Date of Award

2022

Degree Type

Thesis

Degree Name

Master of Science in Systems Engineering

Department

Systems Engineering

First Advisor

Manbir Sodhi

Abstract

Microplastic pollution is now everywhere, from the highest elevation of Mount Everest to the deepest dives of the Mariana Trench. The use of synthetic polymers has contributed to the transformation of our modern world. Nonetheless, the growing presence of plastics in the natural environment constitutes a sense of urgency to develop sustainable solutions to address the global plastic pollution crisis. Approximately 80 percent of all the plastics ever produced have been discarded. Our relationship with plastic needs rethinking.

Achieving a circular economy requires a holistic approach to redesign the systems that make, use and reuse plastics. Evaluating the life cycle of plastic products is key to effective advancements in the collection, separation and sorting systems of mixed plastic waste streams. This thesis critically reviews bulk recycling methods used in industry. Recycling provides significant opportunities for recovering material resources through mechanical and/or chemical processes, which in return reduces petrochemical usage, greenhouse gas emissions, and the quantity of waste requiring disposal. Yet, recovering the resource value of mixed plastic waste streams presents critical challenges in materials identification and recycling process design.

Bulk recycling models consider the selection of the best sequence for isolating target materials from a mixed material stream. This thesis models the separation of single and multiple target materials using density separation techniques to minimize the total processing volume and cost. Furthermore, a selection algorithm is implemented to calculate the processing costs of each pass, determine the minimum cost of separation, and present the optimal separation sequence.

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