AWWA Water Science Author Spotlight: Conner C. Murray

Having recently published an article in AWWA Water Science, Conner Murray answered questions from the publication's editor-in-chief, Kenneth L. Mercer, about the research.

Characterizing PFAS Concentrations in Drinking Water Treatment Residuals

Conner C. Murray, Alexander S. Gorzalski, Erik J. Rosenfeldt, Christine Owen, and Chris Moody

Conner Murray conducts ion exchange pilot testing at a Colorado utility.

I completed my undergraduate work in environmental engineering at North Carolina State University (Raleigh), where I was able to dip my toes into PFAS research as an undergraduate research assistant. After participating in a summer program at Colorado School of Mines called Research Experiences for Undergraduates, I knew that I was moving West after graduation from North Carolina State.

In the summer of 2017, I moved to Colorado to attend Colorado School of Mines in Golden to work with Dr. Chris Bellona. My PhD research at the School of Mines focused heavily on PFAS adsorption from a variety of PFAS-impacted matrices. Upon finishing my PhD in 2021, I started working at Hazen and Sawyer, where I have continued my interest in working on PFAS-related challenges.

“Characterizing PFAS Concentrations in Drinking Water Treatment Residuals” was really about understanding the unintended consequences of potential PFAS disposal regulations moving forward. While mitigating the reintroduction of PFAS into the environment by regulating the disposal of PFAS-laden waste is undoubtedly a step in the right direction, there may also be unintended side effects for drinking water utilities that are merely “pass-through” (and increasingly treatment) facilities for PFAS. These disposal regulations may put utilities in a bind as they face heightened disposal costs for large residual quantities that they may not have anticipated would contain PFAS.

Our research was primarily motivated by recent regulatory developments associated with perfluorooctanesulfonic acid and perfluorooctanoic acid (commonly known as PFOS and PFOA, respectively) being designated as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act and a proposed listing of additional PFAS species as hazardous constituents under the Resource Conservation and Recovery Act. Our team was really interested in understanding the implications of these regulatory developments for “pass-through” water treatment facilities, where PFAS are not necessarily removed but may still accumulate in various residual streams, impacting their ultimate disposal.

Conner works on a PFAS destruction pilot test in New Mexico.

In the absence of experimental/analytical characterizations of PFAS-impacted residuals, our team didn’t necessarily employ any new experimental techniques to quantify PFAS partitioning in drinking water residuals. However, our team, specifically Dr. Alex Gorzalski, adapted a concentration-factor approach for estimating the relative PFAS partitioning into residual streams as a function of PFAS removal and the fraction of influent flow that results in waste generation. This concentration-factor concept was central to our research to understand the approximate range of PFAS concentrations that can be expected in various residual streams.

I think perhaps the most surprising element of this particular research project was the lack of information specifically related to the quantity and quality of conventional drinking water residuals generated nationally. In an attempt to research the full breadth of PFAS impacts in drinking water residuals, our research team was able to piece together generated residuals quantities from a number of existing data sets from the US Environmental Protection Agency to quantify these residuals generation rates on a national scale. Using this information, we were able to get a sense of the potentially huge regulatory implications of regulating PFAS concentrations in drinking water residuals. We also got a sense of the cascading financial implications for utilities generating these waste streams.

Conner camping with his dog Watson.

I like to spend time outside with my wife, Mary, and dog Watson. I also like to go on runs through town or on nearby trails and hang out with friends! I’m an avid basketball fan, attending many Denver Nuggets games and playing pick-up with my friends.

The most exciting aspect of working the water sector is just taking a step back to see what a big impact every tweak to the water treatment process has. I had a professor in graduate school (shout-out to John Spear!) say that modern water treatment is one of the greatest achievements in human history. Of course I’m biased to say that it's true, but how cool is it to say that you play a tiny role that?

To learn more about Conner's research, visit the article, available online at https://doi.org/10.1002/aws2.1367.