Effects of ambient temperature and aeration frequency on emissions of ammonia and greenhouse gases from a sewage sludge aerobic composting plant

This study analyzed emissions characteristics of NH3 and greenhouse gases (i.e. N2O, CH4, and CO2) from a municipal sewage sludge aerobic composting plant. Samples were collected during different seasons in which ambient temperatures and aeration frequencies varied. Results revealed (1) the maximum gas emissions occurred during the mesophilic phase for N2O (22%-56%) and CH4 (65%-95%), and in the thermophilic phase for NH3 (84%-86%) and CO2 (65%-74%); (2) raising ambient temperatures promoted emissions of NH3 and greenhouse gases, while improved aeration frequency increased NH3 but decreased greenhouse gas emissions; (3) CO2 and N2O were found to be the key greenhouse gases emitted during aerobic composting according to assessment of the CO2 equivalent. The results obtained from this study suggest that adjusting ambient temperature to −3 to 5 °C and aeration frequency in composting workshops can be useful approaches for the reduction of NH3 and greenhouse gas emissions from municipal sewage sludge composting plants.