DEVELOPMENT OF FOULINGAND CHLORINE-RESISTANT REVERSE-OSMOSIS MEMBRANES

REVERSE OSMOSIS (RO) IS A PROMISING NEW PROCESS FOR SHIPBOARD PRODUCTION OF POTABLE WATER FROM SEAWATER. HOWEVER, CURRENT RO SYSTEMS SUFFER FROM TWO PROBLEMS: 1) FOULING CAUSED BY THE FEED STREAMS,AND 2) CHEMICAL DEGRADATION OF THE RO MEMBRANES DUE TO DISINFECTANTS (USUALLY CHLORINE) USED IN THE FEED STREAM. EXTENSIVE PRETREATMENT IS THUS NEEDED WHEN CURRENT RO SYSTEMS ARE USED ON SEAWATER. THUS, THE DEVELOPMENT OF A FOULINGAND CHLORINE-RESISTANT MEMBRANE IS CRITICAL FOR PRACTICAL OPERATION OF SUCH SYSTEMS. BEND RESEARCH (BRI)HAS DEVELOPED A FOULING-RESISTANT MEMBRANE MODULE THAT TREATS FOULING-PRONE FEED SOLUTIONS WITHOUT SUBSTANTIAL LOSS IN PERFORMANCE. NAVY FUNDING IS THUS NOT NEEDED FOR THAT ASPECT OF THE PHASE I PROGRAM. PREVIOUS WORK AT BRI HAS ALSO PRODUCED "FIRST GENERATION" CHLORINERESISTANT MEMBRANES CAPABLE OF MAINTAINING HIGH SALT REJECTIONS WHILE OPERATING ONCHLORINATED FEED STREAMS. HOWEVER, THESE MEMBRANES EXHIBIT EXCESSIVE FLUX DECLINES WHEN EXPOSED TO CHLORINE. WE PROPOSE HERE TO DEVELOP "SECOND GENERATION" MEMBRANES--MEMBRANES CAPABLE OF MAINTAINING HIGH SALT REJECTIONS AND HIGH WATER FLUXES WITH CHLORINATED FEED STREAMS. IN A PHASE II PROGRAM, THESE MEMBRANES WOULD BE INCORPORATED INTO OUR FOULING-RESISTANT HOLLOW-FIBER MODULES.