TECHNOLOGY | SORTING


HolyGrail 2.0 technologies are successful in industrial testing


In this article, Margherita Trombetti at AIM - European Brands Association provides an update on a key sorting initiative


The packaging industry is buzzing with anticipation as the implementation of mandatory European Union-wide rules for packag- ing and packaging waste draws near. A key aspect of these rules – enshrined in the EU’s Packaging and Packag- ing Waste Regulation – is the requirement to incorporate a specific percentage of recycled content in plastic packaging, necessitating a significant shift in the industry from a linear model to full circularity. Digitalisation, powered by innovative technologies, presents a unique opportu- nity to spearhead this transformation in the waste industry.


In this context, the Digital


Watermarks Initiative HolyGrail 2.0, driven by AIM - European Brands Associa- tion and powered by the Alliance to End Plastic Waste, continues the journey towards industrial trial validation of the digital watermarks technology, approaching the end of R&D phase. The consortium has reached a new mile- stone with the successful validation of the digital watermark technology’s advanced sortation capabil- ity in combination with NIR in an industrial environment, delivering positive results in


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relation to the separation of hygiene-grade LDPE films and food-grade PP films. Industrial trials took place


at the Hündgen Entsorgung material-recovery facility in Swisttal, Germany in December 2023 and in February 2024 using a prototype detection module developed by machine vendor Pellenc ST and digital watermarks technol- ogy provider Digimarc, as part of the initiative. Digital watermarks are


imperceptible codes that can be added to the surface of consumer goods packag- ing, and which carry a wide range of packaging-related attributes. The idea is that the digital watermark can be detected and decoded by a special high-resolution camera once the packaging enters a waste sorting facility, hence achieving more granular sorting and higher-quality recyclates. Tests were performed on


real streams that were bulked up with additional quantities of digitally watermarked PP films, as well as LDPE films, produced


PLASTICS RECYCLING WORLD | September 2024


by some brand owners including Essity, Kraft Heinz, PepsiCo and Procter & Gamble. The focus was on sorting flexible packaging to create specific types of output fractions – food- grade PP flexibles and hygiene-grade PE flexibles – from a mixed waste stream. During trials in December 2023, single-pass sorting achieved, on average, 95% detection efficiencies, 85% sorting efficiencies, and 70% purity. Two-pass sorting, typically used in recycling plants, is expected to improve purity of the output fractions by around 20%. In February 2024, trials on contaminated streams showed 89.9% detection efficiency, 75.1% sorting efficiency, while purity was 88.1% despite harsher conditions (i.e. multiple baling/unbaling, mix of flexi- bles and rigids, high throughputs up to 2,500 kg/h, dirtier) that are not reflective of normal indus- trial settings. The overall sorting results


were consistent despite challenging conditions,


suggesting that the Decem- ber results are more indica- tive of typical performance in standard industrial settings. The upcoming step involves a three-month trial aimed at sorting post-con- sumer rigid packaging, digitally watermarked and introduced to the Danish and German markets by various HG2.0 member companies. If successful, the test will further confirm the technology’s detection and sorting capabilities in an industrial environment, demonstrating the system’s robustness and indicating that the technology has reached TRL 9 – watermark- based sorting proven in actual operational setting. In parallel, the HolyGrail


2.0 Initiative has engaged in a new separate project aimed at testing the capability of another watermark technology – the CurvCode watermarking technology by FiliGrade – to close the loop on HDPE milk bottles in the Netherlands. If successful, the technology will be brought to TRL 7. � www.digitalwatermarks.eu


www.plasticsrecyclingworld.com


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