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IDEAS

Is there a future for plastic recycling?

Despite what it says on the packaging, most plastic can’t readily be turned into another new product. But some researchers aren’t giving up.

Compressed plastic bottles that were collected from the Nile by volunteers and fishermen were used to build a plastic pyramid in Cairo, Egypt, on Sept. 15. It was part of an effort to raise awareness about plastic pollution in that river and other waterways.Amr Nabil/Associated Press

On the bottom of your plastic takeout container, three small arrows make a promise. They seem to move in a cycle, showing how, if you deposit the plastic in the right bin, it will be born anew and soon be in the hands of another diner.

“People are told, ‘Don’t worry about your heavy use of plastics — just toss that in your recycling bin,’” says Judith Enck, a senior fellow at Bennington College, in Vermont.

But this year, reports from both the Department of Energy and a nonprofit run by Enck that examines the use of plastics estimated that only 5 percent of plastic items disposed in the United States are recycled at all; the rest are burned or go into landfills. This has been the reality for some time. And it’s not just because you didn’t wash your takeout container right. The fact is that plastics, for the most part, aren’t designed to be recycled the way we’ve been told they are. There are thousands of separate varieties, each of which, if a market for recycling them even existed, would require completely separate facilities and treatment. What’s more, many are made with dyes and additives that rule out recycling from the start.

As we face the serious environmental challenges of the coming decades, could acknowledging that plastics fall short of our expectations help show the way to a better future and help us create plastics like the ones in our dreams?

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Even the tiny number of plastics that can be recycled — like polyethylene in soda bottles — can’t be reused indefinitely. The strength and toughness of many plastics, which are made of fossil fuels treated with softeners and other substances, is determined by the length of the fibers that make them up, says Susannah Scott, a professor of chemical engineering at the University of California, Santa Barbara. Recycling breaks the polymer chains that make up those fibers. As a result, recycled polymers have to be mixed with virgin polymers to make a new bottle. If we made, say, polyethylene bottles just from recycled plastic, each successive generation of bottles would grow weaker; they’d probably disintegrate after three or four rounds, she estimates. They would also be more expensive than bottles made from new plastics. And in fact, recycled plastics typically don’t wind up in the kinds of products they originally came from. They get downgraded into things like building materials.

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Most plastics can’t even get this treatment. There are no economically viable processes for reclaiming them.

“If you want to recycle a newspaper, your old newspaper will become a new newspaper or cardboard,” says Enck. “You put an aluminum can in your recycling bin and it will become a new aluminum can. We don’t have the same solution for plastic.”

Plastic bottles littered in Abidjan, Ivory Coast.ISSOUF SANOGO/AFP via Getty Images

One idea for what to do with used plastic is to heat it until it becomes a kind of fuel oil, a process called chemical recycling. But while that’s a way to extract some energy from plastics that would otherwise be in a landfill, chemical recycling doesn’t stop new plastics from being made. You could argue, as the National Resources Defense Council has, that it actually provides an incentive for making more of them — a way for chemical companies to get public subsidies for “recycling” while continuing business as usual. Local opposition recently forced one chemical recycling company, Brightmark, to withdraw plans to build a plant in Macon, Ga.

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A circular economy, one in which everything is reused, would require a very different set of materials than we currently have. In recent years, Scott has turned her attention to this problem. She and her colleagues lay out in a new paper a process for breaking polyethylene down into its building blocks, using catalysts that slice the bonds between the polymers’ carbon atoms. The process releases propylene, which can be used to make polypropylene plastic as good as that made from virgin materials, and the polyethylene’s building blocks can be reused as well. Her engineering colleagues built a tiny reactor where the process, which requires very little energy, can take place. “At the moment it’s about the size of a coffee maker on a benchtop,” she says. “If you want to do this at the commercial scale, not in my lab, it would be the size of an oil refinery.”

The process is still in the early stages of development, but it’s a step toward a world where plastics are recyclable by design.

At the same time, says Enck, many plastics could be replaced by truly recyclable materials, like glass, aluminum, and paper. She has noticed a proliferation of companies, like Plaine Products and Blue Land, that use refillable, recyclable packages people can mail back for free. And if companies were made responsible for the afterlife of their plastics, through legislation called extended producer responsibility, we might see fast changes in the right direction.

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For plastics that can’t be replaced by other materials, perhaps we might someday have varieties designed to be easily taken apart and reused. No fillers, no complicated dyes to get in the way. “If you make products that way, you get to still use plastics that serve a critical role,” says Scott. “You know you can recycle them and incentivize people to bring them back, and it doesn’t cost a huge amount. We’re in this transition period — how do we accomplish this?”

Ultimately, getting to a place where plastic helps us meet our sustainability goals rather than torpedoing them requires fundamental social change, as well as new processes like Scott’s. “I hope we get to the point where we think about the material we’re making,” she says, “and get to use this beautiful chemistry.”

Veronique Greenwood is a science writer who contributes frequently to Ideas. Follow her on Twitter @vero_greenwood.