Effect of aeration on characteristics of the activated sludge and membrane fouling in a submerged membrane bioreactor

Laboratory experiments on submerged MBR were carried out to investigate the influence of aeration on characteristics of the activated sludge and membrane fouling. Results showed that membrane fouling included 2 stages under different level of aeration, with the membrane fouling rate of MBR-B (0.6 m3/h of aeration ) higher than MBR-A (0.2 m3/h of aeration) in Stage 1 of the first 20 d, and lower in Stage 2 after 20 d. Different aeration led to viscosity discrepancy, which however didn’t show clear relationship with membrane fouling. It was found that mixed liquid suspended solids(MLSS)was no different in 2 MBRs, i.e., aeration didn’t play an important role on MLSS. The influence of aeration was important on loosely bound extracellular polymeric substances(LB-EPS) but not on tightly bound EPS (TB-EPS). LB-EPS and LB protein had strong positive effect on membrane fouling, which indicated that protein was the major pollutants.