Cornell Manages Half its Food Waste into High-quality Compost
Cornell University in Ithaca, N.Y., collects and processes food scraps and animal bedding into nutrient-rich compost. The amount of compost it processes makes the university the second largest recycler in Tompkins County.
Cornell Farm Services, which runs the operation, trucks some 8,000 tons of organic garbage from 57 campus waste streams—from dining halls to greenhouses—each year to its composting site a mile off campus. Time was when that waste would travel 65 miles to a landfill, incurring fees of more than $50,000 a year.
Last year, the facility received:
- 850 tons of food scraps and biodegradable utensils from 11 dining halls and other food locations;
- 3,300 tons of animal manure and bedding; and
- 300 tons of plant material and soil from greenhouses.
"It's far more cost effective to send this waste to our composting site than to send it to the landfill," said Andrew Lewis, director of agricultural operations for the Cornell University Agricultural Experiment Station.
The site produces up to 6,000 tons (4,000 cubic yards) of garden-ready compost each year that is used to nurture plant growth on campus or sold to local landscapers, garden centers, vineyards, and farms for $15 per cubic yard.
Through compost sales and tipping fees for moving the waste, the compost site is largely self-funded and is set up to run as a not-for-profit facility. "If we make a profit in a given year, the following year we lower tipping fees," said Lewis.
Composting on such a scale requires a lot of cooperation. Cornell Dining, for example, sends both waste from food preparation and plate scrapings and compostable packaging, cups, and cutlery made from corn or potato starch from dining halls to the compost site.
"The biggest challenge for us [at dining] is raising consumer awareness and encouraging people to separate their waste," said Doug Lockwood, office manager for Cornell Dining. Two Cornell Dining student coordinators have the job of raising awareness about composting in all dining halls and campus food retail outlets, working to educate diners about separating trash from compostable and recyclable items.
Also, the dining hall kitchens use pulping machines to turn food waste into a sort of "salsa" before it is trucked away.
"Because of the high volume and large-production kitchens in the 'all you care to eat' dining halls, we have these pulper machines in place," Lockwood added.
Once at the compost site, the material is spread into 18-foot-wide, 7-foot-tall windrows. About 15 such windrows sit on a four-acre gravel pad reinforced with an impervious geotextile fabric.
Gary Tennant, Farm Services manager, explains that the fabric and berms that create channels along either side of the pad direct excess water into a 250,000-gallon retention pond. The water from the pond is then pumped back onto the windrows to keep them moist. The water is also sprinkled on a 30-acre field on a hill above the windrows where grass and soil filter the water before it re-enters the watershed. The containment pond is home to muskrats, frogs, geese, and turtles, but not fish, since the dark water has very low oxygen levels.
In the windrows, microbes heat the decomposing waste up to 150 degrees Fahrenheit, and each week the facility's staff uses a large compost turner with a rotor to churn up and aerate the rows so the microbes get the water, air, carbon and nitrogen they need. In six to nine months, the compost is ready.