Bio-based and biodegradable plastics (BBPs) are, in specific situations, a promising alternative to conventional petroleum-derived plastics. An example of this is the application in agriculture for sheet mulching, i.e., sheets used to protect the roots of crops from temperature fluctuations and weeds. In this case, a compound with soil biodegradability characteristics could reduce the costs of removing and disposing of conventional sheets, limit the formation of microplastics and soil removal that generally occur when removing the sheets after the cultivation cycle, and contain burning incidents. Another case is that of so-called single-use packaging applications, including tea bags and carrier bags, where the industrial-scale compostability characteristics could ease the pressure on mechanical recycling plants.
However, their real environmental and social impact and their integration into a sustainable circular bioeconomy are still debated. The recent study entitled ‘Linking bioeconomy, circular economy, and sustainability: Trends, gaps and future orientation in the bio-based and biodegradable plastics industry’ (Eleonora Foschi, Selena Aureli and Angelo Paletta – University of Bologna) explores trends, gaps and future perspectives in the European BBPs industry, providing new insights to accelerate the transition towards a sustainable circular bioeconomy.
According to the study, the bio-based plastics sector is expanding rapidly, with global production set to grow from 2.12 million tons in 2022 to about 6.3 million tons by 2027. These materials, produced in whole or in part from biomass (e.g., polylactic acid – PLA, polyhydroxyalkanoates – PHA), are underpinned by the urgency to reduce dependence on fossil sources and, therefore, greenhouse gas emissions generated by the petrochemical industry. However, pressure on plastics from plastic islands and evidence of the impacts of microplastics on animal and human organisms has shown a market trend toward one-to-one substitution, with use of these materials even in applications where the added value of biodegradability and/or compostability was not being adequately perceived or valued.
Despite the potential environmental benefits, the impact of BBPs is not yet fully demonstrated. This is also caused, as the study points out, by the absence of standardized tools and metrics to assess the circularity and sustainability of BBPs. Life cycle analyses (LCAs), accurate as they are, fail to account for variability in boundary systems. For example, due to different temperature and humidity conditions as well as soil characteristics, a sheet used in Northern Europe will be subject to a slower degradation process than in Southern Europe. It is, in addition, difficult to emphasize the benefits because monitoring ecotoxicity is still extremely complicated.
Another critical point concerns the end-of-life management of these plastics. Even if we talk about biodegradation, a clear reference to the environment in which this process takes place is necessary (open environment, such as soil or sea/river/lake or closed and controlled environment such as anaerobic biodegradation and/or industrial composting plants). Moreover, the problem is accentuated when we talk about compostable plastics widely used in food-use packaging. As of today, there is no harmonized management of compostable packaging in Europe: while in Italy such packaging should be disposed of with organic waste and processed in industrial composting plants, in Sweden it is disposed of together with mixed waste and waste-to-energy. Such diversification does not help citizens who find it difficult to recognize the material (bioplastics can be both biodegradable/compostable and non-biodegradable, such as bio-PET – bio-polyethylene terephthalate) and associate the correct disposal procedure. All this hampers the ability of BBPs to close the materials cycle and fully contribute to resource regeneration.
The study proposes several recommendations for overcoming these barriers, including the development of local and integrated supply chains that can make use of local production waste/residues and reduce production and transportation costs. In addition, in line with the principle of systems thinking and life cycle approach, the authors suggest the implementation of guidelines for design for biodegradability and/or compostability. These guidelines should provide for the design of applications that take into account the renewability, biodegradability, and compostability properties of the materials, as well as the degradation time, which must be appropriate for the end use, as well as the receiving system, which must be able to properly valorize the material at the end of life.
Another key point that emerged from the study concerns the need to update compostability and biodegradability standards to ensure robustness for in-situ testing but also consistency across geographies. Crucial will also be the role of collaboration among all actors in the supply chain, from material suppliers to end users, to optimize the management and recycling of BBPs.
In conclusion, while BBPs offer significant potential in terms of sustainability compared to traditional plastics, their real contribution to a sustainable circular economy is still being defined. Foschi, Aureli and Paletta’s study makes a valuable contribution to the debate, highlighting the need for a systemic and multidimensional approach to address the challenges of this emerging sector.
To learn more about this topic, you can read the full article, “Linking bioeconomy, circular economy, and sustainability: Trends, gaps and future orientation in the bio-based and biodegradable plastics industry,” published in the European Journal of Social Impact and Circular Economy.
Also, in support, two white papers have been published for the toy industry https://cris.unibo.it/handle/11585/939607 and agriculture https://cris.unibo.it/handle/11585/954406.
