Gas emissions as influenced by home composting system configuration

Abstract

Home composting systems (HC) are known to facilitate municipal solid waste management, but little is known about their environmental impact including their greenhouse gas emissions (GGE). The present research focused on selecting HC configuration producing the least CH4 and N2O. Thus, 4 HC types were used to compost food and yard waste for 150 days and monitored for CO2, CH4 and N2O as of day 15: the wood and plastic bins (WB and PB), the mixed and unmixed ground pile (GPM and GP). Using the same waste recipe, all HC were filled at once (batch fed) to maximize gaseous emissions. Weekly as of day 15, CO2, N2O and CH4 emissions were measured during 2-h sessions using a closed chamber inserted into the compost surface. Monitored compost characteristics indicated little differences over time except for moisture content. From day 15 to 150, CH4 emissions were not measurable. Generation of N2O occurred between day 20 and 120 with PB producing the least because of top and bottom slots providing continuous convective aeration, as compared to the WB with slats over its full height and the naturally aerated mixed and unmixed ground piles. Total N2O emissions of 56 kg CO2-eq (tonne wet waste treated)−1 for PB, 75 for GP, 97 for WB and 99 for GPM represented average value for centralized composting facilities. Present and past scientific works suggest the need for more research to establish the combined effect of management and HC configuration on gaseous emissions, with close CH4 measurements from day 0 to 15.