Abstract
Nitrous oxide (N2O), a greenhouse gas, can be released from both nitrification and denitrification during wastewater treatment. In this study, N2O emission under three aerobic conditions (aeration rates of 100, 250, and 500 ml/min, respectively) were examined, one with only endogenous heterotrophic activities, one with heterotrophic activities using internal stored organic carbon (polyhydroxybutyrate, PHB), and the other with heterotrophic activities using external organic carbon (acetate). Under the condition with PHB as the organic carbon, the released N2O-N to the produced oxidized nitrogen (NOx-N) was 10.0% at 100 ml/min, 3.6% at 250 ml/min, and 0.6% at 500 ml/min. Under the condition with acetate as the organic carbon, the released N2O-N to the produced NOx-N was 14.5% at 100 ml/min, 4.1% at 250 ml/min, and 0.7% at 500 ml/min. Under the condition without organic carbon, the released N2O-N to the produced NOx-N was 0.18% at 100 ml/min, 0.20% at 250 ml/min, and 0.41% at 500 ml/min. These results showed that (i) heterotrophic activities affected N2O emission during nitrification significantly; (ii) there was no significant difference in N2O emission during nitrification affected by heterotrophic activities using internal or external organic carbon; and (iii) a high aeration rate with a high dissolved oxygen concentration reduced N2O emission significantly under aerobic conditions.
Acknowledgments
This research was supported by the National Natural Science Foundation of China (No. 51108242) and Shenzhen Science and Technology Development Funding-Fundamental Research Plan (No. JC201006030878A).
Notes
Presented at the 13th International Conference on Environmental Science and Technology (CEST 2013), 5–7 September 2013, Athens, Greece