Functions and behaviors of activated sludge extracellular polymeric substances (EPS): a promising environmental interest

Extracellular polymeric substances(EPS) are the predominant constituen ts of activated sludge and represent up to 80% of the mass of activated sludge. They play a crucial role in the flocculation, settling and dewatering of activat ed sludge. Furthermore, EPS also show great efficiency in binding heavy metals. So EPS are key factors influencing reduction in sludge volume and mass, as well as activity and utilization of sludge. EPS are of considerable environmental int erest and hundreds of articles on EPS have been published abroad, while informat ion on EPS in China is limited. In this paper, results of over 60 publications r elated to constituents and characteristics of EPS and their influences on floccu lation, settling and dewatering of sludge are compiled and analyzed. Metal-bindi ng ability of EPS is also discussed, together with a brief consideration of poss ible research interests in the future.