About 25 percent of what ends up in the blue bins is contaminated, according to the National Waste & Recycling Association. For decades, we’ve been throwing just about whatever we wanted—wire hangers and pizza boxes and ketchup bottles and yogurt containers—into the bin and sending it to China, where low-paid workers sorted through it and cleaned it up. That’s no longer an option. And in the United States, at least, it rarely makes sense to employ people to sort through our recycling so that it can be made into new material, because virgin plastics and paper are still cheaper in comparison.

Even in San Francisco, often lauded for its environmentalism, waste-management companies struggle to keep recycling uncontaminated. I visited a state-of-the-art facility operated by San Francisco’s recycling provider, Recology, where million-dollar machines separate aluminum from paper from plastic from garbage. But as the Recology spokesman Robert Reed walked me through the plant, he kept pointing out nonrecyclables gumming up the works. Workers wearing masks and helmets grabbed laundry baskets off a fast-moving conveyor belt of cardboard as some non-cardboard items escaped their gloved hands. Recology has to stop another machine twice a day so a technician can pry plastic bags from where they’ve clogged up the gear.

Cleaning up recycling means employing people to slowly go through materials, which is expensive. Jacob Greenberg, a commissioner in Blaine County, Idaho, told me that the county’s mixed-paper recycling was about 90 percent clean. But its paper broker said the mixed paper needed to be 99 percent clean for anyone to buy it, and elected officials didn’t want to hike fees to get there. “At what point do you feel like you’re spending more money than what it takes for people to feel good about recycling?” he said.

https://www.theatlantic.com/technology/archive/2019/03/china-has-stopped-accepting-our-trash/584131/