title: Aerobic biotransformation and fate of N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) in activated sludge.
abstract: Processes affecting the fate of perfluorinated organics are of increasing concern due to the global dispersal, persistence, and bioaccumulation of these contaminants. The volatile compound N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) and its phosphate esters have been used in protective surface coatings. In this report, we describe the fate of N-EtFOSE in aerobic batch assays. These assays were performed using undiluted activated sludge in serum bottles that were sealed to prevent the escape of N-EtFOSE and volatile transformation products. Separate assays were performed with N-EtFOSE and reported transformation products. N-EtFOSE degraded to N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) with an observed first-order rate of 0.99 +/- 0.08 day(-1) and a pseudosecond order rate of 0.26 +/- 0.02 L/mg VSS day(-1). N-EtFOSAA underwent further transformation at a slower rate (0.093 +/- 0.012 day(-1)) to N-ethylperfluorooctane sulfonamide (N-EtFOSA). N-EtFOSA then transformed to perfluorooctane sulfonamide (FOSA). FOSA transformed to perfluorooctane sulfinate (PFOSI), and PFOSI transformed to perfluorooctane sulfonate (PFOS). Perfluorooctanoic acid (PFOA) was not detected as a transformation product of any compound. Using the measured rate of N-EtFOSE biotransformation and literature values for phase partitioning and mass transfer in aeration basins, we modeled the fate of N-EtFOSE in a typical activated sludge aeration basin open to the atmosphere. The model predicts that 76% of the N-EtFOSE is stripped into the atmosphere, 5% sorbs to waste solids, 13% undergoes transformation to N-EtFOSAA, and 6% is discharged in the wastewater effluent.
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Rhoads
authors.forename: Elisabeth M L
authors.initials: EM
authors.lastname: Janssen
authors.forename: Richard G
authors.initials: RG
authors.lastname: Luthy
authors.forename: Craig S
authors.initials: CS
authors.lastname: Criddle
mesh_terms: D000332:Aerobiosis; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D004785:Environmental Pollutants / Q000378:metabolism*; D006845:Hydrocarbons, Fluorinated / Q000378:metabolism*; D007700:Kinetics; D012722:Sewage; D013449:Sulfonamides / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D005466:Fluorocarbons
chemical_list: D004785:Environmental Pollutants; D006845:Hydrocarbons, Fluorinated; D012722:Sewage; D013449:Sulfonamides; C435127:2-(N-ethylperfluorooctanesulfonamido)ethyl alcohol; D005466:Fluorocarbons