METHANE PRODUCTION OF RAW AND COMPOSTED SOLID-WASTE IN SIMULATED LANDFILL CELLS

Methane contributes approximately 20% to the annual increase in global warming, and is explosive at concentrations of 5 to 15% in air. Landf ills are the origin of approximately 15% of the total global methane e missions. This study was conducted to determine the potential decrease in methane production from municipal landfills if the organic compone nts of solid waste (SW) are composted Frier to landfilling. The quanti ties and rates of methane production were measured using simulated lan dfill cells containing composted and raw simulated SW. The SW was comp osted in an open pile and characterized by temperature, pH, ash conten t and CO2 evolved during aerobic respiration. Assuming a 10% lignin co ntent, the labile carbon fraction was reduced by an estimated 71% duri ng composting. Over a 6-month period, simulated landfill cells filled with raw waste generated 66 liters methane per kg of dry refuse, while cells containing composted SW produced 31 liters methane per kg of dr y compost. Per unit weight of the original dry raw SW, composted SW pl aced in a simulated landfill environment produced only 15 liters metha ne per kg dry raw SW which is 23% of the methane that was generated wh en the raw SW was placed directly in the simulated landfill cells.