LIFE-CYCLE ANALYSIS OF ADVANCED MANURE MANAGEMENT SYSTEMS FOR A WISCONSIN CONFINED ANIMAL FEEDING OPERATION (CAFO)

摘要

Manure management is becoming an increasing burden for large dairy farms in Wisconsin and across the United States due to land application limitations for nutrients and hauling costs. One solution is to install advanced manure management systems, which remove large portions of water from the manure and treat it to a level sufficient for surface water discharge, livestock consumption, or irrigation. These systems can be divided into a pretreatment stage, which consists of solids removal, and a treatment stage, which generally consists of membranes. Not only does this approach reduce the quantity of material that is land applied, it can separate the nutrients into individual manure streams that can be more easily managed. However, there is still limited understanding regarding the costs and operation and maintenance requirements of these systems. To this end, a life-cycle analysis was completed for five commercially available advanced manure management systems based on how they would treat manure from a 3,500-cow dairy farm in Wisconsin, which was concerned only with the drawbacks of hauling and not application limitations. The evaluation included both an economic and non-economic analysis. The economic analysis consisted of a 20-year total present worth life-cycle cost analysis. The non-economic analysis consisted of a comparison of a set of non-economic factors that matched the management goals and strategies identified by the participating farm. Overall, all five systems evaluated addressed nutrient limitations and hauling costs. No treatment system had a payback less than 20 years at a hauling cost of $0.0040 L-1 ($0.015 gal(-1)). However, two systems had a payback period less than 20 years for a hauling cost of $0.0053 L-1 ($0.02 gal(-1)). Furthermore, if capital costs were ignored, the cost of recovered water was comparable to hauling costs for four of the alternatives. Still, there was high uncertainty in the estimated costs due to the low number of current installations of these systems on CAFOs. There was also a wide range of responses to the non-economic evaluation metrics, especially regarding performance, nutrient management techniques, chemical usage, and estimated regular operation and maintenance, which was again, likely due to the limited number of farm installations. Future work will verify actual costs and performance of these systems once implemented.