Composting machine at work  Oscar the Composting Machine

Housing & Dining Services has invested in a state of the art, fully-automated composting system called the Earth Flow. This enclosed, 30-yard capacity compost bin is located on the CSU Foothills Campus (three miles west of main campus). Pre- and post-consumer food waste from CSU Dining Centers is composted in the Earth Flow. The program is in its fourth year and last year diverted over 250,000 pounds of food waste. Materials produced were used by the student farm, community non-profit organizations and as soil amendment for the new Laurel Village complex

Dining Center Pulpers

  • Ram’s Horn, Braiden, and Durrell Center Dining Centers have pulpers in their kitchens.
  • The pulpers mix all of the food and paper waste with water, and then grind up the material. This slurry is then taken by pipe to a centrifuge, which removes excess water and recycles it through the system. The pulped organic waste is emptied into collection containers outside the building.
  • This pulped material is perfect for anaerobic digestion systems because it is already broken down into small pieces with excess water removed. The pulpers have helped reduce the waste stream volume by 70 percent and water consumption by 80 percent in the dining centers.

Earth Flow Living Lab

  • The Earth Flow in-vessel composting system, located on the CSU Foothills Campus, accepts 2,000 pounds of material per day.
  • The system operates as a living lab with student interns from Soil & Crop Sciences loading materials, taking measurements, and making recommendations for recipe and operational improvements. A faculty adviser in the College of Agriculture serves as a member of the Compost Team and selects the intern each semester. The Compost Operator provides hands-on instruction on site and the Senior Sustainability Coordinator for Housing & Dining Services supervises the interns. 
  • Organic waste is loaded into one end of the vessel by placing the collection container on an automated tipper. Every time food waste is added, bulking material like straw, wood chips, and horse manure from the Equine Center is added at a 1:2 ratio. 
  • Material is composted for about three weeks inside the bin. Finished compost is discharged through an end door of the vessel. The compost is piled on site to cure for at least 3-4 weeks before being used in landscaping projects on campus.

For more detailed information about how the Earth Flow system works, download our Composting Fact Sheet (PDF).

Adding compost to Oscar the compost machine  Composting: The finished product

Clean Waste-to-Energy Program

  • In 2014, Housing & Dining Services partnered with A1 Organics to reduce the amount of food waste that ends up in the landfill. The food waste from the dining halls is processed and then returned to campus to be used in various landscaping projects. The program now process about 26,027 pounds of food waste monthly.
  • The generated methane is used to heat the plant process and buildings.