Sorting with the digital watermarking technology from provider Digimarc and the add-on module from machine manufacturer Pellenc ST was subjected to various tests in the material recovery plant. The tests were carried out with real waste streams, which were supplemented with additional quantities of PP films with digital watermarks and LDPE films from the four brand manufacturers PepsiCo, Procter & Gamble, Essity and Kraft Heinz. The focus was on sorting flexible packaging in order to produce certain types of output fractions from a mixed waste stream – food-grade PP films and hygiene-grade PE films.
According to AIM – European Association of Brands, over 95 percent of these were identified in one pass, more than 85 percent sorted and with a purity of over 70 percent. Even with more heavily contaminated and fragmented streams, including rigid material and high throughput, almost 90 percent were detected and 75 percent sorted – with a purity of around 88 percent.
The results achieved enable the creation of new, higher quality recycling streams with an efficiency that is currently not possible with other technologies. Achieving the EU's binding targets for the use of recycled plastic in packaging by 2030 will require significant changes throughout the value chain, particularly among manufacturers and retailers who use plastic packaging.
Further Recycling Tests
In addition, a three-month sorting trial of rigid packaging with digital watermarks has been launched by various Holy Grail 2.0 member companies on the Danish and German markets. This will be supported by two prototypes, jointly developed by Pellenc ST and Digimarc, which will be installed on Hündgen Entsorgung's commercial sorting line.
If successful, the test will further validate the detection and sorting capability of the technology in an industrial environment as well as the robustness of the system, indicating that watermark-based sorting has reached TRL 9 and is therefore proven in an operational environment.
Two industrial-scale recycling trials with the sorted material will then complete phase 3: Testing of the PP films and flexible PE fractions collected at Hündgen Entsorgung will be carried out by Borealis. Testing of the separated non-food PET bottle stream from the rigid bottle trial will take place at a different location.
In 2016, consumer goods giant Procter & Gamble launched the “Holy Grail” project in collaboration with the Ellen MacArthur Foundation as part of the New Plastics Economy. The project was led by P & G until 2019 and included several studies on improved sorting, for example using fluorescent markers or digital watermarks.
“Holy Grail” was then followed by "Holy Grail 2.0" in 2020. The follow-up project focuses exclusively on digital watermarks for intelligent sorting and is being driven forward by the industry association AIM with the support of the Alliance to End Plastic Waste initiative. The semi-industrial test run with more than 100 products started in Europe in September 2021.
