Do the things we throw into the Bay Area’s blue bins really get recycled? Here’s why the answer is changing

Inside the GreenWaste Material Recovery Facility in San Jose, both human and mechanical hands work to separate the pieces of ink-stained paper, dented multi-colored plastic and crushed metal that can be resold and recycled from the piles of collected material. A wall of rotating metal disks slaps against clean cardboard as workers pull thin plastic bags off the belt by hand. Aluminum cans are flung into a chute by pressurized air.

But if processing recyclables is complicated, the web of...