Characterising contamination levels

Having just read UNEP’s recent Global Plastics Treaty draft policy, it is interesting to note their suggested approaches per country to the areas NextLoopp and Nextek have been focusing on. Reviewing and upgrading how we manage and maximise recycled plastic contents, through to reviewing product design for sustainability and enhancing waste management is our mission.
As such closing the loop on post-consumer food-grade polypropylene (PP) packaging is very much in-step with our commitment to save CO2e by extending the lifecycle of plastic. The reason for this is that, from a climate change perspective, 1.6 tonne/1.8 ton of CO2e could be saved if we were to use food-grade recycled PP versus using virgin PP resin.
Polypropylene accounts for more than 20 percent of global plastics production with food packaging being this prolific polymer’s primary product. In fact, some 55 percent of PP rigid packaging (1 Mt) is food-contact, equivalent to around 10 percent of total PP demand.
According to Plastics Recyclers’ latest report the net demand for PP in Europe is 10.5 Mt., yet PP recyclate from post-consumer rigid product applications only meets 3 percent of this demand.
This is the driving force behind NextLoopp’s continued science-based exploration to close the loop on post-consumer food-grade PP
Achieving this has required addressing each and every roadblock along the way and deep-diving into the specific sorting and decontamination requirements for the recycling processes for PP. This has led to our most recent investigations to determine the residual contamination levels of post-consumer PP packaging, which up until now, have not been characterised.
The lack of data showing the misuse rate within PP feedstocks has meant there was no reliable way of defining the residual levels that could potentially migrate into food as well as understanding which molecules to target via decontamination processes.

Nextek’s study aimed to identify substances that might cause samples to be outliers from the expected input stream which could represent challenges to the final safety of the recycled plastics. Key was to check whether the substances observed could potentially be genotoxic. This is a critical criterion for EFSA safety evaluations given that the substance could be derived from the mis-selection of an item of non-food PP packaging, which is not necessarily a case of misuse.
Although, being olefinic, PP has very similar properties to HDPE, the packaging format of PP reduces the chances of it being in a consumer-misuse scenario. A large proportion of PET packaging is relatively durable, with a tight closure, making it a container of choice when used for the storage of hazardous materials.
Likewise, HDPE packaging is also in bottle form with a closure, meaning it, too, may be used in such a scenario. PP food containers, on the other hand, are less likely to come in bottle form and much more likely to be pots, tubs, or trays with limited closure capability.
Characterising the residues in post-consumer packaging that have been sorted into mono-polymer fractions was done by analysing and testing multiple batches of food/non-food samples to see what molecules are present and if there are any areas of concern.

To achieve this Nextek’s team of scientists worked on a 20-tonne batch of PP bales sourced from a UK-based materials recovery facility (MRF). Using automatic optical sorters to separate colour fractions of natural (clear), white and coloured articles, each colour fraction was hand-sorted into articles from food applications and articles from non-food applications.
The analytical study involved 700 tests, representing approximately 17,500 different PP packs based on 25 significantly sized flakes per test. This was estimated to be a cross-sectional representation of 7% of the packs from the combination of batches of 260,000 packs.
Following this contamination study, Nextek characterised the contamination levels in PP and concluded that they are in the order of 10x less than what we expect in HDPE milk bottles and 100x less than expected in PET.
These results further validate Nextek’s global multi-participant project, NextLoopp, as it breaks through the final barriers to closing the loop on food-grade recycled PP.
By deploying innovative technology to sort post-consumer PP packaging effectively, the project is now harnessing these study findings to fast-track the production of INRT-grade and food-grade rPP.
The growing need to recycle post-consumer PP packaging into a suitable material for primary food contact packaging is driven by the European Union policy to include at least 10% recycled content for all packaging, increasing to 50% by 2040.
Understanding the sorting and decontamination requirements needed to enhance the recycling processes is a major step towards achieving this. More importantly, this data is essential towards enabling food-grade PP packaging to be recycled into high-value recyclates that can safely be used in new food-contact packaging, and this takes us back to the climate change debate.
Back to UNEP’s draft Global Plastics Treaty, it would be beneficial to scientifically model the impact of adopting the various options to gain a clearer understanding of which steps will have the greatest impact on the current direction of plastic waste.
In my opinion we must flip our perspective on recycling. If we are to simultaneously reduce our waste and our reliance on virgin resources then we must pivot from recycling to re-looping.
In other words, we must focus on turning used products back into equal-value products. Instead of recycling plastic packaging to achieve commodity resins we should re-loop plastic packaging into the highest quality resins possible. Our recent study now gives us the leverage to work towards this.

Background
Although a commonly used packaging material for food across the globe, unlike, for example, PET bottles, post-consumer PP packaging is not widely recycled in conventional mechanical recycling infrastructure. One reason for this is that mechanical recyclers have, up until now, not been able to differentiate between PP bottles that once contained chemical products from those containing food. As a consequence, current food-grade recycled PP is currently limited to advanced recycling technology processes.
The NextLoopp project, initiated and led by sustainability consultancy Nextek is a two-year multi-participant project aimed at closing the loop on food-grade rPP. The project uses a combination of technologies to first separate food-grade PP from the rest, and then decontaminate the polymer. Sophisticated decontamination technology is used in combination with an innovative, commercially-proven fluorescent marker sorting technology called PolyPrism. PolyPrism applies high performing luminescent materials to labels on plastic packaging, creating an invisible ‘barcode’ for plastics recycling. used on the labels. When applied to food-grade packaging labels, these UV-fluorescent markers can be used to sort food from non-food packaging. The markers can be removed during recycling leaving no traces for the next cycle of use.
The goal of the project is to validate the process developed to manufacture food-grade recycled polypropylene and its commercial viability in order to receive acceptance from the UK’s Food Standard Agency (FSA) and European equivalent (EFSA). A consortium of companies from across the value chain are taking part in the project.