Roles of soluble microbial products and extracellular polymeric substances in membrane fouling

Abstract Soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) are produced and secreted out of the cell by microorganisms such as bacteria, fungi, algae, protozoa, metazoa, etc. and regarded as crucial biopolymeric substances that determine the properties of mixed liquor, i.e., activated sludge, including aggregation, flocculation, sedimentation, hydrophilicity, hydrophobicity, adhesion properties, etc., and hence they significantly affect membrane fouling in membrane bioreactor (MBR). In the membrane-fouling studies of MBR, over the 310 papers related to SMPs and EPSs researches have been published from 2005 to the second quarter of 2019 at Web of Science. However, not all papers have the same conclusions, and there is still somewhat ambiguity about the relationships and roles of biopolymeric substances (e.g., SMPs and EPSs) and membrane fouling in MBR. Therefore, in this chapter, we aim to provide the summaries, discussions, and suggest further research for perspectives regarding SMPs, EPSs, and membrane fouling in MBR.