Using heat-activated persulfate to accelerate short-chain fatty acids production from waste activated sludge fermentation triggered by sulfate-reducing microbial consortium

• Published in: The Science of the total environment 2023-02, Vol.861, p.160795-160795, Article 160795
• Main Authors: Liu, Shuli, Zhou, Aijuan, Fan, Yaxin, Duan, Yanqing, Liu, Zhihong, He, Zhangwei, Liu, Wenzong, Yue, Xiuping
• Format: Article
• Language: English
• Subjects: acetates; acidification; activated sludge; Anaerobic fermentation; Bacteroides; biotransformation; Carbon; carbon dioxide; Desulfovibrio; environment; Fatty Acids, Volatile; Fermentation; Hot Temperature; Hydrogen-Ion Concentration; metabolites; Microbial Consortia; Morganella; oxidation; Persulfate; Sewage - microbiology; Short-chain fatty acids (SCFAs); Sulfate-reducing bacteria (SRB); Sulfates; Sulfur Oxides; Thermal activation; Waste activated sludge (WAS)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.160795

Persulfate has been applied extensively for waste activated sludge (WAS) decomposition due to the strong oxidizing sulfate radical generated as a product. However, the efficiency is not improved without activation to produce free radicals. In this study, a novel coupling strategy of heat-activated persulfate (Heat_PS) pretreatment and sulfate-reducing bacteria (SRB) triggering was explored to enhance short-chain fatty acids (SCFAs) produced by WAS fermentation. The remaining sulfate acts as an essential acceptor of electrons for the metabolism of synergistic SRB, thereby boosting WAS acidification by energetic cooperation with anaerobic fermenters. The results showed that SCFAs yield in the Heat_PS + SRB group peaked at 431.89 mg COD/gVSS, with the proportion of acetate reaching 57.8 %. This was 6.33 and 1.75 times higher than that in raw and single Heat_PS treated WAS, respectively. Carbon balance revealed a conversion rate of 26.1 % of carbon content in WAS to SCFAs, with 4.5 % lower CO2 equivalents emitted than that in raw WAS fermentation by the assessments of environmental impacts. This was partially attributed to the strong decomposition of WAS by SO4•− and •OH oxidation from heat-activated PS and the SRB trigger. In addition, the synergistic relationship among acidogenic/fermentative bacteria and SRB consortia was further verified by the positive correlation among Desulfovibrio, the hydrolytic Escherichia-Shigella, Morganella and the fermetative Macellibacteroides and Bacteroides, as revealed by molecular ecological networks (MENs) analysis. The results of this study may highlight the cooperation of the synergistic micribial consortia as an additional perspective for the recovery of value-added biological metabolites from complex biotransformation. [Display omitted] •The coupling effect of heat-activated PS pretreatment and SRB trigger was creatively proposed.•Heat activated PS was efficient in decomposing WAS by multiple free radicals.•High yields of SCFAs and HAc accumulation was realized with lower CO2 equals emitted.•Significant changes in microbial community structures was observed.•Synergistic relationship of SRB and acidogenic/fermentative bacteria was revealed.