Abstract: Based on the first-phase project of a wet waste treatment plant in Shanghai, aiming at the problems of insufficient reduction and resource utilization rates in wet waste treatment, experimental research on the organic solid residue recirculation prehydrolysis technology was carried out. A process channel of “biological leaching hydrolysis-squeeze solid and liquid separation-three phase separation extraction-reflux hydrolysis” was constructed to explore its optimization effects. Based on the component characteristic analysis of wet waste, mixed residues, organic solid residues, and digestate, the optimization effects were verified through on-site experiments. The results showed that the recirculation prehydrolysis technology could effectively reduce the overall plant residue discharge rate by more than 5%, while increase the COD concentration in the anaerobic system, and raise the biogas production rate per ton of waste by more than 10 m3/t. The data from the second-phase of the project were used to verify the technology’s role in improving the organic matter conversion rate and resource utilization level. In view of the limitations of the temporary process channel for the field experiment of recirculation prehydrolysis, a technical renovation plan for the original first-phase process route was proposed. The economic analysis of the proposed technical renovation plan showed that the annual comprehensive economic benefit after the retrofit could reach 2.221 3 million yuan, which mainly from the reduction of residue disposal costs and the increase in biogas power generation revenue. The study aims to optimize wet waste treatment processes, enhance the levels of waste reduction and resource recovery, and provide a feasible solution for the technical optimization and economic benefit improvement of similar projects.

Key words: 　wet waste, anaerobic digestion, resource utilization, reduction, recirculation prehydrolysis