Removal of greenhouse gas in biofilter using organic and inorganic media

Abstract

A biofilter using organic (compost) and inorganic (pumice, porous silica pellet or poremat) media was applied to the removal of methane (CH₄) and nitrous oxide (N₂O) to minimize the impact of off-gasses from municipal solid waste disposal global. The objective was to determine the appropriate biofilter media for CH₄ oxidation and N₂O conversion. The off gas (59.6% CH₄, 1.0% N₂O) was fed simultaneously with air (1:3 ratio) into the biofilter. CH₄ oxidation and N₂O conversion rates were observed over a 101-day period through the analysis of gas concentration along the biofilter’s depth using gas chromatography. Higher CH₄ oxidation in the biofilters containing organic and inorganic media was achieved, especially for the compost-poremat biofilter with 70.1 g CH₄/m³/d realised. The most active methane oxidation zone was found near the gas inlet at the bottom of the biofilter. The presence of inorganic material helped promote aerobic conditions for CH₄ oxidation, especially during the initial period. N₂O was also more completely removed with the biofilter containing inorganic media. Higher methanotrophic activities in matured biofilter media and the presence of methanotrophs type I, which prefer oxygen-rich conditions, were confirmed.