Abstract:Biological nitrogen removal is one of the important links in the nitrogen cycle of the earth dominated by microorganisms, mainly including nitrification, denitrification, and anaerobic ammonia oxidation (anammox). Under the combined action of microorganisms, organic nitrogen and ammonia nitrogen in sewage are transformed into nitrogen through a series of actions in sewage. The cost-effective and environment-friendly treatment has been widely applied all over the world. Quorum sensing (QS) is mediated by signal molecules to regulate the behaviors of microorganisms by changing the density of bacteria and the surrounding environment. Many studies have confirmed that the regulation of QS signal molecules has application potential in biological nitrogen removal. This paper introduced various types of signal molecules, summarized the application and detection methods of various signal molecules from the aspects of genomics and practical application, and introduced in detail the role of acyl homoserine lactones (AHLs) in biological nitrogen removal. However, the deficiency was that the study of signal molecules only stayed in the laboratory stage and only studied the effect of a single signal molecule on biological nitrogen removal. In the future, signal molecules can be applied to actual sewage to study the interaction of multiple signal molecules and QS phenomenon among multiple microorganisms.