Glass, paper, plastic, metal—there was a time when you had to sort recyclables before pickup. Now many municipalities have switched to single-stream recycling—which means that everything goes into one bin—because it increases the likelihood that people will recycle. So what happens after the truck picks up your mix of cans, bottles, and newspapers?
1. Most of our region’s recyclables end up in Elkridge, Maryland, where Waste Management runs the nation’s largest single-stream recycling facility. The plant processes 70 tons of recyclables an hour.
2. The incoming materials start their journey on a conveyor belt, where Waste Management workers remove trash, large objects, and plastic bags, which can clog the machinery.
3. The belt leads into a “disk screen,” where rows of spinning disks push large pieces of cardboard up and out of the stream as the smaller recyclables fall below.
4. The remaining materials land on another conveyor belt, where more workers remove any trash and leftover cardboard they spot.
5. The belt leads into another disk screen—this one a double-decker—that separates out lighter paper products such as newspapers. Smaller items like soda cans and water bottles fall below.
6. The remaining materials enter an enclosure where a magnet removes steel from the stream; glass bottles and jars are screened out and shattered by steel discs, their shards falling below; and aluminum cans pass through an eddy current, which imparts an electrical charge so another magnet can repel them onto a separate belt.
7. The items remaining in the stream—plastics and some trash—pass through a device called a TiTech PolySort. It hangs near the end of the final belt and uses an ultraviolet light to scan each item’s composition. When a plastic item is scanned, the PolySort registers its position on the belt. A few milliseconds later, the item reaches the precipice; just as it begins its plunge, the PolySort activates tiny air jets to shoot it into a receptacle above. Everything else falls below.
Illustrations by Chris Philpot.
This article appears in the June 2012 issue of The Washingtonian.