Plastic islands floating around our oceans may not be in the media as much these days, but the problem remains. We produce and consume too much plastic. Despite many efforts, we are still far from a fully circular economy for plastics. It is estimated that of the 359 million tonnes of plastic produced worldwide each year, 150 to 200 million tonnes end up in landfills or in the natural environment. How can this be prevented? How can systems and processes be designed to better close the loop? What are the alternatives to oil-based plastics? The designer Sophia Reißenweber from the Burg Giebichenstein University of Art and Design in Halle, Germany, has taken on these big questions and set an example with her ‘Break-up Lab’ project, in which she uses enzymes to recycle polyester into textiles.

Environmentally-Friendly Recycling Process

Enzymatic recycling of plastics is seen as the new beacon of hope in the circular economy discourse – after all, it has clear advantages over mechanical or chemical recycling processes. It is much more energy efficient and requires little or no chemicals because it is biochemical and at the molecular level. Another advantage is that enzymatic recycling produces high-quality monomers that are equivalent to virgin plastic – so there is no downcycling, as there is with mechanical recycling of textiles, where the garments are often just shredded and end up as painter’s fleece. Of course, there are disadvantages too, but more on that later.

Finalist at the Newcomer Award 2025

For the ‘Break-up Lab’ project, which was completed as part of her Master’s thesis in 2024 and shortlisted for the German Design Awards 2025, Reißenweber investigated not only how enzymatic recycling can be used, but also how it can generate new local economic growth through biotechnological processes, circular products and new recycling systems. She worked directly with local companies and institutions, including textile recycler Soex in Bitterfeld. It was “just horrifying” to see what was being thrown away and how each textile had to be sorted by hand. She also got in touch with the team led by biochemist Christian Sonnendecker at the University of Leipzig, who discovered the PHL7 enzyme. With my work, I am trying to make the potential of this biotechnology visible and to combine the different skills of the individual players in order to develop more sustainable processes,” says Reißenweber.

Textiles are mainly composites (also known as compounds). Enzymatic recycling, as carried out by Reißenweber, enables the separation of polyester components. This has two advantages, explains Reißenweber. Firstly, a mono-material can be obtained – for example, pure cotton from a T-shirt that previously contained polyester. Secondly, the enzymatically recycled polyester can be used to produce new polyester. Up to 90 percent of new polyester of the same quality can be made from enzymatically recycled polyester.

High Pressure in the Biotech Sector

It remains to be seen whether enzymatic recycling will be the breakthrough that solves the global plastics dilemma. Research is underway in many countries, although it is still in its early stages. The hype around enzymatic recycling of PET originally started in Japan: in 2016, researchers there discovered that an enzyme from the bacterium ‘Ideonella sakaiensis’ could metabolise polyethylene terephthalate (PET) and break it down into its individual components. PET, a member of the polyester family, is widely used for packaging, plastic bottles and textiles. However, the enzyme process is difficult to implement on an industrial scale. Ester Biotech, a start-up company founded by Sonnendecker’s team at the University of Leipzig, and the French company Carbios are among the companies involved.

Noch nicht als Recycling anerkannt

Despite its great potential, biotechnological recycling of plastics still faces a number of challenges: The biggest hurdle is implementing the enzymatic process on an industrial scale. Biologically produced enzymes are sensitive to changes in temperature and pH, making it difficult to scale up the process. In addition, production costs are still higher than traditional recycling methods and the necessary infrastructure is not yet widely available. Another important point highlighted by the Ester Biotech team is the legal situation: enzymatic recycling is currently only partially recognised as an official recycling process in Germany. However, there are already positive signals from the Federal Environment Agency and in the coalition agreement of the new German government that this could change in the near future.

Sophia Reißenweber believes that the traditional polyester recycling process is inadequate. It doesn’t solve the problem,” she says. Polyester is still made from fossil fuels, and polyester fibres continue to pollute the environment when they are washed. Alternatives are needed, such as bioplastics like polyhydroxyalkanoates (PHAs). We need to shift our focus away from fossil-based resources and towards bio-based material flows,” says the designer. These are often easier to recycle enzymatically – PHA, for example, can also be broken down by the enzyme PHL7. Bioplastics also open up new design possibilities: In her ‘Break-up Lab’, Reißenweber has created garments as modular or mono-material designs that are easier to mechanically disassemble, recombine and recycle.