Advanced Water Management Centre, The University of Queensland, St Lucia 4072, Australia.
Water Res. 2011 Nov 15;45(18):5934-44. doi: 10.1016/j.watres.2011.08.055. Epub 2011 Sep 7.
Ammonia-oxidising bacteria (AOB) are a major contributor to nitrous oxide (N(2)O) emissions during nitrogen transformation. N(2)O production was observed under both anoxic and aerobic conditions in a lab-scale partial nitritation system operated as a sequencing batch reactor (SBR). The system achieved 55 ± 5% conversion of the 1g NH(4)(+)-N/L contained in a synthetic anaerobic digester liquor to nitrite. The N(2)O emission factor was 1.0 ± 0.1% of the ammonium converted. pH was shown to have a major impact on the N(2)O production rate of the AOB enriched culture. In the investigated pH range of 6.0-8.5, the specific N(2)O production was the lowest between pH 6.0 and 7.0 at a rate of 0.15 ± 0.01 mg N(2)O-N/h/g VSS, but increased with pH to a maximum of 0.53 ± 0.04 mg N(2)O-N/h/g VSS at pH 8.0. The same trend was also observed for the specific ammonium oxidation rate (AOR) with the maximum AOR reached at pH 8.0. A linear relationship between the N(2)O production rate and AOR was observed suggesting that increased ammonium oxidation activity may have promoted N(2)O production. The N(2)O production rate was constant across free ammonia (FA) and free nitrous acid (FNA) concentrations of 5-78 mg NH(3)-N/L and 0.15-4.6 mg HNO(2)-N/L, respectively, indicating that the observed pH effect was not due to changes in FA or FNA concentrations.
氨氧化细菌（AOB）是氮转化过程中一氧化二氮（N2O）排放的主要贡献者。在实验室规模的部分硝化系统中，作为序批式反应器（SBR）运行时，在缺氧和有氧条件下都观察到了 N2O 的产生。该系统实现了将合成厌氧消化液中 1g NH4+-N/L 的 55±5%转化为亚硝酸盐。N2O 排放因子为铵转化的 1.0±0.1%。pH 值对富集培养的 AOB 的 N2O 产生速率有重大影响。在所研究的 6.0-8.5 pH 值范围内，在 pH 值为 6.0-7.0 之间，N2O 的比产生速率最低，为 0.15±0.01mg N2O-N/h/g VSS，但随着 pH 值的增加，在 pH 值为 8.0 时达到最大，为 0.53±0.04mg N2O-N/h/g VSS。同样的趋势也观察到了比氨氧化速率（AOR），最大 AOR 出现在 pH 值为 8.0。观察到 N2O 产生速率与 AOR 之间存在线性关系，表明增加的铵氧化活性可能促进了 N2O 的产生。在 FA（游离氨）和 FNA（游离亚硝酸）浓度分别为 5-78mg NH3-N/L 和 0.15-4.6mg HNO2-N/L 时，N2O 产生速率保持不变，表明观察到的 pH 值效应不是由于 FA 或 FNA 浓度的变化引起的。
