In the ISOPREP project, a novel recycling process for polypropylene (PP) from waste carpets is developed. The Department of Life Cycle Engineering at the Fraunhofer Institute for Building Physics IBP evaluates the environmental impact of the process using a Life Cycle Assessment (LCA) and compares it with primary PP production from crude oil. Even though the novel recycling process represents a step toward a circular economy that can conserve primary resources and thus has a positive aspect per se, the ecological impact of the process on the environment should still be as low as possible.
In the course of the life cycle assessment, the processes and individual inputs into the system that are associated with the greatest environmental impact are identified. In the ISOPREP project, it was thus possible to show that the quantity of solvents used has the most significant influence on the environmental impact of the entire process. In addition, the energy consumption and the PP content in the incoming waste carpets also have a non-negligible influence. The ISOPREP consortium is working to reuse and recycle the solvents used in the process as much as possible, thus keeping losses to a minimum, which also makes sense from an economic point of view. In addition, the pre-sorting of the waste carpets has been adapted with the aim of achieving a high PP content in the input material to the process.
The LCA experts at the Fraunhofer IBP have also structured the model in such a way that influencing variables of the individual process steps can be varied easily and quickly. This means that a large number of options can be represented and their effects on the environment can be examined in an uncomplicated manner. For example, the project partner London South Bank University (LSBU) wanted to know how much the environmental impact of the process would change if the process temperature was raised by 10 K. Using LCA, it was shown that the temperature increase has no significant effect on the environmental impacts. Now it can be investigated experimentally whether increasing the process temperature also has a positive effect on the process result, which in turn could have a positive effect on the ecological performance of the process. Thus, scientists from different disciplines are working together in the ISOPREP consortium to ensure that the novel recycling process becomes an environmentally friendly way to close a raw material loop.