Resource-efficient circular economy: thinking from the outset

The circular economy is considered as a key approach to conserving resources and achieving climate policy goals – particularly in the plastics sector. Around 535 million tonnes of plastic waste are produced worldwide every year, of which approximately 52 per cent is landfilled, 19 per cent incinerated and only 9 per cent recycled. The remainder is referred to as ‘mismanaged waste’ and largely ends up in the countryside or the oceans [1]. The team led by Steinbeis expert Markus Klätte has investigated the current state of plastic recycling and the reasons behind the current underutilisation of recycled materials, publishing the findings in the study “Rezyklateinsatz in Kunststoffverpackungen: Techniktrends und Entwicklungspotenziale” in the Steinbeis-Edition.

Plastic consumption in Germany amounted to 11.25 million tonnes in 2023, representing a 9.3 per cent decrease compared to 2021. Around 17 per cent was recycled: 1.64 million tonnes of recycled materials from post-consumer waste and 0.37 million tonnes from post-industrial waste. The remaining portion was primarily thermally recycled [2].

Material recycling can substitute fossil raw materials and reduce CO₂ emissions. Nevertheless, despite significant progress in sorting and recycling processes, this is not possible for a large proportion of plastic waste because the complexity of the waste and the resulting separation effort often make neither economic nor ecological recycling feasible. A key reason for this is the heterogeneous composition of plastics: polymers, additives, fillers and copolymers are combined to achieve specific properties and are further supplemented by contaminants from use and collection.

The heterogeneity of plastic waste is exacerbated by the following factors [3]:

• Contaminants: Introduced through use or incorrect disposal during collection (e.g. organic residues, dust), which migrate into the polymer matrix and cause odour problems.
• Accompanying materials: Functional elements such as labels or adhesives, which reduce the quality of the recycled material (e.g. transparency, strength) and generate residual fractions.
• Component mixtures: Base polymer supplemented by additives (stabilisers, pigments) and fillers; homo-, co- or blend polymers.
• Polymer types: Within a single type (e.g. PE), differences in structure (HD, LD, LLD) and chain lengths.
• Compound materials: Multilayer structures, barrier layers, metallisation or fibre reinforcement [3].

“600 chemicals in a yoghurt pot is insane” – this quote illustrates the challenges involved in separating materials [4].

It is not just technology that matters 

In addition to heterogeneity, usage-related ageing, changes caused by recycling technologies [5] and the associated mechanical and chemical properties of the waste must also be considered. Recyclates from the mechanical recycling of non-product-specific collections therefore always differ from virgin material [6]. This leads to downcycling, for example from food packaging to applications without food contact.

This results in legal liability risks for companies using recyclates, as product properties are difficult to guarantee. There are particularly high risks associated with durable goods containing legacy substances, which can cause financial losses and damage to reputation. In addition to efficient technology, risk management and quality assurance are therefore essential. Material recycling therefore focuses largely on homogeneous waste fractions, which enable targeted process optimisation, predictable risks and economic viability.

Three processes – one goal

From a technical perspective, mechanical, physical and chemical recycling processes can be utilised. Mechanical recycling is well established and offers the greatest environmental benefits. Single-material collections, such as those for PET bottles followed by repolymerisation, or the Rewindo programme for recycling PVC windows, enable largely closed-loop systems.

However, heterogeneous waste streams require extensive sorting, resulting in recyclates with mixed properties that are often unsuitable for high-quality original applications – for example, in food contact or technical applications. Solvent-based processes, as a form of physical recycling, expand the possibilities by purifying the base polymer. However, residual materials may also remain in the recycled material here.

Chemical recycling is being pursued as a further approach, as it allows even heterogeneous plastic mixtures to be broken down into low-molecular-weight substances, enabling better purification. Notable examples include solvolytic processes for polyamides (e.g. PA6), polyethylene terephthalate (PET) and polyurethanes, as well as thermal processes such as pyrolysis, oil production and gasification. The production of polymers in virgin-grade quality is thus fundamentally possible. Chemical recycling thus enables complete separation and conversion back to monomers – albeit with material losses and increased energy requirements [7].

Public perception prioritises mechanical recycling for good reason [8]. Nevertheless, the various approaches are complementary: mechanical for more homogeneous fractions, physical for intermediate ones, and chemical for more heterogeneous plastic waste. However, all processes benefit from collection that is as free of mixed materials as possible, as this allows processes to be operated in a more technically stable and economical manner [9]. Solvent-based processes are therefore preferred where the impurity content is below 10 per cent. Even for thermal processes, polyolefin contents of over 85 per cent are recommended.

Increasing the recycling rate – promoting sustainability

To improve the quality and quantity of recyclates, the following measures, among others, are conceivable [3]:

• Product design: Strengthening ‘design for recycling’ and selecting materials to facilitate disassembly and separation.
• Collection: Establishing collection channels that are as sort-specific as possible (drop-off systems, deposit-refund schemes, reusable options). Where this is not feasible, early separation of waste streams by type, grade, colour and origin should be ensured.
• Recycling technologies: Integration and expansion of physical and chemical recycling processes for suitable fractions, as well as the provision of pollutant sinks through downcycling or thermal recovery.
• Use of recycled materials: Gradual enhancement of the image of secondary raw materials, initiation of sector-specific solutions and use of legal incentives to reduce risks associated with the use of recycled materials.
• Research and development: Further development of efficient sorting and recycling methods, including AI-supported traceability, and promotion of corresponding research and development in recycling technologies.

These and other measures can significantly increase the recycling rate and thus contribute to a more sustainable plastics economy [3].

Outlook and need for action 

With a mechanical recycling rate of 37.9 per cent for 5.91 million tonnes of waste in 2023 [2], Germany is making progress. Nevertheless, a global circular economy requires close interdisciplinary cooperation between chemistry, materials science, engineering and politics. The integration of complementary recycling processes and appropriate regulatory frameworks are crucial to minimising resource loss and permanently reducing environmental impact.

[1] World Ressources Institute. “Insights: Ocean.” Zugriff am: 23. Februar 2026. [Online.] Verfügbar: www.wri.org/insights/plastic-pollution-global-plastics-treaty-explained
[2] C. Lindner, J. Schmitt, J. Hein und H. Fischer. „Stoffstrombild Kunststoffe in Deutschland 2023. Zahlen und Fakten zum Lebensweg von Kunststoffen.“ Zugriff am: 22. Februar 2026. [Online.] Verfügbar: www.bkv-gmbh.de/files/bkv/studien/Kurzfassung%20Stoffstrombild%202023.pdf
[3] M. Seitz, B. Langer, U. Sauermann und M. Klätte, „Rezyklateinsatz in Kunststoffverpackungen: Techniktrends und Entwicklungspotenziale“ (Schriftenreihe Ressourcen-Technologie und Management). Stuttgart: Steinbeis-Edition, 2026.
[4] Chemiker fordert Plastik Umdenken: „600 Chemikalien in einem Joghurtbecher sind irre.“ Der Spiegel, 2018. Zugriff am: 23. Februar 2026. [Online]. Verfügbar unter: youtu.be/9sSAVa0AP5U
[5] L. Starke und S. Fiedler. „Recyclingfähigkeit sortenreiner Verarbeitungsabfälle“ (Kunststoff-Recycling 3). Moers: Agst, 1993.
[6] D. Stapf, M. Wexler und H. Seifert. „Thermische Verfahren zur rohstofflichen Verwertung kunststoffhaltiger Abfälle“, 2019.
[7] P. Quicker und M. Seitz. „Abschätzung der Potenziale und Bewertung der Techniken des thermochemischen Kunststoffrecyclings.“ Zugriff am: 22. Februar 2026. [Online.] Verfügbar: www.umweltbundesamt.de/system/files/medien/11850/publikationen/154_2024_texte_thermochemisches_kunststoffrecycling.pdf
[8] GAIA. “Chemical Recycling: Distraction, Not Solution.” Zugriff am: 22. Februar 2026. [Online.] Verfügbar: www.no-burn.org/wp-content/uploads/2021/11/CR-Briefing_June-2020.pdf
[9] M. Seitz, V. Cepus, M. Klätte, D. Thamm und M. Pohl. „Evaluierung unter Realbedingungen von thermisch-chemischen Depolymerisationstechnologien (Zersetzungsverfahren) zur Verwertung von Kunststoffabfällen.“ Zugriff am: 22. Februar 2026. [Online.] Verfügbar: opac.dbu.de/ab/DBU-Abschlussbericht-AZ-34351_01-Hauptbericht.pdf