Modelling Gas Production in Managed Sanitary Landfills

Abstract

Gas production and recovery from managed sanitary landfills can be simulated by describing the time and space variation of the total pressure and composition of the mixture of gases (CH4, CO2, and N2) in the landfill. The variation of the total pressure and the composition of the gas mixture is described by the equations for mass conservation for each component (including a generation term for CH4 and CO2), the equation of motion, and the equation of state. Simulations of gas production compare well with field data from the Mountain View controlled landfill project field experiment. The function used to approximate the shape of the methanogenesis curve (based on equations describing the biochemical processes) consists of a rising hyperbolic branch and a decaying exponential branch. The conceptual framework of the model has been designed to incorporate equations describing the physics, biology, and chemistry of gas production in landfills.