Scrub Hub: Where does my recycling go after it's picked up from the curb?
It starts when you drag your recycling out to the curb.
Your aluminum cans, the peanut butter jar you remembered to carefully, lovingly clean out, that drawing your kid made for you four years ago that you’re finally getting rid of (don’t worry — we won’t tell): All of the recyclable remnants of your day-to-day life are ready to be sent away for eventual reuse.
But how exactly does all of that happen?
Since we started our Scrub Hub initiative a few months ago, we’ve received dozens of questions involving recycling in one way or another.
In our last edition, we answered your questions about what exactly is supposed to go in the bin. Now, we’re going to answer your questions about what happens next.
The short answer
First things first: Make sure you’re recycling correctly.
If you haven’t read our most recent Scrub Hub story outlining the dos and don’ts of recycling, be sure to check it out. Putting the right items in the bin becomes important down the line, once your items start moving through the sorting process. Incorrect recycling can contaminate other materials and lead to more waste in the landfill.
Contamination has spiked this year, as people sheltered in place, said Republic Recycling's Craig Lutz. Where a 20% to 25% contamination rate is normal, this year they've seen rates in the 40% range.
"We finally started seeing a lot of just trash," Lutz said. "It still runs across the production lines, and trying to pull it out is just harder."
Once you’ve checked to make sure you're recycling correctly, your materials are ready to be picked up — either from your curb or from one of the many recycling drop-off locations around the city — and taken to the facility to be sorted.
There, a process resembling an enormous, sprawling Rube Goldberg machine sifts through each of your items and directs them to their respective containers.
Some of the tools used for this process seem like they could be right out of a sci-fi movie: reverse magnets that repel aluminum cans onto separate conveyor belts, giant rotating barrels and jets of air that detect and target certain plastics.
For details on how your materials traverse the process, keep reading below.
The long answer
First, you throw it in your blue bin. An empty aluminum can, one of the thousands that will be repurposed to make machine parts, bicycles or more cans down the line.
The bin is picked up by a truck and transported to the nearby sorting facility. There, your can might sit for a while, underneath a massive pile of other recyclables accumulated from across Indianapolis.
But once it’s dumped into a contraption called a drum feeder, which supplies a steady stream of materials on the conveyor belt, the fun begins.
Your can falls on the conveyor belt and rises up an incline to the place where sorters stand, picking out objects that don’t belong. In a nearby container for non-recyclable items rescued from the line sit a lawn chair, a baking rack and a garden hose.
These aren’t the strangest items to come through these lines. Indianapolis recycling facilities have seen far stranger — things like car parts, toys and animal parts.
Past the pre-sort area now, your aluminum can rolls into a large separating machine which, with enormous gear-like spinning wheels, allows large cardboard to float along the top while smaller, heavier objects such as bottles, cans and plastics fall below.
Tangled in the gears, a plastic garbage bag whops against the materials, flinging some into the wrong line and interrupting the otherwise smooth process. Soon, the machines will be shut down and workers will have to enter and remove these plastic bags.
And when workers have to stop and clear these bags several times a day it costs time and efficiency.
"They can damage the equipment, they can get in the way of how the process works," said Calvin Davidson, general manager at Ray's. "It's a lot of moving, spinning wheels. And so things that are long and stringy or heavy and dense can cause damage to downstream equipment."
Everything that's not cardboard falls onto a "breaker screen," which shatters glass and allows it to fall through the cracks into a separate sorting machine. Glass is one of the more difficult materials that comes through the system, and actually costs Republic money to recycle.
Meanwhile, the cardboard, paper and other fibers will follow their own path, being separated by a few more rounds of sorting. A full book whizzes past, and a sorter down the line picks it up and dumps it into the non-recyclable bin. Next, a couple of tarot cards drift by. A flyer. A copy of the Indianapolis Star.
Your can is still moving along its own conveyer belt, and reaches a large spinning magnet that snaps up steel, like soup cans.
Unaffected, your aluminum can rolls along, falling from one conveyer belt to another until it reaches a strip of bright light. Once the light detects certain plastic materials, such as shampoo, detergent or water bottles, a jet of targeted air shoots out at them and bounces them upward onto a separate converter belt. Sorters check for mistakes before the bottles fall into a large silo, next to the containers for steel, aluminum and other plastics.
Next, your can meets a curve in the line that's circulating an Eddy current, an electric charge that acts like a reverse magnet. This repels aluminum onto another conveyer belt, allowing the leftover material to fall below. Your can's moment has come.
The can is shot upward into the aluminum sorting line. After a quality checkpoint, where a worker swiftly removes a cat food container from the line, your aluminum can finally rolls into a silo with other cans.
Eventually, your can — alongside the other sorted papers, plastics and steel — will be compressed into a large cube and stacked on others, dozens of feet high. Then, it will be loaded onto a truck and shipped out to a mill, where it will be melted down and eventually remade into a new object.
The sorting process is complex, with multiple lines running at once, but it goes smoothly — so long as things such as plastic bags, books or lawn chairs don't get in the way.
When messy items like food waste or liquids share the lines, it can also make clean objects non-recyclable. Then it won't matter how lovingly you cleaned out your peanut butter jar or whether you remembered not to bag your materials: your items won't make it through to the end.
But if everything goes according to plan, your aluminum can will make it exactly where it needs to go.
Do you have more questions about how the recycling process works? Tell us! Fill out our Scrub Hub form online here.
Can’t see the form? Click here.
Connect with IndyStar’s environmental reporters: Join The Scrub on Facebook.
IndyStar's environmental reporting project is made possible through the generous support of the nonprofit Nina Mason Pulliam Charitable Trust.