Waste Mechanics and Sustainable Landfilling Technology: Comparison Between HFWC and LFWC MSWs

Abstract

Waste mechanics focuses on the degradation characteristics and mechanical behaviors of municipal solid waste (MSW). Knowledge of waste mechanics helps solve the severe geoenvironmental challenges for MSW landfills. This paper first summarized and compared the physical components and chemical composition of MSWs from 20 countries, including developed and developing countries, and proposed a MSW classification system based on the food waste content and the ratio of cellulose to lignin. Secondly, the degradation characteristics between high food waste content (HFWC) and low food waste content (LFWC) MSWs, originated from their differences in chemical composition due to the distinctions in physical components of MSWs, were compared quantitatively by mass loss, leachate generation, landfill gas (LFG) generation, and contaminants in leachate. Thirdly, mechanical behaviors closely related to the degradation characteristics of both HFWC and LFWC MSWs, including permeability, compressibility, shear strength, and lateral pressure, were elaborated on. Fourthly, degrees of hydrolysis, methane generation, and consolidation, calculated by the stabilization-consolidation model, were introduced to characterize the stabilization process of HFWC MSW landfills, which provided a basis for sustainable landfilling for HFWC MSW landfills. The obtained features of HFWC MSW landfills, including the distributions of leachate mounds and LFG, settlement, and slope stability, showed the causes of main geo-challenges at HFWC MSW landfills, including high risks of leachate leakage and slope instability, and low LFG collection efficiency, were consistent with the monitoring results of several cases. Finally, technologies, practices, and designs towards sustainable landfilling for HFWC MSW landfills in China were presented, which could also serve as useful references and guidelines for other countries in similar situations.