A new report by Closed Loop Partners’ Composting Consortium, which examined five years of research, field testing and cross-industry collaboration, revealed best practices for compostable packaging recovery and composting infrastructure in the US.
Caroline Barry, senior program manager at Closed Loop Partners, said the Composting Consortium’s work, led by Closed Loop Partners’ Center for the Circular Economy, uncovered critical insights into how compostable materials perform outside of controlled environments.
“The Composting Consortium unearthed numerous insights on compostable packaging disintegration––many of which were brought to light during our field tests,” she said. “What surprised us most was not that certified compostable packaging could successfully disintegrate in real-world composting systems, but how clearly the data showed that disintegration performance is closely tied to operating conditions.”
In what was the largest singular field test of certified, food-contact compostable packaging in North America, compostable plastics averaged 98% disintegration by surface area, while compostable fiber averaged 83%, with both exceeding industry thresholds.
“One finding that challenged common assumptions was the performance of compostable plastics,” Barry said. “In many parts of the industry, there has been a persistent concern that compostable packaging—particularly compostable plastics—do not break down quickly enough for facilities with shorter processing timelines. Our field data helped challenge that assumption.”
She noted that by approximately 47 days into the composting process, compostable plastics had already reached 98% disintegration on average, while compostable fiber reached roughly 78%.
“That midpoint result is important because it speaks directly to the operational concerns of compost manufacturers managing for throughput, efficiency and product quality,” Barry said.
The research also highlighted widely held beliefs about fiber-based materials.
“The study also surfaced a more nuanced point about compostable fiber packaging,” she said. “Fiber is often viewed as the more benign material in composting systems, yet our data showed that compostable plastics, on average, disintegrated more consistently across the composting technologies and operating environments we studied.”
While the findings do not suggest one material is universally better than another, the report does highlight the importance of process conditions.
“That does not suggest compostable plastics are inherently superior,” she said. “Rather, it points to a more important operational reality that certain compostable fiber formats may require stronger process conditions including sufficient agitation, turning and consistent moisture to break down effectively in compost piles.”
Beyond material performance, contamination remains a major operational challenge for composters.
“On average, composters in our study spent 21% of operating costs on contamination removal, and conventional plastics accounted for 85% of the contamination they received by volume,” Barry said.
That reality, she explained, shifts the conversation away from consumer behavior alone and toward system-level solutions.
“There are certainly upstream steps that matter—clearer differentiation between compostable and non-compostable packaging, better alignment across accepted-material lists and stronger coordination across brands, municipalities, haulers and processors,” she said. “But if the question is what is most realistic in the near term, targeted investment is one of the most immediate levers available.”
The Consortium has already taken steps in that direction through its national Composting Consortium Grant Program.
“We supported eight municipal and composter-led projects designed to expand access, strengthen infrastructure and improve regional recovery capacity,” Barry said.
Despite progress, achieving a standardized national system remains a work in progress.
“The US has made meaningful progress over the last five years, but there is still a lot of work needed to achieve a truly standardized national system for compostable packaging acceptance,” she said, pointing out that composting in the US is still highly localized, with acceptance decisions influenced by facility conditions, policy and infrastructure.
“Acceptance decisions are shaped by facility configuration, permitting conditions, end-market requirements, contamination tolerance, collection system design and local policy,” Barry said. “Acknowledging the landscape of the US composting system, the goal should not be a one-size-fits-all national mandate. What matters more is building greater consistency where it counts.”
For brands investing in compostable packaging today, the biggest opportunity Closed Loop Partners sees is to approach it not simply as a packaging material decision, but as part of a broader organics recovery strategy.
“Collaboration will be critical to moving the needle,” Barry said. “The more brands can engage early and directly with the broader recovery ecosystem, the more progress can be made.”
Ultimately, the Consortium’s work underscores a central lesson that compostable packaging can only succeed when the systems around it are designed to support it.
