Methane Emission Estimation and Control through the Life Cycle of MSW Landfills

Abstract

This paper describes a study that uses a fitted modeling approach to calculate methane emissions during the operation and post closure care period of a bioreactor and a regular landfill. It focuses on the feasibility of using soil cover to eliminate landfill methane emission before, during or after post-closure care period such that the active gas control system could be phased out as part of the termination of post-closure care. A numerical model had been developed to simulate landfill gas emission before, during, and after post-closure care period by using landfill gas generation curve. The soil physics model was used in combination with the USEPA LANDGEM to directly estimate surface emissions and oxidation from an example landfill during its operation and post closure period. When the gas collection system is operational, the collection efficiency of the gas collection system was assumed to be 75%. The remaining landfill gas (25% of total gas generation) was assumed to escape through the landfill cover. Gas collection was assumed to start during the first year of waste acceptance of the bioreactor landfill, while it would start only after five years of operation for the case of the regular landfill. The simulations showed that surface emission from bioreactor landfill were lower than those from the regular landfill during the simulated 52 years. Thirty years after closure, surface emissions were zero from the bioreactor landfill even when the gas collection system was turned off. Emissions from the regular landfill continued 30 years after closure and increased as soon as the gas collection was turned off.