News & Events

Environmental Engineering Seminar: Impacts of fluorochemical production & use on water quality in NC

Friday, October 06, 2017, 2:00PM - 3:00PM


Detlef R.U. Knappe

Dept. of Civil, Construction, and Environmental Engineering, North Carolina State University


SEEC room N124


Because of their persistence, bioaccumulation potential, and (eco)toxicity, long-chain perfluoroalkyl substances (PFASs) are being replaced with short-chain PFASs and fluorinated alternatives. Perfluoroalkyl ether carboxylic acids (PFECAs) are one important class of fluorinated alternatives. However, almost no information exists about the occurrence of PFECAs and their behavior during drinking water treatment. The objectives of this research were determine (1) occurrence of PFECAs and traditionally studied PFASs in the Cape Fear River (CFR) watershed, (2) fate of PFECAs in drinking water treatment processes, and (3) PFECA adsorbability on powdered activated carbon (PAC). In the headwater region of the CFR basin, PFECAs were not detected in the raw water of a drinking water treatment plant (DWTP), but concentrations of traditionally studied PFASs were high. The US Environmental Protection Agency’s lifetime health advisory level (70 ng/L) for perfluorooctane sulfonic acid and perfluorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. In raw water of a DWTP downstream of a PFAS manufacturer, the mean concentration of GenX, a replacement for PFOA, was 631 ng/L (n=37). Six other PFECAs were detected with three exhibiting chromatographic peak areas up to 15 times that of GenX. At this DWTP, PFECA removal by coagulation, ozonation, biofiltration, and disinfection was negligible. PFAS adsorbability on PAC increased with increasing chain length. Replacing one CF2 group with an ether oxygen decreased PFAS affinity for PAC, while replacement of additional CF2 groups with ether oxygens did not lead to further affinity changes. The implications of our findings on affected communities will be touched upon as well.


Detlef Knappe is a Professor of Civil, Construction, and Environmental Engineering at NC State University. In 1985, he moved from a small Black Forest town in Germany to a small prairie town in Illinois, where he began his undergraduate studies. In 1996, he received his PhD degree in Environmental Engineering from the University of Illinois at Urbana- Champaign and joined the Civil and Environmental Engineering faculty at North Carolina State University in Raleigh. Current efforts in the Knappe research group focus on (1) developing and evaluating physical-chemical (and sometimes biological) treatment processes for the control of disinfection byproduct precursors and organic micropollutants (carcinogenic volatile organic contaminants, 1,4-dioxane, perfluoroalkyl substances), and (2) overcoming gaps between the Clean Water Act and the Safe Drinking Water Act by developing information about the effects of reactive and unregulated wastewater contaminants on drinking water quality and treatment. Detlef was recently selected to serve on the Science Advisory Board of the United States Environmental Protection Agency, and he serves as Trustee on the Water Science and Research Division of the American Water Works Association. Apart from his passion for clean drinking water, Detlef likes to kayak, garden, and brew beer in his somewhat limited spare time.


Free and open to the public.