Biodigesters fight food waste at University of Nebraska-Lincoln

The goal: Diverting food waste from the dining halls away from landfills and reducing the University of Nebraska’s carbon footprint. One solution: Biodigesters. These pieces of equipment use special enzymes to digest food waste that previously went into heavy garbage bags and got hauled away to a landfill. The biodigesters—now at all four main campus dining centers—save tons of CO2 emissions from transportation of the trash, and the staff appreciates the reduced mess and Dumpster dependency.

We asked David Annis, director of University Services at the University of Nebraska, about his experience with the biodigester over the past year and the ins and outs of getting it set up.

All four main dining centers at the University of Nebraska-Lincoln have biodigesters, which have been proving themselves since 2019.

Q: How did you first learn about biodigesters?

A: I first learned about biodigesters about 8 years ago when I was at the University of Oklahoma (OU). There was a company outside of Tulsa that was making them for the government. We toured the production facility and it really all made sense with how something like this could really impact the amount of food waste we sent to the landfill.

Q: Did you look at other operations for reducing food waste as well?
A: At the time, I knew we didn’t have the space or manpower to do composting like the University of Montana, and I didn’t think the system that the University of Texas was experimenting with—drying the food waste—would work for us, either. So, we bought a small biodigester and started testing at OU. When I came up to the University of Nebraska in early 2019, I knew I wanted to continue using them here.

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Q: What does it take to get this up and running?

A: Actually, it’s pretty straightforward. You need to place the digester near a floor drain and bring power and data to it. I can get daily metrics on how much food is being added to the machine, how much it is digesting in an hour and a whole lot more.

Q: Can you walk us through the nitty gritty of installing this?

A: Find a suitable location for the installation. Being near a drain in the dishroom is the big thing here. Once it’s plumbed in and with power, you add the Power Chips, small, porous black pellets where the enzymes live and grow. While the chips are soaking, you mix the “starter” food, which is brown rice, sugar and more enzymes. You add warm water and let it rest for a few hours. It’s like adding yeast to a dough. Then, add that to the machine and let it work. After that, you just start adding food.

Q: That seems pretty easy! How does this affect the staff?

A: It’s fun when you can find a win-win situation. With much less hauling of heavy trashcans to the Dumpsters, there’s no mess, no flies…all the things associated with having a Dumpster outside your building. The Dining and Facilities teams saw the benefits right away. There has been no increase in labor, and in many ways, this has made peoples’ jobs easier.

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Q: Great. What about training on the biodigester?

A: There is some training about what can and cannot go into the digester. We have to make sure we remove the paper and plastic from the waste stream. We don’t want big bones (like rib bones), but bones from chicken wings and such are okay.

Q: Now that you’ve been doing this for a while, and seen measurable results, how do you let the campus community know?

A: The students have been big advocates for this and have done a number of articles in the student newspaper as well as used the data in class projects. The Office of Sustainability has also helped us promote this initiative.