Coupled bio-hydro-thermo-mechanical interactions of landfilled MSW based on a multi-phase, multi-component numerical model

A clear understanding of long-term bio-hydro-thermo-mechanical (BHTM) behaviors of landfilled Municipal Solid Waste (MSW) is essential to better design and manage landfills, which requires the development of both analytical and numerical models that can represent typical behaviors of MSW. In this study, a novel multi-phase, multi-component numerical model, which incorporated the diffusion of landfill gas components, changes in the pH of leachate, and its solute migration as well as phase changes, was presented and adopted to investigate long-term coupled behaviors of MSW and the spatial and temporal variations of MSW properties. The numerical simulations were conducted on a typical landfill column and a landfill slope with relatively clear initial and boundary conditions to explore the coupled BHTM interactions of landfilled MSW. Based on the simulation results, the coupled mechanisms of MSW biodegradation, leachate and gas flows, MSW deformation, and heat transfer were revealed, and some significant insights on qualities of both leachate and landfill gas were also given. It has been found that the coupled model associated with its numerical code successfully predicted the long-term behaviors of landfilled MSW and qualities of leachate and landfill gas.