Response of aerobic sludge to AHL-mediated QS: Granulation, simultaneous nitrogen and phosphorus removal performance

Abstract The effects of different species and concentrations’ signal molecules on aerobic activated sludge system were investigated through batch experiments. Results showed that the fastest NH4+-N oxidization rate and the most extracellular polymeric substances (EPS) secretion were obtained by adding 5 nmol/L N-hexanoyl-L-homoserine lactone (C6-HSL) into the aerobic activated sludge. Further study investigated the correlation among N-acyl-homoserine lactones-mediated quorum sensing (AHLs-mediated QS), nutrient removal performances and microbial communities with the long-term addition of 5 nmol/L C6-HSL. It was found that C6-HSL-manipulation could enhance the stability and optimize the decontamination performance of aerobic granular sludge (AGS) system. Microbial compositions considerably shifted with long-term C6-HSL-manipulation. Exogenous C6-HSL-manipulation inhibited quorum quenching-related (QQ-related) activities and enhanced QS-related activities during the stable period. The proposed C6-HSL-manipulation might be a potential technology to inhibit the growth of harmful bacteria in AGS, which could provide a theoretical foundation for the realization of more stable biological wastewater treatments.