Effects of 2,4,6-trichlorophenol on simultaneous nitrification and denitrification: Performance, possible degradation pathway and bacterial community structure

This study aimed to investigate the effect of different 2,4,6-trichlorophenol (TCP) concentrations on the performance of simultaneous nitrification and denitrification processes established in a sequential batch biofilm reactor. And the degradation and the possible degradation pathway of 2,4,6-TCP and microbial community structure were also explored. Results indicated that 2,4,6-TCP inhibited the nitrification with the decrease in ammonium nitrogen removal. However, 2,4,6-TCP had different effects on denitrification. Nitrate accumulation showed the tendency to decrease first and then increase, whilst nitrite accumulation showed the opposite with a small change. The adaptation and recovery time of 25 mg/l 2,4,6-TCP was longest. In addition, the process had a good degradation effect on 2,4,6-TCP. Comparing the degradation of 2,4,6-TCP under different concentrations, the result showed that 2,4,6-TCP was mainly reduced to 2,4-dichlorophenol. With the increase in 2,4,6-TCP concentration, the differences in the bacterial community in the reactor were significant.