The SULKI project, part of the SPIRIT programme, set out to explore how a closed‑loop recycling system for polypropylene food packaging could be established in Finland, following the model developed for PET bottles. Orthex played a central role in this project with Chief Supply Officer Tom Ståhlberg and development engineer Unna Paavolainen involved in advancing both technological understanding and collaboration across the value chain.
Early ambitions and unexpected challenges
Chief Supply Officer Tom Ståhlberg from Orthex comments on the SULKI project as follows: “Our project began with a clear intention to work with the value chain to develop a functioning closed‑loop system for polypropylene-based food packages. As the work progressed, unexpected organisational changes among key partners disrupted a bit the momentum. Overall, these experiences have helped clarify the path forward and strengthened our understanding of how crucial resilience and long‑term collaboration are in circular initiatives.
What the trials revealed
The project achieved promising technical results. Simulated manual sorting trials with several hundred kilos trials showed that polypropylene waste could be sorted manually into three streams: white, transparent and coloured: Fractions clean enough for further processing were achieved.
Development engineer Unna Paavolainen at Orthex explains: “Together with the project partners, we explored several identification technologies for sorting of food packages from the waste stream including tracer pigments, machine vision and shape‑based sorting. Insights from European initiatives such as the Holy Grail project supported this work. The findings demonstrated that sorting itself is not the main bottleneck, provided that cleanliness, batch control and identification methods are standardised.”
Tom Ståhlberg illustrates the project using a practical scenario, highlighting the potential impact: “If, for example, 10 percent of the consumer collection stream consisted of ketchup bottles, their reliable identification would allow the material to be recycled back into new ketchup bottles.” The project studied how package design, colour, markings or other identifiers could enable this circular flow.
Regulatory considerations and food safety
Dialogue with the Finnish Food Authority (Ruokavirasto) played a central role, particularly regarding technological approval and compliance. Migration tests carried out in an accredited laboratory confirmed that the fractions sorted in the pilot experiment met requirements for food‑grade use. Unna Paavolainen notes that European Food Safety Authority (EFSA) has not yet issued any approvals for this kind of mechanical recycling systems so far, leaving the sector without external reference points.
Building shared understanding across the value chain
Regular meetings and shared site visits strengthened cooperation among participants. These activities helped the group build a mutual understanding of mechanical recycling processes, ecosystem dynamics and the steps required to reach industrial‑scale trials. The project’s insights have been communicated not only to the value-chain partners, but e.g. to Finland’s parliamentary stakeholders, contributing to wider awareness of regulatory needs.
Unna Paavolainen notes that the upcoming EU Packaging and Packaging Waste Regulation (PPWR) was not an initial driver but became increasingly relevant as the project advanced, showing the importance of future requirements and opportunities.
Implications for Orthex and the sector at large
Tom Ståhlberg sees that for Orthex and project partners, the project increased understanding of technical feasibility and the requirements. These learnings will encourage future equipment investments aimed at ensuring readiness for closed‑loop recycling of plastic food-packages. While re‑engaging packaging manufacturers will take time, the foundations for collaboration are already strong. The SULKI project also strengthened the case for domestic resilience and self‑sufficiency regarding raw materials for packaging production through recycling.
Participation in the SPIRIT programme has been highly important for Orthex as their strategy focuses on increasing use of recycled or bio‑based raw materials in products. In addition, SPIRIT projects such as Reusify studying re-use of plastics products supports their long‑term direction.
Next steps
Achieving true circularity requires packaging to be designed for recognition and sorting. Decisions in the design phase, such as colour selection and other identification features, must enable easy and reliable separation. The project emphasised the importance of harmonised approaches, consistent practices and close collaboration across the value chain from sorting and recycling operators to packaging manufacturers and consumers.
The SULKI project succeeded in pioneering new approaches, strengthening networks and building momentum for future co‑innovation. Ståhlberg and Paavolainen agree that motivation among participants remained high throughout and without the SPIRIT programme, such collaboration and progress may not have taken place.