A new report issued by the California Environmental Protection Agency shows that at least half of California’s landfill-bound food waste could be processed at the state’s wastewater treatment plants and serve as an innovative power source.
Waste can be “co-digested” at these facilities, which involves adding organic wastes including municipal food scraps and industrial food processing wastes such as chicken blood to a facility’s anaerobic digester.
Building on a survey of the nearly 225 wastewater treatment plants in California, the report finds that many have the existing anaerobic digestion capacity to accommodate diverted food waste. While maximising the use of that excess capacity would require additional infrastructure investments, the report shows such investments would benefit California’s economy while advancing environmental goals.
“We release this report just as California is experiencing the very real impacts of climate change,” said Jared Blumenfeld, California’s Secretary for Environmental Protection. “As our environmental problems become more tangled, we have to start planning for cross-cutting solutions like this. Co-digestion can be a triple threat against climate change: it can reduce organic waste in landfills while cutting greenhouse gas emissions and helping to clean wastewater.”
The report estimates the statewide capital investments required to use the co-digestion capacity range between $900 million and $1.4 billion. The net benefits to the state could be up to $255 million each year.
Maximising co-digestion capacity could reduce statewide greenhouse gas emissions by as much as 2.4 million metric tons of CO2-equivalent per year. That’s more than half of the emissions from landfills that California committed to reducing by 2030.
“The report’s findings are very promising,” said State Water Board Chair E. Joaquin Esquivel. “It shows California’s wastewater treatment plants have the existing anaerobic digestion capacity to accommodate at least half of California’s landfilled food waste—likely more. We look forward to working with our industry partners to get more of these projects off the ground.”