February 24, 2020

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John Merrill Coauthored a Paper on Water Filters for PFASs in Environmental Science & Technology Letters

John Merrill (California) coauthored a paper entitled "Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFASs)" that was published in the Environmental Science & Technology Letters on February 5, 2020.

John's coauthors were Nicholas J. Herkert, Cara Peters, David Bollinger, Sharon Zhang, Kate Hoffman, P. Lee Ferguson, Detlef R. U. Knappe, Heather M. Stapleton.     

John is a Staff Engineer based in California focused on environmental site assessment and remediation, litigation support, and applied research projects in collaboration with university partners. He also has experience related to emerging contaminants, including PFAS, 1,4-dioxane, and 1,2,3-tricholorpropane (TCP).

Published by ACS Publications, Environmental Science & Technology Letters is an international forum for brief communications on experimental or theoretical results of exceptional timeliness in all aspects of environmental science (pure and applied), and short reviews on emerging environmental science & technology topics. Manuscripts describing cross-disciplinary research or addressing emerging issues are of particular interest.

Founded in 1876 and chartered by the U.S. Congress, American Chemical Society (ACS) is the world's largest scientific society. Their mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and its people. Their vision is to improve people's lives through the transforming power of chemistry.


Per- and polyfluoroalkyl substances (PFASs) have come under increased scrutiny due to concerns about their potential toxicity and prevalence in the environment, particularly drinking water. PFASs are difficult to remove in full-scale water treatment systems because of their physicochemical properties. Here we evaluated the effectiveness of point-of-use (POU) and point-of-entry (POE) residential drinking water filters in removing a suite of three perfluoroalkyl sulfonic acids, seven perfluoroalkyl carboxylic acids, and six per- and polyfluoroalkyl ether acids in homes in central (n = 61) and southeastern (n = 12) North Carolina. POU systems included countertop and pitcher filters, faucet-mounted filters, activated carbon block refrigerator filters, activated carbon block under-sink filters, under-sink dual-stage filters, and under-sink reverse osmosis filters. All under-sink dual-stage and reverse osmosis filters tested showed near complete removal for all PFASs evaluated. In contrast, all other filters containing activated carbon exhibited variable PFAS removal. In these filters, PFAS removal efficiency was dependent on chain length, with long-chain PFASs (∼60–70% removal) being more efficiently removed than short-chain PFASs (∼40% removal). A few whole-house activated carbon POE systems (n = 8) were also evaluated; however, results were variable, and in some cases (four of eight systems), increased PFAS levels were observed in the filtered water.

More Information

Learn more about the article: https://pubs.acs.org/doi/10.1021/acs.estlett.0c00004
Learn more about the: https://www.acs.org/content/acs/en/about.html?sc=180808_GlobalFooter_od
For consultation regarding Per- and Polyfluoroalkyl Substances (PFAS), contact John Merrill at This email address is being protected from spambots. You need JavaScript enabled to view it..
Learn more about John: https://www.linkedin.com/in/jpmerrill/