Nitrogen removal and nitrous oxide emission from a step-feeding multiple anoxic and aerobic process

摘要

The multiple anoxic and aerobic (AO) process is an advanced biological nitrogen-removal process, and nitrous oxide (N2O) emission might affect its sustainable application. Nitrogen removal and N2O emission in a step-feeding multiple AO sequencing batch reactor (SBRS) was examined, in comparison with a one-feeding sequencing batch reactor (SBRO). Nitrogen removal was enhanced by 12.6% in SBRS compared to the removal percentage of 75.8% in SBRO. Activated sludge in SBRs possessed a higher N2O emission factor during nitrification, denitrification and simultaneous nitrification and denitrification (SND) than in SBRO. A high N2O emission factor was observed during SND in both reactors, with the emission factor of 4.38% in SBRS and 4.66% in SBRO. More N2O emission occurred in the presence of nitrite. Bacteroidetes and Proteobacteria dominated in both SBRS and SBRO. A similar abundance of Thauera, Dechloromonas and Zoogloea possible for denitrification was observed in SBRS and SBRO. Moreover, nosZ from Proteobacteria dominated in both SBRS and SBRO, with dominating genus of Acidovorax, Ralstonia, Thauera and Marinobacter.