Carbios's Plastic-Eating Enzyme May Help Alleviate The World's Pollution Problem

The negative health impacts of plastic on both wildlife and humans have been well-documented. However, the versatile material, which is used for everything from grocery bags to drink bottles to food packaging, is hard to avoid. Experts estimate that of the 359 million tons of plastics produced annually worldwide, about 150–200 million tons end up in landfills or the environment. To make matters worse, the material derived from the small percentage of plastic that is recycled is of lower quality and can only be used a few times for items like clothing or carpets before it has to be discarded.

Now, French start-up Carbios wants to help alleviate the world's plastic pollution problem with a mutant bacterial enzyme that digests PET — the most abundant polyester plastic used to produce packaging, textile fibers, and plastic bottles — and turn it into its chemical building blocks. The resulting material can be used to create anything and, more importantly, can be continuously recycled.

Mechanical recycling, which entails washing, shredding, and melting the polymer, "is limited," explains Carbios CEO Martin Stephan. "To make a transparent bottle with that technology, you need a transparent bottle as a feedstock. And you cannot do that infinitely. After six or seven cycles of recycling, the plastic might only be good enough to use for something like the plastic on the backing of a carpet, and eventually, it will have to be thrown away entirely. So it's not a solution for the end of life of plastics, whereas our solution is an infinite recycling solution."

The company's quest for the optimal plastic-eating bacteria began about a decade ago, with 100,000 promising candidates. The list was soon whittled down to one — a leaf compost bug, which was first discovered in 2012. "It had been completely forgotten, but it turned out to be the best," said Alain Marty, a professor at the Univerité de Toulouse and the chief science officer at Carbios.

Once the perfect contender had been identified, Carbios scientists introduced mutations to improve its plastic digesting prowess and keep it stable at 65 degrees Celsius — the ideal temperature for fast degradation. The new and improved enzyme was able to downgrade 90 percent of a metric ton of shredded plastic in less than 10 hours.

To breakdown the plastic, the waste is placed in a reactor with water and the enzyme and heated for 16 hours at 65 degrees Celsius. The resulting mix is then filtered and purified. This allows for the recovery of the building blocks that make up PET plastics — PTA (Purified Terephthalic Acid) and MEG (Mono Ethylene Glycol) — and also extracts any additives and colors that may be present. "These [PTA and MEG] are then repolymerized into virgin PET and transformed into a bottle, without the need of having to use new monomers [molecules] made from fossil resources," says Benjamin Audebert, the company's head of investor relations.

The recycling process, which is currently in its pilot stage, will be tested on a larger scale at a new, bigger facility in Lyon, France, by the end of 2020 or early 2021. Once all the kinks have been removed, Carbios hopes to launch the technology commercially. Not surprisingly, the company has already signed up several large customers, including L'Oréal, Nestlé Waters, PepsiCo, and Suntory Beverage & Food Europe, who are all eager to reduce their ecological footprint. "We are the first company to bring this technology on the market," said Stephan. "Our goal is to be up and running by 2024, 2025, at large industrial scale."

Though Carbios's recycling technique will certainly help reduce plastic pollution, Stephan believes it is only part of the solution. The CEO thinks we can only win the battle if people do a better job of ensuring that plastic waste does not end up in the environment or in landfills. So the next time you use a plastic bottle or container, be sure to make the extra effort to place it in a recycling bin.

Resources: Forbes.com, Fastcompany.com, Time.com