Matthew

A Tale of Two Compost Bins

By Matthew Worsham

As long as I’ve been at UD, composting has been one of the hottest topics in sustainability.

Our colleagues in Dining Services pioneered the UD composting program years ago. Since 2009, they’ve operated what’s thought to be the largest university dining facility composting program in the country, and have been leaders in other areas of sustainability as well. They’ve also made it easy for all of their diners to participate. The best way to reduce dining waste is to dine in-house on reusable china, or if that’s not possible, to return your to-go container to the dining hall after you’re done. When you return your tray, dining services staff separate the materials based on whether they are reusable (china plates, silverware), recyclable (plastic bottles), or compostable (food waste, plant-based plastic utensils). Currently, we send these compostable materials to a commercial facility that turns them into soil.

Now, Dining Services, Facilities Management, and the Hanley Sustainability Institute are working together to develop new composting capabilities on campus. By recycling some of these materials ourselves, we can reduce our carbon footprint and also create nutrient-rich soil and organic fertilizer for our grounds crews to test on campus. Grounds already has a yard waste composting program, so one of our goals is to enhance this program by producing richer compost in less time. It also might give us the flexibility to expand the campus food waste composting program. This is a common request from the campus community, but as it stands now, we’ve met the capacity of our current composting program. By controlling the types of materials that would go into the compost pile, we might be able to collect different types of materials from new locations on campus.

UD composting wormsComposting is simply a method of recycling organic materials. One example of such a solution is vermicomposting: the process of breaking down organic material using live earthworms. Now, on the roof of Fitz Hall, we’re testing a vermicomposting system that can break down 10lb of food waste and paper every day. The worm bin is filled with thousands of “red wigglers,” a worm variety bred specifically for vermicomposting. The vermicompost system makes it easier for building occupants to compost their food waste, since the alternative would be to take it across campus to KU dining hall to be processed at the central location. It also allows Brown Street Bistro to compost some of its food waste, which it currently does not have the capacity to do.

Building compost binWe’re also testing a more traditional composting system called aerated static pile, or ASP. Compared to vermicomposting, ASP can handle more durable materials like wood chips and compostable plastic utensils, and it can do so at larger volumes. This makes it a potential solution for larger waste streams than what’s possible with vermicomposting, for example KU Crossing dining hall. In the fall, HSI student leaders and volunteers conducted a waste audit of the KU kitchen to determine the volume and composition of the compostable material produced there. They then constructed a 4’x6’ compost bin which we’re using to compost our first batch of food waste. Pictured here, Matthew Worsham (center) working with UD master carpenter, Jeanie Doe (right) to build the compost bin.

For this composting process, our target temperature is 131 degrees F, which is the temperature required to kill off pathogens and weed seeds that can accumulate in our feedstock materials. Most composters say that these higher temperatures are also required to break down compostable plastics like the forks and knives used by Dining Services. As you can see in the graph below, we’ve found that warmer weather allows us to reach these temperatures, but we struggle to maintain high temperatures during periods of extreme cold.

Graph of compost pile temperature

We’re looking forward to the finished product, which should be ready very soon. Then we can see how well the food waste, compostable utensils, and other materials broke down in the process. We’ll continue to refine our composting process and “recipe” until we find the best way to incorporate ASP composting into our program.

Composting has been an exciting journey for Facilities and our partners, and we’re looking forward to where it takes us next. Someday the grass you walk on could be growing in compost made right here on campus. Until then, I’m happy to share that there are faculty, staff, and students across campus that are actively engaged in improving the sustainability of campus operations, and we’re always looking for more help. Contact sustainability@udayton.edu to learn how you can get involved this spring.

Matthew Worsham graduate from UD in 2015 with a Bachelor of Mechanical Engineering and in 2017 with a M.S. in Renewable and Clean Energy. He now works in UD Facilities Management as Energy & Sustainability Coordinator. 

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