausted, hot water is then passed to backwash the system as regenerant. The volume of production and the operational expense will be the great difference as thermal resins remove bulk of dissolved salts.