A table with various Petri dishes displaying everything from an exhibit made of natural fiber-reinforced plastic to material infested with fungus to plastic granulate.

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Recycling natural fiber-reinforced plastics: Closing the loop with fungi and WEIMA

Plastic

At the Zittau/Görlitz University of Applied Sciences, an interdisciplinary team has been working for almost twenty years on breaking down plant biomass into valuable components. With the NFK Recycling Project, researchers are focusing on natural fiber-reinforced plastics (NFRP), which are primarily used in lightweight construction in the automotive sector. Since conventional recycling processes reach their limits here, the consortium consisting of the Zittau/Görlitz University of Applied Sciences, the TU Dresden, WEIMA and Maschinen Schmidberger is jointly developing an innovative, recyclable plant.

Why fungi? The ecological drive

Due to stricter CO₂ regulations and growing environmental awareness, materials are increasingly being evaluated based on how well they can be recycled at the end of their life cycle. Although natural fibers are renewable, they are so firmly embedded in composite materials that they cannot be easily removed. The NFRP recycling team therefore uses white rot fungi – the same organisms that decompose dead wood in the forest. They break down the cellulose-containing fibers while leaving the plastic untouched. The resulting fungal mycelium is then liquefied into organic acids that can be used in biogas plants.

A person is holding a piece of natural fiber-reinforced plastic from a car door

Component of a car door made of natural fiber-reinforced plastic

A researcher in a white lab coat examines a Petri dish containing a mushroom culture.

Mushroom cultures for the NFRP recycling project

Several plastic cups filled with mushroom cultures in a refrigerator

Various cultivated mushroom cultures

Three researchers in white coats standing in front of an orange shredder with various exhibits in their hands.

Zittau/Görlitz University of Applied Sciences x WEIMA | NFRP Recycling Project

The NFRP Recycle project demonstrates how natural fiber-reinforced plastics (NFRP) can be processed sustainably using biorefinery processes.

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The first step: Shredding with WEIMA

In order for the fungi to reach every single fiber, the NFRP must first be shredded into pieces that are as small as possible. At the same time, energy consumption must remain low. With its Compact Shredder, WEIMA supplied a robust single-shaft shredder that offers precisely this compromise. Mycologist Marzena Poraj-Kobielska says that particle size and energy input are the decisive parameters. The WEIMA shredder creates a homogeneous substrate, the perfect basis for fungal growth.

A small orange shredder in a small warehouse

The WEIMA Compact Shredder for the NFRP recycling project

A woman in a white lab coat drops a piece of natural fiber-reinforced plastic into the funnel of a shredder

Filling the WEIMA shredder with natural fiber-reinforced plastic

Fungi as a biorefinery

The shredded NFRP pieces are sterilized and inoculated with white rot fungi. The fungi grows through the composite material and breaks down the natural fibers without affecting the polymer content. At optimal humidity and temperature, the fungal network forms a dense mycelium. Since only non-toxic, non-spore-forming species are used, handling is safe. In some cases, the fungi even form edible fruiting bodies, which can be marketed after appropriate testing.

Pieces of natural fiber-reinforced plastic overgrown with fungal cultures in a large Petri dish

Shredded natural fiber-reinforced plastic overgrown with fungal cultures

Hydrolysis and separation – the cycle closes

After fiber degradation, the pieces permeated by the mycelium are fed into a hydrolysis reactor. Water and enzymes break down the fungal biomass into organic acids and amino acids. These acids can be fermented into biogas in a downstream plant, thus providing renewable energy. The remaining plastic is left as a clean solid fraction and can be processed into new composite materials or other plastic products.

A woman in a white lab coat fills a hydrolysis reactor with a piece of NFK.

Filling the hydrolysis reactor with a piece of NFK containing mushroom culture

Close-up of a hand holding a piece of natural fiber-reinforced plastic being placed into a chamber of the hydrolysis reactor.

Filling the hydrolysis reactor chamber

Two researchers in white lab coats determine values using a measuring device.

Measuring biogas production

The advantage of our process is that no residual materials or waste are produced. All products created become substrates for new processes, enabling us to recycle all components.

Marzena Poraj-Kobielska | Mycologist Zittau/Görlitz University of Applied Sciences

Partnership for global action

For the research team behind the NFRP recycling project, it was crucial to find an industrial partner with proven shredding expertise and international experience. In WEIMA, they found both requirements combined: technical expertise in the processing of sophisticated composite materials and a global sales and service network that enables the technology to be distributed beyond Saxony. Project manager Matthias Tirsch emphasizes that the process developed “should be used not only here in the region, but worldwide” – a vision that is becoming a reality through this collaboration.

NFK Recycling Project Team

With increasing environmental regulations and rising quantities of composite materials, the NFRP recycling project demonstrates how biological processes and mechanical shredding technology can complement each other. Thanks to WEIMA shredders, which deliver a homogeneous feedstock, and fungi, which break down the organic content, natural fiber composites can be transformed from a recycling problem into a source of energy and new raw materials. The project proves that joint innovations from science and industry pave the way for a circular economy.