Plastic-eating enzymes to the rescue? 

Scientists at the University of Portsmouth are to develop “plastic-eating” enzymes that could help solve the ever-growing problem of waste polyester clothing.

Polyester is the most widely used clothing fibre in the world but is currently not a sustainable textile option. Made from polyethylene terephthalate (PET) – one of the most common consumer plastics – most polyester clothing will more than likely end up discarded in a landfill or polluting the environment.

Researchers at the University’s Centre for Enzyme Innovation have already developed enzyme technology to reduce single use plastics (including PET) to their chemical building blocks, leading to safe and energy efficient recycling. Now, they have set their sights on creating a similar process for polyester textiles.

The process of recycling synthetic fabrics using enzymes will not be an easy one, though. These textiles account for an estimated 60% of all clothes that are worn by people around the world, and are often chosen for their durability. 

The addition of dyes and other chemical treatments makes it even harder for these tough oil-based materials to be “digested” in a natural process. Developing enzymes that can efficiently “eat” polyester clothing without energy intensive pre-treatment is the biggest challenge.

“We will develop enzymes that can deconstruct the PET in waste textiles, tolerating the challenges that this feedstock poses – namely its toughness and the presence of dyes and additives,” says Professor Andy Pickford, director of the Centre for Enzyme Innovation at the University of Portsmouth.

“We will test the compatibility of our engineered enzymes with additives, dyes, and solvents to select those enzymes that are best suited to polyester textile deconstruction,” he continues. “Then we will apply these enzymes to appropriately pre-treated waste polyester textiles in laboratory-scale bioreactors, to evaluate the potential and limitations of scaling up the technology.”

Clothing has some of the lowest rates of recycling, with much of it being incinerated or ending up in landfills. Whilst it is possible to turn good quality oil-based textiles into carpets and other products, current recycling methods are highly energy intensive. Scientists hope that enzymes developed at the University of Portsmouth will help them create an environmentally friendly circular economy for plastic based clothing. 

“Our research will establish the feasibility of using enzymes to deconstruct the PET in waste textiles into a soup of simple building blocks for conversion back into new polyesters, thus reducing the need to produce virgin PET from fossil fuel-based chemicals. This will enable a circular polyester textiles economy and ultimately reduce our dependence on taking oil and gas out of the ground,” Pickford points out.

“We want a system that uses plastic in the same way we use glass or tin cans – infinitely recycled. The ultimate aim is to close the loop – however, this requires not only the technology but also the will to do so,” he adds.

The research, which is funded by the Biotechnology and Biological Sciences Research Council, started at the end of January 2023 and will run for 18 months. The university team will work with project partners Biomimicry Institute – which will provide expertise in natural solutions to sustainability challenges – and Endura Sports clothing, which will share its knowledge of fabric dyes and provide samples of end of life polyester textiles.