Mar 20: A new study highlights the potential for wastewater treatment plants (WWTPs) across the United States to transform food waste from a major environmental burden into a valuable resource, reducing greenhouse gas emissions while producing renewable energy and nutrient-rich fertilizer.
Each year, the U.S. discards about 97 million metric tons of food, with roughly 37 million metric tons ending up in landfills. Buried in anaerobic conditions, this organic waste emits methane, a potent greenhouse gas, and permanently loses nutrients and energy stored in the food.
Researchers found that by redirecting food waste to existing wastewater treatment facilities, communities can achieve net-negative greenhouse gas emissions, turning a problem into an opportunity. In conventional WWTPs, methane capture and energy recovery prevent the release of 58.2 kilograms of carbon dioxide equivalent per ton of food waste that would otherwise escape from landfills. Advanced facilities further improve emissions reductions, achieving –0.19 kilograms of CO₂ equivalent per ton.
“The systems to process organic matter already exist,” said Shelley Wunder-Smith, lead researcher at Georgia Tech. “Wastewater treatment plants are designed to handle microbial breakdown of organics, capture methane, and recover nutrients. Redirecting food waste into these systems is both environmentally and economically viable.”
At the study site, trucks collected food waste from households and transported it to the treatment plant, where it was processed and blended into a slurry with sewage solids. Anaerobic digesters then broke down the material, producing methane for electricity and heat and solid material suitable for fertilizer production. The addition of food waste did not overload the plant, which processed over 107,000 tons annually – representing 38% of the county’s landfilled food waste – while consistently meeting regulatory standards.
Financially, this model can be sustainable. Treatment plants can charge tipping fees for food waste, generate energy from methane, and recover fertilizer for sale or local use. These benefits may offset operational costs and make the process economically attractive for cities.
This research demonstrates that local governments already possess the infrastructure needed to handle food waste sustainably. With minimal upgrades in smaller plants, communities can reduce emissions, recover valuable resources, and move closer to circular waste management solutions.
