Date of Award
Master of Science in Oceanography
Per- and polyfluoroalkyl substances, or PFAS, are a class of chemicals that have been widely used since the late 1940s for a variety of applications including industrial uses and consumer products. Some of these compounds are highly persistent in the environment, are distributed worldwide, and are known to cause adverse health effects, particularly when present in drinking water. The state of Massachusetts, which has a known problem of contaminated drinking water, mandated a Maximum Contaminant Level (MCL) in public water supplies for six PFAS. The Town of Barnstable, in Southeastern MA, implemented granular active carbon (GAC) filters, which are known to remove PFAS from drinking water, to keep the public drinking water below the legally binding MCL.
While it is known that GAC is able to remove PFAS, there is little literature on the efficiency, and therefore the cost, of this process on various PFAS of interest in the field. This research seeks to quantify the efficiency of using GAC to remove PFAS from drinking water, both in the field and in a laboratory setting. The Town of Barnstable has been sampling for the presence of PFAS in their public well water since 2013. Data from three public wells were analyzed to understand the performance of the filters used to remove PFAS. A laboratory experiment was conducted in which the GAC filtration system used in Barnstable was recreated to understand the efficiency of PFAS removal in a controlled setting.
Analysis of Barnstable’s field data showed that the total concentration of PFAS in the raw well water varied across the three wells, but the ratio of the different compounds was consistent throughout the dataset. The performance of the filters used within each well varied despite fairly steady levels of PFAS contamination over time. This variation in performance could be due to the presence of other compounds and organic matter competing with PFAS for the sorption sites on the GAC, or on the properties of the GAC itself. PFAS sulfonic acids were removed more efficiently than carboxylic acids and within each group, the removal efficiency increased with increasing carbon chain length. The well that was the most efficient at removing PFAS had the highest concentrations and the greatest cumulative mass of PFAS in the raw well water as well as the greatest volume of water pumped through the filters. This suggests that GAC is more efficient when treating higher PFAS loads.
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Yanishevsky, Tatyana, "CARBON FILTER EFFICIENCY IN REMOVING PFAS FROM DRINKING WATER IN BARNSTABLE, MA" (2023). Open Access Master's Theses. Paper 2437.