How Does Plastic Recycling Work?

What are the different plastic resin codes? 

Plastic resin codes are a set of numbers that instantly identify what sort of plastic a product is made of. The lower the resin code, the more probable the plastic type will be easily recyclable. 

1. Polyethylene Terephthalate (PET) 

E.g. water bottles and plastic trays

2. High Density Polyethylene (HDPE) 

E.g. milk cartons and shampoo bottles

3. Polyvinyl Chloride (PVC)

E.g. piping and clothing

4. Low Density Polyethylene (LDPE)

E.g. food bags

5. Polypropylene (PP)

E.g. margarine tubs and ready-meal trays

6. Polystyrene (PS)

E.g. plastic cutlery

7. Other

What are the two main types of plastic recycling?

The two main methods used in plastic recycling are: 

1. Mechanical recycling

This is the process of recovering plastic waste by mechanical processes such as sorting, washing, drying, grinding, re-granulating and compounding. Mechanical recycling does not change the chemical structure of the material, which permits multiple reuse/recycling of polymeric materials, creating a closed loop.

2. Advanced recycling (also known as chemical recycling)

This uses thermochemical reactions to break plastics down into completely new products such as new monomers, new polymers, fuel, energy and other commodities. The development of advanced recycling is at a very early stage and will take several more years to mature. There are questions around legislation, energy consumption, environmental impact and financial viability that constitute obstacles.

What other types of recycling are there? 

There are three types of recycling that are more or less effective at renewing the value and quality of the material in question. In order of decreasing effectiveness these are:

– Upcycling converts a material into something of greater value than it originally was. For example, reupholstering a vintage armchair. 

– Recycling converts a material into something of roughly the same value as it originally was. For example, creating a yoga mat made from recycled wetsuits.

– Downcycling converts a material into something of less value than it originally was. For example, transforming plastic bottles into carpeting or fleece fibres. 

What is the waste hierarchy? 

The waste hierarchy, created by the British Plastics Federation (BPF) suggests that waste should be managed in accordance with a hierarchy. 

This inverted triangle hierarchy starts with prevention at the top. This should be the first and most commonly used step. Prevention involves minimising the use of virgin plastic and  ensuring the products are high quality and can be used for a long time. 

Next on the hierarchy is preparing for reuse, which involves repairing and refurbishing, or washing the product to be used again. 

In the middle of the hierarchy is recycling, which is the process of breaking down the plastic to be used for another product. 

Next is other recovery, which can include pyrolysis to produce either heat, fuel or electricity from plastics. 

Lastly, we have disposal, which should only be used as a last resort.