[October 2025] Dr Melanie Walther is a junior researcher and head of a junior research group at the Institute of Chemistry. She studied economic chemistry at Christian-Albrechts-Universität zu Kiel, where she obtained her Bachelor’s degree in 2016 and her Master’s degree in 2018. In 2023, she completed her PhD in the field of organic functional materials at the University of Bremen. This was followed by her postdoctoral research, also in the field of organic chemistry.

Under her supervision, one postdoctoral researcher and three doctoral candidates will be conducting research: Producing fully biodegradable plastic from garden waste, hay and algae, suitable for medical products, car components, insulation and packaging – this is the aim of a new junior research group at the University of Oldenburg. The research team led by chemist Dr Melanie Walther aims to combine environmentally sustainable and application-oriented approaches to achieve this: The plan is to develop a cost-effective and energy-efficient technology that will be used to produce new plastics based on polybutylene succinate (PBS), consisting of 100 per cent organic waste. The Federal Ministry of Research (BMFTR) is funding the ‘EcoPBS’ project with around 2.7 million euros.

“The work of the new junior research group aims to offer plastics made from renewable raw materials as an industrially viable alternative to conventional plastic,” says Prof. Dr Ralph Bruder, President of the University of Oldenburg. “The BMFTR’s funding approval also recognises our university’s outstanding research infrastructure in this field and underlines the potential of ‘EcoPBS’ for an environmentally and climate-friendly circular economy.”

Making bioplastics fully recyclable and competitive

PBS is similarly robust and processable to plastics such as polypropylene and polyethylene. The key difference is that it is readily biodegradable. However, it has not yet been possible to produce a fully bio-based material that is completely recyclable. Furthermore, the manufacturing processes are not yet suitable for the chemical industry. “To achieve a high yield, we need microorganisms that are easy to cultivate and stable enough to withstand low-cost, energy-efficient process engineering,” explains industrial chemist Walther, highlighting the research gap.

In three sub-projects, the junior research group is therefore investigating how the biological substrate – in the form of garden cuttings and crop waste – can ultimately be converted into bio-PBS. To this end, the researchers are first optimising the fermentation process: They are testing how effectively the organic material is converted using various microorganisms in a newly developed biotechnological process. What makes this unique is that the team is investigating two types of fermentation – acetone, butanol and ethanol fermentation, and succinic acid fermentation.

New production processes for the bioplastic

The second sub-project focuses on what is known as ‘downstreaming’, i.e. the purification of the converted material to remove impurities. The researchers aim to refine the organic compound n-butanol into 1,4-butanediol – a dihydric alcohol that is an important raw material for plastics. Using process simulations and machine learning methods, they are investigating how the material and energy balances can be improved.

A special chemical is also required to remove interfering substances and thus produce fully biodegradable BPS for the first time. The researchers have already developed the basic principles of this and have filed a patent for it. As part of the third sub-project, they aim to further refine this technology. Another objective is to use the residues generated during the production of bio-PBS to produce renewable electricity and heat, which can then be used to power the laboratory facilities. With the aid of digital 3D models and the fully bio-based PBS, the researchers ultimately aim to produce the first practical products – such as packaging and medical materials.

There are currently a total of nine such externally funded groups at the University of Oldenburg. These groups are designed to support outstanding and highly qualified early-career researchers, such as Walther, on their path to a professorship or another senior academic role. The ‘EcoPBS’ project involves the following associated university partners: Hanze University of Applied Sciences (Groningen, Netherlands), the University of Twente (Enschede, Netherlands) and Christian-Albrechts-Universität zu Kiel. Other collaborating partners include the horticultural and landscaping firm Oeltjen (Westerstede), the Fair-Fusion research institute (Emmen, Netherlands) and the plastics supplier Biovox (Darmstadt).