AI camera can sort and separate 12 types of plastic

Researchers from Aarhus University have demonstrated for the first time computer vision technology that can be used to differentiate between a wide range of plastics according to their chemical composition. Applied on an industrial scale, this could enormously increase the rate of plastic recycling.

The plastics that pervade the world today are combinations of many materials (polymers) with varying chemical compounds and additives, such as pigments or fibres, depending on its application. This makes it extremely difficult to tell the difference between types of plastic, making it hard to separate and recycle them. Consequently, the vast majority of plastics (more than 90 per cent) have not been recycled.

The new technology – developed by researchers from the department of biological and chemical engineering at Aarhus University, in collaboration with Vestforbænding, Dansk Affaldsminimering ApS, and Plastix – allows for differentiation between 12 different types of plastic which constitute the vast majority of household plastic types. The plastics are: PE, PP, PET, PS, PVC, PVDF, POM, PEEK, ABS, PMMA, PC and PA12.

The camera separates plastics based on a purer chemical composition than is possible today, opening up new opportunities for plastic recycling. It has already been piloted and will be implemented at Plastix and Dansk Affaldsminimering ApS early this year.

“With this technology, we can now see the difference between all types of consumer plastics and several high-performance plastics,” said Professor Mogens Hinge, who is heading the study. “We can even see the difference between plastics that consist of the same chemical building blocks, but which are structured slightly differently.

“We use a hyperspectral camera in the infrared area, and machine leaning to analyse and categorise the type of plastic directly on the conveyer belt. The plastic can then be separated into different types. It’s a breakthrough that will have a huge impact on all plastics separation.”

Plastics are currently separated using near-infrared technology or via density tests (e.g. testing whether it floats or sinks in water). These methods can separate certain plastic fractions – such as PE, PP, and PET – but not with the same accuracy as this new technology, and therefore not with the chemical purity in the composition. This is vital for boosting the recycling rate of plastic waste.

Plastix CEO Hans Axel Kristensen commented: “The technology we’ve developed in collaboration with the university is nothing short of a breakthrough for our ability to recycle plastics. We look forward to installing the technology in our processing hall and starting in earnest on the long journey towards 100 per cent utilisation of waste plastic.”

Plastic must be at least 96 per cent pure by polymer type to be recycled according to conventional industrial processes. This means that the plastic has to be separated to an almost pure product in terms of chemical composition. Hinge says that the new technology is a big step from this, adding that the technology is continuing to be refined and data indicate it may soon be possible to differentiate even further between polymer and additive types.

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