The Digital Watermarks Initiative HolyGrail 2.0 – driven by AIM, the European Brands Association, and powered by the Alliance to End Plastic Waste (AEPW) – has reached a new milestone in its mission to prove the viability of digital watermarking technology for accurate sorting of plastic packaging at scale.
The latest trials, conducted at the Hündgen Entsorgung material recovery facility (MRF) in Swisttal, Germany, assessed the efficiency of digital watermarking applied to rigid household packaging collected in Germany and Denmark. The facility, which processes 100,000 tonnes of waste annually from 3 million households, was equipped with detection prototypes and add-on modules co-developed by technology provider Digimarc and machine supplier Pellenc ST. These modules combined near-infrared (NIR) and digital watermark (DW) technology for enhanced sorting accuracy.
The trials ran from 19 August to 19 December 2024, with a view to assessing sorting performance across multiple packaging material types and formats. The sorted material volumes were remarkable, with detection rates reaching an average of nearly 56,000 detections per day, totalling 5.66 million detections of 5,949 unique SKUs over the 100-day period. Detection efficiency ranged from 87.9% to 93.8%, consistently exceeding 90% through rigorous cloud-based analysis.
Key Outcomes
The trials focused on post-consumer rigid packaging waste across four different types and formats: PET non-food bottles, rigid PP, rigid PE (including tubes), and PET trays. Participating companies Aldi, Arla Foods, Netto Marken-Discount, Haleon, Hochland, Mondelēz International, Orkla, and Procter & Gamble had previously enhanced their SKUs with digital watermarks, and placed them on the German and Danish market for consumer use, disposal and collection in designated areas.
The streams were additionally bulked up with further quantities of digitally watermarked drinking cups by Coca-Cola and McDonald's as well as tobacco canisters by Imperial Brands.
Sorting efficiency and purity were measured across the different material fractions, achieving the following sorting efficiency and purity results:
The results confirm that digital watermarking enables high-precision sorting, even under challenging industrial-scale conditions characterised by material overlap and dirty object surfaces. Two-pass sorting, as commonly applied in recycling facilities, is expected to further improve sorting efficiency and purity – as proven in previous HolyGrail 2.0 sorting trials.
The trial confirms the remarkable potential of digital watermarks for accurately sorting post-consumer rigid household packaging, achieving ~90% – or higher – sorting efficiency even under challenging real-world conditions and single-pass sorting.
While results were obtained from a single-pass sorting, they are expected to improve in industrial settings with additional processing, proving the technology’s readiness for full commercial deployment. Besides the accuracy and unlike current industrial sorting technologies, digital watermarks also enable an unprecedented level of granularity, reaching SKU-level sorting.
Towards Market Adoption
These findings mark a significant step forward in the adoption of intelligent detection and sorting solutions. The trials demonstrated that Digimarc digital watermarking technology can facilitate traceability of packaging waste at SKU level, providing a pathway to compliance with the Packaging and Packaging Waste Regulation (PPWR), most notably the recycled content requirements for plastic packaging set to become applicable as of 1 January 2030.
With the conclusion of HolyGrail 2.0, the focus now shifts to market adoption programmes under the HolyGrail 2030 – Circular Packaging initiative. The objective will be to prove the economic viability of smart sorting and reprocessing into high-quality recyclates – that can be used again in packaging applications, including food packaging – for all packaging chain stakeholders.
Early-adopter market demonstrations will be launched in Belgium (for flexible PP food packaging) and Germany (for rigid PP food packaging), with the objective of further scaling the technology and allowing participants access to dedicated recycled PP food-grade materials.
To find out more, visit: www.digitalwatermarks.eu