[Nitrous oxide emission during denitrification for activated sludge acclimated with methanol as the organic carbon].

Denitrification of wastewater is one of the important sources of nitrous oxide (N2O). In this study, denitrifies were acclimated in a sequencing batch reactor with methanol and nitrate (NO3(-) -N) as the electron donor and acceptor, respectively. N2O emission during denitrification was examined both in typical cycles and in batch experiments under conditions of different electron acceptors, carbon/nitrogen (C/N) ratios and initial nitrite (NO2(-)-N) concentrations. With methanol as the organic carbon, the N2O emission was high with NO2(-)-N as the electron acceptor and the N2O emission was low with NO3(-) -N as the electron acceptor. The C/N ratios affected the emission of N2O by affecting activities of denitrifiers, and both the activity of denitrifiers and the emission of N2O decreased with decreasing C/N ratios. The N2O emission increased with increasing initial NO2(-) -N concentrations, and a certain range of NO2(-) -N concentrations enhanced the activity of denitrifiers. The N2O emission could be correlated very well with initial NO2(-) -N concentrations.