Methane oxidation in landfill waste biocover soil: kinetics and sensitivity to ambient conditions.

Waste biocover soil was investigated as an alternative in regions with a shortage of landfill cover soil. In the work, effects of the composition, ambient conditions and nitrogen stress on CH4 oxidation in waste biocover soil were studied. The results showed that the optimal composition of waste biocover soil as a landfill cover material for CH4 oxidation was original pH value, 45% moisture and a particle size of ⩽4mm. CH4 oxidation rate increased rapidly over a CH4 concentration range of 0.01–10% (v/v), and kept stable at CH4 concentrations of 10–30% (v/v). The Michaelis–Menten model showed a good fit for the kinetic of CH4 oxidation in landfill waste biocover soil with a maximum of 9.03μmol/gd.w./h. The average Q10 was 10.6 in the batch experiments. A level of 5% of oxygen concentration was enough to sustain the activity of methanotrophs community structure in waste biocover soil. Waste biocover soil had low baseline concentrations of NH4+-N and NO3--N. Ammonia volatilization from landfills and nitrification in landfill waste biocover soils might stimulate CH4 consumption at concentrations below 600mg/kg. However, the contents of NH4+-N and NO3--N above 1200mg/kg would inhibit CH4 oxidation in landfill waste biocover soil. Compared with NO3--N, NH4+-N had a greater stimulating action as nutrient at lower concentrations and inhibitory effect at higher concentrations on CH4 oxidation in landfill waste biocover soil.