絮体是高负荷厌氧氨氧化颗粒污泥反应器中氧化亚氮的主要来源：来自宏基因组学和分批培养实验的见解。
Flocs are the main source of nitrous oxide in a high-rate anammox granular sludge reactor: insights from metagenomics and fed-batch experiments.
机构信息
National Engineering Laboratory for Industrial Wastewater Treatment, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China.
National Engineering Laboratory for Industrial Wastewater Treatment, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China.
出版信息
Water Res. 2020 Nov 1;186:116321. doi: 10.1016/j.watres.2020.116321. Epub 2020 Aug 19.
Nitrous oxide (NO) emissions from anammox-based processes are well documented but insight into source of the NO emission in high-rate anammox granular sludge reactors (AGSR) is limited. In this study, metagenomics and fed-batch experiments were applied to investigate the relative contributions of anammox granules and flocs to NO production in a high-rate AGSR. Flocs, which constitute only 10% of total biomass contributed about 60% of the total NO production. Granules, the main contributor of nitrogen removal (95%), were responsible for the remaining ~40% of NO production. This result is inconsistent with reads-based analysis that found the gene encoding clade II type nitrous oxide reductase (nosZ) had similar abundances in both granules and flocs. Another notable trend observed was the relatively higher abundance of the gene for NO-producing nitrite reductase (nir) in comparison to the gene for the nitric oxide reductase gene (nor) in both granules and flocs, indicating nitric oxide (NO) may accumulate in the AGSR. This is significant since NO and NO pulse assays demonstrated that NO could lead to NO production from both granules and flocs. However, since anammox bacteria, which were shown to be in higher abundance in granules than in flocs, have the capacity to scavenge NO this provides a mechanism by which its inhibitory effects can be mitigated, limiting NO release from the granules, consistent with experimental observation. These results demonstrate flocs are the main source of NO emission in AGSR and provide lab-scale evidence that NO-dependent anammox can mitigate NO emission.
基于厌氧氨氧化的工艺的一氧化二氮（NO）排放已有大量记录，但对于高负荷厌氧氨氧化颗粒污泥反应器（AGSR）中 NO 排放的来源了解有限。在本研究中，应用宏基因组学和分批实验来研究高负荷 AGSR 中厌氧氨氧化颗粒和絮体对 NO 生成的相对贡献。虽然絮体仅占总生物量的10%，但贡献了约 60%的总 NO 生成量。颗粒是脱氮的主要贡献者（95%），负责剩余的约 40%的 NO 生成量。这一结果与基于读段分析的结果不一致，因为该结果发现编码 clade II 型一氧化二氮还原酶（nosZ）的基因在颗粒和絮体中的丰度相似。另一个值得注意的趋势是，与颗粒和絮体中的一氧化氮还原酶基因（nor）相比，产生 NO 的亚硝酸盐还原酶（nir）的基因相对丰度较高，表明在 AGSR 中可能会积累一氧化氮（NO）。这很重要，因为 NO 和 NO 脉冲测定表明，NO 可能导致颗粒和絮体都产生 NO。然而，由于被证明在颗粒中丰度高于絮体的厌氧氨氧化细菌有能力清除 NO，这为减轻其抑制作用提供了一种机制，限制了 NO 从颗粒中的释放，与实验观察结果一致。这些结果表明，絮体是 AGSR 中 NO 排放的主要来源，并提供了实验室规模的证据，表明依赖 NO 的厌氧氨氧化可以减轻 NO 排放。
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