By Presca Sportswear: Can end-of-life polyester clothing be recycled?

A couple of years back our team based in the NE noticed an article in the local rag about an innovative new recycling company, Poseidon Plastics, who were setting up stall in Teesside to develop a bottle-to-bottle recycling plant to close the loop on single use drinks bottles.

Ever thinking of the bigger picture our CEO Rob got right in touch to ask whether there could be the potential for end-of-life polyester clothing to be put through this system.

Fast forward a few months and together with Poseidon plastics, the University of Teesside, and environmental consultancy firm ENV23, we embarked on a recycling trial to test the idea of chemical recycling of our clothing into virgin quality polyester (which could be used to make new clothes, or bottles, or duvets, etc etc).

How does chemical recycling work?

The Poseidon process is “chemical” recycling. Note, that’s different to the “mechanical” recycling that turns plastic bottles into the fibres we use in a lot of our clothing. Chemical recycling uses a solvent to break the polyester down into its building blocks known as BHET. We’re not going to pretend we know how to explain that one.

BHET is then filtered to very high purity, and can then be put back into the polyester manufacturing process to create new “recycled” polyester of virgin quality.

Dissolving the fabric/bottles into the solvent also removes anything that’s been added to it, such as filler, dyes, plasticiser, and a range of other chemicals.

How did the fabric recycling trial go?

We provided four different samples of fabric for Poseidon to test, ranging from our own unprinted 100% polyester (simplest to recycle) to a mix of damaged BMX jerseys from a range of competitors that has heavily used, courtesy of our friends at ENV23 and Team Mind BMX. The material was expected to be 100% polyester, based on the care labels, but we had no way of knowing that for sure at the outset. We also submitted samples with elastane in (the stretchy stuff that makes “Lycra”). It’s a different chemistry to polyester and up until now it’s been notoriously difficult to recycle clothes that contain elastane.

The results of the trial have proved really successful. In all instances the purity of the BHET was really high, giving us great confidence in the ability to put this back into new polyester. Poseidon have since run their BHET through the repolymerisation reaction and have created brand new bottles from the BHET!

To turn our clothing back into a brand-new bottle is a stunning achievement.

The ratio of polyester recovered to everything left over, was heavily affected by what went into the front end of the system.

As expected, the white unprinted 100% polyester was the easiest to recycle. The process was easily able to selectively recycle the polyester and leave the elastane, which is a great step forward. Perhaps the most surprising result was the amount of contaminants in the mix of competitor materials. Some of this will be from residues of washing liquid, etc, there’s probably a fair bit of BMX track mixed in there (!) but there was also a lot of other fibre types, such as cotton, which was a surprise. Just goes to show that as customers we’re not always getting what we’re sold!

So what’s the potential of this technology?

The ability to separate polyester from elastane is a big step forward, which will open up the recycling of a large number of previously hard-to-treat clothes.

Taking bottles and/or clothing back to its constituent building blocks also lets you remove and contaminants of potential concern – e.g. Antimony Trioxide.

Mechanical recycling is known to produce shorter fibres and there’s only a limited number of times you can mechanically recycled polyester. It’s also colour sensitive and needs different colour fabrics to be recycled together to avoid ending up with a nondescript mix of colours. Chemical recycling gives the opportunity to create higher quality longer fibres time and time again. All colours are removed as well, which means it doesn’t mean what mix of colours you start with (even black plastic food trays).

Once a commercial plant is operating and lab-scale losses have been minimised the polyester that results from this process should in theory be infinitely recyclable

And are there any drawbacks to chemical recycling?

The biggest drawbacks of chemical recycling are the use of chemicals (the clue’s in the name!) and the higher energy use compared to mechanical recycling.

In and of itself the use of a chemical solvent isn’t an issue, as long as (i) the process is kept completely closed-loop so none of the solvent is emitted to the environment, and (ii) the solvent can be economically recycled within the system, because it’s one of the biggest cost items.

In terms of energy use, the way to drastically reduce the impact of the recycling would be to source this from 100% renewables.

Both energy and chemical costs will directly affect how economically viable the process is at scale.

The other big challenge is what to do with the leftover recyclate, or “stuff” in layperson’s terms, which contains the dyes and other contaminants. Some of the dyes used in textiles are very expensive so there should be a financial incentive to being able to extract these from the recyclate. As to how the rest is treated, to minimise any environmental impact, that’s another question that will need to be answered before the technology can get to commercial reality.

In summary

There’s no doubt there are some challenges to address before the closed-loop process is perfected for bottles and clothing, but this trial has shown that the principle is sound and gives us a lot of confidence that for all the polyester elements of our clothing we’re very close to being able to recycle them into virgin quality clothing (or other products).

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