Insights into the Combined Treatment Strategy of Fe0 and Peroxysulfate for Enhancing Anaerobic Fermentation of Waste Activated Sludge: Performance and Mechanism

This study proposed a new concept of “co-processing” waste activated sludge with low organic content (WAS-LOC) with peroxysulfate and environmentally friendly nanoscale zero-valent iron (Fe0). Fe0, peroxysulfate, and the combination of peroxysulfate with Fe0(co-processing) were added to different alkaline pretreatment sludge fermentation systems. The results showed that the peroxysulfate fermentation system displayed a remarkable hydrolysis performance compared with other fermentation systems with the highest production of proteins and polysaccharides of 482.04 and 224.21 mg chemical oxygen demand (COD)/L, respectively. However, the co-processing fermentation system exhibited a good acidification performance with the highest production of short-chain fatty acids (SCFAs) of 754.52 mg COD/L. The co-processing fermentation system enhanced the activity of protease, dehydrogenase, and alkaline phosphatase, which guaranteed the transformation of organic matter. It also restrained the activity of coenzyme 420, which declined the consumption of SCFAs. Comamonas, Soehngenia, Pseudomonas, and Fusibacter were highly abundant in the co-processing fermentation system, which was beneficial for producing SCFAs. These findings proved the feasibility of co-processing with Fe0 and peroxysulfate to enhance WAS-LOC anaerobic fermentation.