BAWIU – Biologisch abbaubare Werkstoffe in der Umwelt : Forschungsprojekt über den Einfluss und Nachweis von biologisch abbaubaren Werkstoffen in der Umwelt

In light of the increasing environmental impact of plastics and the uncertainties surrounding biodegradable materials (BM), the «Biodegradable Plastics in the Environment» project (BAWIU) aims to analyse the impact of these materials on the environment in a differentiated manner and to develop suitable detection methods based on literature research, market analysis and experimental laboratory work. Overview of the current status of BM in Switzerland: In 2022, the reported quantity of biodegradable material (BM) products introduced into circulation in Switzerland was, according to the survey, 8,600 tonnes. In a previous study (2016), 3,000 tonnes were recorded, meaning the amount of BM introduced into circulation has increased by a factor of 2.9. In relation to the total plastic consumption in Switzerland, which totals approximately 1 million tonnes annually, BM products account for only a small proportion of that quantity. Nevertheless, their impact should not be underestimated, especially in relation to ecological innovations, new material developments and the increasing demand for sustainable alternatives. The majority of BM products (85 %) are circulated within the business-to-business (B2B) sector, with a particular focus on catering establishments, including take-away restaurants that require items such as plates or cutlery. A further 10 % comprises retail products such as food packaging and compost bags. The remaining 5 % can be found in small quantities in various industries as packaging, novel materials, household supplies and hygiene products. Following the survey, a list of stakeholders was created with 124 entries to identify relevant importers, distributors, innovative companies, educational institutions and interest groups, of which 26 stakeholders completed the survey in full. The survey was carried out between 2022 and 2024 for data from 2022. The largest material group is cellulose-based materials (74 %), followed by PLA (21 %) and PBAT (4 %), and the remaining 2 % is accounted for by other materials. Of the total quantity of 8,600 tonnes, it is estimated that 1,077 tonnes (13 %) were disposed of via green-waste systems. The majority of the remainder was used for energy recovery, i.e. waste incineration. There is a need to improve data collection and labelling, in particular in terms of material declaration and material flows. Coordination of disposal options for reprocessing and recycling is necessary in order to improve the reuse of suitable materials and to reduce waste. Standards, labels and regulations: In Switzerland, there are only a few regulations relating to BM. The EU, on the other hand, has developed a comprehensive strategy for dealing with plastics in recent years, including the use of BM. This is predominantly based on the waste hierarchy, which dictates that reducing the consumption of short-lived products, increasing the lifetime of products, reusability, and repair or sharing of products are given a higher priority than replacing them with biodegradable materials. BM should only be used in the EU if their use results in a lower environmental impact or other benefits, for example, if the introduction of plastics into the environment cannot be prevented. Furthermore, life cycle assessments should be used to assess the environmental impact. In order to prevent trade barriers, Switzerland aligns itself with EU regulations on plastics. However, since EU regulations are not legally binding for Switzerland, well-established industry solutions, such as labels like Gitterdruck, can continue to be used to identify BM. In order to ensure the environmental and process compatibility of BM existing standards for green waste plants should be revised and further standards developed. Certification programmes and labels should be harmonised and always based on application-specific standards. In the recycling of BM, usage aspects should be taken more into account, i.e. they should only be recycled in green waste plants if there are benefits in terms of logistics, recycling technology or products (recycled fertiliser). There is also a need for further action concerning standardised and easily understandable labelling of BM as well as a duty to inform consumers. For example, the EU envisages introducing disposal instructions from 2028 that will use easily understandable pictograms to show correct disposal procedures. According to the authors, disposal instructions for consumers are more important than information on degradability, as the latter can lead to unwanted misuse. Currently, the Compostable by Design (CbDP) platform and Swiss Recycle’s Bioplastics Group are working with relevant stakeholders in Switzerland and the EU to establish framework conditions for sustainable design, safe and environmentally friendly recycling, as well as the labelling of and communication of information concerning BM. The Safe and Sustainable by Design platform (SSbD) also develops appropriate framework conditions for non-BM materials and products. Grouping and characterisation of BM: Since there is no standardised and complete classification for BM, a new system has been developed that includes both product level (application context) and material level (material properties) considerations. Investigations show that a differentiated, multidimensional system is necessary to map the complex properties of BM products. Cellulose- and starch-based materials in particular form large groups that require more differentiated classifications to allow for targeted assessment. The newly proposed grouping considers a variety of criteria such as material type, shape, reusability, degree of contamination, visual recognition, degradation rate and biogenic potential. By integrating feedback from stakeholders (Chapter 2), the system can be designed to be practical and application oriented. To assess the relevance of BM products, information about the pathways through which plastics enter the soil and the quantities of conventional plastics in the environment is needed. The aim of the following analysis is to therefore identify and evaluate the potential of BM to replace other products. The analysis of the pathways through which plastics enter the soil is based on a literature review that examines the potential for replacing conventional plastics with BM. The largest release of (conventional) plastics into soil has been identified as being connected to roads, especially through tyre abrasion. This is followed by releases that occur from construction, demolition, and the use of buildings, sports grounds and play areas. Further releases originate from agriculture, households and industry. To assess replacement potential, however, it is not so much the sources of release as much as the actual inputs into the environment that are decisive, since restraint mechanisms can be an effective tool for reducing environmental pollution. In this context, there is a significant need for reliable data on releases, restraint mechanisms and the resulting inputs. A central starting point remains the fight against littering. Plastics are priority candidates for replacement by BM, as they enter the environment through diffuse pathways and they are not subject to restraint mechanisms, such as those that exist for microplastics (MP). A central result of the literature review on the biodegradability of BM is the discrepancy between the potential degradability of materials and their actual degradation in the environment. The heterogeneity of test conditions, the variety of polymer blends and additives as well as the differences between the materials and resultant products make it difficult to standardise assessment. The studies analysed indicate that none of the investigated materials reliably and completely degrade under open-air conditions. Only PHA (PHB) and a study on a PBAT/PLA blend showed a degree of degradation within the target range. According to the literature research, only PHA (PHB) can be safely degraded in soil. However, partial degradation has been documented for PBAT and PBS, and PHA is readily degradable under home composting conditions. PLA and PBAT, whether used individually or in blends of PLA starch/PBAT starch/PLA-PBAT and PBS, also show a certain degree of degradation. However, they do not generally meet the degradation rates required for certification. In industrial composting plants, most of the materials investigated are considered to be degradable. However, recent studies show that not all materials degrade better at higher temperatures (thermophilic process control). This applies to PHA (PHB) and PBAT-starch blends in particular. In fermentation plants, only PHA is reliably degraded under mesophilic conditions. Under thermophilic conditions, PLA and PBAT/PLA blends are easily degradable, PHA and PBAT-starch blends exhibit a certain degree of degradation, while PBAT and PBS do not degrade sufficiently. From a precautionary perspective, the use of certain BM products such as PLA mulch films without recovery is currently not recommended under Swiss climate conditions, as biodegradation at low temperatures is insufficient and residues may remain in the soil. Ongoing research into degradation under realistic environmental conditions is key and should be included in future assessments to enable informed progress to be made. This applies not only to environmental and material factors but also to product properties, since finished products (e.g. complete compost bags) may degrade differently to crushed samples (e.g. powder) in laboratory tests. Research into the ecotoxicological effects of BM is still in its earliest stages. There are few experimental results on the (long-term) effects of microplastics from BM on soil systems. The potential effects of BM can be broadly classified into endocrine disorders; altered or reduced enzyme activity and diversity of microorganisms; cytotoxic and genotoxic effects; inhibition of biomass productio