Peroxymonosulfate-steel slag combination enhances short-chain fatty acids production from waste activated sludge anaerobic fermentation: Microbial community and metabolism analyses

Anaerobic fermentation (AF) is a sustainable approach for producing short-chain fatty acids (SCFAs) from waste activated sludge (WAS). In this study, peroxymonosulfate (PMS) combined with steel slag (SS) was employed to improve the SCFAs yield. The results indicated the SCFAs production peaked at 328.6mg COD/g VSS on day 8 in the group treated with 0.11g/g TSS of PMS and 0.3g/g TSS of SS. Mechanistic investigations demonstrated that the PMS-SS combination significantly promoted WAS solubilization, hydrolysis, and acidification, while suppressed methane production. Microbial community analysis revealed an increase in the abundance of hydrolytic and SCFAs-producing functional microbial communities in the PMS-SS treatment group. Moreover, metagenomic analysis identified an enhancement in pathways and genes associated with fatty acid biosynthesis in the PMS-SS group. Post-AF, the PMS-SS combination also improved sludge dewaterability and reduced the phosphorus concentration in the fermentation liquid. This study provides a novel perspective on the resource recovery from WAS.