Universities turn food waste into compost

May 6, 2014

  Food waste is something we all produce, but don’t like to think about. That’s why several large universities in Missouri are turning food waste from dining halls into compost.

At Missouri State University in Springfield, campus dining services feeds 3700 students and 1000 faculty and staff members. That’s a lot of food, and also a lot of food waste.

Missouri State dining services resident district manager Tony Hein says a quarter of a pound, on average, is thrown away with every meal. That’s why Missouri State decided to start composting the food waste about four years ago as part of its university-wide sustainability initiative.

A big part of reducing food waste is making sure students only take the amount of food they will actually eat, Hein said. That starts with the people who serve the food.

“Sometimes we have the grandma mentality where they feel like they have to make sure the students don’t go hungry, and some of that is educating the students to just take what they want and they can always come back for more," he said.   

All of the uneaten food is scraped off of plates and collected in separate containers. It’s picked up and taken to a third party composting company three times a week.

Mizzou also produces a lot of food waste at its residential dining halls, cafes, and restaurants.

In 2011, the university got a grant from the Mid-Missouri Solid Waste Division. That combined with an investment from the school’s campus dining services was enough to build a covered composting facility at Bradford Research Farm. Now a fraction of Mizzou’s food total waste, about 3500 pounds per week, is sent there to be turned into compost.

Eric Cartwright is the executive chef for MU Campus Dining Services. Don't let his title mislead you, you see he doesn’t actually do that much cooking. He’s more of a business manager. And he says composting food waste makes good business sense.

“We’re paying a fee per ton to have waste hauled to the landfill. By having it done internally, and we’re kind of unique in how we’ve arranged this with Bradford. We’re incurring no cost to have brought out there. And so in time, that waste actually pays for itself,” he said.

Food waste is collected from seven of MU’s dining facilities. Then, it’s loaded into green trash bins and taken to Bradford Research Farm just southeast of Columbia, where students will turn it into compost.

Tim Reinbott is the superintendent at Bradford and supervises the compost program. Composting is a scientific process where bacteria heat up and break down food waste over time, he explained.  

"The trick to making good compost is to get the right balance of carbon and nitrogen," he said.

At the Bradford center, they do that by mixing the food waste with horse bedding taken from South Farm, another MU facility.

“They put equal parts food waste and horse bedding. And then this starts the whole reaction. So you can see what’s in there is less than seven days old and you really can’t see food anymore. That process is fast and it gets started really quickly,” he said.  

The compost is piled under a shelter in bays that are big enough to park a truck in. Each bay holds compost at different stages.  And for piles of decomposing food, it actually doesn’t smell that bad. It smells more like soil, moist and earthy.

“When I come out here and I almost smell a putrid smell, almost like vomit, I know one thing. It’s anaerobic. And that means it’s either too wet or it’s too much food waste and not enough horse bedding. And we need to adjust our system. Whether we need to aerate in some way or mix it up or put some horse bedding in. So, it’s an art too, you’ve got to use your sensing about it,” Reinbott said.

Reinbott knows when the compost is done when its temperature evens out. It’s then spread over several fields at Bradford, where students grow vegetables to sell back to campus dining. That starts the process all over again.

“We’re recycling so many nutrients instead of our nutrients going to the landfill and never getting used again, now we get to use them. And I’m talking about nitrogen, phosphorus, calcium, there’s this limited supply of all this. So it’s really good to get the nutrients back. Also, the compost feeds the soil life and that’s incredibly important because if you have a good healthy soil, then our plants are healthy, he said”

Reinbott said the program’s ultimate goal is to process even more food waste, so they can bag and sell any extra compost in the commercial market.