Undesirable effects of exogenous N-acyl homoserine lactones on moving bed biofilm reactor treating medium-strength synthetic wastewater

Abstract Exogenous AHLs are gradually reported to facilitate biofilm growth, however, whether they play a universal role in promoting biofilm formation and pollutants removal remains to be investigated. The pollutant removal, biofilm properties, microbial community and the distribution of AHLs were investigated in three lab-scale MBBRs by continuous dosing 100 nM N-Hexanoyl-L-homoserine lactone (C6-HSL) and N-Octanoyl-L-homoserine lactone (C8-HSL) in synthetic wastewater under normal nutrition (40 mg/L NH4+-N with C/N = 20). Results showed that adding AHLs didn't affect organics removal and exogenous C6-HSL even significantly suppressed NH4+-N removal by 0.44–20.29% after 16 days (p