What happens to my recycling?
How is the material sorted?
The process begins with people. Sorters manually remove visible contamination. Contamination simply means items that can’t be recycled through your yellow bin, like coffee cups, batteries or soft plastics.
Next, various technologies are used to identify and separate the remaining material streams:
- A giant spinning trommel separates different items by size – small items fall through its holes, and large items like cardboard pass through its centre.
- Optical sorters use near-infrared light to identify materials based on their composition – such as paper or plastics.
- 3D scanners identify and separate materials based on their shape.
- Eddy-current machines and other equipment identify and separate aluminium and other metals. An eddy current acts like a giant magnet, but instead of attracting items like cans, it repels them, sending them into a cage, before being crushed and baled.
What happens to each of the streams?
Recyclable plastics are sorted into their different types, PET (Code 1), HDPE (Code 2) and PP (Code 5) and then baled. They’re sent to one of two Circular Plastic Australia Facilities in Melbourne. Here, they’re processed into granules and eventually used to make food and beverage-grade containers.
Paper and cardboard are pressed into bales and transferred to a manufacturer. The bales are then shredded and mixed with water, producing separate paper fibres. The pulp is cleaned, diluted with water and mixed with small amounts of paper-making additives. New paper and cardboard products and packaging are then produced.
Aluminium items like cans and aerosols are baled and sent to an offshore processing plant. They are melted at very high temperatures, and the liquid metal is cast into blocks. These ‘ingots’ are then taken to mills, where they can be turned into products as diverse as cans and aeroplane parts.
Steel items like bottle lids and food cans are baled and transferred to a processor – either locally or offshore. Here they are melted down and eventually recycled into car parts, appliances and more.
Glass is transferred to a ‘beneficiation’ plant where it is separated into colours – clear, amber and green. This sorting determines the colour of the new bottles. Glass is then crushed, cleaned and treated. It’s then melted, mixed with cullet (other broken/recycled glass) and remoulded into new bottles and jars. Further sorting occurs to remove impurities like oven proof glass (e.g. Pyrex), ceramics and any other product that will not melt down.
The cost of contamination
In the last financial year, we collected nearly 8000 tonnes of mixed recycling. According to our waste processor’s audits, nearly a quarter of this was contaminated and could not be recycled.
Contamination in recycling has several negative consequences:
- It can spoil what can be recycled. For example, if oven-proof glass like ‘Pyrex’ is mixed in with glass from bottles and jars, it can result in the whole load being thrown out. This is because impurities like non-recyclable glass can weaken a new bottle or jar, even causing it to explode.
- It carries financial penalties. Our waste processor charges us set fees for contamination levels under 15 per cent. Once contamination is higher than this, fees increase steeply. Ultimately, these charges are passed onto ratepayers.
- It’s dangerous. When placed in recycling, certain items like batteries or electronics can cause fires or explosions, putting workers and the public in danger.
This is why it’s so important that we get mixed recycling right. For more information on what we can accept in the yellow bin, see Guide to recycling bins and services.