How is polystyrene recycled?

How is polystyrene recycled?

Plastic Recycling, Sustainability

Despite being one of the most widely used forms of plastic, used in cups, packaging, and packing materials, polystyrene is not as widely recycled as many other plastics. In the UK, local authorities aren’t able to collect polystyrene from the curb-side, unlike paper, cardboard, and other widely recycled materials. However, that doesn’t mean that polystyrene can’t be recycled. While many businesses and consumers are pushing for the UK’s polystyrene recycling infrastructure to be expanding, private recycling companies are picking up the mantle with their own services and recycling sites.

How is polystyrene recycled?

Polystyrene is recyclable, especially expanded polystyrene (or EPS), which can be immediately reused and it accepted by some local council plastic recycling schemes. There are three common methods of recycling, known as granulation, compacting, and densifying. They work as follows:    
  1. Granulation: Lighter density forms of polystyrene can go through a machine known as a granulator. This machine separates down to the tiny beads that make it up, which are then are mixed into unused polystyrene granules. In these cases, there is no reduction to the strength, insulating properties, or other qualities of the material. Recycled EPS has all the same benefits of brand new polystyrene after it has gone through granulation.
  2. Compacting: For denser forms of polystyrene, they have to go into a compactor that presses them together. The resulting material is a very heavy and thick bale of pure polystyrene. These bales go through a machine that then shreds them into new General Purpose Polystyrene Pallets.
  3. Densifying: There are other methods of recycling that are used less frequently, too. For instance, expanded polystyrene can be fed into a machine called a foam densifier. After it’s shredded, this machine exposes the foam to heat and pressure, melting it down into a paste which is then cooled into a block of solid polystyrene, extracting all of the air. Like compacting, the blocks of polystyrene can then be shredded into new General Purpose Polystyrene Pallets.

Which types of polystyrene are recyclable?

There are three main types of polystyrene commonly used, known as polystyrene (PS), expanded polystyrene (EPS), and extruded polystyrene (XPS). There are all recyclable, but EPS, the lightest kind of polystyrene foam, is the most widely recycled of them all, and some local councils will collect it as part of their plastic recycling scheme. It’s sometimes referred to a Styrofoam, but this is, in fact, a brand name for a particular polystyrene foam product. XPS, or extruded polystyrene is also recyclable. It has a stronger cell structure than EPS, so breaking it down into reusable polystyrene is more difficult, but it can be recycled through the process of compacting.  

Challenges with recycling polystyrene

The low density of many forms of polystyrene are also what makes it difficult to recycle widely, at the moment. The process of granulation can be expensive, and transporting compacted pallets after compacting can be expensive due to their weight, as well. Besides the costs of recycling, another challenge is that the material has to be free of contaminants before its recycled, which means that polystyrene used in food packaging and the like is often not fully recycled. That said, as of 2018, 52% of the UK’s polystyrene packaging production is from recycled polystyrene, according to Styropack.      

Uses for recycled polystyrene

Recycled polystyrene can be reconverted into general purpose polystyrene pallets, which can be used for storage, transport, and other purposes. They’re especially useful for industries that have high sanitation standards, such as food production and pharmaceutical environments. EPS can be shredded back down to its constituent beads which can be instantly reused in new EPS products, such as foams, cups, toys, packaging, refrigerator trays and more. A growing use is repurposed polystyrene plastic furniture. This material is popular for affordable, long-lasting garden furniture. The pellets used in this furniture can also be used in fence panels, plant pots, roof tiles, and traffic cones. The uses for these pellets is ever expanding, so they may be used even more widely in the future.      

The importance of recycling polystyrene

Besides the fact that it can be widely reused in creating new polystyrene packaging, furniture, and much more, it’s important to recycle polystyrene due to the ecological impact it can have. Polystyrene is entirely non-biodegradable. Modern landfills are designed to be sealed, so there is no chance of it biodegrading regardless. That said, less dense forms of polystyrene can disintegrate into small particles over time, which can find their way into the water, where they regularly endanger water life by clogging up the digestive system when eating.