Effects of ferroferric oxide on propionate methanogenesis in sequencing batch reactors: Microbial community structure and metagenomic analysis
2022
Wang, Zifan | Zhang, Weikang | Xing, Xiujuan | Li, Xiu | Zheng, Derui | Bao, Huanyu | Xing, Lizhen
This study investigated the effects of ferroferric oxide (Fe₃O₄) on propionate methanogenesis in anaerobic sequencing batch reactor (ASBR). Compared to ASBRC (without Fe₃O₄ addition), the addition of 10 g/L Fe₃O₄ (ASBRFₑ) decreased the maximum methane production rate by 69.6 % when propionate was used as the sole substrate. The addition of Fe₃O₄ reduced the contents of humic substances, riboflavin and nicotinamide adenine dinucleotide in extracellular polymeric substances. Therefore, Fe₃O₄ inhibited interspecies electron transfer of microorganisms through electronic mediators. Microbial community analysis revealed that Fe₃O₄ addition increased the relative abundance of acetate oxidizing bacterium (Mesotoga), but decreased the abundance of hydrogenotrophic methanogen (Methanobacterium). Further metagenomics analysis indicated that Fe₃O₄ increased the abundance of acetate oxidation genes and decreased that of hydrogenotrophic methanogenesis, quorum sensing and V/A-type ATPase genes. Thus, Fe₃O₄ reduced propionate methanogenesis during anaerobic digestion. The overall results indicate that Fe₃O₄ addition inhibits methanogenesis for treatment of propionate-contaminated wastewater in ASBR.
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