Circular Textile Economy: Study Shows How Textile Waste Can Be Turned into Bioplastics

Polyester-containing textiles are often considered difficult to recycle and are incinerated at the end of their life cycle. The “TexPHB” feasibility study demonstrates an alternative approach: Researchers and industry partners have investigated how such textile waste can be converted into the biodegradable bioplastic polyhydroxybutyrate (PHB). The process could enable new circular flows between the textile industry, recycling, and plastics production.

Textile waste poses major challenges for the circular economy. In the European Union alone, around 6.95 million tonnes of textile waste were generated in 2020. Mixed, polyester-containing waste, such as fast fashion, workwear, and industrial cleaning textiles, is particularly difficult to recycle.

The feasibility and potential study “Applications for the Biopolymer Polyhydroxybutyrate (PHB) from Textile Waste”, or TexPHB for short, investigated how such residual materials could nevertheless be used as a raw material. The project involved the Fraunhofer Institute for Applied Polymer Research IAP, the Beneficial Design Institute, and matterr GmbH, formerly RITTEC 8.0 Umwelttechnik. The project was funded by the State of Brandenburg.

The result: Even textiles from the lowest waste category can in principle be used as a feedstock for PHB production. All 18 types of textile waste tested as part of the study were successfully depolymerized, demonstrating the fundamental technical feasibility of the approach.

At the heart of the process is a combination of chemical recycling and biotechnology. First, the polyester-containing textiles are selected and prepared. Hydrolysis is then used to break down the polyethylene terephthalate (PET) they contain. This process recovers the PET building blocks terephthalic acid and ethylene glycol.

Biotechnology then comes into play: Researchers at Fraunhofer IAP use the recovered ethylene glycol as a feedstock for bacterial fermentation. The microorganisms convert it into polyhydroxybutyrate (PHB). The resulting thermoplastic bioplastic is biodegradable and biocompatible.

In addition to technical feasibility, the project also investigated potential applications for PHB derived from textile waste. Thanks to its material properties, the bioplastic is suitable for various processing methods, including injection molding and 3D printing.

The researchers see potential applications in agriculture, geotextiles, medical technology, water protection, coatings, and textiles, among other areas. Possible products include tree protection products, erosion control systems, and medical applications. Biodegradability is particularly relevant for products that may remain in the environment or the human body after use. Other applications, however, would require take-back and recycling systems.

Further development is still required before practical application. For geotextiles, for example, the processing of PHB into filaments needs further development. Products made from the material must also meet the relevant technical requirements, including tensile strength, UV stability, and permeability.

For now, TexPHB demonstrates the fundamental technical feasibility of the approach. Large-scale industrial implementation has not yet been achieved. Instead, the results provide a basis for further research and development.

One possible next step is the development of regional textile biorefineries that combine hydrolysis and fermentation. In addition, the project team recommends further research and development programs, building expertise in the circular textile economy, and improving the digital collection of material-flow data along the textile value chain.

The approach demonstrates how textile recycling and plastics production can be linked: Textiles that are difficult to recycle serve as a source of raw materials from which a new plastic can be produced using chemical and biotechnological processes. Further process development and scaling will determine whether this approach can ultimately result in an economically viable circular system on an industrial scale.