HolyGrail 2.0 digital watermarks project validates detection sorting in semi-industrial trials

31 Mar 2022 --- The HolyGrail 2.0 digital watermarks initiative has successfully validated its prototype detection unit from semi-industrial testing mimicking real-life conditions. The results indicate that the digital watermark technology can achieve more granular sorting of packaging waste at scale, such as developing separate food and other new post-consumer recycled (PCR) streams, like cosmetic or detergent applications.

The initiative’s leaders AIM – European Brands Association and Alliance to End Plastic Waste describe the validation as a “significant milestone,” opening up new recycling streams by overcoming the limitations of current near-infrared (NIR) sorting technologies.

The first prototype demonstrated consistently high results across all tested plastic packaging material categories, recording 99% detection, 95% ejection and 95% purity rates on average.

Industrial pilots next
Developed by the machine vendor Pellenc ST and the digital watermarks technology supplier Digimarc, the detection unit is now ready for industrial-scale pilots, which are planned to start later this year. Details on industrial partners and packaging scope will be released soon.

“We have achieved our objective of proving digital watermarks can increase intelligent sorting of packaging waste at scale, enabling new recycling streams that currently do not exist. This [technology] would be a fantastic leap forward in achieving the EU recycling goals,” comments Michelle Gibbons, AIM’s director general.

“Innovation and digital are the core drivers toward the Green Transition, and this has been brought to life through HolyGrail 2.0. The engagement across the value chain by dedicated experts and teams to get to this point has been remarkable; now, market participants can decide to be part of industrial-scale pilots to test this at an even bigger scale in Europe.” 

“The completion of the semi-industrial trials is a very important milestone in the HolyGrail 2.0 initiative. We are one step closer to making intelligent waste sorting a reality through digital watermarks,” adds Jacob Duer, Alliance to End Plastic Waste’s president and CEO.

“The HolyGrail project is an excellent example of how engaged and committed businesses coming together around a very clear goal can accelerate the development of new solutions. As we move into the next stage of in-market demonstrations, we strongly encourage more businesses and partners to join us in scaling up testing and adoption.”

Semi-industrial tests in detail
The semi-industrial tests of the Pellenc ST/Digimarc prototype started in October 2021 at the Amager Resource Center in Copenhagen, Denmark. The purpose was to evaluate the technology by replicating real-world industrial conditions.

Comprehensive sets of tests were successfully performed on approximately 125,000 pieces of packaging from 260 stock-keeping units (SKUs) at 3 m/s belt speed, with soiling/crushing and throughput representing routine industrial operations. Additional tests were also performed at a higher belt speed of 4.5 m/s, with severe soiling and crushing, without performance loss. AIM’s director general says digital watermarks represent “a fantastic leap forward” in achieving the EU recycling goals.

Validation tests commenced in January 2022 as concluding evaluations of the wide-ranging semi-industrial tests, focusing on the readiness of the Pellenc ST/Digimarc prototype for deployment in large-scale pilots in commercial sorting and recycling facilities.

Success criteria included detection efficiency, ejection efficiency, purity, prototype stability and routine function, ease of programming, the sorting operation, and counting capabilities of the prototype.

The ejection operation comprised a software combination of digital watermark detection and NIR detection to identify watermarked and non-watermarked items, as would be encountered in an industrial sorting or recycling facility. Based on observations from the January tests, the combined NIR/digital watermark detection signal was refined to improve the purity of the sorted output further. 

Final validation
Final validation tests were completed this month at the headquarters of Pellenc ST, where detection/ejection efficiency and purity for sorting PET, PP and PE rigid and flexible films were evaluated.

Each category was sorted at 3 m/s, as close to nominal throughput and occupancy as feasible for the prototype system setup. Parameters for the combination of digital watermark detection and NIR detection and ejection were set appropriately for each category. The sorting program was configured to eject or reject items on an SKU-specific basis. 

Several leading packaging suppliers support the HolyGrail 2.0 initiative, including Paccor and Greiner Packaging.

By Joshua Poole