Dynamics of CH4 oxidation in landfill biocover soil: Effect of O2/CH4 ratio on CH4 metabolism

The CH4 oxidation dynamics was investigated by observing the CH4 oxidation rates at concentrations (from 1.0 × 104 ppmv to 2.0 × 105 ppmv) mixed with O2 (from 5.0 × 104 ppmv to 7.5 × 105 ppmv). The CH4–O2 dual-substrate model based on Michaelis–Menten equation (Km,CH4 = 1.4 × 105 ppmv; Vmax = 7.6 × 102 μmol kg−1 d−1; Km,O2 = 5.5 × 104 ppmv) was got and agreed well with the experimental data when the initial O2/CH4 ratio reached 3:1, indicating full aerobic CH4 oxidization. Anoxic CH4 oxidation gradually became predominant with decreasing O2/CH4 ratios. The effect of CH4 is more significant than O2, as evidenced by higher slope (0.58 kg−1 d−1) of VCH4−[SCH4]VCH4−[SCH4] line graph compared with that of VCH4−[SCH4]VCH4−[SCH4] line graph (0.062 kg−1 d−1). The paper presents the dynamics of CH4 oxidation and proposes that ratio of O2/CH4 need to be considered for their dynamically changing in environmental habitats. The findings provide an important parameter for optimizing the operations of breathing biocover systems.

► A CH4–O2 dual substrates model based on Michaelis–Menten equation was established.
► O2/CH4 ratio is the key parameter determines CH4 oxidation rate.
► CH4 was fully aerobically oxidization when O2/CH4 ratio reached 3:1.
► Anoxic CH4 oxidation gradually became predominant as O2/CH4 ratio decreasing.
► The rate of CH4 oxidation has higher correlation ship with CH4 than O2.