(194p) Assessing Environmental Impact from Acid Whey to Value-Added Products

Greek yogurt environmental impact is driven by milk production. Unlike stir or set yogurt types, Greek yogurt uses a straining process that creates acid whey. Acid whey is a by-product, but cannot be treated by current wastewater plants. In the United States, acid whey is transported to farms and used as animal feed or fertilizer. But transport of raw acid whey to farms is costly, inclusion in animal diet is limited, and fertilizer land application poses environmental risks due to odor and run-off; thus, transport to farm does not provide an optimal solution for the acid whey problem. A coupled anaerobic digester-cogeneration system is one option to treat acid whey. In this scenario, an anaerobic digester produces biomethane and cogeneration produces renewable electricity and clean-in-place hot water. Recently, a division of the American Chemical Society collected global patent applications related to the use of yogurt acid whey. The search found 3,500 patents, with most patents focused on extracting proteins and lactose from acid whey using membranes. Market research predicts that acid whey will attain a second life as the raw material to produce acid whey drink, lactose, and Greek whey protein concentrate (GWPC).

The goal and scope of this research was to (1) perform a cradle-to-gate life cycle assessment (LCA) of the yogurt processing plant including acid whey membrane scenarios, (2) find environmental hot spots, and (3) compare membrane scenarios to the baseline whey-to-feed scenario. LCA is a standard method used to assess environmental impacts of products and food. Data collection for impact assessment is a central activity of the LCA. Some Greek yogurt plants already implemented membrane technology such as reverse osmosis of the acid whey, but data on energy and membrane use is not available. We built membrane scenarios in the SuperPro Designer software and used literature and dairy membrane producer data to populate models. The value-added products included (1) lactose produced by ultrafiltration and enzymes and (2) Greek whey dried concentrate (GWDC) produced by reverse osmosis, nanofiltration, and diafiltrating.

Production of dried whey concentrate and lactose increased the Greek yogurt plant climate change impact by 5% due to spray drying, which was also primary impact driver for other impact categories. Dried products reduced transport volume by 75% and eliminates the need of HazMat trucks. Thus, primary benefits of whey concentrates and lactose production include reducing transport cost, removing cost based incentive for farmers to use acid whey, and potential use in food preparations, if approved by the U.S. Food and Drug Administration (FDA).