Long-Term Exposure of Triclocarban to the Performance of Partial Nitrification Process: Its Fate and Microbial Dynamics

Abstract

Triclocarban (TCC), as an antibacterial agent, is widely used in personal care products. Large amount of TCC utilization led to its frequent detection in sewage. The present study aimed to investigate the effect of TCC on the partial nitrification (PN) process and its interaction with nitrifiers via the nitrite accumulation, TCC degradation path, and microbial community response at long-term exposure. The results showed that the accumulation of NO2--N was observed after a long period of operation. Interestingly, the concentration of NO3--N was also decreased. Moreover, long-term exposure of TCC increased the activity of ammonia monooxygenase (AMO) and increased the secretion of extracellular polymeric substances (EPS) to resist the toxicity of TCC. Mass balance analysis showed that the biodegradation efficiency of TCC adsorbed in sludge increased from 4.30% to 70.57%. Meanwhile, abundance of AOB with long-term exposure of TCC increased, while abundance of NOB decreased. In addition, the abundance of TCC degrading bacteria (i.e., Sphingomonas) also increased. This indicated that TCC inhibited NOB and enriched TCC-degrading bacteria. This work contributed to a better understanding of the effects of TCC on wastewater treatment systems, which provided a basis for the comprehensive management of TCC in the future.

Keywords: nitrogen removal, partial nitrification, Emerging contaminants, Triclocarban