(306d) Optimal Waste Management Infrastructure Design for Post-Industrial Plastic Waste - A Case Study on Multilayer Plastic Films

The increasing accumulation of plastic waste poses a threat to the environment and human welfare. Plastic post-industrial waste (PIW) makes up a significant - though poorly documented – share of total plastic waste and offers a valuable recycling opportunity due to its relatively low contamination levels and well-defined composition¹. Recycling plastic PIW can significantly reduce resource consumption, mitigate environmental impacts, and reduce costs. However, current plastic PIW management strategies mostly involve landfilling and incineration, placing stress on the environment and wasting valuable resources that could be reintroduced into plastic manufacturing. In particular, multilayer film (ML) production generates substantial amounts of waste due to inherent process inefficiencies, with estimates indicating that up to 20% of the total production is discarded as PIW.² Despite their recyclability potential, the complex structure of multilayer films prevents recycling through conventional technologies such as mechanical recycling, resulting in their continued disposal via landfilling or incineration.^3,4 To advance a circular economy, it is essential to develop optimized waste management strategies that lead toward the minimization of environmental impacts and economic costs.⁵

Effective waste management of ML or mixed plastic film streams requires evaluating a diverse range of technologies, including innovative processes like pyrolysis,⁶ gasification,⁷ and solvent-based recycling processes such as the solvent targeted recovery and precipitation (STRAP^TM) process,² as well as conventional methods like incineration, and landfilling. Each technology presents trade-offs between economic viability and environmental performance. Therefore, considering combinations of these technologies is often required to achieve both objectives. Understanding the trade-offs between these conflicting objectives is crucial for selecting the most effective infrastructure configuration. This results in a complex decision-making problem that requires a process systems engineering framework capable of comprehensively navigating the combinatorial nature of the technology decisions while simultaneously considering economic and environmental aspects to find optimal strategies.

This study aims to identify the optimal waste management infrastructure for plastic PIW films by evaluating both their economic and environmental performance. The proposed approach integrates optimization techniques with techno-economic analysis (TEA), life cycle assessment (LCA), and a green solvent screening framework for selective dissolution in solvent-based recycling technologies.⁸ A multi-objective mixed-integer linear programming (MILP) model is developed to determine the optimal infrastructure configuration that minimizes both economic costs and environmental impacts. The technologies considered include innovative technologies like STRAP, pyrolysis, and gasification, and traditional technologies like incineration and landfilling. The optimization model selects the most suitable recycling technologies and, for solvent-based processes, determines the optimal polymer removal sequence along with the corresponding solvents to use. Additionally, it identifies the optimal facility location and processing capacities for the selected recycling facilities. The environmental assessment considers multiple impact categories, including global warming potential, human toxicity, and freshwater ecotoxicity. Additionally, a circularity assessment based on the MIcro CirculaR ecOnomy iNdex (MICRON) framework that considers the Circular Economy (CE) goals is conducted.⁹ The study examines a case study involving a mixed plastic feedstock of polyethylene (PE), polyethylene terephthalate (PET), nylon (N6), and ethylene-vinyl alcohol (EVOH). This integrated approach provides insights into the most effective waste management strategies, balancing sustainability and economic feasibility while supporting the transition to a circular economy.

References

(1) Munguía-López, A. del C.; Göreke, D.; Sánchez-Rivera, K. L.; Aguirre-Villegas, H. A.; Avraamidou, S.; Huber, G. W.; Zavala, V. M. Quantifying the Environmental Benefits of a Solvent-Based Separation Process for Multilayer Plastic Films. Green Chemistry 2023, 25 (4), 1611–1625. https://doi.org/10.1039/D2GC04262B.

(2) Walker, T. W.; Frelka, N.; Shen, Z.; Chew, A. K.; Banick, J.; Grey, S.; Kim, M. S.; Dumesic, J. A.; Van Lehn, R. C.; Huber, G. W. Recycling of Multilayer Plastic Packaging Materials by Solvent-Targeted Recovery and Precipitation; 2020; Vol. 6. https://www.science.org.

(3) Schmidt, J.; Grau, L.; Auer, M.; Maletz, R.; Woidasky, J. Multilayer Packaging in a Circular Economy. Polymers (Basel) 2022, 14 (9), 1825. https://doi.org/10.3390/polym14091825.

(4) Millican, J. M.; Agarwal, S. Plastic Pollution: A Material Problem? Macromolecules 2021, 54 (10), 4455–4469. https://doi.org/10.1021/ACS.MACROMOL.0C02814/ASSET/IMAGES/MEDIUM/MA0C02….

(5) Munoz-Briones, P. A.; Munguia-Lopez, A. del C.; Sanchez-Rivera, K. L.; Zavala, V. M.; Huber, G. W.; Avraamidou, S. Optimal Design of Food Packaging Considering Waste Management Technologies to Achieve Circular Economy. In Foundations of Computer Aided Process Design (FOCAPD 2024); PSE PRESS, 2024; pp 820–828. https://doi.org/10.69997/sct.154335.

(6) Anuar Sharuddin, S. D.; Abnisa, F.; Wan Daud, W. M. A.; Aroua, M. K. A Review on Pyrolysis of Plastic Wastes. Energy Convers Manag 2016, 115, 308–326. https://doi.org/10.1016/j.enconman.2016.02.037.

(7) Saebea, D.; Ruengrit, P.; Arpornwichanop, A.; Patcharavorachot, Y. Gasification of Plastic Waste for Synthesis Gas Production. Energy Reports 2020, 6, 202–207. https://doi.org/10.1016/j.egyr.2019.08.043.

(8) Ikegwu, U.; del Carmen Munguía-López, A.; Van Lehn, R. C.; Zavala, V. M. Screening Green Solvents for Multilayer Plastic Film Recycling Processes. January 16, 2025. https://doi.org/10.26434/chemrxiv-2025-zrmnp.

(9) Baratsas, S. G.; Pistikopoulos, E. N.; Avraamidou, S. A Quantitative and Holistic Circular Economy Assessment Framework at the Micro Level. Comput Chem Eng 2022, 160. https://doi.org/10.1016/j.compchemeng.2022.107697.