Evaluation of methane oxidation activity in waste biocover soil during landfill stabilization

Biocover soil has been demonstrated to have high CH4 oxidation capacity and is considered as a good alternative cover material to mitigate CH4 emission from landfills, yet the response of CH4 oxidation activity of biocover soils to the variation of CH4 loading during landfill stabilization is poorly understood. Compared with a landfill cover soil (LCS) collected from Hangzhou Tianziling landfill cell, the development of CH4 oxidation activity of waste biocover soil (WBS) was investigated using simulated landfill systems in this study. Although a fluctuation of influent CH4 flux occurred during landfill stabilization, the WBS covers showed a high CH4 removal efficiency of 94–96% during the entire experiment. In the LCS covers, the CH4 removal efficiencies varied with the fluctuation of CH4 influent flux, even negative ones occurred due to the storage of CH4 in the soil porosities after the high CH4 influent flux of ∼137 g m−2 d−1. The lower concentrations of O2 and CH4 as well as the higher concentration of CO2 were observed in the WBS covers than those in the LCS covers. The highest CH4 oxidation rates of the two types of soil covers both occurred in the bottom layer (20–30 cm). Compared to the LCS, the WBS showed higher CH4 oxidation activity and methane monooxygenase activity over the course of the experiment. Overall, this study indicated the WBS worked well for the fluctuation of CH4 influent flux during landfill stabilization.

► Evaluation of CH4 oxidation activity in waste biocover soil (WBS) during landfill stabilization.
► CH4 oxidation activity in the WBS cover could quickly adapt to the variation of CH4 loading.
► Negative CH4 removal efficiencies occurred in the landfill cover soil (LCS) after high influent CH4 fluxes.
► LFG induced a higher methanotrophic activity in the WBS than that in the LCS.