Why Chemical Recycling Enables Circular Plastics Value Chains

A circular economy aims to keep materials in use for as long as possible, reduce waste and limit reliance on virgin fossil resources. For plastics in particular, this means increasing recycling rates, improving material recovery and ensuring that recycled materials can be used across a wide range of applications.

Achieving circular economy targets will require a combination of recycling routes. ISCC certifies those different recycling and chain-of-custody options and ensures transparency about the option applied, enabling credible, differentiated claims across circular value chains.

Mechanical Recycling: The Established Practice

Mechanical recycling is fundamental to the circular economy. It enables waste plastics to be collected, sorted, reprocessed, and reintroduced into supply chains with relatively low energy use and a well-developed infrastructure. For many uses, mechanical recycling will remain the preferred method. However, it has technical and material limitations. Some plastic waste streams, such as mixed, contaminated, multi-layered, or heavily degraded, cannot be mechanically recycled while maintaining quality. This makes mechanical recycling unsuitable for value chains that place high demands on product quality or safety, such as in the food or medical industries.

Chemical Recycling: The Developing Complement

During mechanical recycling, plastics keep their polymer structure and are mainly sorted and processed into recyclates. However, during chemical recycling – or advanced recycling, another term for the same concept – plastics undergo a fundamental transformation: they are broken down into basic chemical building blocks. These are then used as an additional alternative feedstock in industrial production and processed in existing infrastructure. The result is new products, partly linked to recycled content, with properties comparable to those of products made from virgin fossil feedstocks. Chemical recycling, therefore, expands the overall recycling potential of plastics. It is an advanced omplimentary recycling route in areas where mechanical recycling reaches its limits.

Mass Balance: The Practical Enabler

Circular solutions must be scalable. To achieve this, chemically recycled and conventional feedstocks are usually processed together in crackers, pipelines, and storage systems designed to handle large, mixed input streams. Physical segregation would entail duplicate facilities, which are neither practical nor economically feasible, and would significantly slow down the integration of recycled feedstocks into industrial value chains.

So if physical segregation is impractical, if not impossible, what mechanism ensures the characteristics and quantity of recycled content? The answer is certified mass balance.

Mass balance is a chain of custody option in which certified and non-certified materials can be physically mixed throughout the value chain but kept separate through verifiable bookkeeping. For many chemical recycling supply chains and companies seeking circular solutions, mass balance is currently the most practical way to integrate recycled feedstocks into existing processes, thus increasing the share of recycled content in products. Furthermore, it is already widely used, has proven effective across industries, and complies with international standards. It provides a practical foundation that now also enables the scaling of circular solutions, while systems and requirements can evolve over time.

Deep-Dive Into the Mass Balance Approach

Most products we hold in our hands, consume and dispose of are the result of complex chemical manufacturing processes that combine a variety of different materials. The input ranges from distinct fossil-based to emerging non-conventional feedstock that include bio-based, renewable and recycled materials and can substitute fossil-based resources.

Have a look at the ISCC article “Mass Balance Explained” » GO

ISCC: The Certification System Behind Credible Circularity

At the same time, chemical recycling and mass balance raise complex questions around traceability, attribution and claims. Addressing these questions requires clear definitions, robust rules and end-to-end verification across the entire value chain – from the point where waste is generated to the final product placed on the market. This is where credible certification becomes relevant.

This sets the scene for this article series on chemical recycling, mass balance and the role of ISCC as a standard-setting organisation. In the following articles, we will examine in greater detail how mass balance operates in practice, how different attribution approaches are applied under ISCC PLUS, and how integrity and transparency are ensured in complex chemical recycling value chains.

For more information about ISCC and ISCC+ certifications, please visit the ISCC System website » GO.

Learn More:

• Circular Economy Principles
• Plastic Recycling Projects
• Sustainable Recycling Technologies

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