If your city allows you to throw all of your recyclable materials in the same bin, then your city uses a process called “single-stream recycling.” Single-stream recycling means there is no need to separate different materials such as paper, plastic and glass into separate bins.

Instead, all recyclables can be tossed into the same bin. They are then collected by a truck and hauled to a sorting center where the real magic begins.

The separation process starts when the truck arrives at the Materials Recovery Facility (MRF). The process may vary from place to place, but each MRF has one goal: to separate and recycle different materials so they can be made into new products.

Let’s take a tour of the Wonderopolis MRF:

Step 1: The recycling truck unloads materials. Materials are carried along a conveyor belt to a v-screen separator. The v-screen separator divides out newspaper, cardboard and other paper items.

Heavier materials like plastic, metal and glass fall through the separator to a conveyor belt below. The collected paper products are bundled to get ready for processing. Plastic, metal and glass items continue their journey onward.

Step 2: Next, metals are recovered from the recyclables using a two-step process. First, giant magnets attract ferrous metals. These items include iron, tin and steel.

The magnets remove ferrous metal products from the belt and place them in a bin where they can be prepared for a metal mill. Can you name some items made of iron, tin or steel that may end up on the magnet during this phase of the metal recovery process (e.g., tin cans, tools, automobile parts, etc.)?

Step 3: Since aluminum products, such as soda cans, are not magnetic, they continue along with the plastic and glass recyclables toward an eddy current rotor. Eddy currents create strong fields of energy around nonmagnetic materials.

Now it’s time for physics to step in to lend a hand. The eddy current causes the aluminum items to shoot away from the other items on the belt and into a collection bin.

Step 4: By now paper, ferrous metals and nonmagnetic metals have been sorted from the bunch. That leaves plastic and glass to continue along the belt. During the next step, an optical scanning system recognizes plastic materials and pushes them off the belt into a bin using a blast of air.

Step 5: Having said goodbye to all the other types of recyclables, only glass remains on the belt. The heavier glass items reach the end of the belt and are collected in a bin. This step completes the recycling process.

Now that you know how the collection process works, let’s tag along with paper, metal, plastic and glass to find out what happens beyond the conveyor belt.

Paper

When paper arrives at the mill, it is loaded into a “de-inker.” This machine removes ink from paper fibers through a chemical washing process. After de-inking, the paper is mixed with water and solvents in a giant blender called a “pulper.” The resulting product is called pulp slurry.

The pulp slurry is then moved to a giant washing machine that spins it at high speed, removing any unwanted particles such as string or glue. After washing, the clean pulp continues on to a press and is wound onto giant rolls.

Unlike some other recyclables, paper degrades each time it is recycled, so it can’t always be used to make new paper. It can be used to make insulation for homes and even toilet paper, though! Can you think of other recycled paper items you have used (e.g., picture frames, paper towels, books, etc.)?

Metal

After leaving the MRF, metals are sent to a metal mill. Using extremely high heat (up to 2800° F!), the recycled metals become a molten liquid. The molten metal is cast into molds, becoming metal bars called “ingots.” The ingots are then shipped to manufacturers who use them to make everything from aluminum cans to file cabinets, tin foil and even bridges!

Plastic

If you look on the bottom of most recyclable plastic items, you will see a number. Each type of plastic is given a number from one to seven. When recyclable plastic arrives at a reclaiming facility, it needs to be divided according to its number. The most common type of plastic is #1. This is the plastic used to make soda and water bottles.

Once sorted, the plastic moves along a belt and is fed through a grinder. Here it is chopped into little bits, kind of like plastic flakes. The flakes are fed into a furnace and melted down into a polymer. The polymer can then be used to make new products such as lawn furniture, garbage cans and carpets!

Glass

Recycled glass may arrive at the reclaiming facility in all sorts of sizes and shapes, but that doesn’t last for long. The first step is to crush all the glass into tiny pieces called “cullet.”

Cullet can either be sent directly to manufacturers or placed in a furnace where it is heated into molten glass for repurposing into new products. Some products made from recycled glass include glass doorknobs, floor tiles, garden ornaments and even jewelry beads.

 

14 Join the Discussion

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  1. Hi Wonderopolis, this is McKenna from Mrs. Caplin’s class. This was a phenomenal WONDER I learned so many new facts that I plan to use in my persuasive writing piece for digital literacy. When I found these facts I was very excited because if we find a WONDER on our topic we get extra credit points. Some of the interesting facts I learned were some paper cannot be reused based on how it degrades, metal turns into a sort of liquid after it is heated at up to 2800 degrees, glass is the last recyclable item to be sorted, plastic products have a number from one to seven on the bottom of them, and that glass is cut into pieces called cullets. My topic for persuasive writing is that people should recycle more. If you have any facts that could add on to my project, I would be happy to include them in my writing. Lastly, I have a few questions, like always. What is the material that is best to reuse and make a new product out of? What does each number mean on the bottom of a plastic item? and How many Materials Recovery Facilities are in each state?

  2. Mrs. Farr’s Class:

    CONNECTIONS: Kaia – the trash reminds me of my messy play room.

    Katelyn – the machine that squished the stuff together reminds me of Wall-e

    Lilly – all the garbage makes me think of the dump.

    WONDERS:
    I wonder how do they make things out of all those empty bottles and cans? Shane

    I wonder if they can make a recycled house? Karissa

    I wonder how long it takes to do all that stuff. Jacob

    • Good morning, Wonder Friends in Mrs. Farr’s Class! We are thrilled that you’ve been thinking about recycling with us! Your thoughts and connections to the Wonder are SUPER! Kaia, Katelyn, and Lilly did a SUPER job of connecting the dots! :)

      Shane, Karissa, and Jacob: we love all these awesome ideas! We hope to build more things, like houses and bicycles, out of recycled material! Great ideas! :)

  3. Hi, I’m Kylee from Ms. Wilson’s 6th grade class. I loved the amount of information I got off of this page. I will be using this information to put into my informational writing about how I think everyone should use re-usable water bottles. I realy needed to know where the recycled materials go and I found it!! I really enjoyed reading this and learned many things off of this website. I hope that the information I got off of here will persuade many people to switch to re-useble materials to use more plastic to keep more plastic out of landfills. Thank you for taking your time reading this. :D I really appreciate this!! ;)

    • Hey Kylee! We are so excited that you’ve been thinking about the importance of recycling and reusing materials! YOU ROCK!

      It sounds like you’re doing a stellar job of preparing your persuasive argument for recycling more often. We will all benefit from reusing materials and keeping our world clean! Thanks for sharing your comment! We can’t wait to hear more about your report! :)

  4. I now know where my recycling goes! It goes to Keens a really cool place. I never knew that my recycling goes into different categories!

    • We’re so glad that you know where your recycling goes. Have you visited Keens before? That sounds like a cool place to do some WONDERing at! :)

  5. The video was so cool. I have always wondered what happens to the recycled items that we use. I learned many interesting things like that paper can be turned into picture frames.

    • We’re so glad you joined us to WONDER about recycling today, lanas64! It makes us smile knowing you learned some interesting facts about recycling. We hope to see you again soon! :)

    • Unfortunately trash isn’t recycled. If you’d like to learn more about trash you may want to check out Wonder #784: Where Is the World’s Largest Pile of Trash?

      Thanks for all your WONDERful questions, reagan2221. Our building is big enough for us to do lots of WONDERing everyday about many different topics! We have been WONDERing for a long time. We have over #1241 Wonders! :)

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Have you ever wondered…

  • Where do recycled items go?
  • What kinds of products are made from recycled items?
  • How are recycled items sorted for processing?

Wonder Gallery

Try It Out

Did you know you can turn a paper flower into a real flower? It’s true! This fun activity will teach you how to bring a little bit of spring into your home this winter using recycled paper!

These paper roses are beautiful (and environmentally friendly) works of art that last all winter long. When spring comes, you can plant the paper flowers in your garden and watch as the seeds grow into real flowers!

 

Still Wondering

To help children identify materials that can be recycled and determine possible uses for these materials, check out this lesson from Science NetLinks.

 

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