Effect of electron competition on N2O production during domestic sewage biological denitrification process

Currently, most studies showed that low COD/N ratio was a key factor leading to N2O production during sewage denitrification process, however, a few studies found that no N2O accumulation at low COD/N. In this study, sequencing bath reactors(SBRs) were operated by feeding with real domestic sewage to investigate the reduction of different electronic receptors(NO3-, NO2-, N2O and their combinations)under various COD/N ratios and to explore the mechanism of N2O production during denitrification process. The experimental results show that: (1)Electron competition occurs among nitrate reductase, nitrite reductase, NO reductase, and N2O reductase in biological denitrication process; (2)Electron competition among the 4 nitrogen reductases could occur under both carbon limiting and carbon abundant conditions; (3)Increasing COD/N ratio can improve the reduction and consumption rate of the electron acceptors, however, accumulation levels of N2O depends on the electron distribution in the N2O reductase rather than the level of COD/N. ©, 2015, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.