Fraunhofer Institute for High Frequency Physics and Radar Techniques FHRThe efficient recycling of plastic waste constitutes a central challenge for a functioning circular economy. In particular, complex material compositions — especially black plastics — impede precise sorting processes and consequently prevent valuable raw materials from being retained within the resource cycle. A system co‑developed by the Fraunhofer FHR aims to change this. Within the Waste4Future project, a sensor suite for high‑precision sorting of plastic waste was developed. The objective is to reliably identify carbon‑containing materials and separate them by type, thereby enabling their reuse as high‑quality feedstock materials.
Sensor Fusion for High‑Quality Plastic Recycling
The approach is based on the combination of multiple measurement techniques. In addition to infrared and thermographic sensing, terahertz technology is employed in particular to capture additional material properties. This sensor fusion significantly increases classification accuracy, even for materials with similar optical characteristics.
A central focus lies on the sorting of black plastics, for which conventional optical methods reach their limits. Terahertz sensing enables reliable differentiation based on material‑dependent signal characteristics. Complementary data‑driven evaluation methods are used to robustly identify complex material mixtures and additives. The sensor system is installed as a type of line‑scan camera above the conveyor belt of the sorting facility and performs material analysis in real time. At a belt speed of 1.5 m/s, the results are transmitted to the sorting unit, which subsequently separates the plastic components accordingly.
The developed system solution enables a significant improvement in sorting quality and provides the foundation for more efficient recycling processes. As a result, resources can be conserved, emissions reduced, and plastic streams reintegrated into industrial value‑creation chains in a targeted manner.
Project Partners and Funding
Waste4Future is a flagship project funded internally by the Fraunhofer-Gesellschaft. Several Fraunhofer institutes collaborate on the development of innovative solutions for the circular economy: IMWS, IZFP, IWKS, IOSB, LBF, IVV, IKTS, and Fraunhofer FHR with its focus on terahertz sensing.
Project duration: 1 January 2021 – 28 February 2025