Beijing is no longer buying, claiming the recycled materials are "contaminated."
For sure, the 900 tons of trash dumped at all hours of the day and night, five days a week, on the conveyor belts at the plant in Elkridge, Maryland -- an hour's drive from the US capital -- are not clean.
Amid the nerve-shattering din and clouds of brown dust, dozens of workers in gloves and masks -- most of them women -- nimbly pluck a diverse array of objects from the piles that could count as "contaminants."
That could be anything from clothes to cables to tree branches to the bane of all recyclers: plastic bags, which are not supposed to go in recycling bins because they snarl up the machinery.
"We've had to slow our machinery, and hire more people" to clean up the waste, says Michael Taylor, the head of recycling operations for Waste Management, the company that runs the plant.
At the end of the sorting line is the end product -- huge bales of compacted waste containing paper, cardboard or plastics.
These have been bought up for decades by businesses, most of them based in China, which clean them up, crush them and transform them into raw materials for industrial plants.
Last year, China bought up more than half of the scrap materials exported by the United States.