recycling process, Bowling Green, Ohio
From the tipping floor to the first conveyor belt. Bowling Green, Ohio. My photo

You take your recycling out to the curb, or maybe to a drop-off center. You feel good about being so conscientious, but you wonder what happens to recycling. Then you find some cynic writing that it all just goes to the landfill anyway. So what really happens to recycling?

The unseen recycling process happens at a materials recovery facility (MRF). The people who try to tell you that recycling doesn’t matter have never visited one. I have toured four of them in two states. Let me describe the recycling process for you.

Presorting recycling

presort line, recycling process
Presort line. High Point, North Carolina. Each chute receives its own material, from trash to recyclables too large to go through the sorting equipment. My photo

Your local recycling program sends a truck that hauls your recyclables to the MRF. The MRF knows the weight of the empty truck. So the truck gets on a scale to find out how much its load weighs. Then it dumps it on a “tipping floor.” 

The MRF may or may not separate residential recycling from what businesses recycle. Commercial recycling tends to be cleaner and more valuable.

A front loader pushes some recycling to the bottom of a conveyor belt for presorting. Too many people put the wrong things in their recycling. These include:

  • plastic bags and other films that get tangled in the sorting equipment
  • Styrofoam™, which breaks into little pieces and contaminates everything else
  • wire coat hangers, extension cords, Christmas lights, and other tanglers
  • heavy scrap metal which can destroy equipment and injure the workers it eventually falls on
  • ordinary trash and garbage that the MRF can’t sell

The people working in the presorting process removes as much of this material as possible. That’s most of what MRFs send to the landfill. And they have to pay tipping fees there.

Presorting also removes some recyclable materials that can’t go through the system. For example, shredded paper is recyclable, but it will get scattered and lost in the process. So shredded paper belongs in a clear plastic bag—the only plastic bags that ever belong in your recycling container. In presorting, they’re set aside and hand carried to the baler. 

In addition, the first MRF I visited used to accept large plastic items like buckets or broken playground equipment. The people working presort would set it aside and hand carry it to the proper place at the end of the recycling process. 

With the Chinese recycling crackdown, it and many other MRFs started to accept fewer items. Accepting large plastic only encouraged “aspirational recyclers” who burden the system with junk. 

Sorting recycling

recycling sort line. recycling process
A sort line. Bowling Green

What happens to recycling is a little different in every recycling program. MRFs combine manual and automated sorting, with some being much more automated than others. They probably all do the same steps, but in a different order and different way. Nonetheless, the recycling process includes all of the following:

The equipment sorts two-dimensional materials such as paper and cardboard from three-dimensional materials such as cans, bottles, and jugs. These materials go in two different directions. Further sorting of them happens simultaneously.

In the 3D stream, in some order,

  • Glass drops off the conveyor belt onto a concrete floor below, where it breaks. (Except some MRFs have glass crushers).
  • A magnet removes the metal cans and lids.
  • An eddy current separates aluminum cans.
  • Optical scanners sort the various kinds of plastic. Most often, they sort it into three categories: PET (number one in the recycling triangle), HDPE (number two), and everything else. Some MRFs further separate numbers 3-7. All these different plastics have different density. Bursts of air send each on its way.
aluminum can bunker. recycling process
Aluminum can bunker, ready for baling. A vacuum tube deposits the cans there. High Point. My photo

The 2D process relies more on human sorting. Workers sort out

  • High-quality office paper
  • Newsprint
  • Magazines
  • Cardboard
  • Chipboard (such a cereal boxes)
  • The mixed leftover miscellany.

The MRF becomes a maze of conveyor belts, with human workers on each side removing items. 

In  some MRFs, they pick trash that never should have come to the MRF in the first place or anything the sorting equipment sent in the wrong direction. If it’s a PET line, all the PET continues until it falls into the proper bin.

In other MRFs, workers pick whatever belongs on the line and let everything else roll past.

Baling and shipping the recycling

cardboard baler, recycling process
Baler for cardboard, Bowling Green. My photo

Eventually, all the sorted materials wind up in their own bin. When enough accumulates, it gets moved to a baler. Again, some MRFs use a single baler for everything. Others have balers dedicated to specific materials. Those bales become the product that the MRF sells.

No MRF that takes all the time and effort to sort and bale recyclables will willingly send them to the landfill. That would be like any other manufacturer making products and landfilling them. It’s bad enough they have to pay tipping fees for all the trash they shouldn’t have received in the first place.

Glass is different from other products. It gets pushed into a pile that a front loader loads onto a flatbed truck. Glass is very heavy and expensive to ship. The Chinese crackdown has caused some recycling programs to stop recycling glass.  The buyer pays freight on most products, but the MRF must pay to ship glass.

Any recycling program prefers to sell to local or regional companies that will make new products from it. There may not be suitable companies for everything nearby. In that case, the MRF sells to a broker. A high percentage of recyclables used to get shipped to China. 

No more. China had to put too much of the world’s recyclables in its own landfills after paying good prices for them. After decades of warnings, it slammed the door shut.

We have met the enemy, and they is us

Unfortunately, many MRFs shipped out bales with a 25% contamination rate. That is, 25% of the weight their product was something that did not belong in that bale. 

Part of the contamination rate comes from the sorting process allowing some materials to go to the wrong bin.

Most of it comes through mistakes in residential recycling. The recycling process doesn’t work the way it’s supposed to. And it won’t until individual households learn how to recycle.

For example, that jar of pasta sauce that spoiled in the refrigerator didn’t get rinsed. So the sauce spilled all over various kinds of paper and ruined it. But it made it through the system and into a bale. 

Reduce. Reuse. Recycle. But you have a part in determining what really happens to recycling. Recycle only what your local recycling program can handle. That includes making sure everything is clean.

recycling instruction for the public
Recycling instruction for the public at a drop-off center (Bowling Green). My photo