What is Chemical Recycling and Why It Is not the Ultimate Solution to Plastic Pollution

Plastic pollution has reached alarming levels globally, with an estimated 300 million tonnes of plastic waste generated annually. Traditional recycling methods, while effective for certain plastics, fall short when it comes to the vast array of complex plastic waste.

Chemical recycling has emerged as a potential solution, offering a way to break down plastics into their molecular components for reuse. Let’s delve into the workings of chemical recycling, explore its potential benefits, and address the concerns and challenges that come with it.

What is Chemical Recycling?

Plastics, derived from oil or petroleum, consist of long chains of molecules forming polymers. Polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polypropylene (PP) are among the most common polymers.

Traditional recycling methods, primarily mechanical recycling, involve sorting, grinding, washing, and melting plastics to create recycled products. However, this method is limited to certain plastics, and contamination or mixed polymers are as not easily processed, meaning far more plastics are incinerated and sent to landfills than are actually recycled.

Chemical recycling, also called advanced recycling, or tertiary recycling, is presented as a solution as it can break down plastic waste into its molecular parts. This allows the reconstitution of polymers into their original raw materials, ready to be converted into new polymers or petrochemical feedstock.

How Does Chemical Recycling Work?

Chemical recycling can be done through various technological processes depending if plastic waste is broken down into its chemical components using heat, pressure, or other chemical reactions. Here a few of the main chemical recycling technologies:

Dissolution / Solvent-based Purification

• Dissolution is a process where plastic waste is immersed in solvents, removing additives and breaking down polymer chains. This molecular unravelling returns plastics to their fundamental polymer stage, enabling the creation of high-quality recycled materials. It is particularly effective for plastics with complex structures and those containing multiple polymer types. Some scientists argue that dissolution is not actually part of chemical recycling, but it should be under physical recycling because this technology is based on physical and not on chemical reactions or changes and only the physical state of the polymer changes from solid to liquid and then back to solid.

Depolymerisation

• Depolymerisation involves using chemical reactions, solvents, and heat to break down polymers into smaller molecules known as monomers. This sophisticated process allows plastics to be deconstructed into their basic building blocks, providing a pathway for recycling plastics with predetermined molecular structures. The resulting monomers can be reintroduced into the plastic production process as secondary raw materials.

Conversion / Feedstock Recycling

• Conversion represents processes using chemistry, heat, or catalytic reactions to break down plastic waste with processes named as gasification, pyrolisis, and hydrothermal treatment. Pyrolysis heats plastic waste to over 400°C under low-oxygen conditions, breaking down long polymer chains into basic hydrocarbon products. These outputs can be utilised as feedstock for petrochemical processes or as a direct fuel.

Diagram source: from Chemical Recycling 101

Related: 5 Ways to Reduce Your Manufacturing Business’ Plastic Footprint

What are the Benefits of Chemical Recycling?

Chemical recycling offers a promising solution to the challenges posed by mixed-polymer waste streams and complex plastic structures, contributing to a more sustainable approach to plastic waste management.

• Recycling Hard-to-Process Plastics

Chemical recycling addresses the challenges posed by contaminated and mixed-polymer waste streams, unsuitable for mechanical recycling, as well as residual waste that has exhausted its potential for further mechanical processing. One of the main benefits assigned to this type of recycling is its potential to contribute to a circular economy for plastic production, because it allows to recycle more easily hard-to-process plastics, reducing reliance on virgin plastics and the fossil fuels used to create them.

• High-Quality Recycled Plastics

Chemical recycling produces plastics of similar quality to virgin feedstock. This high-quality recycled material can be used in food packaging, and other industries where traditional plastic is in high demand, offering a more sustainable alternative.

• Reduced Fossil Resource Dependency

By enabling the reuse of chemically recycled plastics as feedstock, the demand for newly extracted fossil resources diminishes.

• CO2 Emission Reduction

Advocates of this process argue that chemical recycling eliminates emissions associated with incineration and energy recovery, reducing the waste management industry’s carbon footprint.

Related: How to Improve the Recyclability of Caps and Closures

What are the Drawbacks of Chemical Recycling?

While chemical recycling offers economic opportunities, concerns persist about its environmental impact. The energy-intensive processes and potential use of harmful chemicals raise questions about achieving a balance between economic gains and environmental sustainability.

• Investment Challenges

The transition to large-scale chemical recycling requires significant investments in infrastructure and technology, as it can be significantly more expensive than traditional mechanical recycling. Funding is essential for developing new technologies, building processing facilities, and obtaining high-quality plastic waste. The industry faces challenges related to unstable energy costs and the need for ongoing technological advancements. The cost of the polymer feedstock and the value of the products made from the resulting monomers can make it economically unviable.

• Environmental Health Risks 

Critics argue that certain chemical recycling processes, particularly those that heat plastics, release toxic substances, such as benzene, lead, particulate matter, volatile organic compunds VOCs etc. which are toxic to human health. All of those toxic substances are ultimally released into the air, the water, and the final products.

• Climate Risks due to a Larger Carbon Footprint

Some scientists argue that from an energy perspective, breaking down plastics into their components to make the same plastics is fundamentally unsound. Pyrolysis, the most commonly used chemical recycling technology, as an example, is supposed to produce more emissions than waste incineration. Furthermore, the greenhouse gas emissions of chemical recycling facilities are often understated due to lack of robust independent reporting, as highlighted in the next paragraph. Therefore, the entire process may result in a larger carbon footprint compared to traditional recycling methods, raising concerns about its environmental impact.

• It won’t Solve the Plastic Pollution Problem

The evolving technology of chemical recycling has faced scrutiny from environmental and scientific bodies. Reports by large reputable environmental organizations like Beyond Plastics and the Ellen MacArthur Foundation suggest potential hazards and a larger carbon footprint, prompting calls for attention to be directed toward reducing single-use plastics instead. In particular, a new report from Beyond Plastics and IPEN (International Pollutants Elimination Network) investigated 11 constructed chemical recycling facilities in the United States, their output, their financial backing, and their contribution to environmental pollution. The results of this research show that this technology hasn’t worked for decades, it’s still failing, and it threatens the environment, the climate, human health, and environmental justice.

Related: Why Big Companies Should Invest in Sustainable and Innovative Plastic Alternatives?

Conclusion

At first sight, this transformative approach holds the potential to alleviate the burden on landfills and oceans, offering one of the solutions to the escalating plastic waste crisis. However, as the industry continues to evolve, careful consideration of its environmental impact and proactive measures are essential to ensure chemical recycling fulfils its promise as a positive force for our planet’s future. At this point in time, the drawbacks seem to outweigh the benefits.

Just as homeowners weigh the benefits and potential drawbacks before investing in a new boiler, stakeholders in the recycling industry must scrutinise the full lifecycle of these processes.  Much like assessing the new boiler cost involves considering its efficiency and long-term impact on energy consumption, evaluating the environmental footprint and efficiency of chemical recycling is critical to ensure that these solutions do not inadvertently contribute to more damage than good.

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