Synergistic removal performance and mechanism in denitrification system under phenol stress

ABS T R A C T Based on the principle of heterotrophic denitrification, the synergistic removal mechanism of phenol and NO3--N in denitrification system under phenol stress was investigated. The denitrification process with phenol as the only carbon source was successfully achieved by running the UASB reactor for 119 days, which had excellent phenol and NO3--N removal efficiency (over 99.5%). Results showed that phenol stress enhanced the ATP level, key enzyme activities to increase denitrification and phenol degradation. Phenol stress also stimulated improvement of cell membrane permeability, which led to the increase of electron transport system activity. Meanwhile, phenol stress promoted the secretion of N-acylhomoserine lactones (AHLs), which increased bacterial activity by modulating EPS to mitigate the external environmental shock. Besides, AHLs-mediated quorum sensing (QS) might regulated the changes of microbial structural, resulting in the optimization of microbial communities within the whole denitrification system. Therefore, a synergistic removal mechanism was proposed to elucidate the excellent performance of the denitrification system under phenol stress. This work provided serviceable information for treatment of high concentration phenol wastewater and the synergistic removal mechanism.