The use of technology to identify and separate specific types of packaging, such as food-grade polymers, from the waste stream in a cost-effective way is an issue that has yet to be solved.
But the Plastic Packaging Recycling using Intelligent Separation technologies for Materials (Prism) project aims to just that.
At the start of February, with £772,000 of funding secured from Innovate UK, the Engineering and Physical Sciences Research Council and the project’s commercial partners, Prism started a two-year research phase. The consortium of partners, led by Nextek, includes Brunel University London, Tomra Sorting, CCL Label, Mirage Inks, WRAP, Evolve Polymers, Johnson Matthey and Enlightened Lamp Recycling.
They will be investigating how new luminescent materials can be applied invisibly to labels on plastic packaging, with the aim of offering a low-cost sorting technology that will boost the purity of recycling streams.
Part of the project will involve developing fluorescent materials from novel metal oxides, and it will investigate converting reprocessed fluorescent powders from lamps – once separated from the mercury – into suitable materials for use in the markers. If this can be achieved, it would create a higher value for the powder and incentivise the collection, safe recovery and preservation of the rare earths they contain.
Professor Edward Kosior, managing director of Nextek, says that fluorescent marking technology “could be the equivalent of an invisible barcode for plastics recycling”. The markers are invisible to the eye except when they are illuminated under special lighting. While fluorescent markers have been known for a long time, they have not been used on a label as a way of sorting plastics before.
Using the markers on labels helps to make the process cost-effective, labels can be applied at high speed and are a normal part of the packaging operation. Most are retained when put into the recycling stream and they can be removed easily at that stage.
The fluorescent system is designed to be integrated into near infra-red (NIR)-based sorting systems currently used in MRFs. NIR systems would retain their role in identifying different polymers, but the new system would be triggered by an ultraviolet (UV) light source that shows markers in the visible spectrum. Once an NIR system had sorted out high-density PE, PP or PET, the UV system could then further sort this into food-grade and non-food-grade material based on the markers.
Kosior explains: “For the first time, we have the opportunity to say ‘this container was used for food and this container wasn’t’, so we can separate the two. Right now, we don’t have any way of doing that except by using a person.”
Claire Shrewsbury, WRAP packaging programme area manager, adds: “The technology could help boost recycling plant yields, and UK plastics recycling as a whole, with more efficient ways of sorting materials such as PP packaging, HDPE milk bottles and sleeved PET.”
Kosior explains that the driving force behind the project has come from WRAP and its desire to create a purer stream of materials and enhance food-grade recycling. The successful first phase of Prism – which was a finalist in the 2015 National Recycling Awards – was funded by WRAP, which worked with Nextek to assess the feasibility of the process and whether or not it would work.
The current phase takes this further: implementing it in commercial formats, developing low-cost fluorescent materials from recovered lights and tubes, how these react through the supply chain and whether the markers get completely destroyed after reprocessing.
Kosior says: “We are trying to provide technology that creates the opportunity to valueadd to recycling. Going to food-grade means commanding prices that are competitive to virgin resin and fulfilling a market need that we know is there.”
Such markers could be used to identify and separate other packaging types such as laminates or bioplastics, packaging containing toxic materials such as pesticides or be applied to WEEE and automotive plastic waste to help identify the polymers used in components.
Kosior says there is interest and demand from brands to bring such technology to market. If successful, it would be an additional high-tech industry in the recycling sector that can create new products and jobs, and add depth to the market for recycled materials.