Effects of EPS on Settlement and Dewatering Properties of Activated Sludge

The extracellular polymeric substances (EPS) are susceptible to microbial degradation, highly efficient, non-toxic, no secondary pollution, etc, and are considered to be the most promising biological polymers. At present, EPS have been considered by many researchers as a potential flocculent for their applications in various water, wastewater and sludge treatment process. They are insoluble organic matter adhesive to the cell surface, and they mainly derive from microbial metabolism and cell autolysis, which are mainly composed of polysaccharides, proteins, extracellular DNA. Based on illustrating content, function and structure composition of EPS, the paper reviews the action mechanism of EPS on flocculation and settlement of activated sludge and those flocculation, settlement and dewatering properties in the sewage treatment system. In addition, it summarizes the development trend and application prospect of EPS, which would provide valuable references for further research and application of EPS.