Developing Strategies to Reduce Microplastic Pollution from Stormwater and Wastewater Systems in Freeport, Maine

Microplastic pollution poses a growing environmental threat, particularly in urban and suburban areas where stormwater runoff and wastewater effluent act as significant pathways for microplastics to enter aquatic ecosystems. This thesis investigates potential strategies for mitigating microplastic pollution through these pathways in the coastal town of Freeport, Maine. By observing Freeport’s stormwater management system in ArcGIS Pro, three sites were identified as potential contributors to microplastic pollution by urban stormwater runoff within Freeport, and recommendations for implementation of microplastic removal systems were made based on site characteristics including impervious surface area, flow direction, flow accumulation, and drainage basin location. Freeport’s wastewater treatment process was analyzed to determine the estimated removal microplastic efficiency of the plant to be approximately 75%, and suggestions were made to increase this removal efficiency with the implementation of a primary settling tank. Additionally, considerations were made on the current limitations of microplastic removal system implementation for municipalities, including the difficulty and inaccessibility of microplastic quantification techniques, and the limited knowledge of microplastic removal technique efficiency. Other ways to reduce microplastic pollution were discussed, including increasing public awareness and enacting policies to limit excessive plastic use. This thesis provides a framework for municipalities to take action against microplastic pollution, while also highlighting the complexities involved.