As part of an Innosuisse project, we collaborated with research and industry partners to investigate the feasibility of a closed-loop system for polypropylene (PP) food packaging in Switzerland. We simulated the first complete Swiss cycle for secondary PP in food applications, from the collection of post-consumer plastic waste to the production of test specimens. The focus was particularly on practical implementation, food conformity, the quality of the recyclate, as well as ecological and economic viability.
Collaboration along the value chain
The project was carried out in collaboration with our research partners KATZ (Kunststoff Ausbildungs- und Technologiezentrum) and the Production Management division of the Institute for Technology Management of the University of St. Gallen (HSG-ITEM), as well as with leading industry partners along the entire value chain: BASF Schweiz AG, Coop Genossenschaft, Emmi Schweiz AG, Greiner Packaging AG, InnoPlastics AG, Migros Industrie AG, Silac AG and Säntis Packaging AG.
At realcycle, we coordinated the project partners and, with our expertise in sustainable circular economy, ecological assessment, and project management, ensured successful and sustainable implementation.
Foundation and Vision
This project builds on the findings of the project «Is a Polypropylene Cycle (Food) Possible and Meaningful?» and the Innovation Booster project «Circular Economy for Polypropylene (CE4PP)», which comprehensively investigated the theoretical recyclability of PP packaging. Building on this preliminary work, the main goal was successfully implemented: the production of recycled polypropylene (rPP) from 100% post-consumer food packaging as part of a large-scale practical test – made possible by the close collaboration of all stakeholders along the value chain.
Scaling such a closed-loop system has the potential not only to conserve valuable resources and contribute to achieving net-zero targets but also to strengthen the resilience and independence of the Swiss economy.
Simulation and Technical Implementation of the PP Cycle in Switzerland
Figure: Overview of the steps of the PP loop, which were simulated in the project «Development of Closed Loops for Food Contact rPP».
To simulate the PP cycle, all steps were carried out with post-consumer material – from collection and sorting to shredding, washing, and de-inking, to decontamination, compounding, and the production of test specimens. A particularly central process step was the sorting of the used packaging material, as separation according to application area (food vs. non-food packaging) as well as according to manufacturing technology (injection molding or thermoforming) or melt flow rate (MFI) is necessary for the production of a high-quality recyclate.
In the project, the sorting into food and non-food fractions could be implemented with existing technologies – using artificial intelligence and near-infrared spectroscopy. However, the degree of purity had to be manually improved, as the state of the art was not yet mature enough for the Swiss fraction. At the time of the project, there was also no suitable technology available for differentiating according to MFI. Therefore, manual sorting was also used, with which high degrees of purity could be achieved. However, the development of suitable automated processes is essential for future industrial scaling.
After sorting, the used packaging was shredded into flakes, washed, and successfully de-inked to over 94 %. The post-consumer PP was then restabilized with the addition of suitable additives and processed into high-quality regranulate.
The recyclate obtained from this was further processed into initial demo packaging in industrial processes at Greiner Packaging AG, Säntis Packaging AG, and Silac AG. In subsequent filling and sealing tests with Emmi Caffè Latte cups at Emmi Schweiz AG, the recycled material showed comparable processing properties and functionality to virgin material. The first migration tests were also promising. However, a noticeable odor was detected, which currently limits the industrial acceptance of the material – further research and development is needed here.
Economic and Ecological Assessment
Accompanying the technical investigations, HSG-ITEM carried out a systemic economic analysis to assess the economic viability of closing the loop. These findings support companies in sustainably integrating the newly gained knowledge into their processes.
The ecological assessment was carried out by us using mass flow analysis of Swiss household plastics and life cycle assessment of PP recycling.
Today's market capacity for recyclate is limited. The mass flow analysis has shown that opening up high-quality recyclate applications – such as in food packaging – is crucial to achieving the targeted recycling rate of 55% for plastics in Switzerland. If this goal were achieved for PP, almost 200,000 tons of CO₂ equivalents could be saved annually – this corresponds to a reduction of 92% compared to the current situation, where the recycling rate is only around 6%.
Conclusion
In February 2025, we were able to publish the interim results in the trade magazine KunststoffXtra. This project impressively demonstrated that a closed loop for polypropylene in Switzerland is fundamentally feasible, ecologically sensible, and economically promising – provided that there is coordinated cooperation along the entire value chain. However, further technical progress is required for successful implementation on an industrial scale.
Project partner
