Experiment and model study of gas preferential penetration of municipal solid waste

Abstract

Municipal solid waste (MSW) has various components, different sizes and strong heterogeneity. The significant preferential flow effect of MSW directly affects the migration path of landfill gas. Laboratory tests on the gas breakthrough curve of MSW under the influence factors of initial pressure and moisture content were carried out by self-developed gas permeability test device. The experimental results showed that the peak value of gas breakthrough curve increased gradually with the increase of initial pressure, and increased with the increase of moisture content. A mathematical model for describing gas migration in the macro-porous region and the fractured region was established based on the theory of pore-fracture seepage in porous media. The whole process of gas passing through the MSW sample was simulated. The simulation results showed that the higher the ratio of permeability between the crack and the pore, the greater the peak value of gas breakthrough curve, and the shorter the time of gas passing through the sample. As the proportion of fractured area in pore space decreased, the peak value of gas breakthrough curve decreased gradually.