Bench-scale study of ultrafiltration membranes for evaluating membrane performance in surface water treatment

Currently, there is no standard bench-scale dead-end ultrafiltration (UF) testing system. The aim of the present study was to design and build a bench-scale hollow fiber UF system to assess the impact of operational parameters on membrane performance and fouling. A bench-scale hollow fiber UF system was built to operate at a constant flux (+/- 2% of the set-point flux) and included automated backwash cycles. The development of the bench-scale system showed that it is very difficult to maintain a constant flux during the first minute of the filtration cycles, that digital flow meters are problematic, and that the volume of the backwash waste lines should be minimized. The system was evaluated with Ottawa River water, which has a relatively high hydrophobic natural organic matter content and is typical of Northern Canadian waters. The testing using different permeate fluxes, filtration cycle duration and backwash cycle duration showed that this system mimics the performance of larger systems and may be used to assess the impact of operating conditions on membrane fouling and alternative pretreatment options. Modeling the first, middle, and last filtration cycles of the six runs using single and dual blocking mechanisms yielded inconsistent results regarding the controlling fouling mechanisms.