18. Methane Emission from Municipal Solid Waste Landfills—Estimation and Control

Methane gas can be generated from the Municipal solid waste (MSW) landfill due to the presence of organic fraction and bacterial activity occurring over a period. Methane production in landfills and the resulting emissions to the atmosphere, representing the second largest anthropogenic methane source; hence, there is a need to estimate methane generation rate accurately followed by devising various technique to mitigate the emission. As the methane generation rate is governed by various factors like waste temperature, waste composition and density, pH within landfill, concentration of substrate, moisture content and toxins, several numerical and mathematical tools have been developed considering one or more of the outlined factors to estimate the landfill gas generation. Moreover, the estimation of methane gas generation and emission is also essential for predicting the settlement, in specific, differential settlement that could occur in the engineered landfills. The differential settlement could lead to the initiation and propagation of cracks on the soil barrier. This in turn, might be able to set a free drainage path for the escape of methane gas. In this chapter, a brief assessment on various existing models to predict the estimation of methane generation rate is discussed. The accuracy of the predicted values obtained from various models is estimated from the experimentally observed dataset. This chapter also highlights the need for the evaluation of methane gas generation rate in modeling the settlement of MSW landfills. In addition, various techniques used to mitigate the emission of the methane from the landfill are also discussed.