METHANE OXIDATION IN ALTERNATIVE LANDFILL COVER SOILS

摘要

Landfills are the largest anthropogenic source of methane in North America. Atmospheric methane concentrations have doubled over the last 200 years and continue to rise. A limited amount of methane (50― 60%) can be collected in landfill gas collection systems; therefore, the remaining 40 ―50% of methane is emitted to the atmosphere. Methane emission appears in a wide range from zero (when a gas collection system is applied) to over 2000 g m~(-2)d~(-1). While the number and efficiency of landfill gas extraction systems is increasing, other significant reductions of methane emissions from landfills are necessary. Methane oxidation, the conversion of methane into carbon dioxide and water through biochemical reactions in the top cover layers, can provide methane reduction of 10 to 90% of the methane generated. Several types of materials were tested under different temperature, porosity, and moisture content. A surface cover that involves soil and compost reduces over 90 g of CH_4 m~(-2)d~(-1). Three different methane oxidation cover design approaches are suggested and discussed depending on the surface emission rates. Each approach will be further tested in the field.