Gaseous emissions and nutrient dynamics during composting of swine solid fraction for pellet production

In this study, swine solid fraction was composted with the objective to obtain a composted manure with a moisture content between 20 and 40% - suitable to pelletize. Three identical SF windrows of approximately 4 m3 and 1800 kg were set up outside, on a concrete pad in an open-sided, roofed facility, and composted for a period of 72 days. An evaluation of the composting process and of the final product was made by monitoring process temperature, ammonia (NH3) and GHG (carbon dioxide, CO2; methane, CH4; nitrous oxide, N2O) emissions, moisture content, pH, volatile solids (VS), total organic carbon (TOC), total nitrogen (TN) and total ammoniacal nitrogen (TAN). In accordance with the results of the investigation it can be concluded that the composting of swine solid fraction in windrows could be a valuable process to concentrate the nutrients in manure and make it suitable to pelletize. However, appreciable amounts of CO2, CH4, N2O and NH3 emissions were detected. Total emission of the investigated gases recorded during the experimental period were 273 gCO2 kgVS-1 , 3.50 gCH4 kgVS-1 , 19.3 gN2O kgTN-1 and 87.4 gNH3 kgTN-1, respectively. These data can be used to carry out detailed life cycle assessments of GHG emissions from the Italian swine farming.