Enhancing anaerobic fermentation of waste activated sludge by investigating multiple electrochemical pretreatment conditions: Performance, modeling and microbial dynamics

Electrochemical pretreatment (EPT) is an efficient technology to improve volatile fatty acids (VFAs) production during anaerobic fermentation of waste activated sludge (WAS). This study investigated the co-effects of different current intensities, electrolyte NaCl dosage and pretreatment time for promoting VFAs production. The results showed that it was considerably enhanced by 51.6 % when EPT was performed at 1.0 A, 1.0 g/L and 60 min, and response surface methodology strategy adjusted the optimal EPT conditions to 1.0 A, 1.2 g/L and 66 min. The potential mechanisms were proposed that EPT at optimal conditions greatly enhanced solubilization and hydrolysis of WAS and selectively inactivated methanogens, causing the enrichment of acidogenic bacteria (i.e., Lactobacillus, Saccharimonadales, Tet-rasphaera and Prevotella) due to generated reactive chlorine species. Finally, the economic analysis indicated the promising application potential with the profit of EPT at optimal conditions increasing by 36.0 %.

Automated summary

Electrochemical pretreatment (EPT) is an efficient technology to improve volatile fatty acids (VFAs) production from anaerobic fermentation of waste activated sludge (WAS). This study examined the combined effects of different current intensities, electrolyte NaCl dosage, and pretreatment time on VFAs production. The results showed that VFAs production was significantly increased by 51.6% when EPT was conducted at 1.0 A, 1.0 g/L, and 60 min. Response surface methodology determined the optimal EPT conditions to be 1.0 A, 1.2 g/L, and 66 min. The potential mechanisms involved enhanced solubilization and hydrolysis of WAS and selective inactivation of methanogens, leading to the enrichment of acidogenic bacteria and increased VFAs production.