Global warming and acidification potential assessment of a collective manure management system for bioenergy production and nitrogen removal in Northern Italy

Collective manure processing facilities to reduce nutrient loads and produce renewable energy are often proposed as feasible solutions in intensive livestock production areas. However, the transferring of effluents from farms to the treatment plant and back to farms, as well as the treatment operations themselves, must be carefully evaluated to assure the environmental sustainability of the solution. This study evaluated the global warming potential (GWP) and acidification potential (AP) of a collective treatment plant for bioenergy production and nitrogen removal as an alternative strategy to conventional on-farm manure management systems. Two manure management scenarios were compared: manure management on individual farms and management by a collective treatment plant. Data were collected at a collective processing plant and at the individual farms of the consortium to estimate emissions of CO2, CH4, N2O, NOx, NH3and SO2. The plant receives manure from 21 livestock production units, treating 660 tonnes day-1of manure. The GWP and AP indicators were calculated to evaluate the potential impact of the two management solutions. The collective solution reduced both GWP (-52%) and AP (-43%) compared to manure management separately by each farm. Further improvement might be obtained in both indicators by introducing mitigation techniques in farm manure storage and manure application to soil.