May 24, 2018 Recycling Written by Greentumble Editorial Team
How is plastic recycled?
Plastic production has been rapidly

increasing since the 1950s. Every 15 years the quantity of plastic being produced has doubled. This is the fastest increase of any man-made material ever [4]. We can see this increase in our daily lives, with plastic being used pretty much everywhere and for everything. Plastic can be found in so many places in our modern world: in our homes, in our automobiles, at our jobs, in our electronics, in our children’s toys, in our gardens… Plastic even surrounds most of our food! 

All of this plastic use is quite significant for the environment, since the majority of plastics available today are derived from petroleum, a non-renewable resource. Globally, we have started to realize that we have a problem, but plastic is so entrenched into our lives it cannot be easily removed.

One good way to stem the production of plastic is to recycle plastic that has already been produced and use it to make new products. Plastic recycling has become more advanced in recent years and is always becoming more efficient. Fortunately, a lot of plastic can be remade into new products. Plastic recycling reduces our need for more fossil fuels, saves energy, landfill space, and emissions of carbon dioxide and other greenhouse gases.
 

So, how is plastic recycled, anyway?

 

 

Plastic recycling process

Plastic recycling is broken up into a few distinct steps. Generally these steps remain the same for most types of recycling facilities, but certain steps can be combined or omitted in some situations.
 

Step 1: Collection

The first step in the recycling process is always collecting the plastic material that is to be recycled.

This step is completely reliant upon businesses, restaurants, and the public to dispose of their plastic waste in the correct place. If plastic waste is disposed of in normal trash bins, it will not be recycled, so it is extremely important to separate common waste and plastic waste.

Additionally, it is ideal for governments to have a recycling collection system that goes to people’s houses or businesses to collect the plastic waste. If this is not possible, local collection points for plastic should be easy for the public to access. Making it easy and convenient for people to correctly dispose of plastic waste is paramount in promoting recycling [1].
 

Step 2: Sorting

After plastics are collected and transported to a recycling facility, the next step is sorting.

Machines sort plastics into different areas based upon a multitude of properties that are often dependent upon the recycling facility or what final product is being produced.

Plastics are usually sorted in a few common ways, such as the type of plastic (material it is made with), color of the plastic, or even how it was made. This is important because different types of plastics must be processed in different ways and some recycling facilities are only capable of recycling one type of plastic. If the wrong type of plastic is processed at the incorrect facility it can reduce the efficiency of the whole process and require the entire batch to be sent back again for resorting [1,2].
 

Step 3: Washing

Just like with clothes, fruits/vegetables, and many other things, plastics must be washed before they are further processed. The goal of this step is to remove impurities and everything that is not made from plastic.

Most containers and packages have labels, adhesive, or even food residue that must be removed. This non-plastic waste cannot be recycled and can cause the final product to have poor structural integrity [2].
 

Step 4: Resizing

Resizing consists of shredding or granulating the plastic waste into small particles. This increases the surface area of the plastic, making it easier to process, reshape, and transport if needed.

Additionally, it gives recycling facilities one last opportunity to remove any non-plastic waste that has made it through the first 3 steps of processing. This is often done with metal detectors or magnets that will help remove any leftover metal in the mixture [1].
 

Step 5: Identification and separation of plastics

The identification and separation of plastics is when the now small plastic particles are tested to determine their quality and class.

The first quality tested is density. This is done by floating the particles in a large tank of water. Particles less dense than water will float and more dense particles will sink.

Next their air classification is determined. Air classification is an official term for how thick or thin a particle is. This is done by dropping the particles into a small wind tunnel. The smaller pieces will fly higher up the tunnel and bigger ones will remain lower.

Two other features plastics are commonly tested for are their melting point and color. These are determined by collecting and analyzing samples from each batch of plastic particles [1,2,3].
 

Step 6: Compounding

The final step in the recycling process is often considered the most exciting because it is when the plastic particles are made into something usable for future production. Compounding is when the small particles are smashed and melted together into plastic pellets. The pellets can then be used in the production of other plastic products [1].

Throughout this process the plastic may be moved to different plants that specialize in different steps of the process. It can be energy intensive and the better educated we are about the process the more we can reduce the time and energy it requires.
 

Example: Recycling of a plastic bottle

Let’s say that you have just finished drinking water from a commercial disposable (but recyclable!) water bottle. As you place your empty water bottle into your home recycling bin as you always do, you wonder, “What will actually happen to this water bottle after I’m finished with it?”

In order for your plastic water bottle to get from your recycling bin and made into new products, it goes on a long journey!
 

    • First, your bottle must be collected by a recycling facility. This can happen when recycling collection drivers pick up your recycling bin on your curb in front of your house, or when you bring your recyclable waste to a local recycling facility.

    • Next, if your local recycling company has implemented a Single Stream Recycling System, by which all materials are collected together, these materials must undergo a sorting process to separate different materials, such as glass, paper, or metals. Most often, the majority of this sorting process is done automatically by machines, but it may also include one manual sort to eliminate as much contamination of the materials as possible.

    • Since there are numerous types of plastics in use today, all of the plastic materials in a recycling facility must be separated by type. Your plastic water bottle will likely be grouped with the other plastic materials made with #1 polyethylene terephthalate (PET or PETE) plastic.

      Unfortunately, certain types of plastics are not as easily recycled as other types of plastics. Many recycling facilities do not have equipment that can handle every type of plastic, and so these items may be sold to another facility that can recycle them or they may end up in a landfill. Ask your recycling company about what they do with items they cannot process.

    • Next, your plastic water bottle will go to an area of the recycling facility where it will be ground up into chips or flakes, and the plastic will then be washed to get rid of any labels or remaining residue.

    • The plastic is dried, melted, and formed into pellets, which can be used for manufacturing new products.

    • These pellets can then be sold to companies and used to make different products, such as artificial fleece, engineered wood products, carpeting, floor mats, tiles, furniture, motor oil, detergent bottles, pipes and pails.

Your water bottle will now be given a new life as something else!
 
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How to recycle plastic?

Despite the efficiency of most recycling facilities, there can still be some difficulties involved with the process of recycling plastic. Materials such as dyes, heavy metals, pharmaceuticals, and sometimes pieces of biodegradable plastic can potentially contaminate an entire batch of petroleum-based plastics and it will all need to be thrown away. This is why it is very important to follow the guidelines of your recycling company regarding which plastics can and cannot be accepted.

The first step in the recycling process is one of the most crucial. If (as the user) we don’t discard our plastic in the correct place, it will never be recycled.

When we recycle plastic there are a few useful tips to remember to speed up the process.

First, keep in mind that almost all plastic bottles and food containers can be recycled. When we recycle these containers it is important to wash them or shake them out to reduce the amount of food waste that is being sent to the recycling center [5].

Second, remove the screw caps from any bottles you are recycling. The caps are made from a different type of plastic than the bottle. If we do not remove them they must be removed by employees at the recycling center before they can be processed [6].

Both of these tips will reduce the amount of work and energy required in the recycling process.
 

What plastics can be recycled?

Not all types of plastic can be recycled, but how do you know which can and which cannot be recycled?

On most plastic containers and bottles you will find a small number denoting the type of plastic that it is. This code is not required, but it is becoming more and more common.

  • Numbers 1, 2, 4 & 5 can be recycled.

recyclable plastic

These plastics are different types of polyethylene and polypropylene. They are used in items ranging from water bottles and toys to grocery bags. These plastics are the most common types used.

  • Numbers 3, 6, and 7 cannot be recycled.

nonrecyclable plastic

These are PVC, polystyrene, and all other types of plastics not mentioned. These plastics have been shown to contain toxins and chemicals that cause human health problems [7].
 

How much plastic is recycled?

Since the mass production of plastics began in the 1950s, we have produced over 8.3 billion metric tons of plastic.

Out of all of this plastic, we have only recycled around 9 percent of it.

Out of the remaining 91 percent, around 12 percent has been incinerated and 79 percent is currently in landfills [4].

plastic recycling chart

This plastic will sit in landfills for the next 400 – 500 years before it degrades and during that time even more plastic will accumulate.
 

Products made from recycled plastic

Over the last 10 years more and more products have begun to be produced using recycled plastics. These products span a huge range: from skateboards to reusable bags to even sunglasses [8]. The opportunity for more and different types of recycled plastic products is nearly endless.

The amount of recycled plastic products is ever increasing. This is a positive sign that people are becoming more environmentally aware of the negative impacts of plastics and benefit of recycling them.

Almost all of the plastic we use becomes waste and a huge amount eventually reaches our oceans, rivers, and terrestrial habitats. We already know this waste has huge implications for our natural ecosystems and cannot be allowed to continue. As a species we need to acknowledge this problem and work together to actively conquer it. A good start to this battle is recycling the plastics that we already use and being positive role models for our peers.

Reducing your use of plastic is best, but recycling your plastic whenever possible is the next-best solution!
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References

[1] https://www.plasgranltd.co.uk/how-is-plastic-recycled/
[2] http://www.norcalcompactors.net/processes-stages-benefits-plastic-recycling/
[3] http://prsi.com/products/air-classifier/
[4] https://news.nationalgeographic.com/2017/07/plastic-produced-recycling-waste-ocean-trash-debris-environment/
[5] https://earth911.com/home-garden/clean-recyclables/
[6] https://www.mnn.com/lifestyle/recycling/stories/remove-bottle-caps-before-recycling
[7] https://www.generalkinematics.com/blog/much-plastic-actually-gets-recycled/
[8] https://www.onegreenplanet.org/lifestyle/beyond-plastic-10-eco-products-made-from-recycled-plastic/