Insight into influence of iron addition in membrane bioreactor on gel layer fouling

Membrane fouling in membrane bioreactor (MBR) remains a primary challenge for its wider application. The focus of this study to investigate the influence of iron distribution in activated sludge on gel layer fouling in MBR. Significant reduction in the transmembrane pressure (TMP) rise rates was observed in the presence of iron as result of retarding the gel layer formation time. The spatial distribution of iron had a significant impact on the stratification structure of extracellular polymeric substances (EPS) fractions, such as proteins (PN) and polysaccharides (PS). A mitigation of PN or PS from the supernatant to the EPS inner layers was observed in the presence of iron. Compared with the control reactor, the reduction in PN and PS of the supernatant and lower PN/PS rates of the LB-EPS were beneficial to decrease the membrane fouling potential during the gel layer formation. Consequently, the iron addition managed to control gel layer fouling could be a useful strategy in MBR.