An innovative solution to the problem of plastic waste

The problem of plastic waste is rapidly growing – quite literally in some parts of the world - into a crisis. An estimated eight million tonnes of plastic makes its way into the oceans every year and only 14% of plastic packaging is recycled globally.

The problem has become so large that there is now an estimated 1.6 million km² (617,800 miles²) island of it floating in the Pacific Ocean. Put into context, the Great Pacific Garbage Patch is slightly bigger than Mongolia. If it were a country, it would be in the top twenty largest. As well as an environmental threat, global plastic waste as a whole also represents a lost resource of around $80 billion every year.

Necessity is said to be the mother of invention and an unsustainable situation represents an undeniable necessity. Most plastic recycling is done at present using mechanical methods, which are energy-intensive and hampered by problems with collection, sorting and contamination, often leading to an overall degradation in quality, and why the process is often referred to as 'down-cycling’.

Add to this situation, the increasing consumer awareness of the environmental damage caused by single-use plastics, with the voices calling for alternatives growing ever-louder and you have something of a perfect storm brewing for the chemicals industry. However, it’s one that can be avoided, says Dr Steve Mahon, CEO of UK-based Mura Technology, if the sector acts now.

“Consumers these days are more aware, and they simply don’t want plastic waste ending up in the environment," he said.

“Plastic, as a material, has many great properties, but we need better ways of recycling it. It's important that the chemical industry is proactive in this because consumers won't give them a social mandate to continue for much longer. Now is the time.”

A game-changer for the chemicals sector?

Mura is the company behind the Catalytic Hydrothermal Reactor, or Cat-HTR - a groundbreaking technology that could well be the game-changer Dr Mahon says the sector needs. Providing a chemical-based solution to a chemical-based problem, Cat-HTR uses supercritical steam - water at an elevated temperature and pressure - to convert plastics back into the chemicals and oils from which they were made.

The supercritical steam acts like molecular scissors, cutting the longer-chain hydrocarbon bonds in the plastics to produce shorter-chain hydrocarbons – as-good-as-new product, and the equivalent of fossil-sourced hydrocarbons – in under 30 minutes. These are then ready to be used to create new, virgin-grade plastics and other materials, with no limit to the number of times the same material can be processed.

What makes Mura’s process especially interesting is its ability to recycle nearly all forms of waste plastic, including many that are considered unrecyclable.

“If you were to put 100% plastic in the front end, you'll get over 99% product - hydrocarbons, gases and so on – out the other end. It has a very high conversion rate of plastic into usable product. It's a very clean, efficient process,” explains Mahon.

“However, the reality is, when working with waste material there's always contamination. You never have 100% plastic going in. There will also be paper, food, pieces of metal, stones and so on. With this process the inorganic materials simply pass through untouched whilst the organic materials like paper and food, which crack at a lower temperature than plastic, are converted into gas. We then use that gas in the boiler to create the supercritical steam.”

The main form of plastic that poses a problem is PVC, due to its chlorine content. The chemical becomes hydrochloric acid and due to its high corrosivity, it needs a certain kind of pipe metallurgy as well as some post-treatment.

“But it’s something we’ll keep an eye on. In theory, we can deal with it, but it’s slightly more complicated. Plus, you don’t get much PVC in consumer waste.”

“But generally, we want to take the materials that the mechanical recycling industry can't recycle, like post-consumer plastic packaging. Otherwise, it ends up being burned or sent to landfills on the other side of the world. Which is pretty appalling. Exporting our pollution to poorer countries cannot be the way forward, and it is increasingly being sent back.”

Not the world's dumping ground

In January 2018, China dropped a bombshell for the waste sector when it announced a ban on all trash imports. Until 2016, the country had taken around two-thirds of global plastic waste, with much of the rest going to other countries in the region.

The Chinese decision was the spark that led a host of other countries in the region – the Philippines, Vietnam, Cambodia, and others – to adopt similar policies.  

In January 2020, Malaysia announced that it was returning 150 containers of plastic waste back to 13 wealthy countries. The country’s then environment minister Yeo Bee Yin seemed to articulate the feeling in the region when she bluntly told the media: “We just want to give a message that Malaysia is not the dumping site of the world.”

With plenty of plastic waste heading back to Europe, the recycling industry will have plenty to work with. This brings us to another of the qualities of Mura’s technology. Unlike mechanical recycling techniques, for Mura, it is relatively easy to upscale, precisely due to its use of water.

“Many other processes use heat, which acts like a sledgehammer. They put loads of energy in, break it apart into individual molecules then condense them back together.

“We do it differently. We apply heat to the plastic to melt it down, then, we mix the supercritical steam in with the molten plastic, heating from the inside out. Other tech does it from the outside in, like cooking in a pan. This is hard to scale up because as you make it bigger, it's harder to transfer the heat from the outside to the inside and have everything at a homogeneous temperature. When you inject water in, however, it imparts the energy and gives much better control over the reaction. Water is the key.”

Partnering to support upscaling

Earlier this month, Mura announced that they had entered into a partnership with Texas-based process engineering giant KBR, to support the global development of Mura’s technology and allow it to be upscaled.

“The KBR partnership is big, and it would be easy to underestimate the impact of it”, said Mahon. “It’s a big name in the petrochemical industry and they have a worldwide presence with a top tier engineering track record. They are a great partner to help us expand quickly.”

“Advanced recycling – also called chemical recycling – is still at an early stage. Nobody has 20 years of operational experience and there are just a handful of small companies operating small plants. We want to move it to the next stage and roll out millions of tonnes of recycling capacity. KBR has the kind of existing infrastructure that few others can bring to the table.”

On top of an 80,000-tonne annual capacity facility in Teesside, Northern England currently under development, Mura is looking at opportunities further afield in the US, Asia, and Germany. The latter, Dr Mahon said, he found to be “a more conducive environment for innovation” than many places in Europe, as well as having well-established chemical and waste sectors, and transport infrastructure.

The present aim is to see one million tonnes of plastic waste processed annually, though Dr Mahon says that number is “by no means the end of it. But it’s a meaningful goal.”

In a perfect world, with this kind of tech, could the manufacture of new plastics be uncoupled from the extraction of fossil fuels?

“It’s possible, yes. Will we ever get there? Not for a while, but theoretically we could,” he said.

“And let's be honest, we don't have ten or twenty years to let this happen in an organic fashion. We have to really try and change things fast.”

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