Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor
Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor
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DOI：
10.1016/j.watres.2016.06.034
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发表时间：
2016-10-01
期刊：
影响因子：
12.8
通讯作者：
Okabe, Satoshi
中科院分区：
文献类型：
--
作者：
Ali, Muhammad;Rathnayake, Rathnayake M. L. D.;Okabe, Satoshi
基于实时 N2O 监测、N2O 同位素组成分析以及颗粒生物质中 N2O 生产率和微生物种群空间分布的原位分析等多种方法，研究了信号级亚硝化-厌氧氨氧化序批式反应器 (SBR) 中一氧化二氮 (N2O) 的生产途径。 N2O排放率在运行周期初始阶段较高，并随着NH4+浓度的降低而逐渐降低。 N2O 的平均排放量分别为输入氮负荷和去除氮的 0.98 +/- 0.42% 和 135 +/- 0.72%。 N2O同位素组成分析表明，N2O同样通过NH2OH氧化和NO2还原途径产生，尽管N2O还原和/或厌氧氨氧化NO2产生的影响未知。然而，N2O同位素分析无法区分硝化反硝化和异养反硝化在NO2还原途径中的相对贡献。因此，应用各种原位技术（例如微传感器测量和 FISH（荧光原位杂交）分析）来进一步识别 N2O 产生者。微传感器测量显示，大约 70% 的 N2O 是在氧化表面区域产生的，该区域主要是硝化细菌。因此，NH2OH 氧化和硝化菌（硝化菌反硝化）还原 NO2 可能是好氧区 N2O 产生的原因。其余的 N2O（约 30%）是在厌氧氨氧化细菌为主的缺氧区产生的，这可能表明共存的假定异养反硝化菌和其他一些未知途径（包括厌氧氨氧化过程的可能性）对 NO2 的还原作用解释了厌氧 N2O 的产生。需要进一步研究以确定厌氧 N2O 的生产途径。我们的多边方法有助于定量研究 N2O 生产途径的相对贡献。充分了解 N2O 生产的关键途径对于制定减少生物脱氮过程中 N2O 排放的策略至关重要。 (C) 2016 Elsevier Ltd. 保留所有权利。
Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4+ concentration. The average emission of N2O was 0.98 +/- 0.42% and 135 +/- 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2- reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox NO2 production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifiler denitrification and heterotrophic denitrification in the NO2- reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that aproximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifler-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2- reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the key N2O production pathways is essential to establish a strategy to mitigate N2O emission from biological nitrogen removal processes. (C) 2016 Elsevier Ltd. All rights reserved.