US’ NREL team finds cheaper way of recycling waste polyester textiles


Scientists from US’ National Renewable Energy Laboratory (NREL) have discovered enzymes that could make it cheaper to recycle waste polyester textiles and bottles than making them from petroleum. The NREL-led team discovered variants of plastic-eating enzymes that adapt to deconstructing all varieties of polyethylene terephthalate (PET)—even durable crystalline varieties.

The team was able to discover the enzymes using advanced methods in machine learning, NREL said in a press release.

Scientists from US’ National Renewable Energy Laboratory have discovered enzymes that could make it cheaper to recycle waste polyester textiles than making them from petroleum. The NREL-led team discovered variants of plastic-eating enzymes that adapt to deconstructing all varieties of polyethylene terephthalate—even durable crystalline varieties.

Created from petroleum refining, PET is a material known for its durability and versatility. It is easily moulded into airtight containers, woven into durable carpets, or spun into polyester clothing.

“The reality is that most PET products—especially PET clothing and carpeting—are not recycled today using conventional recycling technologies,” explained Gregg Beckham, senior research fellow at the NREL and CEO of the US Department of Energy BOTTLE Consortium. “The research community is developing promising alternatives, including enzymes designed to depolymerise PET, but even these options have tended to lean on energy-intensive and costly preprocessing steps to be effective.”

As a result, most PET produced today eventually finds its way into landfills or the environment—even PET products that actually make it into the recycling bin.

Still, Beckham said that narrative is changing quickly. Advanced methods in machine learning and synthetic biology have given scientists an unprecedented look into the fundamental biology of PET-deconstructing enzymes. As detailed in an article published in Nature Communications, Beckham and colleagues at University of Portsmouth and Montana State University used these methods to discover new enzyme variants that show promise at deconstructing even the toughest PET without extra preprocessing.

“Not only could that mean we are on the cusp of enzymatic recycling for all forms of PET, including carpeting and clothing—it means it could soon be cheaper to recycle PET than making it from scratch with petroleum,” NREL said on its website.

Cleaning, shredding, and heating—steps needed to prepare PET for deconstruction—are among the most important sustainability drivers of an industrial-scale enzymatic recycling facility, according to Beckham.

“Minimising these preprocessing steps is critical for making enzymatic recycling cost competitive with creating PET resin from petroleum,” Beckham explained.

In follow-up experiments, the team noted that some of the enzymes flagged by their machine learning methods were equally effective at breaking down crystalline and amorphous PET. Those enzymes simply did not need preprocessing to help soften the bonds of the plastic.

Fibre2Fashion News Desk (DP)



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