Modeling of Methane Gas Generation and Emissions from Landfills

This study was carried out to develop a model capable of predicting the generation and potential emission of methane gas into the environment. Ryerson Landfill Gas Model (RLFGM) was developed using the IPCC tier two model (revised guidelines), the most recent national assessment model (Brown et. al. 1999) from UK and the model developed from DEFRA, UK. This report outlines the findings of the study and its recommendations. The study was performed on detailed characterization of solid waste as RDO, MDO and SDO and by dividing these waste components into nine waste fractions. The waste fractions are described by the percentage of moisture content of the fraction, the proportion of cellulose and hemi-cellulose, and the percentage of the degradability of the cellulose and hemi-cellulose fraction. Methane generating potential (L₀) was calculated from DOC and DOC(subscript f) value. The three methane generation rate constants (k) were used. Methane oxidation, methane correction factor, percentage of methane gas recovery, percentage of methane content in landfill gas were assumed based on comprehensive literature review. After the verification of the output of the RLFGM model with the LandGEM model it was found that the model is producing similar type of output graph as the LandGEM model but the rate of emissions of methane gas into the environment is lower in RLFGM model. It has been concluded that RLFGM model gives the realistic output with respect to individual landfill sites, taking into account of specific waste streams and deposition rates.