New Australian technology promises to make plastics infinitely recyclable. Can it deliver for the environment?
It started about five years ago in Professor Colin Jackson’s protein engineering lab at the Australian National University (ANU).
PhD students Vanessa Vongsouthi and Matthew Spence wanted to study plastic-degrading enzymes found in nature, hoping to be able to recycle or degrade plastic more efficiently.
“It’s a funny thing,” said Jackson. “It’s never really something where you’re, like, ‘It’s done!’ So, there was never a ‘dance around the lab’ moment … [although] there were a couple that were close to it. It’s more a process of continual iterative improvement.”
By 2020, the team had boosted the enzymes to the point the duo was featured in the university magazine, ANU Reporter.
The article was seen by Paul Riley, an entrepreneur-in-residence at Main Sequence Ventures, who had spent almost a year searching for plastic alternatives and recycling technologies.
Riley approached the ANU team, and plastic recycling start-up Samsara Eco was born.
Recycling 2.0
Vongsouthi and Spence’s plastic-eating enzymes are able to revert complex plastic polymers to their monomer building blocks, ready to be made into new products.
“It’s a type of recycling called molecular recycling,” said Jackson, who is now Samsara Eco’s Chief Science Officer.
“Rather than just melt and reform the bottle — which is essentially how we currently do it — you use the enzymes to break the bottle back down to the molecules that it was made from in the first place.”
While plastic recycling already exists, traditional mechanical processes are a low-tech solution. Plastics are typically only recycled a couple of times, often into products like roads that remove them from the circular economy.
“It actually isn’t recycling, it’s ‘down-cycling’,” said biotechnologist Dr Jestin George, Samsara Eco’s Head of Communications.
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“The quality is too low for a lot of applications. What that means is, even though we’ve had recycling for a long time, something like 82 per cent of new plastics on the shelves are made with no recycled content. It’s still just virgin plastic.”
Unlike mechanical recycling, George said Samsara Eco can extract the colour from plastics. The technology can also handle multi-layered products, such as food packaging that is coated with a different type of plastic.
The technology can also recycle polyester fabrics, the polyurethane found in upholstery and carpet underlay, and polycarbonate, such as CDs and screens, George said.
Samsara Eco is now poised to partner with a global fashion brand on new plastic textiles.
One thing the company can’t recycle at the moment is soft plastics — the sort that can be easily scrunched into a ball, such as plastic bags and bread bags. A solution to this problem has been in demand since the collapse of the REDcycle program in November 2022.
“In theory, we can design enzymes for every plastic,” George said. “But in reality, there are some that are on our work order.”
Recycling some products — such as the bioplastic PLA — should be straightforward, but the company hasn’t tried them yet, George added.
“Then there are ones that we think we might be able to do, but they are very challenging at a chemical level — the ideas our scientists have might not work. And those are things like polyethylene and polypropylene and PVC.”
The company has also made strategic decisions not to pursue recycling plastics like polystyrene, which is being banned around the world.
“There will be no feedstock, so it doesn’t actually make sense for us to do that one,” George said.
“And that’s great news … we want to see these plastics being eradicated.”
Breaking it down
Samsara Eco’s technology uses enzymes to attack complex plastics and revert them to their original chemical building blocks — like removing individual bricks from a house and using them to build a new dwelling.
“Plastic is a polymer,” said Jackson. “It’s made up of a chain of monomers that are joined together. The enzyme [cracks] this chain to break it back down to the chemicals that were used to produce it in the first place. These chemicals can then be isolated, and then used to make brand new plastic.”
Different enzymes can be used to target different types of plastic, including traditionally difficult-to-recycle products such as plastic fibres and mixed plastics.
Samsara Eco believes it can develop enzymes for any type of plastic, not just the ones scientists are working on today.
“Part of our technology is actually a proprietary algorithm,” said George.
“Our scientists … can mine the data that exists about all these organisms that have all these amazing evolutionary capabilities, and then design new-to-nature enzymes that don’t exist. That’s also why we can do different types of plastics.”
Enzyme library
After Samsara Eco’s launch, the company was quick to garner support from ANU, Woolworths and CSIRO’s Main Sequence innovation fund.
In November, the start-up announced it had raised $54 million in a Series A funding — cash that will be used to grow the engineering team and expand its library of plastic-eating enzymes.
Jackson said enzymes found in the wild are interesting, but not really suited to industrial applications. They have evolved to help the bacteria eat plastic.
“But those conditions aren’t the same as the conditions that we’d want to use in a factory to do this,” he said.
“So the main challenges have been around how do we engineer the enzyme to be more stable, so it can last longer in our reactors? How can we engineer it to be more active on the particular plastics that we want it to work on? And how can we engineer it so that we can make a large volume very cheaply?”
Another goal is ensuring the process has a low carbon footprint. It’s been a challenge for other advanced recycling technologies, which can be expensive and come with a high carbon cost.
George said the carbon footprint of Samsara Eco’s recycled PET comes in well
below that of virgin plastic.
“We’ve made design and innovation decisions along the way that have always had that carbon footprint in mind,” she said. “It has to be infinitely recyclable and circular, and it has to have a low carbon footprint. Otherwise, there’s no point in doing it.”
Samsara Eco has big goals. George said it will start producing recycled plastics for customers for the first time this year, with an aim of recycling 1.5 million t of plastic by 2030. The company plans to open a large-scale infinite recycling facility in regional New South Wales this year.
It’s also pursuing policy change, including a minimum target for recycled plastics. The company has also been engaging with peak bodies, including the Australian Council of Recycling and Australian Fashion Council.
Jackson is excited to be working on a genuinely new technology.
“Once we get it working, it should result in a massive increase in the amount of plastics that are recycled, and it should reduce the amount of fossil fuels that we need to use to make the plastic,” he said.
George said there’s some eight billion tonnes of plastic waste on Earth — enough to supply the world’s need for plastic more than 20 times over.
“It is really not acceptable to be making plastics from fossil fuels anymore,” she said.
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