How is waste separated for recycling?

The importance of recycling to care for the environment is indisputable and we are all familiar with the green bin for glass, the brown or grey bin for organic waste, the blue bin for paper and cardboard, but what about the yellow bin? This is where you throw packaging, which can be metal cans or plastic containers. In other countries, however, all products that can be recycled are thrown into a single bin, which makes the task of sorting even more difficult.

To understand how the sorting of materials arriving at a recycling plant is done, you can try making your own homemade recycling machine (and you can also see how electromagnetism works).

Materials required

  • Minimum two dozen metal paper clips
  • Paper
  • Scissors
  • Magnets
  • Small containers (about the size of a cup)
  • For step 7: In addition, cardboard tubes from toilet paper or kitchen towels, plastic bottles, rubber bands

What do we have to do?

Step 1. Cut the paper into small pieces, regular or not, approximately one-centimetre square.

Step 2. Place the pieces of paper in a small container together with the metal clips.

Step 3. Cover the top of the bowl with one hand and shake until everything is well-mixed.

Step 4. Pour the mixture onto a table or flat surface.

Step 5. Take the magnet and hold it close to the top of the pile. You will be able to see how the elements separate from each other.

Step 6. You can also add other materials to the mixture in step 2 and see how the magnet acts.

Step 7. Want to go one step further?

  • Cut a bottle in half. The part we are interested in is the mouthpiece.
  • Glue or rubber band the magnets to the outside of the bottle.
  • Put the bottle with the nozzle downwards on a small container (the aim is that the bottle rests on the recent one).
  • Through a cardboard tube (toilet paper, for example), we gently drop the mixture and see how the magnets attract the different materials.


In the same way that the magnet attracts metal, recycling plants use machinery capable of discriminating some materials from others, although some have to be done mechanically. This can also happen in your home recycling machine if, for example, there are too many metal objects stuck to the magnet, it is likely that others will not stick to it or that the metal will remain under the paper or plastic and go straight into the bin. It is therefore necessary that recycling plants also have operators who are responsible for checking that the entire sorting process is working properly.

In order to protect the environment, it is not only important to recycle but also to reduce and reuse. Consider that the cardboard from eight recycled cereal boxes can be used to make a new book, a shoebox from six milk cartons, or 40 soft drink bottles can be used to make a fleece lining.

Once you have finished your experiment, don't forget to recycle and reuse the materials you have used and you will be learning while helping to care for the environment.

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