Digital watermarks deliver multilayer packaging recycling
Pharmaceutical and food packaging plays a critical role in ensuring the effectiveness and safety of products. Multiple layers of plastic and aluminium are often used to shield contents from possible damage from heat, light, temperature fluctuations and moisture. This complexity however can make the separation and recycling of such packaging challenging. This was something that the EU-funded Sol-Rec2 project sought to address. “Our main objective was to develop an environmentally friendly process to separate individual materials from complex multilayer composites,” explains Sol-Rec2 project member Martin Goosey, who worked as a technical expert for project leaders IPM2. “These materials are typically incinerated or consigned to landfill. Our intention was to recover these valuable materials, recycle them, and then reuse them in similar applications.”
Applying digital watermarks and ‘green’ chemicals
To achieve this, the project set out to develop a novel process based on digital watermarks and ‘green’ chemicals, known as deep eutectic solvents and ionic liquids (DES/ILs). Digital watermarks were applied to the surface of the packaging in the form of a series of dots, almost invisible to the naked eye. “At end of life and during the sorting process, a scanner is used to read the dot code on the waste product,” adds Goosey. “This immediately identifies the type of packaging and the materials it contains.” This information is then used to guide automatic high-speed sorters to separate and produce discrete output streams of materials that can be individually treated in the next part of the process. “Following sorting, the multilayer packaging waste is subjected to delamination,” remarks Goosey. “This is achieved by exposing it to a selected DES/IL with heating and stirring.” Delamination involves the separation of discrete plastic and metal layers, which can then be individually collected and recycled. A library of DES/ILs was compiled to enable the selection of the most appropriate chemical for specific types of multilayer packaging waste.
Environmentally friendly sorting and recycling process
The project team was able to successfully demonstrate this novel environmentally friendly sorting and recycling process for multilayer packaging waste at pilot-plant scale. One of the project partners was able to use recovered materials for its commercial products, thereby replacing virgin materials and achieving a true circular economy approach. “The potential positive impacts of this include the recovery, recycling and reuse of plastics that would otherwise be incinerated or landfilled, as well as the recovery of aluminium,” explains Goosey. “Reusing materials in a circular economy approach offers end users cost savings compared to the use of virgin materials.”
Circular economy for multilayer packaging
Next steps include engaging with interested potential end users of this technology to develop a larger-scale pilot plant. This would be used to showcase the economic potential of this innovation through a cost-benefit analysis and the production of large quantities of recycled materials. “There is already a need to recycle materials from multilayer packing waste,” adds Goosey. “This will only grow as legislation sets increasingly stringent recovery targets both throughout Europe and more widely.” It is hoped that further refinement of the Sol-Rec2 process will result in this technology being widely adopted, helping to reduce volumes of plastic waste and enabling materials to be recycled. “This could be one approach for enabling the implementation of a true circular economy for multilayer packaging,” says Goosey.
Keywords
Sol-Rec2, packaging, recycling, pharmaceutical, aluminium, plastic
