Turning garden and crop waste into plastics

(Press-News.org) Turning green waste, hay and algae into fully biodegradable plastics for use in medical products, car components, insulation and packaging is the goal of a new Junior Research Group at the University of Oldenburg in the northwest of Germany. Led by chemist Dr Melanie Walther, the team will combine eco-friendly and application-oriented approaches to develop a cost-effective, energy-efficient technology for making innovative plastics based on polybutylene succinate (PBS) which are made entirely out of organic waste. The Federal Ministry of Research, Technology and Space (BMFTR) is providing around 2.7 million euros in funding for the EcoPBS project.

“The work of the new Junior Research Group aims to offer plastics made from renewable raw materials as an industrially viable alternative to conventional plastics,” said Prof. Dr. Ralph Bruder, President of the University of Oldenburg: “The BMFTR’s funding approval also acknowledges our university’s outstanding research infrastructure in this field and highlights the potential of EcoPBS in creating an environmentally and climate-friendly circular economy.”

Making bioplastics fully recyclable and competitive

PBS resembles the conventional plastics polypropylene and polyethylene in terms of robustness and processability, with the major advantage of being readily biodegradable. However, scientists have yet to produce an entirely bio-based material that is fully recyclable, and the manufacturing processes are not yet suitable for use in the chemical industry. “For a high yield, you need microorganisms that are easy to grow and stable enough to be efficient in low-cost, low-energy processes,” Walther explains.

In three sub-projects, the Junior Research Group will therefore investigate how to turn a biological substrate consisting of garden cuttings and crop waste into Bio-PBS. The team’s first step will be to optimise the fermentation process: in a newly developed biotechnological process they will assess how effectively the organic material can be converted into bioplastics using different types of microorganisms. A key factor here is that two different fermentation processes – Acetone-Butanol-Ethanol (ABE) fermentation and succinic acid fermentation – will be tested.

New manufacturing processes for bioplastics

The second sub-project will focus on “downstreaming” – the process of removing foreign substances from the converted material. The goal here is to convert the organic compound n-butanol into 1,4 butanediol, a bivalent alcohol and important raw material for plastics. With the help of simulations and machine learning they will look for ways to improve the material and energy balances of this process.

A new chemical substance is also needed to remove contaminants and thus produce the first fully biodegradable BPS. The team has already developed a basic blueprint for this substance and applied for a patent. In the third sub-project it plans to further refine the technology. Another goal is to use the residues from the production of bio-PBS to generate renewable electricity and heat that can be used to operate the laboratory facilities. In the final step, the researchers aim to manufacture the first products for industrial use – for example, packaging and medical materials – using digital 3D models and fully bio-based PBS.

Collaboration with external partners and other universities

Melanie Walther has joined the University of Oldenburg to set up the Junior Research Group. A postdoctoral researcher and three doctoral students will conduct research under her supervision. Walther studied Business Chemistry at Kiel University (CAU), where she earned her bachelor's degree in 2016 and her master's degree in 2018. She completed her doctorate in the field of organic functional materials at the University of Bremen in 2023 and went on to conduct research in organic chemistry as a post-doctoral researcher.

There are currently nine third-party funded Junior Research Groups at the University of Oldenburg. The aim is to support outstanding and highly qualified early-career researchers like Walther on their path to a professorship or other top-level academic positions. The other partner universities in the EcoPBS project are the Hanze University of Applied Sciences (Groningen, Netherlands), the University of Twente (Enschede, Netherlands) and the Christian-Albrechts-Universität zu Kiel. The gardening and landscaping company Oeltjen (Westerstede), the research institute Fair-Fusion (Emmen, Netherlands) and the plastics supplier Biovox (Darmstadt) are also partners in the project.

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