ABSTRACT

Pyrene exerts toxic effects on methanogens during anaerobic digestion of sludge, thus affecting the efficiency of sludge treatment. This study evaluated the facilitated direct interspecific electron transfer (DIET) between bacteria and methanogens when bio-nano FeS or magnetic carbon is added into anaerobic reactors. Results showed that adding 200 mg/L bio-nano FeS or magnetic carbon clearly reduced the accumulation of short-chain fatty acids and avoided acidification during 25 days of anaerobic digestion. The methane productions were 98.38 L/kg total solid (TS) and 73.69 L/kg TS in the bio-nano FeS and magnetic carbon systems, respectively, which accelerated methane production by 58.1% and 33.4%, respectively, compared with the control system (40.26 L/kg TS). The pyrene removal rates reached 77.5% and 72.1% in the bio-nano FeS and magnetic carbon systems, whereas it was only 40.8% in the control system. Analysis of microbial community structure revealed that methanogens (e.g. Methanosarcina and Methanosaeta) and extracellular electron-transfer bacteria (e.g. Pseudomonas, Cloastridia, and Synergistetes) were enriched in the reactors added with bio-nano FeS or magnetic carbon. This result indicates that the addition of bio-nano FeS or magnetic carbon may promote the activity and growth of microorganisms to improve the efficiency of methane production and pyrene degradation by enhancing DIET.

摘要

芘在污泥厌氧消化过程中对产甲烷菌产生毒性作用，从而影响污泥处理效率。这项研究评估了当生物纳米 FeS 或磁性碳加入厌氧反应器时细菌和产甲烷菌之间促进的直接种间电子转移 (DIET)。结果表明，在 25 天的厌氧消化过程中，添加 200 mg/L 的生物纳米 FeS 或磁性碳明显减少了短链脂肪酸的积累并避免了酸化。在生物纳米 FeS 和磁碳系统中，甲烷产量分别为 98.38 L/kg 总固体 (TS) 和 73.69 L/kg TS，与对照系统相比，甲烷产量分别提高了 58.1% 和 33.4% (40.26 升/公斤 TS)。芘去除率分别达到77.5%和72%。在生物纳米 FeS 和磁性碳系统中为 1%，而在控制系统中仅为 40.8%。微生物群落结构分析表明，产甲烷菌（例如Methanosarcina和Methanosaeta）和细胞外电子转移细菌（例如假单胞菌、梭菌和协同菌）在添加生物纳米 FeS 或磁性碳的反应器中富集。该结果表明，添加生物纳米FeS或磁性碳可以促进微生物的活性和生长，通过增强DIET来提高甲烷产生和芘降解的效率。