A novel and effective pretreatment to stimulate short‐chain fatty acid production from waste activated sludge anaerobic fermentation by ferrous iron catalyzed peracetic acid

Abstract BACKGROUND This study investigates a novel, efficient and green pretreatment approach using ferrous iron catalyzed peracetic acid oxidation (Fe2+/PAA) on anaerobic fermentation of waste activated sludge. The underlying mechanisms are also studied for both the chemical and microbial effects. RESULTS The results indicate that Fe2+/PAA exhibit significant positive synergistic effect on short‐chain fatty acid (SCFA) generation, especially acetic acid. The maximal SCFA concentration of 272 mg COD g−1 VSS is obtained with Fe2+ (2.7 mmol L–1)/PAA (3.0 mmol L–1), which is 5.2 times that of the control test. Fe2+/PAA can effectively facilitate sludge solubilization due to the disruption of extracellular polymeric substances structure and microbial cells. The biodegradability of released organic substance is also improved due to the oxidation of non‐biodegradable substances. The activity of functional enzymes for hydrolysis and acidification is enhanced but that for methanogenesis is inhibited. Further analysis on microbial community structure indicates that phylum Firmicutes and genera Proteiniclasticum showed the maximal positive correlation with SCFA production, while the abundance of methanogenic archaea especially acetoclastic methanogenic archaea is inhibited by Fe2+/PAA treatment. Moreover, the presence of Fe2+ lengthened the oxygen release period of PAA, the main functional reactive oxygen species are hydroxyl radicals and Fe2+ facilitated PAA generates more hydroxyl radicals thus enhancing the oxidation ability of PAA. CONCLUSION This study demonstrated that Fe2+/PAA can be used as an effective pretreatment method for SCFA accumulation in sludge anaerobic fermentation process. The findings obtained in this study will supply information for the application of Fe2+ catalyzed PAA pre‐oxidation in sludge treatment. © 2019 Society of Chemical Industry