Research progress on the regulation of sludge bulking by quorum sensing.

Sludge bulking is a great challenge in the activated sludge process, seriously affecting the stable operation of the wastewater treatment system. Traditional methods can not fundamentally overcome the competitive advantage of filamentous bacteria. Quorum sensing, as the core mechanism of communication among microbial cells, has been proven to be important in regulating sludge bulking. We reviewed the types, mechanisms, and limitations of traditional methods for sludge bulking, and summarized the basic principles and main signaling molecules of quorum sensing. We further focused on analyzing the regulation of sludge bulking pathways through extracellular polymer synthesis and microbial community structure based on quorum sensing, and summarized the quorum quenching control strategy. Finally, we provided an outlook on quorum sensing-regulated of sludge bulking and pointed out the main challenges faced by current research during the transition from laboratory research to engineering applications. This review could provide theoretical references for a deeper understanding of the regulatory role of quorum sensing in controlling sludge bulking and to promote the engineering application of targeted control strategies based on quorum sensing regulation.