Plastics such as polyethylene (PE), polypropylene (PP) or polystyrene (PS), which are currently produced almost entirely from fossil raw materials, are fundamental to many everyday products and modern technologies. The carbon contained in plastics is an important resource for the chemical industry. If it is possible to better identify such carbon-containing components in waste, to recycle them more effectively, and to use them again to produce high-quality raw materials for industry, the carbon can be kept in the cycle. This not only reduces the need for fossil resources, but also pollution with CO₂ emissions and plastic waste. At the same time, the security of supply for industry is improved because an additional source of carbon is tapped.

The "Waste4Future" lighthouse project therefore aims to create new opportunities for recycling plastics in order to make the carbon they contain available as a "green" resource for the chemical industry. "We are thus paving the way for a carbon circular economy in which valuable new base molecules are obtained from plastic waste and emissions are largely avoided: Today's waste becomes tomorrow's resource," says Dr.-Ing. Sylvia Schattauer, deputy director of the Fraunhofer Institute for Microstructure of Materials and Systems IMWS, which is heading the project. "With the know-how of the participating institutes, we want to show how the comprehensive recycling of waste containing plastics without loss of carbon is possible and ultimately economical through interlocking, networked processes." The outcome of the project, which will run until the end of 2023, is expected to be innovative recycling technologies for complex waste that can be used to obtain high-quality recyclates.

Specifically, the development of a holistic, entropy-based assessment model is planned (entropy = measure of the disorder of a system), which will reorganize the recycling chain from process-guided to material-guided. A new type of sorting identifies which materials and in particular which plastic fractions are contained in the waste. Based on this analysis, the total stream is separated and a targeted decision is then made for the resulting sub-streams as to which recycling route is the most technically, ecologically and economically sensible for this specific waste quantity. What cannot be further utilized by means of mechanical recycling is available for chemical recycling, always with the aim of preserving the maximum possible amount of carbon compounds. Burning waste containing plastics at the end of the chain is thus eliminated.

The challenges for research and development are considerable. These include the complex evaluation of both input materials and recyclates according to ecological, economic and technical criteria. Mechanical recycling must be optimized, and processes and technologies must be established for the key points in the material utilization of plastic fractions. In addition, suitable sensor technology must be developed that can reliably identify materials in the sorting system. Machine learning methods will also be used, and the aim is to link them to a digital twin that represents the properties of the processed materials.

Another goal of the project is the automated optimization of the formulation development of recyclates from different material streams. Last but not least, an economic evaluation of the new recycling process chain will be carried out, for example with regard to the effects of rising prices for CO₂ certificates or new regulatory requirements. The project consortium will also conduct comprehensive life cycle analysis (LCA) studies for the individual recycling technologies to identify potential environmental risks and opportunities.

For the development of the corresponding solutions, the participating institutes are in close exchange with companies from the chemical industry and plastics processing, waste management, recycling plant construction and recycling plant operation, in order to consider the needs of industry in a targeted manner and thus increase the chances of rapid application of the results achieved.

About Fraunhofer IOSB

In the area of visual inspection, Fraunhofer IOSB has been developing systems and equipment in the field of optical bulk material sorting for 20 years for various tasks from industry, e.g. for sorting dried foodstuffs, heat-resistant and lead-containing glass, plastic and rubber granulate, industrial minerals as well as precious stones and diamonds. The basis for this is the development of optimized material feeding components, the selection of optimal sensor solutions for image acquisition in different spectral ranges and the development of hardware-supported real-time algorithms for image processing and evaluation. Based on material analyses, problem-specific and efficient sensor solutions can be developed for different tasks. One focus of the research is on insufficient or unsolved sorting problems.

The following Institutes are involved in the Fraunhofer lighthouse project "Waste4Future":

• Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB
• Fraunhofer Institute for Microstructure of Materials and Systems IMWS
  
• Fraunhofer Institute for Non-Destructive Testing IZFP
• Fraunhofer Institute for Materials Recycling and Resource Strategy IWKS
• Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR
• Fraunhofer Institute for Structural Durability and System Reliability LBF
• Fraunhofer Institute for Process Engineering and Packaging IVV