THE CO-OXIDATION OF METHANE AND DICHLOROMETHANE IN LANDFILL BIO-COVER

摘要

Municipal solid waste landfills are a major source for anthropogenic methane (CH4) emissions.A reduction in these CH4 emissions can be done by utilizing methanotrophic bacteria present in landfillcover. The affect of non-methane organic compounds (NMOCs) on the rate of CH4 oxidation has notbeen effectively studied. This paper addresses the presence of dichloromethane (DCM) on the oxidativecapacity of CH4 by these methanotrophic bacteria. This was done by using laboratory scale batch studieswith stabilized compost and gas chromatography to determine the co-oxidation rates of CH4 and DCM forthree atmospheric temperatures (5°C, 22°C and 35°C) and for three DCM concentrations. The resultsshowed that a DCM headspace concentration of only 3 ppmv resulted in a significant decrease in the CH4oxidation rate and that DCM had been completely oxidized. At a concentration of 21 ppmv there was noCH4 or DCM oxidation. Temperature played a major role, with very little oxidation occurring attemperatures of 5°C compared to those at 22°C and 35°C. Finally no oxidation of DCM occurred in theabsence of CH4 from the batch reactor. Major conclusions from the study are that it will be critical toreduce the NMOC concentrations in landfill gas if CH4 is to be oxidized by a bio-cover. One way toachieve this would be to increase restrictions on the type of waste that can be dumped in landfills, thusreducing DCM and other NMOC concentrations.