How Are PET Bottles Recycled?

It is hard to reuse or recycle used plastic bottles due to there are so many different types of plastic and the mismatch between the amount of contaminants and the quality of used plastic. It is also true that to reuse or recycle plastic bottles sometimes is more expensive than to produce virgin plastic pellets, this is one of the main reasons that plastic bottles are one of the most dominant waste in the landfills and the ocean.

However, if cleaning and sorting are not difficult or costly for recycling, the whole story will change. PET is a widely used plastic in a variety of industries because of its fantastic chemical and physical characteristics. Moreover, with the growth of global population, a greater demand for PET bottles has been consequently generated. It is time for us to take more actions to be less dependent on our Earth’s limited resources by recycling PET bottles already produced.

What Does PET Stand For?

PET stands for polyethylene terephthalate, is a strong, stiff, durable, clear, non-reactive, lightweight and recyclable plastic. PET was first invented in 1940s with the aim to be developed for use as textile fibre, around 30 years later, PET began to to be used for food and beverage packaging. Nowadays, PET has become the most popular packaging material for food, beverage and even pharmaceutical industries in the world due to its one main characteristic which is its environmental aspect, as it is 100% recyclable.

The Low Melting Temperature of PET

PET has a very low melting temperature compared with its alternatives such as aluminum and glass which means PET can be heated easily and moulded into different shapes and sizes over and over again. This makes PET sustainable by turning PET packaging into a closed loop which can be also called a circular economy.

Two Ways of Recycling

There are two different ways to recycle used PET bottles back into PET pellets and then make into new products: chemical recycling and mechanical recycling. Chemical recycling of PET refers to using chemical agents to depolymerize PET waste which may release toxic substances and harm the environment potentially.

Mechanical recycling of PET, conversely, no chemical agents needed, the PET is melted and formed into pellets or flakes which can be used directly in the process of producing new PET products. Mechanical recycling of PET is the most widely adopted way as it is fully eco-friendly and sustainable. Normally, there are 7 steps to recycle PET bottles.

Step 1: Collection of PET Bottles

In the past, PET bottles were thrown away with other waste after use and this added difficulties of sorting to subsequent recycling steps. Now many countries have urban waste sorting collection and sorting treatment policy which makes it much easier to sort different types of waste, for example, people can easily see a recycling bin on the streets and then put recyclable products, such as PET bottles into the recycling bin instead of throwing them into the waste bin. In this way, recyclable products are collected and then delivered to a recycling center.

Step 2: Separation of PET Bottles

At the recycling center where PET bottles are separated out from other recyclable materials such as glass, aluminum and so on. This kind of separation of PET bottles are usually done by automatic systems or by hand sometimes, because there are some many other types of plastic bottles such as HDPE, LDPE, PVC, PP, PS bottles, mixture of any type of those bottles will reduce the quality of recycled PET and consequently, the end PET products.

Step 3: Compression of PET Bottles

After used PET bottles are sorted out by machine or hand, they will be put on conveyer belt for compression. Thanks to the advantage of lightweight of PET, the machine can compress PET bottles into small bales while squeezing out the possible liquid in the PET bottles. The benefits of doing this is that the compressed bales of PET bottles can be a good fit for a container and it is more sustainable to transport the PET bottles to a processing centre.

Step 4: Grind of PET Bottles

When the compressed bales of PET bottles are delivered to a processing centre, they get decompressed and then get washed roughly and after that, they will be sent into a grinder where the PET bottles are ground up into small flakes by color so as to make them fit for further process of recycling.

Step 5: Washing and Decontamination

After the PET bottles are ground up into small flakes, the flakes will be washed carefully to remove labels, glues, metals or any other residues.

After the washing process, the flakes will be transferred to a decontamination section where harmful substances and flavors will be removed from the PET flakes, this process makes the flakes food approved again and good to use such recycled PET for packaging for food, beverages or pharmaceutical industries. Washing and decontamination process is crucial because it makes it safe to use the recycled PET again.

Step 6: Making the Flakes into Pellets

The washed and decontaminated flakes will be heated & melt and then made into round, clear PET pellets again for the production of new PET bottles. When this process is completed, the PET pellets are ready to be delivered to bottle manufacturers where the recycled PET pellets will be used or together with virgin PET pellets to produce new bottles.

Step 7: Reform of PET Bottles

When the recycled PET pellets are delivered to bottle manufacturers, they are ready to be made into new bottles. The recycled PET pellets will be heated and melt and then formed into different sizes and shapes, this is the end of the closed loop which makes the packaging more sustainable.

As the recycling processes can be done again and again, it is inevitable to get some plastic that is not of high enough quality to be used in this way, under such circumstance, the recycled PET will be ground up into flakes and washed, then made into fiber to be used for bags, carpets, shoes, seat belts and clothing.