Ultrasound-sodium percarbonate effectively promotes short-chain carboxylic acids production from sewage sludge through anaerobic fermentation

Short-chain carboxylic acids (SCCAs) production from sewage sludge via anaerobic fermentation is usually restricted by low substrates availability and rapid products consumption. Therefore, the ultrasound (US)-sodium percarbonate (SPC) technique was proposed to effectively break the bottlenecks. Results showed the total SCCAs yield, acetate yield and particulate organics reduction respectively attained 392.8 mg COD/g VSS, 204.6 mg COD/g VSS and 47.4 % under the optimal condition. Mechanistic explorations disclosed that US + SPC largely reduced biodegradation resistances of particulate organics and improved sludge biodegradability. The destruc-tion of spatial structure was the inherent mechanisms for initial solubilization and further degradation of solid -phase sludge. Besides, US + SCP up-regulated hydrolytic and SCCAs-forming enzymes, but downregulated the key enzyme for methanation. Meanwhile, US + SPC altered the microbial structure and stimulated functional microorganism enrichment, well correlated with substrate biotransformation and products output. Overall, this strategy could effectively enhance SCCAs production from WAS and reduce the environmental risk for subse-quent sludge disposal.

Automated summary

This study proposes the use of ultrasound-sodium percarbonate technique to enhance short-chain carboxylic acids (SCCAs) production from sewage sludge. The results show that under the optimal conditions, the total SCCAs yield reaches 392.8 mg COD/g VSS and the particulate organics reduction rate is 47.4%. Mechanistic explorations reveal that this technique reduces biodegradation resistances, improves sludge biodegradability, and alters microbial structure to promote functional microorganism enrichment.