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Carbon-Restricted Anoxic Zone as an Overlooked Anammox Hotspot in Municipal Wastewater Treatment Plants
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2023-12-14 , DOI: 10.1021/acs.est.3c07017
Qi Zhao 1 , Liang Zhang 1 , Jianwei Li 1 , Tipei Jia 1 , Liyan Deng 1 , Qiyu Liu 1 , Jun Sui 2 , Qiong Zhang 1 , Yongzhen Peng 1
Affiliation  

The anoxic zone serves as the core functional unit in municipal wastewater treatment plants (MWWTPs). Unfortunately, in most cases, the downstream range of the anoxic zone is severely lacking in available organic carbon and thus contributes little to the removal of nutrients. This undesirable range is termed the “carbon-restricted anoxic zone”, representing an insurmountable drawback for traditional MWWTPs. This study uncovers a previously overlooked role for the carbon-restricted anoxic zone: a hotspot for anaerobic ammonium oxidation (anammox). In a continuous-flow pilot-scale plant treating municipal wastewater (55 m3/d), virgin biocarriers were introduced into the carbon-restricted anoxic zone (downstream 25% of the anoxic zone with BOD5 of 5.9 ± 2.3 mg/L). During the 517-day monitoring, anammox bacteria highly self-enriched within the biofilms, with absolute and relative abundance reaching up to (9.4 ± 0.1) × 109 copies/g-VSS and 6.17% (Candidatus Brocadia), respectively. 15N isotopic tracing confirmed that anammox overwhelmingly dominated nitrogen metabolism, responsible for 92.5% of nitrogen removal. Following this upgrade, the contribution ratio of the carbon-restricted anoxic zone to total nitrogen removal increased from 9.2 ± 4.1% to 19.2 ± 4.2% (P < 0.001), while its N2O emission flux decreased by 84.5% (P < 0.001). These findings challenge stereotypes about the carbon-restricted anoxic zone and highlight the multiple environmental implications of this newfound anammox hotspot.

中文翻译:


限碳缺氧区是城市污水处理厂中被忽视的厌氧氨氧化热点



缺氧区是城市污水处理厂(MWWTP)的核心功能单元。不幸的是,在大多数情况下,缺氧区的下游范围严重缺乏可用的有机碳,因此对营养物的去除贡献甚微。这个不理想的范围被称为“碳限制缺氧区”,这是传统MWWWTPs无法克服的缺点。这项研究揭示了碳限制缺氧区以前被忽视的作用:厌氧氨氧化(anammox)的热点。在处理城市废水的连续流中试规模工厂(55 m 3 /d)中,将原始生物载体引入碳限制缺氧区(缺氧区下游 25%,BOD 5为 5.9 ± 2.3 mg/L) 。在517天的监测中,厌氧氨氧化菌在生物膜内高度自我富集,绝对丰度和相对丰度分别达到(9.4±0.1)×10 9 个拷贝/g-VSS和6.17%( Candidatus Brocadia)。 15 N同位素示踪证实厌氧氨氧化绝对主导氮代谢,负责92.5%的氮去除。此次升级后,限碳缺氧区对总氮去除率的贡献率由9.2±4.1%提高到19.2±4.2%( P < 0.001),而N 2 O排放通量下降了84.5%( P < 0.001)。 )。这些发现挑战了关于碳限制缺氧区的刻板印象,并强调了这个新发现的厌氧氨氧化热点的多重环境影响。
更新日期:2023-12-14
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