Regulating performance of CANON process via adding external quorum sensing signal molecules in membrane bioreactor.

ABSTRACT

In this study, the regulation effect of the external quorum sensing signals, N-dodecanoyl homoserine lactone (C12-HSL) on CANON process were investigated in a membrane bioreactor. C12-HSL significantly enhanced the aerobic ammonia-oxidizing bacteria and improved the ammonia monooxygenase activity to 0.134 from 0.076 µg NO2--N mg-1 protein min-1, while suppressed anaerobic ammonia-oxidizing bacteria and limited the TN removal to 0.07 from 0.22 kg m-3 d-1. Key enzymes synthesis were enhanced during the operation without C12-HSL addition, enabling the resistance of CANON system to high C12-HSL. As a result, the hydroxylamine oxidoreductase and nitrite reductase activity reached 35.9 EU g-1 SS and 1.28 µg NO2--N mg-1 protein min-1, respectively; Nitrosomonas and Candidatus Kuenenia, with the abundance as 12.5 % and 22.9 %, cooperatively contributed to the TN removal, which maintained at 0.19 kg m-3 d-1. C12-HSL was profitable for aerobic ammonia oxidation, which could be adopted for regulating the nitrite production rate.