Advances in extracellular polymeric substances of bio-aggregates in biological wastewater treatment system

Abstract

Extracellular polymeric substances (EPS) are the key component of bio-aggregates, such as activated sludge, biofilm and granular sludge. They play an important role in the bio-aggregates because of their physic-chemical characteristics and special situation of directly wrapping on the cell wall. The effects of EPS on the settleability and dewaterability of bioaggregates and membrane pollution in membrane bio-reactor (MBR) are reviewed in this paper. It is concluded that the composition and structure of EPS affect the settling and dewatering characteristics of bio-aggregates and the membrane pollution in MBR via changing the sludge surface potential and hydrophobic. At the same time, the role of EPS in the sludge granulation is emphasized that the components and distribution of EPS also influence the formation and structural stability of granular sludge. Finally, the future researches concerning EPS, such as extraction method standardization and incorporation of the physicochemical analysis method and molecular biotechnology, are prospected, showing promise in revealing the EPS production and regulatory mechanism during the formation of bio-aggregates.