Biocover Performance of Landfill Methane Oxidation: Experimental Results

Abstract

An experimental passive methane oxidation biocover (PMOB) was constructed within the existing final cover of the St-Nicéphore 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 CH 4 emissions when submitted to an increasing methane load. The CH 4 load applied started with 0.3 g CH 4 m −2 h −1 . When the site had to be closed for the winter, the CH 4 input was 27 g CH 4 m −2 h −1 . Throughout the study, practically all the CH 4 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 CH 4 was not reached during the study period. Surface CH 4 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.

Can soil gas profiles be used to assess microbial CH4 oxidation in landfill covers?

“…Another caveat is that the application of the method to field profiles may lead to an underestimation of the total oxidation efficiency if a relevant share of the oxidation occurs very near the surface (Cabral et al, 2009(Cabral et al, , 2010, while the top most samples of gas profiles are taken from below this upper crust. It is thus advisable to collect samples from as shallow depths as possible.…”

“…Setup of the first laboratory column study using mineral soils. (Cabral et al, 2009(Cabral et al, , 2010. The gravel-sand-compost mixture was compacted to 77% of the Proctor, again to simulate actual field conditions.…”

“…This is particularly important when at some point gas extraction systems are turned off, while biogas production may continue for several decades, and alternative measures are required to reduce emissions. However, a reliable quantification of methane removal rates is possible only when the magnitude of the fluxes into and out of the cover are known -which rarely is the case (Cabral et al, 2009(Cabral et al, , 2010) -or estimated (e.g. Einola et al, 2008Einola et al, , 2009.…”

Fugitive Methane Emissions From Two Experimental Biocovers Constructed With Tropical Residual Soils: Field Study Using a Large Flux Chamber

“…Biogas mass fluxes at the surface were calculated based on the results obtained using Equation 1 (according to Cabral et al, 2010a andPerera et al, 2002), corrected for the standard temperature and pressure (STP).…”

“…Several studies have shown that a passive biosystem (where the biogas passes through the cover naturally, without pumping it) installed in the cover system (interim or fi-nal) can be a very effective complement to active systems in reducing fugitive emissions of methane and odorous substances (Abichou et al, 2006a;Cabral et al, 2010a;Capanema et al, 2013;Capanema et al, 2014;Geck et al, 2016;Lucernoni et al, 2016;Roncato and Cabral, 2012;Sadasivam and Reddy, 2014;Scheutz et al, 2009). Most of these studies documented the performance of passive biosystems in temperate climates, while (to the authors' knowledge) no field-scale studies have been performed to document the performance of passive biosystems in Brazil (a tropical country) and employing residual soils.…”