LAUSR

Abstract Extracellular polymeric substances (EPS) are high molecular weight polymers secreted from microorganisms attaching to the cell surface dividing into tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) according to the binding degree to cell. The functional groups existing in EPS exert a great influence on sludge performances. EPS are responsible for pollutant's removal and especially they are closely related to the removal of exogenous toxic compounds, which protect sludge aggregates in WWTPs when exposed to toxic substances. It is necessary to understand the interaction mechanism of EPS and exogenous toxic compounds in order to provide instructions to improve performance of Wastewater treatment plants (WWTPs) when confronting toxic substances. This paper overall reviews the EPS definition, structure, chemical composition, source, extraction methods and interaction mechanism between EPS and heavy metals, toxic organic compounds. In addition, based on these understandings, several future research niches are provided for further study of EPS.