Plastics recycling

The recycling industry takes care of many different types of plastics. Plastics are divided into PET (Polyethylene terephthalate), HDPE (High Density Polyethylene), PVC (Polyvinyl Chloride), LDPE (Low Density Polyethylene), PP (Polypropylene), PS (Polystyrene) and other mixed plastics.

Styrofoam is another type of plastic, commonly called EPS or EPP. This is the ‘Expended’ variant of PS or PP.

Plastic recycling is done by separating the material by type. After this, the plastic is washed and granulated. This granulation is done by heating the plastic to a certain temperature. The melting temperature differs for each material type.  

The input it then transformed into small granules. These fractions are tested per load, usually in a big bag, to verify the purity of the recycled plastics.

How is plastic separated?

The plastic scrap is transported in a waste container, typically along with mixed waste. If you want to use the material again in new products, the flow must be as clean as possible. Therefore, it the plastic is washed thoroughly and sorted into different material categories. It is advised to collect plastics separately before it is processed to further improve recycling efficiency.

For example, plastic soft drink bottles are made of PET, but the cap is made of PP or PE. The recycler can separate this mechanically. However, it is better and more efficient if people start doing this at home.

Some bottles of detergent, for example, also come with a plastic label, called a sleeve. These represent two different types of plastics – the outer layer of which is difficult or impossible to recycle. This issue is still a problem the plastic recycling industry is trying to overcome.

Manual sorting or not?

In the past, everything was sorted by hand. Nowadays, many plastic recyclers have high-tech installations that separate the materials for them. This is done with the help of sensors. These sensors can see what type of plastic is on the conveyor belt. And that brings us back to the sleeves around plastic bottles.

The sensor only sees the sleeve, and not what kind of plastic is inside. As a result, the sorting facility thinks that the entire bottle cannot be recycled and throws it into the ‘reject’ pile.

The same goes for flexible packaging and black plastics, which are often not accurately identified on the conveyor belt. This means if such scrap is not separated by hand, valuable recyclables may still end up being incinerated.

There are modern-day solutions that are attempting to achieve better sorting results. These include smart recycling lines driven by new types of laser technology, artificial intelligence (AI) and robotic systems.