Optimizing Food Waste Anaerobic Digestion at Water Resource Recovery Facilities: Skid-Mounted Mobile Pilot/Education Units for Source-Separated Organics/Biosolids Processing with Cogeneration Capabilities
October 27, 2022
Energy Research and Development (500)
Electric Program Investment Charge - EPIC
Alex West, P.Eng., James Dunbar, PE., Kim Domptail
This project integrated a small-scale skid-mounted system with a food waste de-packaging unit (separation of food waste from non-organic materials) with anaerobic digestion and thermal hydrolysis capabilities to efficiently process food waste and support California’s efforts in diverting organic waste from landfills. Food waste digestion or co-digestion at wastewater treatment facilities leverages existing infrastructure and onsite expertise, reduces greenhouse gas emissions, and enhances production of biogas, which is a renewable energy source.
The complete system, installed at the Goleta Sanitary District in Santa Barbara County, California, included a containerized de-packaging unit; two 2,000-gallon anaerobic digesters; flare, feed, and discharge equipment; and a full system for process control and data collection. The system pre-processed food waste from dining halls at the University of California, Santa Barbara into an organic slurry in the de-packaging system before pumping to the anaerobic digesters.
The project team investigated the effects on anaerobic digestion from pre-treating the organic slurry using Lystek thermal hydrolysis, which increased biogas yields from difficult-to-digest food wastes. After initial acclimation, digester gas production was 21% higher with the thermal hydrolysis product than from untreated organic slurry.