At the factory, processed milk is sent through a processing line to be packaged into cartons or bottles.
Cartons are made from cardboard lined with a polyethylene plastic, while plastic bottles are made from high-density polyethylene (HDPE).
The cartons are stored flat until just before they’re filled. They’re then formed into their proper shape, filled with milk, heat sealed, stamped with the use-by date, packed into milk crates and stored in a cool room until they’re collected from the factory and sent to shops and supermarkets.
Milk cartons appeared in Australia in 1958, when the Model Dairy in Melbourne began packaging milk in 150 ml and 500 ml Tetra Pak tetrahedron-shaped cartons. At the time, 160,000 new glass bottles were needed every week in Melbourne alone to keep up the delivery of 1.3 million bottles of milk a day.
- In 1968 only about 1% of milk in Victoria was sold in cartons. By 1972, milk cartons had 20% of the market.
- In 1970 the blow-moulded disposable plastic milk bottle was introduced.
- In 1987 only about 2% of milk was still being sold in glass bottles.
Ever wondered what happens to your milk and yogurt containers after you wheel your recycling bin out onto the kerb? Chances are, they’re back in your house in another familiar shape!
The Australian dairy industry is committed to sustainable practices – both on and off the farm.
Recycling your milk and yogurt containers has enormous benefits for the environment. Not only are materials diverted from landfill when we recycle, but we also save natural resources and reduce our environmental impact.
Whether your milk container comes in plastic or a cardboard, it’s life isn’t over once you’ve drained the last drop!
Recycling plastic milk and yogurt containers
Plastic milk bottles and many yogurt tubs are made from HDPE. After your recycling bin is picked up by the local council it’s taken to a materials recovery facility, where the containers are separated from other types of plastic. The plastic is then sent to a reprocessing plant and chopped into small flakes, washed with recycled water to remove residual milk, labels and caps, melted and filtered to remove any other contamination. The molten plastic is then turned into pellets that can be remoulded into new products like outdoor furniture, planking, signs, benches, bollards and bins.
These products are coloured right through so they don’t need to be painted, are graffiti-proof, won’t split, rot or be eaten by termites and can last five times longer than the timber alternative, even in harsh coastal weather conditions. For this reason, they’re often known as ‘ever-wood’, a durable, long-lasting substitute for wood.
Recycled HDPE plastic can’t be used to make food packaging because its low melting point means bacterial contamination is possible. But chances are you have an old milk bottle somewhere else in your house; the recycled pellets can also be mixed with new pellets and made into containers for non-food products like detergent and shampoo.
Yogurt tubs are sometimes made from polypropylene (PP) or rigid polystyrene (PS), which can also be processed into pellets for recycling. Look for a Plastic Identification Code (the universal recycling symbol with a number in it) on the container to see what type of plastic it is. HDPE is 2, PP is 5 and PS is 6.
Recycling milk cartons
The milk carton you emptied over your cereal this morning could be sitting on your desk at work shortly!
Milk and custard cartons are made from liquid paperboard (LPB). A one-litre LPB carton is made from the equivalent of five sheets of office-quality A4 paper.
LPB gets its strong card-like feel from a mixture of hardwood and long softwood fibres, making it great for recycling. It’s also bleached in the initial production process, so it doesn’t need extra bleaching when it’s recycled.
After it’s collected from your recycling bin and separated at a materials recovery facility, the carton heads to the paper recycler, where it’s shredded and washed to remove residual milk products.
The carton’s waterproof plastic/polyethylene coating is separated from the paper and strained off for reuse by a plastics recycler. The shredded carton then gets reprocessed into a pulp, formed into sheets of paper, pressed and dried.
The result? It could be the sheet of high-quality office paper on your desk now!
- A product made from recycled materials uses far less energy than one made from new raw materials such as coal, iron ore, oil and trees.
- For every 41 plastic bottles you recycle, you save enough energy to run your fridge for an hour.
A two-seater bench made from 100% recycled plastic contains the equivalent of 680 two-litre milk bottles and saves six cubic metres of landfill.
- Every tonne of LPB recycled saves 2.5 barrels of oil, 4100 kilowatts of electricity, 31,780 litres of water, four cubic metres of landfill and 13 trees.