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Nitrogen removal, nitrous oxide emission and microbial community in sequencing batch and continuous-flow intermittent aeration processes

Sun, Yuepeng;Xin, Liwei;Wu, Guangxue;Guan, Yuntao

  • Received : 2018.04.11
  • Accepted : 2018.06.20
  • Published : 2019.03.31

Abstract

Nitrogen removal, nitrous oxide ($N_2O$) emission and microbial community in sequencing batch and continuous-flow intermittent aeration processes were investigated. Two sequencing batch reactors (SBRs) and two continuous-flow multiple anoxic and aerobic reactors (CMRs) were operated under high dissolved oxygen (DO) (SBR-H and CMR-H) and low DO (SBR-L and CMR-L) concentrations, respectively. Nitrogen removal was enhanced under CMR and low DO conditions (CMR-L). The highest total inorganic nitrogen removal efficiency of 91.5% was achieved. Higher nitrifying and denitrifying activities in SBRs were observed. CMRs possessed higher $N_2O$ emission factors during nitrification in the presence of organics, with the highest $N_2O$ emission factor of 60.7% in CMR-L. SBR and low DO conditions promoted $N_2O$ emission during denitrification. CMR systems had higher microbial diversity. Candidatus Accumulibacter, Nitrosomonadaceae and putative denitrifiers ($N_2O$ reducers and producers) were responsible for $N_2O$ emission.

Keywords

Continuous-flow multiple anoxic and aerobic reactor;Intermittent aeration process;Nitrogen removal;Nitrous oxide;Sequencing batch reactor