December 4, 2015
Every truck of organic material diverted away from the landfill strengthens ASU’s commitment to sustainable business practices.
Compost is immensely beneficial because it decreases methane emissions from landfills; treats waste as a resource; employs locally; saves money; supports alternatives to the outdated, linear economy landfilling model; and creates fertilizers to rejuvenate soils and grow food.
Composted organics from ASU benefit the local economy and environment, and a lot of work goes into the process.
Items including food scraps, paper plates and napkins are picked up by custodians, kitchen staff and Zero Waste department staff, then placed in centralized bins for collection by Sonoran Waste Disposal’s organics transportation truck. Organics are collected from athletic venues, the Memorial Union on the Tempe campus, large events, all dining halls on the Tempe campus, as well as one dining hall on the Polytechnic and West campuses.
Office building pilot programs are currently underway at University Sustainability Practices, Wrigley Hall and the University Service Building. Almost 300 tons of food waste was diverted in fiscal year 2015 through these collection routes.
Material is brought to a Phoenix facility called GOR (Green Organics Recycling), which is about 20 minutes away from the Tempe campus. Facility employees pick out a lot of plastics and bioplastics because these items cannot currently be composted. Contamination slows down the composting process, so properly sorted waste can save the university time and money.
The compost is mixed with wood chips, a byproduct of the logging industry in Northern Arizona. Organic material is then combined with material from other commercial and industrial sources in the Valley. One client, Whole Foods, collects their organics in blue drums.
Sonoran Waste Disposal is eager to work with Valley companies who wish to divert their organics and provide the utmost transparency to clients. Sonoran owner David Hertzberg offers tours to clients and believes transparency is key to effective circular-economy solutions.
The organic material is transported about seven minutes down the road to the main organics processing facility, which is operated by Growell. This company has successfully competed in this tight-margin industry for more than 40 years.
Growell uses both aerobic (with oxygen) and anaerobic (no oxygen) processes to decompose the composted material. Anaerobic processes comprise the majority of operations because they require less space. In seven months to a year, organic waste from ASU is transformed into rich humus, a natural component of fertilizer. More than 20 truckloads a day and 150,000 tons of material a year are processed at this facility.
Gypsum is included in the compost process because it changes the pH of a fertilizer and makes it more desirable for certain types of vegetation. Since drywall is comprised of gypsum and fibers, Sonoran transforms this waste product into a valuable component of its resource recovery process.
The composted material is then combined with other resources like peat moss. In some cases, chemicals are combined with the compost to create fertilizer to be sold at major home improvement stores and nurseries. Each buyer has specific blends they ask for, which require different compositions of resources.
As ASU continues to expand its composting bins across campus, Sonoran has the capacity to scale up its operations. As the Assistant Director of ASU’s Zero Waste program, Alana Levine and her team are working to divert waste from the landfill in many ways beyond organics collection.
The focus of the Zero Waste Program and the broader movement, however, is to reduce the amount of waste generated in the first place. Although the compost heap is a great destiny for food scraps and paper plates, not letting food rot and using reusable plates is a superior solution. To learn more about ASU’s recycling and composting efforts, click here.
Contributed by Alex Slaymaker, Masters of Sustainable Solutions and Zero Waste Club President, and Ashley Knudsen, BA Sustainability, University Sustainability Practices.