Landfill leachate generation mechanism study: a review

Leachate is one of the main sources of pollution from landfills, posing a greater threat to the quality of soil, surface water and groundwater, and bringing serious environmental and human health problems. The composition and properties of leachate are very complex, so studies on leachate yield prediction, leachate treatment technology and physicochemical properties are premised on understanding the mechanism of leachate generation. This paper starts from the physical and chemical characteristics of municipal solid waste to study the generation mechanism of leachate. The biggest difference in the composition of municipal solid waste between developing and developed countries is the content of kitchen waste. The initial water content and field water holding capacity of municipal solid waste with high kitchen waste content are higher than those of municipal solid waste with low kitchen waste content, with better water holding performance and better liquid production capacity. The degradation characteristics of municipal solid waste with high kitchen waste content and low kitchen waste content are quite different. The content range of each compound in the two types of MSW is given, and their degradation rates are classified. The degradation process and transformation mechanism of different degradation stages were summarized, and the degradation rate of each stage and its influencing factors were analyzed. The characteristics of the different stages of leachate are also discussed. This study will provide insight into the research of physicochemical properties and treatment methods of leachate.