October 10, 2024
Article by Kelly Walker I Photo: Shutterstock
UD Researchers Uncover Key Challenges and Opportunities in Plastics Recycling
As scientists across the globe race to find solutions to the ever-growing plastics waste crisis, one team of researchers from the Center for Plastics Innovation at the University of Delaware is exploring methods to increase the likelihood that promising processes and technologies can translate to real-world viability.
In a new article, published today in Nature Chemical Engineering, the research team—including Kevin Nixon, Zoé Schyns, Yuqing Luo, and professors Marianthi Ierapetritou, Dion Vlachos, LaShanda Korley, and Thomas Epps, III—makes a compelling argument for the critical need for more holistic and transparent approaches to assessing advanced plastics waste recycling technologies. While many innovative processes developed in research labs hold potential for advancing a circular plastics economy, the review reveals that existing studies often lack rigorous, universal, and comprehensive assessments of the processes’ economic and environmental implications.
Plastics waste recycling can significantly reduce landfill volumes, greenhouse gas emissions, and reliance on petroleum resources; however, the review cautions that numerous studies report benefits without conducting thorough lifecycle assessments (LCAs) and techno-economic analyses (TEAs). Or, more often, they rely upon calculations that are late-stage, regionally limited, or based upon undisclosed assumptions. When assessing a recycling process or technology, LCA is used to determine the overall environmental impacts—such as carbon dioxide production, water use, global warming potential, ozone depletion, and human health implications, among others. TEA evaluates commercial viability of the process from an economic standpoint.
The authors argue that a “cradle to grave” analysis framework is essential to accurately evaluate the full lifecycle of plastic products, from raw material extraction to disposal. Neglecting crucial factors like waste transportation, sorting, and pretreatment, for example, in economic evaluations can result in misleading predictions and pose obstacles to the commercialization of advanced recycling methods. They caution that without comprehensive assessments, researchers and industry stakeholders may miss critical economic and environmental trade-offs, ultimately jeopardizing the success of new technologies.
The review illustrates their arguments through real-world case studies where underestimating the complexity of consumer plastics waste has led to operational failures. One example discusses a technology aimed at recycling multi-layer sachets, such as single-use condiment packets, that failed to hit its projected outputs. The shortfall is attributed to overlooked steps such as waste preparation, shredding, and decontamination.
“Think of a ketchup packet after you have finished using it,” explains co-author and post-doctoral researcher in UD’s Department of Chemical and Biomolecular Engineering, Kevin Nixon. “There is still ketchup inside. There are all types of components in ketchup that could have adverse effects in the actual recycling chemical reaction, for example lower catalyst efficiency. For successful recycling of real-life consumer plastics waste, practitioners would need to consider washing and/or possibly shredding the waste material, or in the case of multi-layer packaging, layers may need to be either chemically or mechanically separated first. All of those things can be costly if they’re not considered early and systematically.”
To prevent such pitfalls in future innovations, the authors encourage researchers to embrace comprehensive, systems-wide interdisciplinary approaches that consider scale-up capabilities from the beginning stages of process development. By adopting a perspective that considers the entire recycling system, from waste collection to processing and end-of-life solutions, researchers can better forecast scale-up opportunities, sustainability, and commercial viability for emerging recycling processes.
Additionally, they recommend standardized methodologies and reporting practices, calling for more transparency in assessments. LCA and TEA evaluations are crucial for making comparisons between different recycling technologies, but reliable conclusions can only be drawn if underlying assumptions are clearly stated and part of a standardized framework. Such a step would move beyond celebrating new technologies simply for innovation, and instead would guide decision-making through easy to compare assessments of economically and environmentally practical scale-up.
Another critical point raised in the review is the tendency to idealize feedstocks in recycling research, an additional issue that can negatively impact progress toward technology scale-up and optimization. Many studies focus on perfect or idealized materials, which can lead to overly optimistic assessments of recycling processes. In real life, however, plastics waste is messy. Whether the plastics are composed of multiple layers of different types of materials or contain dyes, product residuals, or other containments from proximal waste, these and other complexities can inhibit success of commercial recyclability. Industrial examples highlighted in the review underscore the perils of decision-making based on laboratory results from pristine feedstock. “By considering the true nature of plastics waste, researchers can better understand the challenges involved in scaling up their processes and developing viable solutions,” Zoé Schyns, co-author and post-doctoral researcher in UD’s Center for Plastics Innovation and Department of Chemical and Biomolecular Engineering, summarizes.
As the global community continues to grapple with the escalating plastics waste crisis, this review serves as a clarion call for researchers, policymakers, and industry leaders to adopt a more integrated and realistic perspective in evaluating recycling processes. The authors aim to guide researchers, encouraging consideration of scale-up viability from the early stages of process development, stressing the significance of interdisciplinary collaboration, and highlighting the necessity for thorough evaluations to confront the multifaceted challenges posed by plastics waste. If adopted, such a paradigm shift would be highly impactful, helping pave a path forward for the development of effective, economical, and sustainable solutions to mitigate the growing problem of plastics pollution.
About the Center for Plastics Innovation
The Center for Plastics Innovation (CPI) is an Energy Frontier Research Center (EFRC) funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. The center brings together researchers from the University of Delaware, the University of Chicago, University of Massachusetts Amherst, University of Pennsylvania, and Oak Ridge National Laboratory to focus on finding solutions to balance meeting the global demand for lightweight and resilient materials while thwarting the environmental threats of plastics waste and pollution. It is one of 40 EFRCs established across the U.S. to accelerate scientific breakthroughs in critical areas.