Reducing Landfill Waste Through Community Composting Initiatives

Americans discard roughly 60 million tons of food waste annually. That’s about 325 pounds per person, per year. This represents approximately 22% of the municipal solid waste that ends up in U.S. landfills. That can harm the environment by increasing landfill methane emissions, and it’s also a missed opportunity to leverage a valuable resource. Recycling this valuable organic material into nutrient-rich compost can benefit soil health, reduce the need for chemical fertilizers, and promote aerobic decomposition. Despite these advantages, current participation remains limited, with only 4% of U.S. food waste being composted.

Considering these issues, the Center for Advanced Hindsight at Duke University, in partnership with the City of Durham, North Carolina, embarked on a new research project to address the growing issue of food waste in landfills, funded by the Environmental Research and Education Foundation (EREF). Researchers Joseph Sherlock and Lyndsay Gavin explored how municipal food waste collection programs could reduce landfill waste and promote other positive environmental behaviors.

Researchers posed four guiding questions:

These led to a behavioral experiment designed with three distinct phases, each designed to build upon the findings of the previous phase.

The research methodology was grounded in principles of behavioral economics and human-centered design, making the program both user-friendly and effective. The first phase focused on exploration and prototyping, where the researchers engaged with Durham residents to gather insights about their perceptions of and experiences with composting. Two small prototypes were developed based on that feedback. Researchers found that Durham residents were more likely to compost due to their values around environmental preservation, but barriers included a lack of knowledge about the composting process and concerns about cleanliness and pests.

Building on these insights, the second phase involved a small-scale pilot program in a local Durham neighborhood, but researchers weren’t initially able to create a demographically representative sample of the entire city. The pilot aimed to test the operational capabilities of the municipal composting program and assess its impact on contamination rates and participant behaviors. Despite some recruitment challenges, the pilot showed promising results. Educational efforts proved effective in reducing contamination (composting the wrong materials), and participants reported a decrease in the amount of waste sent to landfills.

The final phase, a randomized control trial (RCT), aimed to test the program’s effectiveness in a larger and more controlled setting. The RCT involved 360 households, divided into treatment and control groups. The treatment group received curbside food waste collection services and educational materials, while the control group did not. The researchers measured the weight of landfill-bound waste and food waste collected from each household as well as changes in participants' pro-environmental and pro-community behaviors. Households in the treatment group sent an average of 5.8 pounds less waste per week to the landfill compared to the control group aligning with the Sherlock and Gavin’s hypothesis. The treatment group also showed signs of improved relationships with Durham’s municipal government and increased engagement in pro-environmental and pro-community behaviors.

Interestingly, while the program did lead to a reduction in landfill waste, the expected increase in pro-environmental identity among participants was not as pronounced as anticipated. However, participants did report a significant increase in positive spillover behaviors, such as recycling and reducing water usage. This suggests that the act of composting itself may have activated a desire to behave consistently in other environmentally friendly ways, even if it did not strongly alter participants’ self-perception as environmentally conscious individuals.

The implications of these findings are profound for both local governments and the broader behavioral science community. For the City of Durham, the success of the composting program provides a case for expanding the initiative citywide, potentially reducing landfill costs and environmental impact. For the field of behavioral science, the study offers valuable insights into how pro-environmental programs can influence broader behavioral patterns, even if the mechanisms driving these changes are complex and multifaceted.

Read the full report here.