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06/30/2025

BioLoop - Microbial Recycling - A Solution for Multilayer Plastic Packaging?

@Plastics engineering

For a new research project, the Department of Resource Management and Waste Technology and the Department of Plastics Technology at the University of Kassel, along with the Department of Microbiology and Biotechnology at the University of Hamburg, are working toward a common goal: They aim to use microbial recycling to develop a method that breaks down multilayer films into their original components in an environmentally friendly way, so that these components can be reused in high-quality applications. The project is funded by the Volkswagen Foundation with just under 1.2 million euros.

The transition to a circular economy, in which plastics are preserved in their most valuable state, is urgently needed to reduce the environmental impact of plastic use. Films are one of the most important applications of plastics. In German households, they account for nearly half of all single-use plastic packaging. In particular, multilayer films—which are used very frequently in the food industry—are considered contaminants in current material recycling processes and can only be processed into lower-quality products. However, if it were possible to recycle these materials into high-quality products, there would be enormous potential for keeping plastic films within closed material cycles.

To achieve this goal, Prof. Dr. David Laner, head of the Department of Resource Management and Waste Technology at the University of Kassel, highlights the need for a new, innovative recycling technology: “Current mechanical recycling processes for plastic films are unable to produce high-quality recycled products on a large scale due to the deterioration of product properties and inconsistent product quality. Another option is chemical recycling, which, although also suitable for plastic waste with a low degree of purity, is less attractive due to the high energy intensity and low product yield of the various processes that break down plastic materials into their constituent parts.” For this reason, the disciplines involved in the project are taking on the challenge of developing a new recycling method to reprocess multilayer plastic films into high-quality products: microbial recycling.

“We aim to develop a new and environmentally optimal recycling technology for polyethylene (PE) films and PE-polyethylene terephthalate (PET) multilayer films that involves the enzymatic depolymerization of PE followed by reactive extrusion of short-chain building blocks (oligomers) into high-quality recycled products,”explains Prof. Dr. Wolfgang Streit, head of the Department of Microbiology and Biotechnology at the University of Hamburg. “This is because PE is found in almost every multilayer film, but unlike PET, for example, it has not yet been enzymatically broken down.”

Prof. Dr.-Ing. Hans-Peter Heim, head of the Department of Plastics Engineering at the University of Kassel, adds: “Although this project is risky due to its completely new approach, it could pave the way for multilayer recycling focused on microbial degradation for engineering plastics and help achieve the recycling targets set by the European Commission.”

Ultimately, the project results will be of interest not only to the food and packaging industries but also, for example, to the automotive and textile sectors. Although these sectors do not deal with plastic films, the wide variety of plastics used in cars, the predominance of black plastics, and the diversity of fillers pose a major challenge for conventional mechanical recycling processes and could make microbial recycling very attractive. The same applies to textiles, where the variety of materials makes fiber-to-fiber recycling difficult using established technologies.

The four-year project “BioLoop: Microbiologically Enhanced Material Cycle for Closing PE and PE-PET Multilayer Plastic Film Loops” is funded by the Volkswagen Foundation with just under 1.2 million euros. Thematically, the project also ties in with the scientific activities of the Kassel research cluster “BiTWerk – Biological Transformation of Technical Materials,” led by Prof. Dr.-Ing. Thomas Niendorf and Prof. Dr.-Ing. Hans-Peter Heim ( www.uni-kassel.de/go/bitwerk )

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