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Project coordination: Patrick Dabert - UR OPAALE

Project partners: Nano-BioGeochemistry from UMR Geosciences of Rennes 1 University - A-C. Pierson Wickmann for the study of materials abiotic degradation and UMR IATE from the University of Montpellier - N. Gontard, L. Chatellard and V. Guillard for their skills in the formulation and design of food packaging made of biobased biodegradable plastics.

The project starts in 2022 for 4 years.

The BioCyPlast project

How to make biodegradable plastics truly biodegradable?

Most so-called “biodegradable” plastics do not completely degrade in biowaste management channels and in the natural environment. To make the best use of biowaste from 2023, it is necessary to develop materials that degrade completely under composting and anaerobic digestion conditions, without risk for the environment. The development of such materials requires a better understanding of their degradation mechanisms right from their design.

Understanding today to better design tomorrow

Plastics have become a major source of environmental pollution and health concern. This pollution arises from direct discharge in the environment (agricultural films, wastewater) and from leaks out of waste management systems. Among them, plastic bags, films and food packaging are difficult to sort and recycle in household waste management systems. Soiled and damaged, they end their life “at best'' in incineration, “at worst” in landfills or in the environment where they generate micro- and nanoplastics (MNPs) and represent a major threat to the environment and health. In Europe, 23 million tons of plastic packaging are wasted every year, most of it after a single and very short use. About 32% leak out from collecting and sorting systems and end up in the soil and oceans.

To limit this pollution, biodegradable plastics have been developed that can be discarded with organic waste to end their life in biowaste management systems. Well-known examples are the starch-based compostable plastic bags used for the selective collection of food waste. However, two drawbacks remain: 1st, some of these plastics are still partly petroleum-based and not completely biodegradable; 2nd, anaerobic digestion is strongly promoted to combine energy production and organic matter valorisation. This leads waste managers to report incomplete degradation of so called "biodegradable plastics" during anaerobic digestion and even sometimes composting.

 To improve biowaste and plastics valorisation, we must develop materials that degrade completely during biowaste management, regardless of the system. However, the rules linking material formulation and biodegradation are still poorly understood, particularly for anaerobic degradation. We hypothesise that designing such material requires: i) to determine the key parameters (physical, chemical and microbiological) responsible for their degradation in biowaste management conditions; ii) to implement these parameters in eco-design models that include the material end-of-life as an intrinsic property, acknowledging that this may also require the adaptation of waste management systems.

The project strategy

• Selecting commercially available biodegradable materials and constructing tailored made ones (with different formulation, structure, size, crystallinity...) dedicated to the study of their biodegradation (WP1),
• Monitoring experimentally their fragmentation and assimilation under controlled conditions of composting and anaerobic digestion using specific analytical methods (WP2 & WP3),
• Developing innovative tools to better monitor and understand the mechanisms of plastic colonization and disintegration up to the generation of nanoplastics (WP3),
• Integrating all these data into predictive modelling approaches to anticipate the ecological footprint of biodegradable plastics, from material conception to biowaste management systems (WP4).

Fig. - laser measurement of the size of nanoplastics (2528).