Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems
Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems
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DOI：
10.1042/bst20110717
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发表时间：
2011-12-01
影响因子：
3.9
通讯作者：
van Loosdrecht, Mark C. M.
中科院分区：
文献类型：
--
作者：
Chandran, Kartik;Stein, Lisa Y.;van Loosdrecht, Mark C. M.
化学自养型 AOB（氨氧化细菌）是自然系统和工程系统中微生物氮循环的重要组成部分。在特定条件下，包括从缺氧条件到有氧条件的转变和/或过量的氨负荷，以及高浓度亚硝酸盐 (NO2-) 的存在，这些细菌也被证明会产生一氧化氮 (NO) 和一氧化二氮 (N2O) 气体。本质上，在非限制性底物浓度（氨和 O-2）存在下的氨氧化与 N2O 的产生有关。导致这种情况的特殊情况是缺氧和好氧条件之间的周期性切换，这在工程脱氮系统中相当常见。特别是，从缺氧条件中恢复而不是施加缺氧条件已被证明会导致 N2O 的产生。然而，迄今为止，应用工程的观点在很大程度上忽略了硝化作用对废水处理厂温室气体清单中氧化亚氮排放的贡献。最近的现场规模测量表明，与硝化相关的 N2O 排放量通常远远高于异养反硝化作用的排放量。在本文中，在与工程脱氮系统特别相关的条件下，对可能有助于 AOB 产生 NO 和 N2O 的代谢途径进行了概念性重建。总而言之，重建的路径、现场和实验室规模的结果表明，实现低废水氮浓度的工程设计也可以最大限度地减少气态氮排放。
Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO2-) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N2O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O-2) is associated with N2O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N2O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N2O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N2O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N2O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.