Catherine McMillen, P.E. is a project manager for Aerostar SES based in Knoxville, Tennessee. She has a B.S. in Civil Engineering and a M.S. in Environmental Engineering and has more than 15 years experience in the environmental field. Over the last 7 years, Ms. McMillen has been focused on conducting PFAS investigations across the US.
PFAAs – Does form matter? A chromatographic area ratio evaluation of branched versus linear PFAAs isomers in GAC and resin
PFAAs are present in both linear and branched isomers, meaning that they have the same chemical formula but different molecular structures. Studies of linear and branched PFAAs isomers are beginning to being studied and are important because their molecular structure likely affects how the compounds behave in the environment. Additionally, these isomers can provide a fingerprint of the source and can be used to evaluate the effectiveness of treatment applications. With more and more drinking water systems being identified with PFAAs over the LHA or applicable state regulatory limits, added emphasis is being placed on the treatment of drinking water. Both granular activated carbon (GAC) and resin have been used successfully as conventional PFAAs treatment approaches. However, an evaluation of PFAAs isomers throughout a treatment system has not been conducted and could prove to be valuable information for the scientific community. At one particular site in the US, more than 200 homes with residential drinking water wells have been affected by a PFAA plume that extends approximately 3 miles from the source. To mitigate these effects, point of entry treatment (POET) systems have been installed on these 200+ wells. Each system consists of GAC and resin to treat 16 PFAAs compounds. Using a subset of the POET system data, chromatographic area ratios of branched versus linear PFAA isomers can be evaluated throughout the treatment system: influent, after carbon vessel, and after resin vessel. Chromatographic area ratio evaluation of linear versus branched PFAAs may benefit remediation engineers in recommending future remedial alternatives and determining treatment effectiveness.