A first nationwide look shows diversion of U.S. food waste from landfills could reduce related climate impacts by 89% and nutrient pollution by 50%, UVM researchers say
Keeping food waste out of landfills provides climate and other environmental benefits, and Vermont requires residents to divert these materials to better management pathways. With other states considering similar policies, UVM researchers studied the potential outcomes of bringing these efforts to a national scale.
The new findings, out today in the journal Nature Food, indicate a need to plan not just for channeling food waste into landfill alternatives—but also for managing the microplastics that can remain in the resulting compost and other organic materials, says study coauthor Eric Roy, professor in the Rubenstein School of Environment and Natural Resources.
Solutions to keep food waste out of landfills include turning it into compost for agricultural use and using anaerobic digestion to produce biogas for renewable energy. While researchers have looked at these disposal options before, none had taken microplastic contamination into consideration at scale, says Roy.
Key findings include that diversion of food waste from landfills to composting and anaerobic digestion at a national scale in the U.S. would reduce the current climate impacts of these wastes by 89 to 99%. Environmental nutrient pollution from food waste management, which can contribute to infamous summer blue-green algae blooms in lakes, could drop by 49 to 54% for nitrogen, and 78 to 98% for phosphorus. But if the organics resulting from composting and anaerobic digestion were spread on agricultural fields, they could also carry around 20,000 tons of microplastics into the soil annually, the researchers found.
“If you don’t intentionally intervene and have a plan for how you’re going to minimize plastic in your recovered soil amendments, there will probably be plastic there based on just how pervasive it is in our food system right now,” says lead author Kate Porterfield, a Gund Institute for Environment postdoctoral researcher. “It’s literally everywhere.”
The work points to the need for better planning at every step of the food recycling process—including the design of packaging before the food’s ever in it, Porterfield says.
Using a combination of data from across the U.S., the team created “life cycle assessment models” to inspect potential effects of nationwide composting, anaerobic digestion, or landfill disposal of food waste. The approach takes into account every step of food waste’s journey, from the moment it arrives at a waste transfer station, to its fate as compost in a field, methane gas converted to electricity, or a slimy pile with plastic, slowly releasing greenhouse gases in a landfill.
The researchers also considered a potential drop in the need for synthetic fertilizers in agriculture resulting from replacement by recovered nutrients in organic wastes—but found that nutrients recovered from food waste would offset only about 2% of annual U.S. demand.
Dealing with food waste is becoming increasingly top-of-mind among some policymakers, with up to 40% of U.S. food wasted, and a quarter of landfills’ already dwindling space taken up by discarded food. Composting food waste has gone from being the domain of avid home gardeners to a legal requirement in some U.S. jurisdictions. Vermont, being an early adopter of required food waste diversion away from landfills, is seeing some of the challenges that can pop up alongside the benefits, says Roy. Additional efforts to increase composting and anaerobic digestion of food waste currently exist as a national patchwork, with tremendous variability from place to place.
Roy, who also directs UVM’s Casella Center for Circular Economy and Sustainability, says he’s not aware of any upcoming national food waste diversion plan. Casella Center research focuses on finding greener pathways for waste management. With more states and municipalities considering food waste recycling, studies like this one can both clarify benefits and reveal potential issues in advance, Roy says, helping to ease the transition. Upfront planning to reduce microplastic contamination in food waste at the outset is needed to maximize the net environmental benefits of food waste diversion programs and policies.
“We thought, we need to think about this at a big scale because Vermont’s leading on this issue,” Roy says. “What if more states jump on board?”