The vision of tray-to-tray recycling

13/12/2023 | 8 min read
Sebastian Diensthuber

How new plastic waste streams will mark the end of the exclusive use of PET bottles as recycled plastic

According to the EU and the Packaging and Packaging Waste Regulation currently in planning, food packaging and disposable beverage bottles should contain at least 30% recyclate starting in 2030. From 2040 onwards, these mandatory quotas are set to rise to 50% and 65%, respectively.1 The quotas are even higher for other plastic packaging, such as crates and pallets. Moreover, more and more consumers are calling for sustainable packaging. But where are we supposed to procure these recycled plastics? The following article explores the challenges of plastic recycling and seeks to highlight the important role rPET can play for future packaging and how the future vision of tray-to-tray recycling can succeed despite the challenges we face. 

Bottle-to-bottle: Plastic recycling the way it should be

The recycling cycle for plastic bottles is easy to explain: Used PET bottles are collected and pre-sorted either via separate collection in household waste, recycling centers or reverse vending machines in supermarkets. The sorted PET bottles are then shredded in order to produce PET flakes. These flakes are thoroughly cleaned to remove impurities such as food residues, labels, and adhesives. After cleaning, the flakes are often sorted by color and quality. This is important because the color and purity of the flakes affect the quality of the final product. After cleaning, the PET flakes are ready for additional processing. This includes heating and degassing to remove any remaining impurities and odors. This decontaminates the PET in accordance with food contact requirements. Following these steps, the flakes can be further processed into recyclate. This may take the form of granulate for use as a raw material for new PET products, or the flakes can be used directly as input material in production processes. At the end of the cycle, new products are manufactured from the PET recyclate. These include not only new PET bottles, but also fibers for textiles, packaging materials, and other plastic products. The new products made from recyclate are returned to the consumption cycle, where they can be reused and ultimately re-collected.


The Recyclingprocess

Theory vs. practice: Recycled plastic yes, but…

What sounds good in theory has just one catch: Due to the current complexity of the collection infrastructure, rPET flakes that have been removed from the bottle stream – for use in other food packaging, for example – are now no longer fed back into it. At present, however, only rPET from PET bottles meets all the necessary requirements for use in food packaging. The reason for this is that, in order to be food-compliant, 95% of the input material – i.e. the plastic flakes – must originate from food packaging. While this is easy to guarantee for PET bottles, it is not for many other types of plastic packaging from household waste. Even if packaging is collected separately – in the “yellow bag” or the “yellow bin” provided for packaging in Germany, for example – the waste is still composed of packaging in a wide variety of materials and shapes. Although there are various sorting processes employed in recycling plants that enable a certain degree of separation (e.g. by material), the variety of packaging currently renders sorting processes difficult, time-consuming, and – in small quantities – uneconomical. Unlike other plastic packaging, PET bottles are easy to sort and recycle. However, the industry looks to the future with optimism: Technological developments can also expand the possibilities of waste separation and sorting to a certain extent, and artificial intelligence may play an important role here in the future. 

The hope of rPET

When it comes to sustainable packaging solutions, therefore, considerable hope is being placed on rPET – which is mainly recycled from bottle streams. As virtually the only mechanically recycled material presently considered to be food-compliant, rPET can be used for food packaging. rPET is readily available on the market and, thanks to its high quality, is a popular material for packaging requiring high transparency or – thanks to its good barrier properties – for products that need a high level of protection against external influences.

The bottle stream determines the high quality of rPET

The recycled PET currently used for packaging is primarily procured from the “bottle streams” mentioned above. As plastic waste streams for PET beverage bottles work well in many countries around the world, PET bottles are available in large quantities for recycling. In addition to the high collection rate, the bottles offer another decisive advantage: They are usually transparent (or bluish) and undecorated, at most merely bearing an easily removable label or sleeve. This increases the quality of the recycled material, with mainly transparent, unprinted material yielding equally pure material in the process of recycling. This transparency in particular makes rPET a popular material for packaging requiring both sustainability and visual appeal.

The challenges of establishing alternative plastic waste streams

Even given the relative availability of rPET, the increased demand for the material means an increased demand for sources. The major goal for the future, therefore, is to be able to recycle rPET from cups and blister packs in a “tray-to-tray recycling stream.” This refers to a waste stream in which cups, tubs, trays, and other packaging made from PET can be recycled and processed into new packaging. However, there are two specific challenges that need to be met in order to achieve this goal:

  • Sorting and separation technologies: A key challenge is the effective sorting and separation of different materials. Many packages consist of a combination of materials (such as plastic, paper, and metal) that are difficult to separate. This makes it crucially important to develop and implement advanced sorting technologies.


  • Profitability: The cost of collecting, sorting, and recycling materials can be high, especially when compared to using new raw materials. This poses an economic challenge, especially in markets where the cost of new materials is relatively low.

In addition, legal and regulatory requirements must be taken into account, as well as possible deteriorations in quality during recycling. The motivation and commitment of consumers also plays a decisive role: The sooner materials can be reassigned to the right streams, the better the yields and quality at the end of the cycle.

Challenges such as these require constant research and development, an improved regulatory framework, and a greater awareness and active involvement on the part of both consumers and industry to make tray-to-tray recycling more efficient and sustainable. As this process will become much more important in the future, the packaging industry is already working diligently to reach the goal of functional tray-to-tray recycling. Many companies have already brought initial projects to completion and even to the market. It is pioneers like these who will continue to drive the industry forward in the future.



Related articles