Anaerobic digestion is a process that uses microorganisms to break down biodegradable material in the absence of oxygen. South San Francisco Scavenger Company and its partner, Blue Line Transfer, are the first in America to use dry anaerobic digestion technology to convert food and yard waste into clean-burning compressed natural gas (CNG). Other digesters produce methane, which is then burned to generate electricity.
The company will use the fuel produced by its digester in its fleet of CNG-powered trucks. “We’re excited about the new digester because it allows us to turn compostable food scraps into fuel for the very trucks that collect those materials. It’s a truly closed loop system,” says company president Doug Button. “Plus, the process keeps organic waste out of the landfill and cuts greenhouse gas emissions—benefiting the communities we serve, the environment and our company.”
Made by Zero Waste Energy, LLC, the Blue Line Transfer anaerobic digester produces up to 500 diesel gallon equivalents (DGE) each day of carbon negative, renewable CNG. In addition, the process provides digestate, a nutrient-rich substance that will become certified organic compost. Compared to traditional composting, the dry anaerobic digestion process creates fewer greenhouse gas emissions and other air pollutants.
SSFSC plans to process 11,200 tons of food waste and food soiled paper every year from its customers in South San Francisco, Brisbane, Millbrae, Colma and the San Francisco International Airport. The new technology will serve an expanded push to sign up businesses for food scrap and food soiled paper collection.
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