Regulation mechanism and resistant strain based bioaugmentation of anammox consortia in response to triclocarban

Triclocarban was emerging pollutants of increasing concern in wastewater treatment process, posing a high risk to ecological and human health. Anaerobic ammonium oxidation (anammox) process was a potential emerging and efficient biological wastewater treatment technology, which converted NH 4 + and NO 2 − into N 2 under anaerobic condition. After the long-term monitoring and analysis of anammox consortia responses to different concentrations of triclocarban, the bioaugmentation strategy based on resistant bacteria inoculation was proposed in this study. Nitrogen removal performance and anammox sludge activity were barely affected by 50 μg L −1 triclocarban, but significantly inhibited by 200 μg L −1 triclocarban. Meanwhile, the extracellular polymeric substances and reactive oxygen species production significantly increased, and cell damage of anammox consortia were also observed. Batch assays revealed the obvious adsorption of triclocarban onto anammox sludge, while molecular docking simulation illustrated the potential binding area of triclocarban and protein molecules. The density functional theory calculations indicated that triclocarban was probably degraded via hydrolysis or dechlorination. The richness and diversity of the anammox consortia decreased under triclocarban exposure. In particular, the relative abundance of Candidatus Kuenenia gradually decreased from 13.1 % to 3.9 %, showing a concentration-dependent manner. The abundance of nitrogen removal-related functional genes also exhibited a downward trend. In addition, three triclocarban-resistant strains were isolated from various aquatic environments, identified as Stenotrophomonas acidaminiphila , Achromobacter mucicolens and Pseudomonas mosselii . They could maintain the high ATP level, NADH content and proportion of viable bacteria under triclocarban stress. Their triclocarban removal efficiency reached 87.5 % in batch experiments. This resistant bacteria-based bioaugmentation is expected to achieve the quick startup and stabilization of anammox system to the stress of non-antibiotic antimicrobial agents, accelerating the widespread application of anammox process in such wastewater treatment.