Determination of as-discarded methane potential in residential and commercial municipal solid waste

Abstract

Methane generation potential, L0, is a primary parameter of the first-order decay (FOD) model used for prediction and regulation of landfill gas (LFG) generation in municipal solid waste (MSW) landfills. The current US EPA AP-42 default value for L0, which has been in place for almost 20 years, is 100 m3 CH4/Mg MSW as-discarded. Recent research suggests the yield of landfilled waste could be less than 60 m3 CH4/Mg MSW. This study aimed to measure the L0 of present-day residential and commercial as-discarded MSW. In doing so, 39 waste collection vehicles were sorted for composition before samples of each biodegradable fraction were analyzed for methane generation potential. Methane yields were determined for over 450 samples of 14 different biodegradable MSW fractions, later to be combined with moisture content and volatile solids data to calculate L0 values for each waste load. An average value of 80 m3 CH4/Mg MSW was determined for all samples with 95% of values in the interval 74–86 m3 CH4/Mg MSW as-discarded. While no statistically significant difference was observed, commercial MSW yields (mean 85, median 88 m3 CH4/Mg MSW) showed a higher average L0 than residential MSW (mean 75, median 71 m3 CH4/Mg MSW). Many methane potential values for individual fractions described in previous work were found within the range of values determined by BMP in this study.