(566e) A Quantitative Circular Economy Assessment Framework for Plastic Waste Management Systems

Plastic production and use have increased nearly 200-fold since their first appearance due to their versatility and outstanding benefits.¹ However, plastic production leads to plastic waste generation that pollutes the environment and threatens the well-being of wildlife and humans. In 2018, nearly 13.6% of plastic containers and packaging generated were recycled, only 16.9% were combusted for energy, and over 69% ended up in landfills.² Plastic packaging remains as one of the most important challenges given its immediate disposal after first use. Circular Economy (CE), as an alternative system, promotes the transition towards sustainability by targeting actions to minimize environmental pollution and promote the closed-loop handling of resources, preserving the value of materials and products for an extended period. Therefore, identifying the optimal waste management technologies under the circularity concept will accelerate the transition to sustainability. Circular Economy assessment frameworks, propose a complete assessment of environmental impacts, expanding beyond greenhouse gas emissions and involving impacts like resource depletion and the reduction of waste simultaneously. To effectively evaluate and compare the circularity of different processes, a quantitative metric is necessary. Some studies suggest CE indicators, but they often concentrate only on a subset of the CE goals or present a narrow scope applicable just to specific products.³

This work aims to adapt a CE framework previously proposed to be applicable for assessing the circularity of different plastic waste management technologies. Our previous work considers the CE main goals and characteristics and proposes indicators to calculate circularity subindexes for specific categories and an overall circularity index.⁴ This work develops a new substitutability category that through the corresponding index will be able to represent the capacity of recycled plastics to replace virgin plastics.^5,6 Besides considering waste, emissions, water, procurement, and energy, the substitutability of plastics is crucial to demonstrate how effectively plastics recycling can reduce the production of plastics and their associated environmental implications. For this category, factors such as mechanical and processing properties, color, and smell define the corresponding indicators and metrics. The recycled plastic properties are compared to reference values of virgin plastic properties. By incorporating the substitutability criteria and applying the circularity metric to different waste management technologies, we expect to identify which technologies are more environmentally friendly and isolate possible improvement areas of the technology in different categories like waste, emissions, or substitutability. To demonstrate the applicability of the framework, the circularity of mechanical recycling, pyrolysis, solvent-targeted recovery, and precipitation (STRAP^TM),⁷ landfilling, and incineration is evaluated and presented.

References

1. Wang, C., Liu, Y., Chen, W. Q., Zhu, B., Qu, S., & Xu, M. (2021). Critical review of global plastics stock and flow data. Journal of Industrial Ecology, 25(5), 1300-1317.
2. EPA. (2023). Containers and Packaging: Product-Specific Data. https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycli…
3. Kristensen, H. S., & Mosgaard, M. A. (2020). A review of micro level indicators for a circular economy–moving away from the three dimensions of sustainability?. Journal of Cleaner Production, 243, 118531.
4. Baratsas, S. G., Pistikopoulos, E. N., & Avraamidou, S. (2022). A quantitative and holistic circular economy assessment framework at the micro level. Computers & Chemical Engineering, 160, 107697.
5. Chialdikas, E., Munguia-López, A. D. C., Aguirre-Villegas, H., & Avraamidou, S. (2023). A framework for the evaluation of the circularity of plastic waste management systems: a case study on mechanical recycling of HDPE. Foundations of computer aided process operations/chemical process control: In-Press.
6. Demets, R., Van Kets, K., Huysveld, S., Dewulf, J., De Meester, S., & Ragaert, K. (2021). Addressing the complex challenge of understanding and quantifying substitutability for recycled plastics. Resources, Conservation and Recycling, 174, 105826.
7. Walker, T.W., Frelka, N., Shen, Z., Chew, A.K., Banick, J., Grey, S., Kim, M.S., Dumesic, J.A., Van Lehn, R.C. and Huber, G.W. (2020). Recycling of multilayer plastic packaging materials by solvent-targeted recovery and precipitation. Science advances, 6(47)