Biocover Performance of Landfill Methane Oxidation: Experimental Results

An experimental passive methane oxidation biocover (PMOB) was constructed within the existing final cover of the St-Nicephore landfill. Its substrate consisted of a 0.80-m-thick mixture of sand and compost. The goal of this experiment was to evaluate the performance of the PMOB in reducing CH4 emissions when submitted to an increasing methane load. The CH4 load applied started with 9.3 g CH4 m(-2) d(-1). When the site had to be closed for the winter, the CH4 input was 820 g CH4 m(-2) d(-1). Throughout the study, practically all the CH4 input was oxidized; absolute removal rates were linearly correlated to methane loading; and the oxidation zone was established between 0.6-0.8 m. These results seem to indicate that the upper limit potential of this PMOB to oxidize CH4 was not necessarily reached during the study period. Surface CH4 concentration scans showed no signs of leaks. The substrate offered excellent conditions for the growth of methanotrophs, whose count averaged 3.91 x 10(8) CFU g dw(-1) soil.