Abstract: In this paper, exogenous N-acyl-homoserine lactones(AHLs) were added to a sequencing batch reactor(SBR) to promote quorum sensing(QS). The effects of AHLs with different carbon chain lengths(C4-L-HSL, C6-L-HSL, and C8-L-HSL) and different substituent structures(C6-L-HSL, C6-DL-HSL, and 3-oxo-C6-HSL) on the SBR system's ability to cope with high salinity stress and the changes in sludge properties were systematically investigated. Experiments showed that under 5% and 8% salinity stress for the first ten days, compared to 2% salinity, the average $ NH_{4}^{+}-N $ removal rate decreased by 6.06% and 18.32%, respectively, with significant $ NO_{2}^{-}-N $ accumulation in the effluent. Among all groups, the group with added 3-oxo-C6-HSL best alleviated salinity stress, reducing the $ NO_{2}^{-}-N $ accumulation peak by 39.54% and 58.09% under 5% and 8% salinity, respectively, and showed remarkable improvement in $ NH_{4}^{+}-N $ removal and $ NO_{2}^{-}-N $ accumulation. Moreover, the analysis of extracellular polymeric substances(EPS) showed that the protein and polysaccharide mass concentrations in the experimental group were increased by 14.4%-38.4% and 26.0%-41.0%, respectively. The $ UV_{254} $ data of EPS showed that the content of large molecular organic matter and aromatic compounds in the experimental group was higher, indicating that the metabolic pathways in the experimental group were more diverse and the products were more complex. Analysis of the microbial community indicated that Proteobacteria was the dominant phylum in the system. community indicated that Proteobacteria was the dominant phylum in the system.
Keywords: quorum sensing(QS); N-acyl-homoserine lactones(AHLs); nitrification; salinity stress