Abstract: Activated sludge wastewater treatment system relies on microbial metabolism to clarify the sewage. Extracellular polymeric substances (EPS) of activated sludge play an important role in pollutants removal and the flocculation, settle ability and dewaterability of activated sludge, and thus affect the stability and improvement of the activated sludge process. Here, we review the role of EPS of activated sludge in wastewater treatment system and compare different extracting methods of EPS. The extraction methods can affect the EPS components and physicochemical properties of activated sludge. Researchers have tried to find the best compromise between high extraction yields and minimum cell lysis during the extraction procedure. Standardization of extraction methods is the foundation of the EPS related research. It is important to better understand the role of EPS in wastewater treatment system and improve the properties of activated sludge with research-specific extraction method of EPS.

Key words: cotton, yield, plant density, partial root zone irrigation, water productivity.