The UW-Madison Compost Journey

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[music] With 60,000 people living and working on
the UW-Madison campus, composting is crucial to sustainable resource
management. But where does your food waste go once you place it in a compost
bin or drop off a tray in the dining hall? Join us on a journey as we follow
leftover food from a plate at the Gordon Dining and Event Center to our composting facility, and back to the soil again. At UW-Madison, our compost system can
process all food items including cheese, bones, and grease. Soiled paper like napkins, cups, takeout containers, and pizza boxes are compostable, too. In the dining facilities, staff sort waste from food trays into compost, landfill, and recycling bins. Compostable material then flows into a pulper before being delivered to a loading dock for pickup. Facilities staff transport that material
to our partner facility 10 miles west of campus: the Gundersen Envision biodigester. At the biodigester, the food waste is dumped out in preparation for processing. First the food waste goes through the depackager machine which separates out contaminants. Material goes up a conveyor belt into one side of the machine where it’s struck by a series of paddles that sort out metals and plastics. Gundersen combines the clean food waste from UW-Madison with manure from local
dairy farms in three large tanks. In these tanks, bacteria and other
microorganisms “digest” the mixture, turning food waste and manure into
biogas, liquid fertilizer, and compost. Gundersen captures this biogas and
generates electricity for the grid making enough electricity for about 1,900
Wisconsin homes for one year. Finally, the compost is arranged in long piles called windrows. These piles are turned regularly to encourage oxygen-loving organisms to finish the digestion process. The final product is sold as high-quality compost, which in turn helps grow plants like the ones we eat at the UW-Madison’s dining halls, bringing our food waste’s journey full circle. We are very fortunate to have such a sophisticated compost system at the UW-Madison, but we still need your help! Reducing food waste starts by only
taking the food you plan to eat. When you put food leftovers into a compost bin on campus, be sure you do not introduce contaminants. Metal cutlery, plastic bags,
chopsticks, and compostable plastic cups and silverware are not compostable in our system. To learn more about how campus food waste is composted, and to find guidelines for what can and cannot be composted, visit sustainability.wisc.edu/composting. Thank you for helping make our campus more sustainable!

 

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