Kingdom of Saudi Arabia and

In hybrid desalination system normally both thermal desalination plant such as MSF and SWRO plant exist side by side. The low salinity product from MSF plant, TDS of less than 50 ppm, is blended with product of SWRO plant, TDS normally less than 1000 ppm to 1200 ppm, to produce final product having TDS with less than 500 ppm. To optimize a hybrid desalination plant it is required to use SWRO membrane with highest possible flux and reasonable, good salt rejection (97%) rather than a membrane with high salt rejection and low flux. Moreover, among other qualities the membranes should have high stability and tolerance to turbidity and chlorine. To establish a SWRO membrane that meets the above criteria, various types of SWRO membranes were investigated through a series of experiments for their performance as well as their tolerance to chlorine and turbidity using flat sheet and minimodules (2.5 X 40 inch) SWRO test units. Membranes chlorine tolerance tests using flat sheet membranes were made at chlorine concentration of 10 ppm, 5 ppm, 1 ppm and 0.3 ppm. While turbidity tolerance tests were made using untreated seawater feed (SDI = 6.4) After 5000 hours of operation, the five commercial SWRO membranes evaluated in this investigation were found to have high salt rejection but not very high flux. All membranes exhibited satisfactory performance, although some variations existed amongst them. Ready made membranes with high flux and membrane salt rejectio