A group of University of Arizona students wants to do something beneficial with the 2,000 tons of compostable waste produced at the University of Arizona each year.
Compost Go Live, a team in the UA's Students for Sustainability program, plans to launch a demonstration composting operation within the next few weeks, said Ashton Inskeep, the compost project's manager.
"The mission of Compost Go Live is ultimately to compost all the University's compostable waste, which includes landscape waste called green waste, manure as well as food waste from the Student Union and other dining facilities, and perhaps potentially to expand to University Boulevard and greater Tucson," said Inskeep, a sophomore in environmental science, land and water sustainability and Spanish translation.
"Another mission we have is to educate people about composting, to sort of spread it as something easy and viable to do in your back yard," she said.
Green waste and food waste now produced at UA is disposed of in a sanitary landfill, while manure produced at the UA farm remains there, she said.
Plans call for transporting this compostable waste to a site near the UA's Arizona Veterinary Diagnostic Lab near Interstate 10 and West Miracle Mile where it will be decomposed into soil mulch for gardening and agricultural use, she said.
The first step, which is schedule to begin in a couple of weeks, will see "feed" materials – green and food waste and manure – ground up into particles about 2 inches by 2 inches and combined in a mixing box before the resulting material is used to form a static aerated pile 6 feet tall and 15 feet long.
A blower will push air through a PVC pipe filled with holes around which the pile is built to make the composting process effective. "Basically the more aeration you have the faster things compost," Inskeep said.
Air and heat – compost should be between 135 and 165 degrees Fahrenheit to achieve maximum efficiency – cause the organic materials, which should contain 40 to 60 percent moisture, to decompose and basically create soil, which can then be used as mulch, she said.
The resulting material will be put to good use.
"We potentially want to market it. We're looking at selling it to local growers," Inskeep said. "Most compost is used as a mulch, a soil amendment where you put it on top and till it in a little bit. In the desert of Arizona it keeps the soil moist and we don't have a lot of organic material here."
There may be bigger industrial customers for the compost end result.
"When you first start out you want to sell large quantities so we are looking towards mines as remediation because a lot of mine sites are very acidic and compost helps regulate in the soil. And it helps plants grow and root in mine tailings," she said.
The program will be student operated, with paid student helpers doing the composting process itself, she said. Revenues will fund the operation.
After the demonstration program proves the concept, the group plans to use a faster, more efficient in vessel system for composting.
"Basically its completely enclosed so there is no vectors, which include odor, leachate, anything that would be a problem to neighboring areas," she said. "The good thing about having it completely enclosed is that it keeps the moisture in and keeps the heat in. You need a really warm core to compost quickly so it helps facilitate that. It's also aerated because aerobic respiration creates compost a lot faster than anaerobic and it smells a lot better."
The Compost Go Live team hopes to have the in-vessel system, which can cost $400,000 and up, in place by fall. "We have been actively researching companies and we have a pretty good idea of what we want. It's just getting the means to purchase it," she said.
The project need not be huge in size.
"Currently we want to keep it small to make sure we have everything figured out before we get into a venture above our heads. But the interns would definitely like to see all of Tucson compost, and there is interest in the community to compost as well," she said. "Composting 2,000 tons a year is really small in comparison to what most composting services offer. If you look at this land, this could potentially compost all of Tucson's waste. "