Advanced oxidation processes (AOPs)-based sludge pretreatment techniques for enhanced short-chain fatty acids production: A critical review

Abstract

Applying advanced oxidation processes (AOPs) in waste activated sludge (WAS) to enhance short-chain fatty acids (SCFAs) from anaerobic fermentation has attracted much interest. The current review critically evaluated the efficiency of AOPs in improving the SCFAs production from WAS. Various oxidants (including CaO2, peracetic acid, sodium percarbonate, O3, persulfate, sulfite, K2FeO4, KMnO4 and periodate) can generate different types of highly reactive species to promote the release of biodegradable substrates, and SCFAs yield. Moreover, the positive effects of emerging contaminants (ECs) on SCFAs production were fully investigated, and the efficiencies of AOPs for ECs removal from WAS were analyzed. Finally, intrinsic limitations and opportunities of AOPs-based conditioning techniques in SCFAs production from WAS were proposed. Based on these developments and challenges, an integrated solution in SCFAs production from WAS in wastewater treatment plants was constructed to realize the transition from “linear economy” to “circular economy”. This review provides theoretical support for the development of practical engineering with more economical, environmentally friendly and high efficiency regarding the application of AOPs in SCFAs production from WAS.