How Recycling Works

Have you ever wondered how recycling actually works? If you have, then you are in luck because SciShow created an video that explains the process of recycling, step by step.

So, what happens to that plastic, that can, or little piece of paper that you threw into the recycling bin? By definition, recycling is the process of collecting waste materials and breaking them down into building blocks that can be turned into new products. Since each material is made from different things, it needs to be broken down in it’s own way. Paper for instances, becomes wood fibers but glass because crushed into tiny pieces.

When did recycling get attention?

Since 1973 scientists and engineers have been working out the cleanest and best ways to sort and process materials in material recovery facilities. There are typically two kinds of recycling plants called single stream recycling plants and dual stream recycling plants. Dual stream recycling means that the curbside bins are split into two categories: mixed paper and everything else. These two categories are kept separate in the truck, dumped into two separate piles and offloaded onto two separate convener belts.

Single stream recycling means that everything is thrown into the same recycling bin and sorted later by a mix of people and high tech machines. Less than half of all material recycling facilities currently use this method. but that number is growing.

Almost anything can be recycled, but some materials like computers, batteries and light bulbs are too complex. If they show up in the recycling pile they are either taken away or sent to specialized facilities. Single stream recycling focuses on 5 different types of waste: paper, steel, glass, aluminum and plastic.


Let’s get started

Paper and cardboard are recycled first thanks to a series of rubber star shaped wheels called rotary screen separators. They are placed into bins separated by newspaper, mixed paper and corrugated cardboard. Paper is made out of two basic ingredients: cellulose fibers from wood and water.

First, the paper is compacted, bailed and sent to a mill to take a hot water bath which breaks the paper down into a mushy substance called pulp. The pulped is forced through screens for cleaning. Next it is sent to the de-inker which contains surfactants that separate the paper from the ink. Now the clean pulp can be easily formed into new paper products.

For non paper products, a cross-belt magnets attracts metals to be separated. Steel is easy to recycle and is simply crushed into bales and shipped away to foundries where it is melted down.

An air classifier, which is a fan that pushes lighter goods like aluminum and plastic into a higher conveyor belt while glass is pushed into a lower conveyor belt. Next the glass takes a ride through a rolling drum and becomes shattered into pieces and sorted by color. 60$ of all the glass in the United States is clear. Once the glass is separated it is crushed into tiny pieces called cullet.

Aluminum is separated from plastic by a machine called an eddy current separator. An eddy current separator is a big drum with a spinning rotor¬†and magnetic¬†induction field which essentially gives the aluminum it’s own magnetic field and the aluminum is pushed away to another conveyor belt. Aluminum is then shredded, washed and turned into chips which are melted and turned into sheets.

Now all that is left is the plastic which can be made out of 6 different types of chemicals. Each kind of plastic has a different type of molecular structure. Plastic is made of long carbon chains and some plastic is easier to recycle then others. For environmental protection purposes, it is essential that all plastics are seperated at the MRFs as they have different recycling processes.

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