Environmental impact assessment of cow manure management

Abstract

Run-off water of agricultural animal wastes from lagoons and direct field applications is a cause of serious contamination in drinking water resources. In this research, highly energy-efficient superheated steam drying (SSD) technology was used to improve the existing manure management methods, such as an open-pond, and anaerobic digestion, that require storages or lagoons due to the long processing time for treatment. The SSD process was incorporated with fly ash, mixing it with cow manure during drying to produce bio solids that can be burned to generate energy. Life Cycle Assessment (LCA) was used in order to quantify the environmental impacts of the SSD process. Environmental impacts of other manure management methods were also analysed using LCA. The assessment results for the existing manure management technologies were compared with the proposed SSD process. The functional unit was defined as the management of cow manure waste of 347 cattle for one year. Each scenario was simulated using Gabi 5 software program. The system boundary covered two stages of manure collecting and three stages of manure treating processes. The global warming potential (GWP) of scenario 3B had the lowest GWP (322,079.19 kg CO2-Equiv). For acidification potentials (AP) of the scenarios, scenario 3B showed the lowest AP (9,397.58 kg SO2-Equiv). The result demonstrated that the proposed process design can reduce GWP and AP compared to the other processes.