Evaluation of Hollow Fiber Ultrafiltration as a Pretreatment for Reverse Osmosis Desalination of Seawater

摘要

An intensive study was conducted at the Wrightsville Beach Test Facility to evaluate the performance of hollow fiber ultrafiltration membranes as a pretreatment for seawater desalination via reverse osmosis. Several polymer types were evaluated to determine the best ultrafiltration membrane. In addition, two different fiber diameters (20 and 43 mil) were studied to investigate the effects of flow through the hollow fiber cartridge on flux, cleaning, and membrane life. The results from these tests show that the polysulfone PM-50 membrane (50,000 M.W. cutoff) which has a 43 mil internal diameter is well suited for seawater pretreatment. Various cleaning chemicals (sodium hydroxide, sodium hypochlorite, citric acid, surfactant types, etc.) were evaluated in several combinations of operating modes (reverse flow, backflush) to optimize the membrane performance. Economic analyses show that the three inch diameter, 26.5 square foot PM-50 hollow fiber cartridge can pretreat seawater at a cost of approximately one dollar per thousand gallons of seawater produced using a totally automated system.