Systems Analysis Approach to Polyethylene Terephthalate and Olefin Plastics Supply Chains in the Circular Economy: A Review of Data Sets and Models

Abstract

The environmental and economic impacts of implementing a circular economy in plastic waste supply chains are not well understood. The proposed systems analysis framework assesses environmental, social, and economic impacts of plastic waste supply chains in a circular economy. The first objective of this article is to identify data sets, models, and knowledge gaps associated with waste plastic supply chain processes, mainly in the U.S. Our literature review indicated that the best data sets exist for virgin plastic resin production, mechanical recycling, landfilling, and incineration, with the materials recovery facility being intermediate, and with chemical recycling the lowest. The second objective of this perspective is to develop an illustrative application of the framework by conducting a preliminary systems analysis of PET bottles with closed-loop recycling. The preliminary systems analysis of polyethylene terephthalate (PET) bottles utilized a linear programming optimization method. Our optimization model indicated that both chemical and mechanical recycling processes are needed to achieve a true circular economy of PET bottles with the least greenhouse gas emissions, specifically reductions of 24% when compared with the linear economy. Good quality and standardized life cycle assessment and techno-economic analysis studies are needed to better understand the environmental, economic, and social impacts of advanced sorting and chemical recycling technologies.

Green Chemistry, Biocatalysis, and the Chemical Industry of the Future

“…75 million tonnes were landfilled, 50 million tonnes burned for energy recovery, 75 million tonnes were improperly disposed in the environment, and 50 million tonnes recycled (Figure 16). [160,161] Plastics for packaging applications consist primarily of polyolefins [polyethylene (PE), polypropylene (PP), and polystyrene (PS)] and polyethylene terephthalate (PET), and the required monomers account for around 4 % of the global production of petrochemicals. [162] Only 9 % of all the plastics ever produced have been recycled, and plastic detritus is ubiquitous in the environment, where it generally does not degrade as such but fragments slowly into microplastics and nanoplastics.…”

Roadmap to sustainable plastic waste management: a focused study on recycling PET for triboelectric nanogenerator production in Singapore and India

“…Treatment techniques such as bottle washing, grinding and flake washing could result in a material loss (8%); a further material loss could occur through the following processing stages: melt filtration (1%), air classifier (7%), material conveying (2%) (Sherwood 2020 ). Typically, the mechanical recycling processing temperature ranges from 280 to 320 °C (Chaudhari et al 2021 ). In India and Singapore, mechanically recycled PET materials were utilized to make polyester fibres.…”

Safety Evaluation of Polyethylene Terephthalate Chemical Recycling Processes

“…On the other hand, PET is the main packaging material for mechanical recycling, and several recycling processes have been established for several years [4]. However, mechanical recycling of PET beverage bottles requires a well-sorted and clean input fraction in order to prevent the recyclate containing bottles from hazardous contamination [5][6][7]. Such well-sorted input fractions are not available in every country.…”

“…Chemical recycling seems to be an alternative to mechanical recycling, which makes less pure or less controlled recollected packaging waste available for circular economy [7]. Chemical recycling of PET has evolved several chemical recycling methods, namely, hydrolysis, methanolysis, glycolysis, aminolysis, and ammonolysis.…”

“…In the end, both chemical and mechanical recycling processes are needed to achieve circular economy of PET bottles [7]. The circular economy might only work if chemical and mechanical recycling are used side by side.…”