Comparative effects of ammonium nitrogen on perchlorate degradation performance under heterotrophic condition with different carbon sources.

Perchlorate (ClO) mainly exists in the form of ammonium perchlorate in industrial production. However, the degradation mechanisms of different concentrations of ammonium nitrogen (NH-N) and ClO mixed pollutants in the environment are not well understood. This study aims to explore the potential of different types of carbon sources for ClO and NH-N biodegradation. Experimental results showed that the concentration and type of carbon sources are decisive to simultaneous removal of NH-N and ClO. Under condition of C(COD)/C(ClO) ratio of 21.15 ± 4.40, the simultaneously removal efficiency of ClO and NH-N in acetate (Ace) was relatively higher than that in methanol (Met). C(NH-N)/C(ClO) ratio of 9.66 ± 0.51 and C(COD)/C(ClO) ratio of 2.51 ± 0.87 promoted ClO reduction in glucose-C (Glu-C). However, high concentration of Glu could cause pH decrease (from 7.57 to 4.59), thereby inhibiting ClO reduction. High-throughput sequencing results indicated that Proteobacteria and Bacteroidetes have made a major contribution to the simultaneous removal of NH-N and ClO. They are two representative bacterial phyla for participating in both ClO reduction and denitrification. Notably, the abundance of main ClO degrading bacteria (such as Proteobacteria, Chloroflexi, and Firmicutes) significantly increased by 528.57 % in Glu-C. It can be inferred that the concentration of carbon source and NH-N were the most important factors determining the removal efficiency of ClO by influencing changes in the core microbial community. This study will provide new techniques and mechanistic insights for the simultaneous removal of mixed ClO and nitrogen pollutants, which can also provide theoretical support for innovation in future biological treatment processes.