You can find it everywhere, from the deepest trenches of the ocean to the atmosphere to our own blood and organs, even in a mother’s placenta. It’s so durable we use it for cables on the ocean floor, water pipes underground, and it remains the go-to method of keeping food fresh. It is of course plastic, the fully-synthetic wonder material invented in 1907 by Leo Baekeland which contains no naturally occuring molecules. And owing to that synthetic durability, nature doesn’t quite know what to do with it: almost every bit of plastic ever produced is still with us, immune to the earth’s natural recycling process.
Today, a staggering 380 million tonnes of plastic is produced worldwide each year. To scale, that’s roughly the weight of 2.7 million blue whales. Only 16% of that is recycled to make new plastics, 40% goes to landfill, 25% is incinerated and 19% is dumped.
Due to a lack of clarity around what’s recyclable and what’s not, those viable as recyclable such as PET (polyethylene terephthalate) often just end up in landfills. Even those that are recyclable degrade the polymer chains, decreasing its strength and viscosity as they are cleaned, shredded, melted and remoulded. Because of this degradation, the new plastic often becomes unsuitable for food packaging.
What if we’ve been coming at it from the wrong direction, altogether, though? The “next grand challenge” for polymer chemistry (the field that created plastic) is learning how to turn those solid materials back into oil. Enter chemical recycling.
Chemical recycling is an attempt to recycle the unrecyclable. Instead of the confusing existing system, where plastics are rejected because their colour, made of composites, or just can’t be sorted properly by eye, chemical recycling aims to see all types of plastic fed into an “infinite” loop, “unmaking” them back into oil where chemists can start fresh. Scientists such as Sharon George, senior lecturer in environmental science at Keele University, have welcomed this development. “This overcomes the quality challenge by ‘unmaking’ the plastic polymer to give us the raw chemical building blocks to start again,” says George. “This is true circular recycling.”
It a process that has existed for decades, but has been so inefficient the economics made it too difficult and expensive to use at any scale. But recent new technologies are facilitating the emergence of efficient chemical recycling, a development many hope will allow for an infinite loop of plastics, and end, or dramatically slow the production of new plastic waste.
The U.K.’s Mura Technology is the first to begin construction of a commercial scale plant designed to recycle all types of plastic, even if they are decayed or contaminated with food. This revolutionary process solves the issue of even heat distribution within the reactor, using water brought to a “supercritical” state where it’s neither solid, liquid or gas. This eliminates the requirement of heating the chamber from outside, and makes the process efficient enough to scale.
“If you heat the reactor from the outside, keeping an even temperature distribution is really hard. The bigger you go the harder it gets. It’s a bit like cooking,” explained Mura’s chief executive, Steve Mahon. “It’s hard to fry a big steak all the way through but if you boil it, it’s easy to make sure it’s cooked evenly all the way through.”
This process boasts a whopping 99% repurposing of all plastics.
“The hydrocarbon element of the feedstock will be converted into new, stable hydrocarbon products for use in the manufacture of new plastics and other chemicals.” Even the “fillers” used in some plastics – such as chalk, colourants and plasticisers – aren’t a problem. “These drop into our heaviest hydrocarbon product, heavy wax residue, which is a bitumen-type binder for use in the construction industry.”
Mura’s Teesside plant has targets set to process 80,000 tonnes of formerly landfill-bound plastic waste as completion of the facility is set for 2022. Plants in Germany and the US are in the works, with a global rollout on the horizon. By 2025, the expect to have processed one million tonnes.
But not everyone is convinced. “These technologies are in their infancy and they are by no means the silver bullet solution to the plastic waste problem.” Says Paula Chin, sustainable materials specialist with the WWF. “We should focus on increasing resource efficiency as a way to minimise waste through greater reuse, refill and repair systems – not relying on recycling to be the saviour.”
Mura’s argument is that this is a crucial step in tackling a major problem of plastic waste “[Chemical] recycling is a new sector, but the scale at which it is developing…is an opportunity to recycle a valuable ready-resource, which is currently going to waste,” Mahon says.
“The interesting thing here is that Mura can find value in plastics that aren’t usually economically viable to recycle mechanically,” says Taylor Uekert, researcher at the Cambridge Creative Circular Plastics Centre, University of Cambridge.
“Unmaking plastic ”is a start, but is still only a dent in the gargantuan, multifaceted problems with plastic pollution. Political will is important, but if a profit incentive can push that forward and expand it, then like plastic, it will endure the test of time.
