We are making huge strides on campus to reduce the amount of organic waste in landfills. One method we’re using is composting, a process that turns organic material into a valuable nutrient-rich soil additive which can be used to fertilize campus gardens and green spaces.
In 2018, UT Recycling composted more than 1,100 tons of food and landscaping waste.
What is Compost?
Compost is made up of organic material that can be used as a soil additive. The materials are made up of two categories: the greens and browns. Greens are rich in Nitrogen and made up of materials such as grass, fruit or vegetable waste, and animal manure. Browns are rich in Carbon and are made up of materials such as dead leaves, branches, and wood chips. In addition to greens and browns, water and oxygen must be present in the compost pile. When mixed at a specific ratio, tiny bacteria and microorganisms use these materials for energy and by doing so, break down the organic waste in a usable material.
Composting helps divert organic matter from landfills. In landfills, organic matter can’t decompose properly because it’s covered under layers of trash; as a result, it produces methane gas as it decomposes, a potent greenhouse gas that is 21 times more potent than carbon dioxide. Solid waste landfills are the single largest man-made source of methane gas in the United States. By trapping heat in the atmosphere, methane gas contributes to the greenhouse gas effect that is fueling global warming. According to the EPA, food scraps account for 28% of solid waste, which equates to 68 million tons last year. By composting at UT, we are doing a valuable part in decreasing our carbon-footprint and emissions.
How Does It Work?
Food waste is collected from all campus dining locations and select buildings on campus at these locations. The compost is brought to UT’s compost site located off Cherokee Trail. At the compost site, the food waste is combined with wood chips and separated into long piles called windrows.
The windrow then goes through a turn cycle. During the turn cycle, the windrow is turned and mixed five times over the course of two weeks. This ensures that all the material in the windrow is exposed to the high heat and high microbial activity inside the windrow, where bacteria is working to break down the raw organic ingredients into mature soil. After being turned, the windrow is left to mature for about 3 months. During this time, the ammonia and CO2 levels decrease in the compost, which makes it more suitable for growing plants later.
The windrows allow waste to biodegrade aerobically, meaning it breaks down with the help of bacteria that use oxygen to survive. This is a relatively quick method that also reduces the amount of methane—a harmful greenhouse gas—that is produced during the process. Periodically, the windrows are turned and watered to manage temperature and biodegredation.
After the compost has reached maturity, it is put through a mechanical screen to remove any contamination, such as plastic bags or silverware, that may have been mixed in at the beginning. The finished, screened compost is then delivered to gardens and plant beds on campus.
Where Does It Go?
Most finished compost is taken to the UT Organic Farm or Grow Lab, where it’s used as a soil additive to fertilize crops. Produce from the Organic Farm then hopefully makes it to your plate at a UT Dining location!
Some compost may be used for erosion control on campus or mixed with fill dirt to create better topsoil, which helps plant growth and development. Alternatively, some of it may even be used at the Anthropological Research Facility, the “Body Farm”.
We are constantly trying to improve, streamline, and expand our composting operation. We are working more closely with campus dining to collect as much food waste as possible, making improvements to our windrow watering system, taking measures to make sure our site is as environmentally friendly as possible, and educating students on composting. If you are interested in taking a tour of the site, please submit your request here.