A fast and reliable approach to benchmark low pressure hollow fibre filtration membranes for water purification

In this study a benchmark protocol for low pressure hollow fibre membranes was developed and evaluated. The benchmark approach involved three main steps: first a systematic membrane characterisation, then a short-term bench-scale testing evaluated by a scoring system, and finally a long-term full scale performance comparison. Four different hollow fibre membranes were characterized with respect to electrical charge, hydrophobicity, surface morphology et al. All hollow fibre membranes and two types of water (river water and secondary effluent) were used in a controlled filtration protocol. The performance of these membranes were evaluated according to the scoring system which included the effect of fouling (TMP development), hydraulic permeability recovery, and membrane chemical cleaning under both moderate and high fluxes. A key result of this study is that the overall performance of the membranes in long-term can be qualitatively predicted using a short-term bench scale test and a scoring system. The benchmark of membranes in the full scale tests showed results comparable to the results obtained in bench-scale. Detailed comparison of the scores from bench and full scale tests highlights some challenges in applying such approach in practice. The study found very limited relationship between membrane characteristics and filtration performance. It was observed that some membrane characteristics influence fouling at the beginning of fouling formation, but the effects were reduced over time as the membrane underwent more intense fouling and several cleaning cycles.