Metrological challenges in plastics recycling

Europe aims at climate neutrality by 2050; to achieve this, plastic recycling needs to be increased through better processes and technologies. There is an increasing need for measurement technology that enable efficient identification of different plastic types mixed with other waste. Due to variety of materials in waste, measurements are challenging and quality control is difficult. On the other hand, material volumes are large and increasing, which calls for efficient on-line measurement and quality control methods. In this work, current sensor technologies used in plastics recycling were reviewed and needs for new measurement and calibration technologies were analyzed. Our review shows that among various sensing technologies developed for plastics recycling, NIR/VIS are most widely applied in commercial sorting systems. Hyperspectral and multi-sensing technologies with AI-based data analysis were concluded to have largest future potential. Significance of proven quality increases with expanding business and with technology development. Efficient and feasible calibration methods including certified reference material supplies should be developed.