Ineffective sorting is currently one of the main barriers to the wider recycling of lightweight packaging waste. Various ways are being studied to tackle this issue - the better the sorting and identification of packaging, the more efficient the mechanical recycling process, and the better the quality of recyclates.
A promising approach is that of the HolyGrail 2.0 project, which uses digital watermarks to enable more accurate sorting and high-quality recycling.
Digital watermarks, which emerged from the New Plastics Economy programme of the Ellen MacArthur Foundation as the development considered most encouraging and worthy of support from the various stakeholders, open up new possibilities that are currently not feasible with existing technologies. The project, now organised as a cross-value chain initiative under the auspices of AIM, the European Brands Association, more than 120 companies and organisations from the packaging value chain - including its most recent member, BASF - has entered the second phase under the name HolyGrail 2.0. This will include the launch of an industrial pilot in order to prove the viability of digital watermark technologies for more accurate sorting of packaging and higher-quality recycling, as well as the business case at large scale.
Digital watermarks are imperceptible codes, the size of a postage stamp, covering the surface of a consumer goods packaging. They can carry a wide range of attributes such as manufacturer, Stock Keeping Unit (SKU), type of plastics used and composition for multilayer objects or food versus non-food usage.
The idea is that once the packaging has entered a waste sorting facility, the digital watermark will be detected and encoded by a standard high-resolution camera on the sorting line. Based on the detected information, the packaging will be able to be more accurately sorted into separate streams. This would result in higher-quality recyclates, benefiting the entire packaging value chain.