Illustration of scientist with beakers, test tubes and a recycling container

Advancing Recycling

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Plastics are incredibly convenient materials. Glass is transparent and aesthetically pleasing, metals are sturdy and easily shaped, paper is lightweight and cheaply produced. But plastic can be any or all of these at once. Plastics are extremely versatile and can be tailored to nearly any need, which has led to the rapid rise of plastic use, particularly in packaging applications. However, of the nearly 36 million tons of plastic produced in the United States in 2018, less than 9 percent was recycled with the majority ending up in a landfill. This leads to a question, or perhaps a crisis: if we want to continue using this incredibly convenient material, how can we reduce the massive amounts of waste that we generate today?

Limited Recycling

When people talk about recycling, they are generally referring to mechanical recycling. During this process, plastics are cleaned, sorted, shredded, and melted or compressed back into a usable form. This is how most recycling is done today, and it is an effective way to reduce the amount of waste. However, there are many shortcomings to this process as well. First, not all plastics can be recovered using this method and only certain types of plastics can be recycled effectively. Some plastics are difficult to sort, others become too damaged to be reused, and some materials are simply not cost effective for recycling facilities to process. Additionally, mechanical recycling results in a product that is lower quality than virgin material, a process usually referred to as downcycling. Recycled plastic has lower purity, and the polymer chains are damaged during the recovery process. Unlike glass or metal that can be recycled any number of times without seeing a drop in performance, plastics perform worse every time they are recycled. Because of these limitations, some have turned to other methods, attempting to address the problem of plastic waste.

Chemical Recycling

Advanced recycling, also known as chemical recycling, does not refer to one specific process but rather a type of approach when it comes to recycling plastic. Chemical recycling aims to break down polymers chemically in order to return them to the supply chain in a purified form. One method is pyrolysis, which uses heat to break apart the chemical structure of plastics and return them to simplified chemicals or oils. The products of pyrolysis would either be used as feedstock to make new plastic, or else burned as fuel oil. A different approach is solvolysis, which uses specialized solvents and enzymes to either depolymerize plastic or reduce it to resin. Resins can simply be recast into new products, and depolymerized chemicals are used to create new plastic. The advantage of pyrolysis is that it can accept a wide variety of plastic waste without needing to separate into specific types of plastic, however the downside is that the outputs need more processing before they can be reused. Solvolysis can potentially produce a high quality output, but the process is specific to each type of plastic, meaning that the recycle stream needs to be carefully sorted before processing and that unique technology needs to be used for each type of polymer. 

Recycling Concerns

Despite the idealistic claims of chemical recycling, many critics worry that the technology is still in its infancy and that it will not be ready fast enough to tackle the problem of plastic waste. There are concerns that pyrolysis is inefficient and dangerous; that the chemicals it produces are of lower value than that of the energy used to break down the recycled plastic in the first place, or that the process produces harmful emissions and dangerous byproducts. Solvolysis, on the other hand, is criticized for being an untested technology in large industrial settings. There is concern that the solvents used can become dangerous when scaled up from laboratory testing to industrial application, and because of the highly selective nature of the technology there are concerns about the economic potential. 

Practical Recycling

Regardless of these concerns, however, there remains a tremendous amount of plastic waste that simply cannot be handled by our current infrastructure. Pushed by need and opportunity, tremendous work has been done to advance the technology of chemical recycling, and perhaps some have seen success. Polystyrene in particular has gained much attention for its potential with advanced recycling; it is considered to be one of the easiest plastics to sort in recycling centers, which could allow for a relatively pure feedstock for recycling processes. In addition, there are companies that claim to have an effective process for recycling styrene, both through pyrolysis and solvolysis. Agilyx is a company that has an open and running pyrolysis center that is able to recycle styrene without a reduction in quality. Another approach is taken by Polystyvert, a technology company that has developed a solvolysis process to recycle polystyrene. Additionally, both of these companies have utilized Life Cycle Assessment (LCA) to prove the environmental benefits of their process. In an LCA conducted by Neue Materialien Bayreuth GmbH, these processes were analyzed alongside incineration as potential end-of-life scenarios for polystyrene waste. Both recycling processes were determined to release fewer GHG emissions than producing virgin material which, when considered on top of the emissions avoided from waste incineration, resulted in a 75 percent reduction of carbon emissions. This study was conducted according to ISO 14040/44 guidelines and is being subject to independent review.

Future Recycling

So what does this mean for plastic waste? At the moment, both critics and proponents of chemical recycling agree that it isn’t a replacement for mechanical recycling. Despite the drawbacks of quality reduction and limited availability, mechanical recycling repurposes a crucial amount of plastic that no other method can currently substitute. Indeed, the criticisms of chemical recycling are valid concerns, and it is important for these new technologies to be transparent and comprehensive when considering the environmental impact of their methods; not just seeking to eliminate plastic waste, but seeking to reduce the impact of plastics from cradle to grave and back again. Still, chemical recycling has the potential to complement mechanical recycling in an important way. The technology certainly has room to develop, but the success stories are exciting and may light the way to a future where a circular economy for plastics is not only possible but commonplace.  Trayak has been helping leading brands of all sizes make data-driven sustainability decisions for over 10 years. If you would like to learn more about our tools and services please contact us.

Sources

Bosmans, W., Brouard Gaillot, S., Faulkner, C., Kathmann, J., Neumeyer, T., & Niessner, N. et al. (2021). Implications of rPS’ favourable LCA results for the value chain. Presentation, https://styrenics-circular-solutions.com/. INEOS Styrolution. (2020). INEOS Styrolution reports final results of research project: post consumer polystyrene waste becomes valuable feedstock. Retrieved from https://www.ineos-styrolution.com/news/ineos-styrolution-reports-final-results-of-research-project-post-consumer-polystyrene-waste-becomes-valuable-feedstock#_ftn3 Plastics: Material-Specific Data | US EPA. US EPA. (2021). Retrieved from https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/plastics-material-specific-data. Rollinson, A., Oladejo, J. (2020). Chemical Recycling: Status, Sustainability, and Environmental Impacts. Global Alliance for Incinerator Alternatives.. Retrieved from https://www.no-burn.org/cr-technical-assessment Tullo, A. (2019). Plastic has a problem; is chemical recycling the solution?. Cen.acs.org. Retrieved from https://cen.acs.org/environment/recycling/Plastic-problem-chemical-recycling-solution/97/i39.

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