Rodowa, A.E., D.R.U. Knappe, S.-Y.D. Chiang, D. Pohlmann, C. Varley, A. Bodour, et al.
Environmental Science: Water Research & Technology 6:1083-1094(2020)

A nine-month pilot study conducted at a military fire-fighting training area evaluated PFAS removal from groundwater contaminated with aqueous film-forming foam using two granular activated carbon (GAC) vessels in a lead-lag configuration. Breakthrough was quantified for branched and linear isomers of 15 PFASs, including PFCAs, perfluoroalkyl sulfonates, perfluoroalkyl sulfonamides, and FtSAs. A total oxidizable precursor (TOP) assay was used to provide information on precursors in the influent and quantify precursor breakthrough. An influent profile was quantified to infer the nature of the AFFFs used at the site. Breakthrough of shorter-chain PFAS and branched isomers occurred before breakthrough of longer-chain PFAS and linear isomers. The order of adsorption ability for head groups of PFAS with equal chain length was -COO^-<-SO₃^-<-CH₂CH₂SO₃^-<-SO₂NH. TOP assay results further showed that precursors of PFCAs broke through GAC in addition to commonly measured PFCAs and PFSAs. Results indicated that chromatographic retention times of PFAS obtained from a single analysis of influent groundwater could be used to predict the relative order of breakthroughs for other PFASs on GAC.