[Effects of DO concentration on N2O production during nitrification for treating domestic wastewater]

In order to reduce nitrous oxide (N2O) production from real wastewater and optimize the DO concentration and the aeration mode, nitrification efficiency and N2O production from nitrification treating domestic wastewater under difference DO concentrations were investigated using lab-scale SBR. The obtained results show energy consumption was saved at DO concentration of 0.4 mg L(-1), whereas, ammonia oxidation rate was very low. Ammonia oxidation rate was increased with DO increasing. N2O was produced during the nitrification for treating domestic wastewater with low ammonium concentration. N2O production at the DO concentration of 0.4 mg L(-1) and 0.9 mg L(-1) were 1.5 mg L(-1) and 1.6 mg L(-1), respectively. While N2O production at the DO concentration of 1.5 mg L(-1) and 2.0 mg L(-1) were 0.5 mg L 1)and 0.4 mg L-'(-1)respectively. When DO concentration increased above 1.5 mg L-'(-1)the ammonia oxidation rate increased slightly with N2 0O production sharply decreasing. Therefore, from the aspects of enhancing the efficiency of nitrogen removal with lower energy consumption and reducing N2 Oproduction, the optimal controlled DO concentration was 1.5 mg L-. -1)