Single Stream Recycling Tour

Single Stream Recycling Tour

Your Recyclables Are Destined for Greatness

That destiny starts with a Materials Recovery Facility (recycling center) or MRF!

  1. You can all recognize it.  Now learn about the popular recycling symbol or “chasing arrows”.
  2. Find out what happens after you drop your recycling at the curb.
  3. See how they separate the recyclables when they arrive at the MRF.

Chasing Arrows

Recycling is a process we copied from nature. In the natural world, everything is used efficiently and there is very little waste.

Do you know where the chasing arrows recycling symbol came from?
In 1970, a producer of recycled products sponsored a logo design contest open to all high school and college students. A panel of design experts judged the contest in Colorado and declared a college student, Gary Dean Anderson winner. Gary’s idea was to take a finite thing and make it continuous to represent our static yet dynamic world. He created the infamous chasing arrows symbol that is so recognizable today. Each of the three arrows in the recycling symbol represent a different step in the closed loop recycling process.

  1. Collect/Sort – The first arrow represents recycling collection.
  2. Manufacture – The second arrow represents recyclable manufacturing into new products.
  3. Purchase – The third arrow represents the sale of the item made from your recyclables.

When you buy recycled the cycle is complete. That is why it is called “closing the loop”!




  1. Stop
  2. Step
  3. Recycle

You recycle at home and most of us have it easy because recycling is single stream.
This means materials can be collected in one container.  Even if you don’t have the single stream method, most of the stuff you throw away can be recycled.  About 70% of waste can be recycled in different ways!


The Breakdown of Trash

What is in our trash? A study was published in 2007 that showed what stuff Missourians are throwing away. The pie chart below shows the breakdown of the trash in Missouri sent to landfills. Notice that many of the materials thrown away could have been recycled or composted. How much stuff do you throw away that can instead be recycled?

  • Recyclable:  Paper and cardboard (34%), Plastics (17%), Metals (6%), Glass (5%)
  • Compostable:  Organics such as yard waste and food waste (32%)
  • Non-recyclable:  Inorganics (4%), Special waste (2%)

Data Source: 2007 Missouri Solid Waste Composition Study



In Saint Louis County, all waste haulers provide the same minimum level of service to one- and two-family homes.  This service includes:

  • Once a week trash collection
  • Once a week recycling collection
  • Twice a year bulky waste pickup

It used to be that the trash hauler sorted the recycling into a special two, three or four compartment truck.  Collection single stream recycling is easy because the haulers don’t need specialized trucks.  A truck that picks up garbage one day can be used for recycling the next day.

Fun fact: One waste truck can collect curbside recycling from about 500 homes!


At the MRF

At home, you mix your recyclables in one container. Once your single stream recycling arrives at the Materials Recovery Facility (MRF) it has to be sorted by material.

  • Aluminum
  • Cardboard
  • Glass
  • Mixed paper
  • Plastics
  • Steel cans

Many MRFs use fancy sorting equipment to sort materials, so you don’t have to. The processing and sorting equipment can cost millions of dollars to purchase and install.

Waste trucks drop (“tip”) the recyclables onto the tipping floor. Then they are loaded onto a conveyor belt which carries the recyclables to the sorting equipment.

Fun fact: Anywhere from 400 to 800 tons of recyclable material is sent to the recycling tipping floor daily!



Different MRFs have different ways of separating materials.  In most cases, the sorting equipment takes advantage of the physics of motion.  Different forces act upon each recyclable object as it travels through the equipment.  Gravity is a force that helps separate different materials.

The mass of an object is important in the separation process.  Mass is the amount of something there is.  A truck has more mass than a bicycle.  A steel coffee can has more mass than a piece of paper.

The following are common methods used to separate single stream recycling.  (Not all MRFs operate this way.)

1. Separate paper

  • All the recyclables are pushed from the conveyor belt over spinning disks.
  • Objects with greater mass fall between the disks due to gravity.
  • Paper and cardboard objects are tossed onto a separate conveyor belt.
  • The fiber material is carried over disk screens arranged in rows that separate large, lightweight material such as cardboard boxes from smaller paper material.


When paper and cardboard go their separate way, the remaining objects are aluminum, glass, plastic and steel containers.

2. Separate plastic

  • The type of plastic sorting depends on the volume of plastic received.
  • Some MRFs use an optical scanner device to separate plastic by resin and/or color.  Just like a grocery store scanner reads the prices, the optical scanner reads the type of plastic in a product.  The scanner can tell the difference between a water bottle and a yogurt cup.
  • Other MRFs use workers to remove the plastic.

Glass, aluminum, and steel are left on the conveyor belt.

3. Separate steel cans

  • At this point, belt magnet separators attract the ferrous (steel) cans.
  • The steel cans stick to the belt until a blade scrapes them into a separate receptacle.
  • Aluminum and steel are two different types of metal.
  • Steel is a ferrous (contains iron) metal and aluminum is non-ferrous.

Aluminum and glass remain on the belt.

4. Separate aluminum

  • The last force applied to the objects is an eddy current.
  • An eddy current is an electrical phenomenon or occurrence that is observed.
  • A repulsive magnetic field is created by quickly spinning magnetic rotors.
  • Non-ferrous (aluminum) metals are repelled and sent to a separate receptacle.

5. Glass falls off the end of the line.



Now that all the recyclables are sorted, they must be baled.  A bale is a large, compact bundle of goods.  Each material is crushed, pressed together, and tied into a huge cube.  The bales are stacked by material and prepared for shipping.

Bales of material can be shipped by truck, train, or sea.  The bales are shipped to a manufacturer.  A manufacturer is someone who turns these materials into new products.


Finally, the products made from your recycled materials are ready to be purchased. 

By buying products made with recycled materials you can:

  • Conserve resources
  • Save energy
  • Prevent waste
  • Prevent pollution

Fun fact: Did you know that since your grandparents were born, the amount of trash each American generates has doubled?