Enhancement of electron transfer via magnetite in nitrite-dependent anaerobic methane oxidation system

• Published in: Journal of environmental management Vol. 357; p. 120843
• Main Authors: Shi, Tianjing, Sun, Dezhi, Dang, Yan, Xue, Yiting, Liu, Xinying
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2024
• Subjects: Electron transfer; Magnetite; Methane oxidation; n-DAMO; Nitrite reduction; Electron transfer; n-DAMO; Magnetite; Methane oxidation; Nitrite reduction
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.120843

Nitrite-dependent anaerobic methane oxidation (n-DAMO) is a novel denitrification process that simultaneously further removes and utilizes methane from anaerobic effluent from wastewater treatment plants. However, the metabolic activity of n-DAMO bacteria is relative low for practical application. In this study, conductive magnetite was added into lab-scale sequencing batch reactor inoculated with n-DAMO bacteria to study the influence on n-DAMO process. With magnetite amendment, the nitrogen removal rate could reach 34.9 mg N·L−1d−1, nearly 2.5 times more than that of control group. Magnetite significantly facilitated the interspecies electron transfer and built electrically connected community with high capacitance. Enzymatic activities of electron transport chain were significantly elevated. Functional gene expression and enzyme activities associated with nitrogen and methane metabolism had been highly up-regulated. These results not only propose a useful strategy in n-DAMO application but also provide insights into the stimulating mechanism of magnetite in n-DAMO process. [Display omitted] •Performance of n-DAMO system amended with magnetite was notably enhanced.•Activities of ETS and electron transfer related enzyme were improved by magnetite.•Magnetite promotes the proliferation rather than abundance of n-DAMO bacteria.•Increased diversities of community in magnetite SBR aid to treat high NLR.•Genes/enzymes for methane and nitrogen metabolism are up-regulated by magnetite.