Here’s Your Guide to How Recycling Actually Works

Hopefully as a reader of Cleantech Rising you separate your trash from your recyclables and place them in the right bins. But haven’t you ever wondered if you’re doing it wrong? Can that sandwich wrap that you licked clean can be recycled? You’re about to become the best cyclist since Lance Armstrong — a REcyclist that is.

An Ingenious System

The recycling bins are emptied out at ‘Material Recovery Facilities’ where advanced optical technology is used to view and sort the waste. A big drum tumbles the waste to separate all fine materials, such as soil and dust, and organics, such as food waste, which would contaminate recycled materials. This stuff gets filtered out and will be turned into a fuel product known as RDF.

2D material is separated from the 3D material. The 2D material goes on a belt under optics that recognize the different classes of material. Then, after a machine separates those materials, a worker sifts through them to make sure all the material is non-contaminated.

Paper: Paper that is separated is sent off to go through a few processes to get turned back into usable paper. Your granola box from this morning may have been made out of recycled paper!

Steel: The 3D material goes past a powerful magnet that removes all the ferrous (magnetic) metals. Steel picked up from the magnet is quite easy to reuse — it’s just crushed and melted down so it can be mixed with new steel and refashioned into new steel products.

Glass: A fan pushes lighter goods such as aluminum (which isn’t magnetic) and plastic upward while heavier glass items drop down to a conveyor belt. The glass is crushed to no larger than 5 cm and sorted by color — clear, brown, and green. The colors are important because they’re permanent on glass. Clear glass is the easiest to make but the material held in the glass can degrade due to light exposure from the sun. Sam Adam’s founder was telling the truth when he said his bottles are brown to preserve the hoppy goodness of the beer.

Aluminum: A big spinning drum called an Eddy Current Separator creates a strong magnetic field called an induction field that repels aluminum away while plastics continue on the conveyor belt. Like steel, aluminum can be fairly easily reused by shredding and melting it to make new sheets of aluminum.

Plastics: All that’s left are plastics — but they’re made up of one of six different chemicals, which correspond to the numbers 1 through 6 you see on the bottom of bottles and containers (a #7 means it’s made from less popular chemicals). Some plastics are much easier to recycle than others. In newer recycling plants, infrared sensors separate the different types of plastics based on the different types of light they reflect. Some plastics are recycled but some, such as styrofoam, are thrown away because it doesn’t make financial sense to recycle them.

Check out this video, which is where most of the information in this post came from, for a visual of the process:

So We Can Throw All Our Trash In One Bin?


“The single biggest problem material at recycling facilities are plastic bags,” says Susan Robinson, Waste Management’s director of public affairs. “We get a surprising number of garden hoses, Christmas lights, and shower curtains. All those materials wrap around equipment, sometimes for hours. One thing we’ve learned is that people do a lot of wishful recycling, where folks want so bad to recycle so they throw things in by default.”

What Can’t Be Recycled

Plastics must be clean to be recycled. If you toss a half-eaten slice of pizza in a plastic container in the recycling bin, you could also contaminate thousands of pounds of plastic (not to mention the sacrilege that will be bestowed upon you for wasting good pizza). The same thing goes with plastic bottles with liquid remaining inside. Clean plastic is essential for recycling.

Paper soiled by food CANNOT be recycled.

Plastic grocery bags CANNOT be recycled. They can shut down and entire recycling plant as they get stuck around the equipment.

Organic materials such as food and leaves CANNOT be recycled.

Electronics, batteries, and light bulbs CANNOT be recycled — not by throwing them into an ordinary recycling bin. They must be taken to other facilities to be recycled.

Here’s a full list of everything that can and cannot be recycled.

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