Every week, carefully sorted piles of plastic waste adorn curbsides across the country, waiting for pickup. It once went overseas, but now China and other former importers have banned or imposed prohibitive costs on shipments, having concluded there is little to do with the stuff. Cities have cut back collection schemes, leaving straws, bottles, utensils, and other detritus to pile up in warehouses or be disposed of as trash.
Those systems, in theory, created a destination for plastics aside from landfills, assuaging consumer guilt about using polluting—and practically indestructible—products. But as the bottom fell out of the international market, an inconvenient truth was highlighted: Most plastics are impervious to traditional recycling.
“Plastic only emerged as a mass-produced material in the 1950s,” says Roland Geyer, an industrial ecologist at the University…
