Field application of biocovers in landfills for methane mitigation

Abstract

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 PBCl, 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 fig CH4 g packing material"1 h"1), CH4 removal efficiency in PBCl 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.