Thiosulfate/FeCl3 pre-treatment enhances short-chain fatty acid production and mitigates H2S generation during anaerobic fermentation of waste activated sludge: Performance, microbial community and ecological analyses

• Published in: Bioresource technology Vol. 398; p. 130548
• Main Authors: Cheng, Boyi, Zhang, Da, Lin, Qingshan, Zhou, Lichang, Jiang, Jinqi, Bi, Xinqi, Jiang, Wei, Zan, Feixiang, Wang, Zongping, Chen, Guanghao, Guo, Gang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2024
• Subjects: Anaerobic fermentation; Ferric chloride; Hydrogen sulfide; Short-chain fatty acids; Thiosulfate; Hydrogen sulfide; Ferric chloride; Short-chain fatty acids; Anaerobic fermentation; Thiosulfate
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2024.130548

[Display omitted] •A S:Fe ratio of 1:1 achieved the maximal SCFA yield and efficient H2S removal.•Lower S:Fe ratios helped hydrolysis, acidification but hampered sulfate reduction.•S:Fe ratios of ≥1:1 enriched acidogens while lower ratios of <1:1 reduced SRB.•The keystone and associations among methanogens, acidogens and SRB were disclosed.•The acidogenic, methanogenic, sulfur and iron metabolisms were revealed. Anaerobic fermentation (AF) has been identified as a promising method of transforming waste activated sludge (WAS) into high-value products (e.g., short-chain fatty acids (SCFAs)). This study developed thiosulfate/FeCl3 pre-treatment and investigated the effects of different thiosulfate/FeCl3 ratios (S:Fe = 3:1, 3:2, 1:1, 3:4 and 3:5) on SCFA production and sulfur transformation during the AF of WAS. At a S:Fe ratio of 1:1, the maximal SCFA yield (933.3 mg COD/L) and efficient H2S removal (96.5 %) were obtained. S:Fe ratios ≤ 1:1 not only benefited hydrolysis and acidification but largely mitigated H2S generation. These results were supported by the enriched acidogens and reduced sulfur-reducing bacteria (SRB). Molecular ecological network analysis further revealed that the keystone taxon (g_Saccharimonadales) was found in S:Fe = 1:1, together with reductions in associations among methanogens, acidogens and SRB. This work provides a strategy for enhancing high-value product recovery from WAS and minimising H2S emissions.