Résumé
Compostable materials represent an innovative solution to reduce the environmental impact of plastic materials, by providing an alternative route for end-of-life treatment. They have the potential to significantly enhance the collection of organic waste such as leftover food, kitchen scraps or green plant waste from the garden, and replace conventional packaging, which can contaminate biowaste stream due to sorting errors. When combined with biowaste, these materials contribute to the circular bioeconomy by creating valuable compost, which serves as a beneficial soil amendment for agriculture.While lab-scale measurement methods exist to certify the biodegradability of a material under industrial composting conditions, they cannot perfectly replicate real processing conditions. Industrial composting involves greater heterogeneity of biowastes in terms of composition and size, less stable environmental conditions than in the laboratory, and the absence of preliminary grinding. Consequently, geometric effects on biodegradation rates are more pronounced in real industrial-scale processing scenarios.To investigate these effects, an industrial-scale experiment was conducted at a composting facility in southern France. This facility uses a low-tech process, specifically open windrow composting on a concrete slab without housing. Approximately 40 tons of biowastes and green waste were split into two parallel compost batches. One of the batches was mixed with a blend of certified compostable materials readily available on the French market, resulting in a plastic mass concentration of 1.3 %, a reasonable estimate of the maximum plastic concentration that can be expected to be found in biowastes over the mid-term.Throughout the composting process, regular measurements of compost parameters were taken, and representative samples were collected. The plastics were isolated from the sampled compost by screening with sieves of different sizes, the smallest size sampled being 1 mm.Under these conditions, all the materials disintegrated in less than 3 months as required by the EN 13432 standard. Surprisingly, the disintegration rate exceeded the expectations of the lab-scale experiments. After the standard 4-month composting process at the facility, only 1 % of the initial plastics remained detectable. An independent laboratory analysed the compost quality, which met current standards requirements for organic farming. A life-cycle assessment comparing composting to incineration demonstrated the benefits of composting in almost all impact categories.In conclusion, this industrial-scale experiment underscores that compostable materials, which are certified and commercially available, perform effectively during composting, even within a very basic composting process.