Abstract: Taking a 150 t/d kitchen waste treatment project as an engineering case, this study investigated the upgrading and reconstruction of the pretreatment process to address the drawbacks of the original “thermal hydrolysis + high-pressure pressing” pretreatment process, including poor operating environment for grab bucket operation and excessive residue yield, as well as to improve the project’s operational economy. The project was completed and put into operation in 2021, and the project completed a technological renovation from March to June 2023. A hydraulic pulping unit was added before the high-pressure pressing section based on the original thermal hydrolysis process, forming an improved pretreatment process system of “thermal hydrolysis+hydraulic cyclone pulping+high-pressure pressing”. The improved process effectively enhanced organic matter separation and pretreatment purification performance of kitchen waste. Operational data showed that after the renovation, the thermal hydrolysis steam consumption per ton of kitchen waste was reduced from 150-200 kg to 110 kg.The output proportion of pretreatment residues decreased from 18%-20% to about 12%,and the direct operating cost was reduced by 11 RMB per ton of kitchen waste. The proposed technological renovation effectively addresses the operational defects of the traditional thermal hydrolysis pretreatment process, significantly improves the operational stability and resource utilization efficiency of the kitchen waste pretreatment system, and greatly reduces operation energy consumption and processing costs. This study provides reliable engineering references and technical support for the upgrading and renovation, energy-saving transformation and process optimization of similar kitchen waste pretreatment projects.

Key words: kitchen waste, pretreatment, thermal hydrolysis, hydraulic pulping