The weight of Municipal solid waste (MSW) leads to a decrease of void ratio in landfill with depth and the biodegradation of MSW also results in decrease of void ratio with time. The spatial and temporal changes of void ratio of MSW have significant effects on its hydraulic properties and consequently influence the leachate recirculation process. In this paper, an advanced coupled hydro-mechanical-biodegradation (H-M-B) model is proposed to analyze the full coupling process for leachate recirculation taking into account the effect of initial density profile and its change due to biodegradation. A new solver is presented using the finite volume method based on the OpenFOAM platform to implement the coupled H-M-B model. The volume change caused by effective stress, degree of saturation and degradation, and the effect of void ratio change on hydraulic properties, can be taken into account in the coupled H-M-B model. The results calculated by the coupled H-M-B model illustrate the effect of void ratio on hydraulic properties, and the effect of compressibility, initial density and biodegradation on leachate recirculation. This study will contribute to the understanding of the leachate recirculation process and enhance the design of MSW landfills.
Keywords: Finite volume method; Hydraulic property; Leachate recirculation; Unsaturated flow; Void ratio.
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