Physical Backwash Optimization in Membrane Filtration Processes: Seawater Ultrafiltration Case

Seawater ultrafi ltration (UF) as a pretreatment of reverse osmosis (RO) process in a thermal power plant was investigated using a 100 kDa hollow fi ber membrane. The choice of the UF physical backwash conditions remains arbitrary or ensuing from a sensibility study. As the optimum must take into account the factors interactions, we led a response surface study to analyze the eff ect of backwash interval BWI (30–90 min), backwash fl ow-rate BWF (10–34 L.min-1) and backwash duration BWD (15–45 s) on two responses: the Specific Flux Reduction (SFR) and the Net Water Production (NWP). Polynomial models describing the responses sensitivity with respect to the three variables were established to determine the optimal conditions corresponding to maximal NWP while assuring lowest fouling. Results showed that fouling is mainly controlled by BWI. For the NWP, all the variables are signifi cant especially their quadratic and interaction terms. Maximal NWP and low SFR can be reached at 30 min BWI, for a BWD and BWF ranges of [15-30 s] and [10-21 L.min-1], respectivel.