Emissions of methane (CH?) and nitrous oxide (N?O) from composting of source-sorted food waste were studied at set temperatures of 40, 55 and 67°C in 10 trials performed in a controlled environment 200L compost reactor. CH? and N?O concentrations were generally low. In trials with 16% O?, the mean total CH? emission at all temperatures was 0.007% of the mineralized carbon (C), while at 67°C this fraction was 0.001%. Total CH? production was higher in the 40°C trial and the limited oxygen (1% O?) trial, with emissions of 0.029 and 0.132% of the mineralised C respectively. An early increase in N?O production was observed in trials with higher initial nitrate contents. Increased CH? and N?O production in trials at 40 and 55°C after 50% of the initial C was mineralised resulted in higher total greenhouse gas emissions. Overall, the global warming potentials in CO?-equivalents from CH? emissions were higher than from N?O, except for composts run at 67°C.
Authors: Ermolaev E, Jarvis Å, Sundberg C, Smårs S, Pell M, Jönsson H. ;Full Source: Waste Management. 2015 Aug 27. pii: S0956-053X(15)30089-1. doi: 10.1016/j.wasman.2015.08.021. [Epub ahead of print] ;