Characterization of Long-Term Foulants Deposited on Full-Scale Membrane Modules in Submerged MBR Processes

摘要

Two full scale membrane modules were sampled at a variety of locations, before and aftermaintenance and recovery cleanings, to investigate the spatial distribution of fouling on themembrane surface and through the fouling layer. Along the length of a fouled membrane fibre,the filtration resistance and biofilm thickness was consistent. Maintenance cleaning decreasedfoulants on membrane surfaces and within membrane pores. Recovery cleaning effectivelyremoved the majority of organic foulants on the membrane surface. The accumulation ofproteins, carbohydrates and lipids within the membrane was minimally decreased, suggestingtheir key role in long-term irrecoverable fouling. There was no correlation found betweenbiofilm thickness and permeability. Furthermore, the deposition of inorganic foulants, inparticularl calcium and magnesium, were identified on the membrane surface even after citricacid cleaning. Testing confirmed the formation of inorganic precipitates identifying them as asan important factor in forming long-term irrecoverable fouling.