HolyGrail is a Pioneer Project that aims to accelerate the transition to a circular economy by focusing on improving recycling; namely improved sorting of post-consumer packaging with the help of chemical tracers and digital watermarks.

Next to designing plastics packaging for circularity and ensuring they are collected after use, high quality sorting is a crucial component to increase current poor recycling rates. Current automated recycling systems cannot match the countless packaging formats, with the capability of recognizing only a few of them. Improved sorting can improve both the quality and quantity of recycled on the market, which would mean more plastics go back to the marketplace and bring value instead of becoming waste.

The HolyGrail project aims to tackle this hurdle by tagging the packaging of an item using chemical tracers and digital watermarks, to enable accurate and high-quality sorting. 

Chemical tracers and digital watermarks tag items by introducing a machine-readable code or identifier into them. Detecting and reading the code provides the sorting system with information unique to that item by pointing to a database where that information is stored.

The information tells the system in which way to sort the item (e.g. food grade vs. non-foodgrade) and these informations can be updated and expanded over time. The main difference is in how the code is applied:

• A chemical tracer is a molecule embedded in the plastic resin or packaging component such as a label, acting as a binary ‘code’ as the chemical is either present or not. The molecule is detectable due to its spectroscopic properties. It is possible to combine several tracer molecules, each with unique spectra, to increase the number of possible codes. 
• A digital watermark is an optical code invisible to the human eye, applied directly within the item’s label artwork or embossed in the mould. In addition to detection by an added camera/processor on a sorting machine, digital watermarks can be detected by barcode scanners and smartphones, in practice turning the tagged items into Internet-of-Things object. The codes can provide a wide range of attributes such as manufacturer, SKU, type of plastics used and composition for multi layer objects, food vs non-food usage, etc. The number of available codes is virtually unlimited, attributes can be added over time, and false positives eliminated.

These methods have several advantages:

• Allow for much higher granularity and quality of sorting.
• Retrofitting existing sorting equipment with add-on modules for detection of chemical tracers or digital watermarks is likely less CAPEX intensive than upgrading recycling facilities with more sophisticated detection technology based on material properties. 
• This method can also be utilized to unable other applications throughout the value chain, such as faster checkouts, information transparency and communication with the consumer.

Since its initiation in early 2017, Project HolyGrail has received a lot of traction from the industry, the local and EU governments as well as from associations such as Petcore Europe, PCEP and Plastic Recyclers Europe.

Project HolyGrail has focused on 2 key activities:

• Compile an overview of the existing technology and ensure that the discussion has input from the entire value chain.
• Conduct real tests and small-scale pilots with the most promising coding technologies to establish a proof of concept.

The project group has involvement from the entire value chain including packagers, manufacturers, material suppliers, brands, retailers and recyclers. A basic proof of concept has been established:

• PRISM (UK funded project) for chemical tracers has been led by Nextek which is also part of the HolyGrail participant group and concluded in 2018. It showed encouraging results for its pilot system.
• Digital watermark testing started later and is in an earlier stage of evaluation. The preliminary tests, are so far encouraging.

Here is a link of the project presentation's video.