Life-cycle Water Use, Nutrient Cycling and Solid Waste Generation of a Large-Scale Organic Dairy
Aurora Organic Dairy (AOD) is a leading U.S. provider of private-label organic milk and butter, managing over 12,000 milking cows and processing over 84 million liters of milk annually. Building on a previous life-cycle energy and greenhouse gas study, this paper benchmarks AOD's nutrient cycling, water use and solid waste generation across the life cycle of producing, processing and distributing fluid milk. Nutrient flows relevant to the impact categories of aquatic eutrophication and acidification were calculated. The acidification potential of AOD fluid milk across the full life cycle is estimated at 1.2 moles H+ / liter packaged milk. The eutrophication potential is 0.66 g N eq. / liter packaged milk. Water use refers to all water that is withdrawn from the natural hydrological cycle and used in various production processes and is divided into consumption and utilization according to Koehler (2008). This study includes all direct water use at AOD's facilities, as well as indirect water use associated with feed production, electricity generation, and the production of liquid transportation fuels. Total life cycle water consumption equals 808 liters water per liter of packaged milk, and life cycle water utilization is 12.3 liters water per liter of packaged milk. Municipal solid waste (MSW) generation at AOD facilities was estimated and characterized. National averages on recycling rates for AOD packaging types were utilized for end of life impacts. Across the whole life cycle, the production of one liter of packaged milk results in 42.3 g direct, 41.2 g indirect MSW, and 24.8 g recycled MSW. Packaging for the milk itself comprises a large portion (71%) of the direct MSW. Water use, eutrophication, acidification, and solid waste from farm operations are compared with total life cycle results to highlight the key inputs, processes, and stages influencing sustainability performance.
[Koehler A. (2008): Water use in LCA: managing the planet's freshwater resources. International Journal of Life Cycle Assessment, 13, pp. 451-455.]