Methane oxidation in landfill cover soil

Abstract

Methane, one of the primary greenhouse gases, negatively affects climate change. Its atmospheric concentration has increased dramatically over the last century and is expected to continue rising due to human activities. Oxidation of methane by methanotrophic bacteria provides a sink for methane. The rate at which methane is biologically oxidized depends on different parameters. This study aims to better understand methane oxidation in landfill cover soils. This was done through laboratory batch reactor experiments, under two levels of moisture content, two soil layer thicknesses and with and without nutrient additions. Adding nutrients to the 200 mm layer of landfill cover soil that contained 30% moisture content (by weight), increased the CH4 oxidation efficiency from 38% to 81% and the CH4 substrate utilization from 2750 mumoles/L to 5540 mumoles/L. The kinetic constants were studied in the landfill cover soil. The maximum CH4 utilization rate for different experimental runs and under different levels of the three specified parameters were between 31 and 699 mumoles/dayxkg of dry soil weight. A statistical design model was developed to describe the expected methane oxidation efficiencies under different levels of moisture content and nutrient addition that can occur in a typical landfill cover soil.