Nitrate or nitrite-dependent anaerobic methane oxidation (n-DAMO) is a microbial process that links carbon and nitrogen cycles as a methane sink in many natural environments. This study demonstrates, for the first time, that the nitrite-dependent anaerobic methane oxidation (nitrite-DAMO) process can be stimulated in sewer systems under continuous nitrate dosing for sulfide control. In a laboratory sewer system, continuous nitrate dosing not only achieved complete sulfide removal, but also significantly decreased dissolved methane concentration by ∼50 %. Independent batch tests confirmed the coupling of methane oxidation with nitrate and nitrite reduction, revealing similar methane oxidation rates of 3.68 ± 0.5 mg CH L h (with nitrate as electron acceptor) and 3.57 ± 0.4 mg CH L h (with nitrite as electron acceptor). Comprehensive microbial analysis unveiled the presence of a subgroup of the NC10 phylum, namely (n-DAMO bacteria that couples nitrite reduction with methane oxidation), growing in sewer biofilms and surface sediments with relative abundances of 1.9 % and 1.6 %, respectively. In contrast, n-DAMO archaea that couple methane oxidation solely to nitrate reduction were not detected. Together these results indicated the successful enrichment of n-DAMO bacteria in sewerage systems, contributing to approx. 64 % of nitrite reduction and around 50 % of dissolved methane removal through the nitrite-DAMO process, as estimated by mass balance analysis. The occurrence of the nitrite-DAMO process in sewer systems opens a new path to sewer methane emissions.

中文翻译：

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通过在下水道中添加硝酸盐引起的亚硝酸盐-DAMO 过程减少甲烷排放


硝酸盐或亚硝酸盐依赖性厌氧甲烷氧化 (n-DAMO) 是一种微生物过程，在许多自然环境中作为甲烷汇将碳和氮循环联系起来。这项研究首次证明，在连续投加硝酸盐以控制硫化物的情况下，可以在下水道系统中刺激依赖亚硝酸盐的厌氧甲烷氧化（亚硝酸盐-DAMO）过程。在实验室下水道系统中，连续投加硝酸盐不仅可以完全去除硫化物，而且还可以将溶解甲烷浓度显着降低约 50%。独立批次测试证实了甲烷氧化与硝酸盐和亚硝酸盐还原的耦合，揭示了类似的甲烷氧化速率，分别为 3.68 ± 0.5 mg CH·L·h（硝酸盐作为电子受体）和 3.57 ± 0.4 mg CH·L·h（亚硝酸盐作为电子受体） 。综合微生物分析揭示了 NC10 门的一个亚群的存在，即（将亚硝酸盐还原与甲烷氧化结合的 n-DAMO 细菌），在下水道生物膜和表面沉积物中生长，相对丰度分别为 1.9% 和 1.6%。相比之下，未检测到仅将甲烷氧化与硝酸盐还原耦合的 n-DAMO 古菌。这些结果共同表明 n-DAMO 细菌在污水处理系统中成功富集，贡献了约。根据质量平衡分析估计，通过亚硝酸盐-DAMO 工艺，亚硝酸盐减少了 64%，溶解甲烷去除了约 50%。下水道系统中亚硝酸盐-DAMO过程的出现，为下水道甲烷排放开辟了一条新途径。