A French company uses enzymes to recycle one of the most common disposable plastics

Because disposable plastics are largely derived from oil, plastics could account for 20% of the world’s annual oil consumption by 2050. Reducing our reliance on plastics and finding ways to recycle plastics that already exist in the world can greatly reduce emissions.

Right now, only about 15% of all plastic worldwide is collected for recycling each year. Since the 1990s, researchers have been trying to find new ways to degrade plastics in hopes of recycling more of them. Companies and researchers have worked to develop enzymatic processes, such as the one used in Carbios, as well as chemical processes, as well as the method used by Loop Industries. But only recently have enzymatic and chemical processes begun to become commercial.

Carbio’s new reactor measures 20 cubic meters – about the size of a truck. It can contain two tons of plastic or the equivalent of about 100,000 ground bottles at a time and break it down into the building blocks of PET ethylene glycol and terephthalic acid — in 10 to 16 hours.

The company plans to use what it learns from the demonstration plant to build its first industrial plant, which will house a reactor about 20 times larger than the demonstration reactor. The full-scale plant will be built near a plastics manufacturer somewhere in Europe or the US and must be operational by 2025, says Alain Marty, Carbio’s chief scientific officer.

Carbios has been developing enzymatic recycling since the company was founded in 2011. Its process relies on enzymes to chop the long chains of polymers that make up plastics. The resulting monomers can then be purified and bonded together to make new plastic. Researchers at Carbios started with a natural enzyme used by bacteria to break down leaves, and then adjusted it to make it more effective at breaking down PET.

Carbio’s demonstration plant in Clermont-Ferrand, France. Image courtesy of SkotchProd.

Carbios estimates that its enzymatic recycling process reduces greenhouse gas emissions by about 30% compared to virgin PET. Marty says he expects the number to increase as they work out the cracks.

In a recent report, researchers estimated that producing PET from enzymatic recycling could reduce greenhouse gas emissions between 17% and 43% compared to making virgin PET. The report was not specifically about Carbios, but it is probably a good estimate for its process, according to Gregg Beckham, researcher at the US National Renewable Energy Laboratory and co-author of the report.

While the development of new enzymes has been a major focus of new research and commercial efforts, other parts of the process will determine how efficient and cost-effective the technology will be, says Beckham, who heads a consortium of new plastic recycling and production methods.

“It’s all the less glamorous stuff,” Beckham says, like getting the plastic into a shape that the enzymes can effectively break down or separate what the enzymes spit out, it can take a lot of energy and time and increase emissions and costs.

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