Migration and Atmospheric Emission of Landfill Gas

Gas generation due primarily to microbial decomposition is an inevitable consequence of the practice of solid waste disposal in landfills. Subsequent gas migration within the landfill and its potential emission to the atmosphere are dependent on the pressure and concentration gradients of the gas inside the landfill as well as many factors related to transport properties of the gas itself (viscosity, diffusivity) and the physical characteristics of the waste (permeability, moisture content, porosity). Temperature plays an important role in defining the gas movement because it strongly influences the gas transport properties as well as biochemical processes controlling gas production within the landfill. This paper presents a one-dimensional numerical gas flow model which predicts the time development of the pressure and gas concentration profiles, and the time variation of the total gas emission from landfills. The model accounts for effects of temperature variations with time on gas transport properties and biochemical processes. It was used to simulate gas emission data from the Mountain View Controlled Landfill Project, California.