How well does compostable packaging actually break down in composting facilities? A mammoth study published by the Composting Consortium, reveals just that – in the largest study ever conducted in North America.

The report, Breaking It Down: The Realities of Compostable Packaging Disintegration in Composting Systems details findings from an 18-month study, testing over 23,000 units of compostable packaging in a range of composting facilities around the US, analysing not only the degradation of products, but also the conditions and methods that best support disintegration and high quality compost output.

The study reveals that compostable packaging and products successfully degrade in all environments and conditions, producing high quality compost. The in-depth report provides real-world research that supports laboratory studies, and field tests conducted around the world.

Key Findings:

On average, compostable plastic packaging broke down 98% by surface area
Compostable plastic packaging degraded successfully in all composting methods
Geographic area made no difference to compostability rates
On average, fibre based compostable packaging broke down 83% by surface area
Higher rates of degradation in fibre based products occurred with consistent moisture levels above 50% and agitation of compost piles

How the Study was Conducted

The study sought to test a wide range of products made of different materials, in facilities using different composting techniques across geographic areas to give as complete a picture as possible. The facilities in the study used in-vessel, windrow and static pile methods of composting, with standard processing times between 49 and 94 days. Samples were measured and analysed at the midpoint and endpoint of the facilities standard processing periods.

Two testing methods to retrieve samples from the compost piles were used: the mesh bag method places the samples into bags with organic samples, whilst the dose method places samples loose into the compost, marked with flags for retrieval. The study also used two methods to measure the results: measuring the mass of the composted items as well as the surface area. Measuring by surface area was found to be more pertinent in field testing, due to products absorbing moisture and being contaminated with organic matter.

In total, 23,000 units of 31 types of certified compostable products were tested. A range of packaging and products were tested, made from compostable plastics and lined and unlined fibre, including coffee cups, lids and pods, cutlery, bags and films. Positive and negative control items were tested to ensure accuracy across the sites and methods of testing.

*Map of locations and facilities taking part in the study. Taken from the report, Breaking It Down: The Realities of Compostable Packaging Disintegration in Composting Systems.*

Confidence in Compostables

All of the products tested as part of the study were certified compostable, giving further confidence in the standards and certification bodies. Across the entire value chain, clear and consistent messaging and labelling is required so that consumers know how to dispose of products and composting facilities need not worry about contamination of non-compostable materials.

One of the aims of the study was to develop best practice guidance together with composting facilities, in order to provide confidence to the facilities in accepting compostable materials together with kitchen and garden organic waste, and to ensure that the resulting compost meets the standards at which they sell the compost.

Commercial Composting Methods

The commercial composting facilities in North America use a range of methods, including in-windrow and static pile composting. These land-intensive sites are common across the United States, but less so in Europe where anaerobic digestion facilities are more familiar

In order to ensure that Solinatra materials are truly compostable, we independently verified the viability of products made of our materials at a commercial site in the UK. In 2022, a range of products made of Solinatra materials were tested at a anaerobic digestion plant in Attleborough, Norfolk. The testing gave conclusive proof that products were fully degraded within 45 day processing period, and the resulting compost showed no evidence of contamination or residual products. The site is a state of the art facility, that produces both biogas to power the local community and a high quality fertilisers and compost.

Solinatra is suitable for producing a wide range of packaging and products, for food and beverage, horticulture, medical products and much more. Made with natural, renewable ingredients, Solinatra materials are the truly sustainable alternative to single use plastics. What’s more, the materials are a drop in replacement for traditional plastics, and work on existing machinery and production lines – making it easy to make the transition to greener, cleaner products. Switch to Solinatra and ditch the polluting plastics, get in touch with our team to find out how our materials can support your journey to plastic-free.

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