Combined strategies for promoting short-chain fatty acids production from waste activated sludge in anaerobic fermentation.

Carbon-neutral strategies are transforming wastewater treatment from pollution removal to resource recovery. Anaerobic fermentation stands out as a promising method for the recovery of short-chain fatty acids from waste activated sludge. However, short chain fatty acid yield is usually unsatisfactory due to the slow hydrolysis rate of organic substances during sludge fermentation, requiring external interventions. Different physical, chemical and biological approaches are available to enhance fermentation. This study systematically reviews the research progress in combining these physical, chemical and biological processes to facilitate short chain fatty acid production via the fermentation of waste activated sludge. The prospects for combined strategies are comprehensively discussed and the feasibility and challenges of applying combined strategies in practical wastewater treatment plants are assessed. The findings are expected to provide valuable insights for future research on sludge reutilization.