Polypropylene progress

3rd April 2024


Around 20% of the plastic recycled is polypropylene, but the diversity of products it protects has prevented safe reprocessing back into food packaging. Until now. David Burrows reports

When you think of recycling plastic, what springs to mind? It’s probably a bottle – one maybe protecting a fizzy drink (likely made of PET, polyethylene terephthalate) or milk (which is mostly HDPE, or high-density polyethylene). These polymers represent success stories of UK plastic recycling. Recycling rates could be higher, but there is the know-how, technology and infrastructure to collect, sort, clean and reprocess them back into ‘new’ bottles in a so-called ‘closed loop’ – replacing virgin plastic and reducing emissions with recycled polymers (rPET and rHDPE).

Now consider polypropylene (PP). In its rigid form, it’s used for everything from yoghurt pots and meat trays to detergent containers and bottle caps (as it’s easy to separate in a float/sink tank from materials such as PET). White PP is often the material of choice for things like pot noodles, which require hot water to be added before eating them. PP is “tough, lightweight and does not mind heat”, writes James Piper in The Rubbish Book. “It keeps products dry and fresh, which makes it an effective option for margarine tubs, yoghurt pots and plastic straws.”

PP in food packaging

It’s not just found in supermarkets, either. Two-thirds (66%) of the global plastic footprint of McDonald’s is PP, while at Starbucks it’s 59%. That’s 107,420 and 90,576 tonnes respectively. The figures, compiled as part of WWF’s ReSource project, don’t show how much of this is recycled content but it’s likely to be very, very little – if anything.

Indeed, the current availability of recycled PP (rPP) for food-grade materials sits at “near zero”, says a spokesperson for Wrap, a charity that runs the UK Plastics Pact with fast-moving consumer goods (FMCG) companies and the plastic packaging supply chain. Research it has carried out shows that PP accounts for around 60% of the rigid plastics stream once PET and HDPE are stripped out. Only material that has been processed via chemical recycling (which comes with its own environmental and economic challenges) has been used in food or drink packaging to date.

In fact, there is very little food-grade post-consumer rPP available anywhere in the world, says Marcian Lee, an analyst with Lux Research in Singapore. “The main issue is that the recycling feedstock must be PP food packaging in the first place, which is a huge challenge to accurately identify,” he adds.

Source: Berry, Quantis, 2023

Under EU legislation, plastic packaging for food can only be made from materials on a ‘positive list’ of substances approved as safe. Which means the simplest way to ensure compliance is to exclude non-food packaging from the material fed into a recycling process. That’s fine if it’s milk bottles or soft drink containers you’re after; they can be easily identified and separated at materials recovery facilities as part of the mechanical recycling process. But not if the target is PP packaging used for food.

Research last year by Eunomia for Plastics Recyclers Europe shows net demand for PP in the EU of 10.5Mt, 37% of which is used for rigid packaging. Around 1Mt is food-contact packaging, almost all of it from virgin polymers.

Recycled post-consumer plastic from rigid packaging meets only 3% of Europe’s demand for PP, according to Edward Kosior, CEO and founder of Nextek, which specialises in the recycling of plastic packaging. PP is one of the most prolific polymers, he wrote recently in an article for Packaging Europe, but there is no recycled PP authorised for use for direct food contact other than those originating from recycling schemes that must use material from a closed loop system. That isn’t good enough to meet new EU regulations.

PP tended to be the stuff that was left over at the end of the sorting belts, Kosior tells Transform. That isn’t the case any more, with PP packaging ending up in a range of products, from cars to electronics, in a market currently worth a reported $8.2bn, and forecast to hit $13bn by 2029. But can rPP for food packaging take a slice of that pie?

There is certainly “optimism in the air”, says Husam Taha, principal analyst (plastics sustainability) at energy consultancy Wood Mackenzie. Taha points to Berry, one of the largest plastics recyclers in Europe, as well as the work Nextek is doing in this space.

Berry, for example, has a new state-of-the-art plastic recycling facility in Leamington Spa. This started producing recycled PP for non-food giants such as L’Oréal and Beiersdorf last spring; it has the capacity to recycle nearly 40% of all the available sorted PP waste in the UK. Some 50,000 tonnes of UK kerbside-collected PP – or more than one billion individual packaging items – will wind through the plant every year.

“The next step is food applications,” says Mark Roberts, circular value chain director at Berry. A ‘letter of no objection’ from the US Food and Drug Administration is in place so Berry can use post-consumer material for its patented recycling process (CleanStream) and then use the resulting material for food-grade packaging.

Source: Plastics Europe

Legal unease

What’s happening in the UK and EU is less certain. In 2022, the European Commission introduced updated requirements for recycled plastic materials and articles intended to come into contact with food.

There is a process to follow, and assessments to be done, to ensure these recycled plastics are safe. Getting this right is perhaps more important than ever, given the scrutiny on plastic recycling, the presence of chemicals in packaging and concerns over a toxic circular economy.

The likes of Berry and Nextek are fully supportive of a robust approach but there is frustration that regulators (the European Food Safety Authority and the Food Standards Agency) are dragging their feet. Brexit and the integration of the EU changes into UK law is a spanner in the works too. “EFSA remains hesitant,” explains Wood Mackenzie’s Taha, and is “constantly requiring more results and more testing to prove the safety of the use of rPP back into food material.”

The concern is that a two-tier system will be created as the US ploughs on while Europe is stuck in the mud – despite its progress and innovation in this space. “The biggest challenge in recycling PP is identifying the polymer in food packaging for recycling,” says Lux Research’s Lee. “There are some interesting developments in the use of AI-waste sorters (such as Recycleye’s OMNI Project) and tracer technologies (such as NextLoopp and HolyGrail 2.0) for enabling the recycling of food-grade PP, which I think will play important roles in increasing PP recycling rates in the near future.”

Those hoping to produce rPP for food packaging are confident that they’ve done enough to secure approvals.

Berry uses deep learning sorting developed by Tomra, a technology provider, to remove contaminants in the PP stream (such as non-food bottles and flower pots). This helps achieve 95% purity, mainly pots, tubs and trays, before the next steps, which include identifying the food-grade PP, extrusion and decontamination and testing.

Nextek, which runs the NextLoopp project, supported by some FMCG brands and companies within the PP supply chain, has developed a fluorescent tracking system, PolyPPrism, which uses luminescent materials applied to plastic packaging labels or sleeves. This allows a wide range of products to be uniquely separated from a mixed stream of packaging items. After that comes a new decontamination process. The results from trials are impressive.

Kosior says: “We’ve spent a lot of time [assessing] … the food-grade stream … and the non-food stream because […] if you’re sorting food from non-food and you make a mistake, you need to know what that mistake might mean in terms of crossover contamination. And so we’ve characterised the types of contaminants in the non-food stream and have that as the worst-case contamination in the food stream. That’s a critical understanding. No one’s ever done that before.”

The contamination levels in PP are reportedly in the order of 10x less than expected in HDPE milk bottles and 100x less than expected in PET. “We now have the technology and expertise at our fingertips to make a fundamental impact on improving plastic packaging’s circularity and, in so doing, reducing our CO2 footprint and our plastic pollution,” said Kosior recently.

Source: WRAP, Valpak

PPatience needed

Lee at Lux suggests more patience may be required from these pioneers of rPP for food packaging. He expects regulations around recycling content in packaging to become “increasingly strict” and, based on the recycling status quo, it will be a lot harder to meet these regulations in PP than PET. But, he says, “some of the developments offer some hope.”

David Burrows is a freelance writer and researcher


Further reading: IEMA - New guide on ‘How to integrate circular strategies into your business model’ launched - November 2023


Image credit: Shutterstock

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