Sewage treatment plants could process food waste to spare landfills and cut emissions

Research using data from a full-scale U.S. wastewater treatment plant found that routing food waste to treatment plants can produce net-negative greenhouse gas emissions compared with landfilling and allow recovery of energy and nutrients.

About 97 million metric tons of food are discarded each year in the United States, with roughly 37 million metric tons sent to landfills. In landfills, organic material decomposes without oxygen and releases methane, a powerful greenhouse gas. Researchers analyzed data from a full-scale U.S. wastewater treatment plant to compare outcomes when food waste is routed to treatment plants instead of landfills. The study notes that many larger wastewater plants already process organic matter and have systems to capture methane and recover nutrients. Key points: - About 37 million metric tons of U.S. food waste are landfilled annually. - The study calculated that landfilling the same food waste would emit about 58.2 kilograms of CO2 equivalent per ton. - The conventional wastewater plant analyzed achieved net-negative emissions of −0.03 kilograms CO2e per ton; an advanced plant in the analysis achieved −0.19 kilograms CO2e per ton. - Larger wastewater plants can capture biogas for energy generation and recover nutrients for fertilizer, but not all facilities are currently equipped to accept additional food waste. Summary: Treating food waste at wastewater plants, according to the study, can avoid methane emissions from landfills while enabling energy and nutrient recovery. Undetermined at this time.