Field application of biocovers in landfills for methane mitigation

Two pilot-scale biocovers (PBCs) were installed in a landfill, and the methane (CH₄ ) concentrations at their inlets and outlets were monitored for 240 days to evaluate the methane removability. Consequently, the packing materials were sampled from the PBCs, and their potential CH₄ oxidizing abilities were evaluated in serum vials. The CH₄ concentration at the inlet of the biocovers was observed to be in the range of 23.7- 47.9% (average = 41.3%, median = 42.6%). In PBC1, where a mixture of soil, earthworm cast, and compost (7:2:1, v/v) was employed as the packing material, the CH₄ removal efficiency was evaluated to be between 60.7-85.5%. In PBC2, which was filled with a mixture of soil, earthworm cast, perlite, and compost (4:2:3:1, v/v), the removal efficiency was evaluated to be between 29.2-78.5%. Although the packing materials had an excellent CH₄ oxidizing potential (average oxidation rate for CH₄ = 180-199 μg CH₄ · g packing material^-1 · h^-1), CH₄ removal efficiency in PBC1 and PBC2 decreased to the range of 0-30% once the packing materials in the PBCs were clogged and channeled. Furthermore, seasonal effects exhibited no significant differences in the CH₄ removal efficiency of the biocovers. The results of this study can be used to design and operate real-scale biocovers in landfills to mitigate CH₄ buildup.