Aarhus University has been awarded a $3.5 million grant (22.7 million DKK) to develop a camera-based system for the separation of plastic waste according to type. Aarhus will be working with waste management and recycling companies Vestforbrænding I/S, Dansk Affaldsminimering ApS, and PLASTIX A/S. Artificial intelligence will control separation in the system, which will contain three types of cameras: a CMOS camera, a hyperspectral camera, and a terahertz camera. The three will together image and discern properties of the plastic material directly on the conveyer-belt system. Plastics, composed of a multitude of chemical compounds and filler materials depending on use, pose difficulties to large-scale recycling. Hyperspectral and terahertz imaging will gather accurate information about the plastics’ chemical composition, and, importantly, how to sort them according to those properties. “Terahertz provides a detailed image of the specific properties of a given plastic material. Using terahertz technology, we can characterize material properties very accurately,” said Pernille Klarskov Pedersen, assistant professor in the department of engineering at Aarhus University. Mogens Hinge, associate professor in the department of engineering at Aarhus University, is leading the Re-Plast project — an effort to improve plastic recycling through advanced camera technology. Courtesy of Søren Kjeldgaard. The project, known as Re-Plast, aims to provide solutions to the challenge of plastic waste management through accurate separation, product documentation, and materials traceability. A goal of the project is to develop a stream of recycled plastic with a plastic purity of at least 96% by polymer type, and sorted according to criteria including unwanted colors and filler materials. “By coupling the spectroscopic signals obtained with the chemical composition of the plastic, we can achieve pure, well-documented plastic fractions, which can then be recycled in the Danish plastics industry,” said Mogens Hinge, associate professor in the department of engineering at Aarhus University and leader of the project. “The Re-Plast project aims to develop this technology, make it work, and then implement it in the industry. We want to take the technology all the way and show that it really does work at plastic recyclers. This will really boost the Danish circular economy.”