Periodic injection of liquefied kitchen and food waste in municipal solid waste: Effects on leachate and gas generation

With continuous advancements in the zero -waste strategy in China, transportation of fresh municipal solid waste to landfills has ceased in most first -tier cities. Consequently, the production of landfill gas has sharply declined because the supply of organic matter has decreased, rendering power generation facilities idle. However, by incorporating liquefied kitchen and food waste (LKFW), sustainable methane production can be achieved while consuming organic wastewater. In this study, LKFW and water (as a control group) were periodically injected into high and low organic wastes, respectively. The biochemical characteristics of the resulting gas and leachate were analyzed. LKFW used in this research generated 19.5-37.6 L of methane per liter in the post -methane production phase, highlighting the effectiveness of LKFW injection in enhancing the methane -producing capacity of the system. The release of H2S was prominent during both the rapid and post -methane production phases, whereas that of NH3 was prominent in the post -methane production phase. As injection continued, the concentrations of chemical oxygen demand, 5-d biological oxygen demand, total organic carbon, ammonia nitrogen, total nitrogen, and oil in the output leachate decreased and eventually reached levels comparable to those in the water injection cases. After nine rounds of injections, the biologically degradable matter of the two LKFWinjected wastes decreased by 8.2 % and 15.1 %, respectively. This study sheds light on determining the organic load, controlling odor, and assessing the biochemical characteristics of leachate during LKFW injection.