How Is Plastic Recycled?
When we talk about plastic recycling we are generally referring to the recycling of thermoplastics. Thermoplastics are plastics which can be changed from a solid state to a molten liquid state by heating. Different plastics (polymers) melt at different temperatures.
Some plastics are thermoset. As the name suggests they remain “set” in a solid state, even when heated and so they cannot be recycled in the traditional sense.
How Is Plastic Recycled – Collection
Most of what you are “allowed” to discard at home or in the workplace is plastic packaging waste. For packaging waste the process starts with bins getting emptied and collected.
Some local authorities still have separate recycling boxes for cardboard and paper, plastics, metal etc. and the materials for recycling are segregated at source by you.
However, the vast majority of local authorities now offer co-mingled collections where you put all you cardboard, paper, tin cans, plastic etc into your recycling wheelie bin. These co-mingled materials are then sorted in a MRF (commonly pronounced “murf”), but is actually an abbreviation for Materials Recycling Facility OR Materials Recovery Facility. The latter is more apt as it is unusual for materials to actually get recycled here – especially in the UK.- more on MRF’s in a bit.
As mentioned previously though, not all plastic destined to be recycled is packaging waste. Plastic manufacturers may have production waste which they cannot re-use directly into their products. Crates, trays and boxes used for transit packaging to transport goods to shops will get damaged and need to be disposed of. Plastic gas and water pipes will get replaced. Even old wheelie bins need to be replaced at some stage. All this plastic is destined to be recycled too. These plastics are generally referred to as “single stream” items and as they don’t need to be sorted, they are more likely to go straight to a plastic recycling or granulation company where the actual recycling process starts.
How Is Plastic Recycled – Materials “Recovery” Facilities
Most MRF’s in the UK are what are known as “Dirty MRF’s” or “Mixed Waste Recovery Facilities” and their main task is to sort co-mingled materials and densify them for onward shipping to recycling facilities both in the UK and overseas.
Using a series of automated equipment that can extract metals and identify particular types and colours of plastic AND manual picking stations where individual workers are tasked to pick a particular kind of waste stream from the conveyor belt,materials are sorted into bays and then fed into balers which press/compact the materials into bales which typically weigh 1/2 a tonne each (depending on the material type)
How Is Plastic Recycled – The Process
Once the plastics have been collected and sorted the next steps in the plastic recycling process (for rigid plastics) are very similar whatever the plastic type:
- Size reduction
Output = Plastic Regrind
- Washing / drying
Output = Pellet / Compound
These processes may be completed by one company or a series of smaller companies depending on their capabilities.
Soft plastics like LDPE film still get size reduced and melted down to form a compound BUT this tends to be done in a single process or single piece of equipment. There is not usually a regrind output for such plastics.
Or to find out more about the plastic and plastic recycling industry check out the British Plastics Federation website.