title: Use of on-site bioreactors to estimate the biotransformation rate of N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) during activated sludge treatment.
abstract: Accurate rates are needed for models that predict the fate of xenobiotic chemicals and impact of inhibitors at full-scale wastewater treatment plants. On-site rates for aerobic biotransformation of N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE), a fluorinated repellent, were determined by continuously pumping mixed liquor from an aeration basin into two well-mixed acrylic bioreactors (4-L) operated in parallel. Known masses of N-EtFOSE and bromide were continuously added to the reactors. Reactor effluents were then monitored for bromide, N-EtFOSE, and metabolites of N-EtFOSE. Of the six transformation products reported in batch studies, only N-ethyl perfluorooctane sulfonamido acetate (N-EtFOSAA) was detected in the effluents. Bromide addition to the reactors enabled rate estimates despite variations in flow rate. Pseudo-second order rate coefficients for the N-EtFOSE biotransformation to N-EtFOSAA, predicted using a dynamic model of the reactor system, were k=2.0 and 2.4Lg(-1)VSSd(-1) for the two reactors, which are slower than the rates previously obtained using batch reactors. Given the relatively slow rate of N-EtFOSE transformation, its sorption and volatilization may be important in wastewater processes. The methodology used in this study should be suitable for similar on-site rate assessments with other contaminants or inhibitors.
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, United States. krr38@case.edu
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Rhoads
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Rostkowski
authors.forename: Peter K
authors.initials: PK
authors.lastname: Kitanidis
authors.forename: Craig S
authors.initials: CS
authors.lastname: Criddle
mesh_terms: D019149:Bioreactors; D001711:Biotransformation; D001965:Bromides / Q000737:chemistry; D004867:Equipment Design; D005466:Fluorocarbons / Q000302:isolation & purification / Q000378:metabolism; D006845:Hydrocarbons, Fluorinated / Q000302:isolation & purification* / Q000378:metabolism*; D008954:Models, Biological; D012722:Sewage / Q000032:analysis*; D013449:Sulfonamides / Q000302:isolation & purification* / Q000378:metabolism*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods; D015262:Xenobiotics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: C435127:2-(N-ethylperfluorooctanesulfonamido)ethyl alcohol; D001965:Bromides; D005466:Fluorocarbons; D006845:Hydrocarbons, Fluorinated; C542083:N-ethyl perfluorooctane sulfonamido acetate; D012722:Sewage; D013449:Sulfonamides; D015262:Xenobiotics