Life Cycle Assessment of Two Manure Treatment Modes in Intensive Dairy Farms

Quantifying the energy and material consumption and environmental emissions of different treatment modes of dairy manure is of guiding significance for accurately assessing the environmental impact of manure management in intensive dairy farms and scientifically formulating emission reduction measures. In this study, life cycle assessment (LCA) method was used to compare the environmental emission of pollutants from mode Ⅰ (i.e., complete utilization of dairy manure) and mode Ⅱ (i.e., standard processing of dairy slurry) in two intensive dairy farms. The results show that the emission of CO₂, SO₂, NO_x, CO, CH₄, VOC and soot in mode Ⅰ were 17.28, 0.14, 0.09, 0.04, 0.02, 0.002 and 0.007 kg, respectively lower than those of mode Ⅱ. The total environmental impact potential was 0.007 6 kg eq per person per year in mode Ⅰ, which was 23.2% lower than that in mode Ⅱ. Meanwhile, it had obvious economic benefits in mode Ⅰ. In the dairy manure treatment process, the environmental impact potential of slurry treatment is the highest. Thus, the optimization of dairy slurry treatment is a focus and also a difficult issue in the dairy manure treatment process. It is suggested that enough farmland should be arranged for recieving the dairy manure. In addition, more precision application techniques and evaluation methods should be developed to enhance the utilization efficiency of nutrient in dairy manure and to reduce the environmental emission of pollutants from dairy manure treatment.