Denitrification synergized with ANAMMOX for the anaerobic degradation of benzene: performance and microbial community structure

To evaluate the effect of anaerobic ammonium oxidation (ANAMMOX) on benzene degradation under denitrification, a sequencing batch reactor (SBR) under denitrification synergized with ANAMMOX (SBR-DenAna) for benzene degradation was established by inoculating anaerobic ammonium-oxidizing bacteria (AnAOB) into a SBR under denitrification reactor (SBR-Den) for benzene degradation. The average rate of benzene degradation and the maximum first-order kinetic constant in SBR-DenAna were 2.34- and 1.41-fold those in SBR-Den, respectively, indicating that ANAMMOX improved the degradation of benzene under denitrification synergized with ANAMMOX. However, the average rate of benzene degradation decreased by 35% in the denitrification-ANAMMOX synergistic reactor when 10 mg N L-1 NO2- was added; the rate recovered once NO2- was depleted, indicating that ANAMMOX might detoxify NO2-. Results from high-throughput sequencing analysis revealed that Azoarcus within the family Rhodocyclaceae might be associated with benzene degradation in the two SBRs. AnAOB affiliated with the family Candidatus Brocadiaceae were just detected in SBR-DenAna.