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Half of California’s food waste could be processed at WWTPs, says report

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At least half of landfill-bound food waste in California, US, could be processed at the state’s wastewater treatment plants (WWTP) and used for bioenergy, according to a new report.

The California Environmental Protection Agency said waste can be ‘co-digested’ at WWTPs, by adding organic waste such as municipal food scraps and industrial food processing wastes to an anaerobic digester.

Building on a survey of almost 225 WWTPs in California, the report found many have the existing anaerobic digestion (AD) capacity to accommodate diverted food waste. While maximising use of that excess capacity would require some additional infrastructure investment, the report shows such investments could benefit California’s economy, while advancing environmental goals.

Jared Blumenfeld, California’s Secretary for Environmental Protection, said: “We release this report just as California is experiencing the very real impacts of climate change.

“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 from landfills while cutting greenhouse gas emissions and helping to clean wastewater.”

The report suggested maximising co-digestion capacity could reduce state-wide GHG emissions by as much as 2.4 million tonnes of carbon dioxide-equivalent annually – 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 WWTPs have the existing AD 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.”