CircuTray-UP: Circular economy for PET trays in food packaging

Circulation for post-consumer PET trays

PET trays are used in everyday life for packaging foodstuffs such as meat, fish, fruit and vegetables or takeaway products, but they are also widely used in the non-food sector. The trays are made from the same material as beverage bottles: polyethylene terephthalate (PET). There is a widespread, well-established, and successful recycling scheme for this plastic.

At present, PET trays are not recycled to a high standard using current technology. This applies to both mono material and multi-layer composites with PE or other polymers. They are sorted into PET fractions in lightweight packaging sorting plants (LVP). A considerable proportion of this material then ends up in energy recovery and is lost to the PET cycle.

The low level of processing of post-consumer PET trays is mainly due to the high proportion of foreign plastics (PE, EVOH, EVA, PUR) and tray-specific material properties. These have a detrimental effect on processing plants that are geared towards PET bottles. In addition, food and non-food trays are collected together via the dual systems. This calls into question the food compliance of reuse in the food sector.

Recycling through optimised separation technology

The "CircuTray-UP" researchers' approach: The implementation phase starts with currently available PET tray fractions, which are obtained in modern waste sorting plants. They contain far too much foreign material for direct reutilization. The three project partners - the Fraunhofer Institute for Process Engineering and Packaging IVV, SRH Kunststoffe and Unisensor - are working on the positive sorting of mono-PET trays and subsequent optimized mechanical processing. In the further course of the project, Fraunhofer IVV and LÖMI will produce PET recyclates from residue fractions with a high proportion of multi-layer PET sorting fractions and process residues - using physical solvent-based recycling. The Öko-Institut is analyzing the innovative products and processes and assessing their sustainability.

In a further step, the companies Reifenhäuser and silver plastics will process the PET recyclates into films, laminate them with a migration barrier made of virgin PET and thermoform trays. Fraunhofer IVV will test the function of the barrier, thus guaranteeing the safe use and recyclability of the trays at the end of their life.

The concept has great potential for the circular economy: around 430 kilotonnes of PET recyclates are currently produced each year, of which only 162 kilotonnes are reused in food packaging in the form of PET bottles. If the PET trays collected by the dual systems in Germany - around 120 kilotonnes - could be processed into high-quality PET and made food-safe, the yield could be almost doubled. In addition, the comprehensive recycling of PET trays is currently the only way to provide PET recyclates for the production of PET trays without disrupting the established PET bottle cycle.

The PET processor SRH and the PET tray manufacturer silver plastics are responsible for implementing the project results. The plant manufacturers Reifenhäuser and LÖMI will provide the necessary equipment for the closed-loop value chain. Accompanying communication of the results with other participants in the value chain is intended to support the rapid and comprehensive implementation of the technologies in the European economic area.

Advancements in PET Recycling and Flake Sorting Technologies (Status April 2025)

Recent results from the CircuTray-UP project include, among other things, the material analysis of various post-consumer PET wastes from waste fraction 328-5, divided into multi-PET and mono-PET fractions. These analyses revealed a mass-based polyolefin content of 5–10% in multi-PET, 0.2–5% in mono-PET, and a PVC content of up to 0.2% in both fractions. In particular, the polyolefin content of the mono-PET fractions highlights the need for improvements in flake-level sorting.

Unisensor has already demonstrated that sorting PET flakes using the PowerSort can significantly reduce the foreign material content, especially PVC. In one trial, a reduction of the PVC content in the flakes to below 30 ppm was achieved in two sorting steps. Additionally, only through flake-level sorting was it possible to reduce the multilayer content in a mono-PET fraction by 50%. The polyolefin content of the multi-PET flakes could be removed at laboratory scale through solvent-based recycling, enabling the processed flakes to be used in flat film extrusion. For scaling up the solvent-based recycling to demonstration scale—consisting of iterative removal of polyolefin components via selective extraction—a plant concept was developed. Preparations for the planned scaling to demonstration scale in the third quarter of 2025 are currently underway; a prior scaling to small technical scale took place in April 2025.

To apply a virgin PET layer as a functional barrier while maintaining thermoformability, various recycling-compatible adhesives as well as single- and double-sided extrusion lamination were tested. All tested application methods allowed processing via thermoforming processes, with adhesive-free extrusion lamination achieving the best optical results. Verification of the actual barrier performance on the thermoformed component will begin from June 2025. Results are expected at the earliest in September 2025.