Digital watermarks for smart packaging recycling
A technology proven at scale
What are Digital Watermarks?
Digital Watermarks (DW) are imperceptible codes, the size of a postage stamp, containing information about the packaging and its content. Placed on the surface of a packaging, they can be read by an optical sorting machine equipped with a DW detection module to enhance sorting performance in combination with NIR/ VIS detection on a standard Optical Sorter. These codes carry attributes such as plastic type, composition, and usage (food or nonfood application) that help the sortation of packaging waste in order to be recycled.
Driven by AIM – European Brands Association and powered by the Alliance to End Plastic Waste, over 130 companies and organizations from the complete packaging value chain have joined forces for the Digital Watermarks Initiative HolyGrail 2.0 with the ambitious goal to assess whether this digital technology can enable better sorting and higher-quality recycling rates for packaging in the EU.
Have Digital Watermarks proven to be efficient?
The initiative began in 2020 with the objective to prove the viability of digital watermarking technologies for accurate sorting and the business case at large scale. As a leader for Intelligent and connected sorting solutions, Pellenc ST has offered to support this initiative by building the first prototype able to both detect and sort digitally enhanced packaging. Pellenc ST supports the 3 defined project phases :
- Phase 1: Prototype validation
- Phase 2: Semi-industrial tests at the Copenhagen Resource Center
- Phase 3: Industrial tests at commercial sorting & recycling facilities in France and Germany
After semi-industrial tests at the ARC – Amager Resource Center in Copenhagen, the Pellenc ST sorting unit prototype equipped with Digimarc module has been successfully validated at scale with average 99% detection, 95% ejection and 95% purity rates.
This phase has demonstrated the performance of the technology and the benefits from a sorting point of view.
Tested on over 125 000 samples that were encoded (260 SKUs), it represented over 3 tons of packaging waste that had been compressed and soiled to stick to real life conditions of a Packaging in a MRF after home collection.
Since November 2022, Phase 3 of the project has started with Pellenc ST installing its prototype at Wellman France Indorama. Quality tests were successfully completed in February (results to be published shortly).
This should be closely followed by an installation at a Material Recovery Facility in Germany.
After the technical validation, this last project phase is offering a large scale sorting and recycling assessment on industrial sites and on post-consumer waste from the German and Danish markets.
What are the benefits of Digital Watermarks for the recycling industry?
As for sorting packaging in order to be recycled, The Digital Watermarks should be seen as an additional technology on top of NIR Spectroscopy to improve sorting quality and address sorting applications that cannot be addressed with existing technologies.
One example is the ability to extract packaging used for food from non-food packaging applications. In order to push for closed loop recycling, this sorting application is essential to ensure quality feedstock for PCR.
In addition, extensive tests of phase two have proven that combining DW detection and near-infrared (NIR) detection greatly improves the sorting quality. Combining these two technologies enables the optical sorter to:
- Complete the unmarked portions of the packaging and identify the full object
- Allow mixed sorting of both marked and onmarked items, as will be encountered in an industrial facility.
- Reject possible encoding errors based on material detection by NIR.
Based on observations from these test phases, the combined signals of NIR & Digital Watermark detection improve the purity of the sorted output.
In order to better understand and determine the economical value of this technology, Roland Berger* were commissioned to work on a Business Case study for DW in advanced sorting by 2030.
The outcome shows that this technology has a positive impacts on:
- Improved recycling rates by +5%
- Additional sorted volumes (+40kta based on France market study)
- 260€/t average bale price premium
*Roland Berger 2022 – Business case study for Digital Watermarks in advanced sorting, France 2030
What is the status today?
Based on the extensive tests that have been run in Copenhagen Phase 2 (over 125 000 samples from 260 SKUs), the technology has proven to be effective on Optical sorting prototypes, with average 99% detection and 95% ejection on Pellenc ST Mistral+ sorting equipment. In addition to technical validation, DW open new sorting applications:
- food / non-food sorting: ensure full traceability on food grade quality content of rPET or rPP
- creat a qualitative feedstock for non-food plastic applications and allow better circularity on these packaging items
As such, DW are not replacing NIR sorting solutions, and can be seen as an additional technology layer to get more sorting performance and/ or address new sorting applications. Other technologies like Artificial Intelligence may also address some of these applications in the future, but so far, they have not offered the same maturity level. DW offer unique traceability and precision through the attributes listed with each code (type of polymer, color, weigh, mono or multilayer, melt flow index, food grade, recycled content, etc.…).
Nevertheless, Brand Owners and Converters still need to be convinced to implement more enhanced packaging into the European markets to fuel the Phase 3.
Therefore, beginning of 2023, AIM launched the HolyGrail 2.0 French pilot market initiative at Pellenc ST HQ in France. Over 90 participants attended the event joining a live demonstration of the Pellenc ST / Digimarc prototype detection unit, and discussions to start a 2024 Test Market in France with a nationwide deployment of DW sorting solutions at Recyclers or PRF level. Brand owners are invited to launch their enhanced packaging into French retail to test the solution at scale, providing all stakeholders with real-life data on the value creation potential of digital watermarks for optimal sorting of packaging waste.
By supporting the HolyGrail 2.0 initiative, Pellenc ST offers its long lasting experience in sorting applications to accelerate the transformation of the recycling industry with more effective resource recovery solutions.
Alongside other innovation projects, Pellenc ST is offering Brand Owners, Converters and the recycling industry to test and validate the Digital Watermarks solutions at industrial scale. Both in our Innovation Center (see picture above) and on industrial sites.