Professor, Department of Civil Construction, and Environmental Engineering
North Carolina State University
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 Drinking Water Committee of the USEPA Science Advisory Board and the Science Advisory Board of the NC Department of Environmental Quality. He also 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 enjoys to kayak, garden, and brew beer in his somewhat limited spare time.
Impacts of Perfluoroalkyl Ether Acids on Drinking Water Quality in North Carolina
Because of their persistence, bioaccumulation potential, and (eco)toxicity, long-chain perfluoroalkyl substances (PFASs) are being replaced with short-chain PFASs and fluorinated alternatives. Per- and polyfluoroalkyl ether acids (PFEAs) are one important class of fluorinated alternatives. PFEAs are also produced as by-products during the production of fluoropolymer monomers. Almost no information exists about the occurrence of PFEAs and their behavior during drinking water treatment. Objectives of this research were to determine (1) occurrence of PFEAs and traditionally studied PFASs in the Cape Fear River (CFR) watershed of North Carolina and (2) fate of PFEAs in drinking water treatment processes. In the headwater region of the CFR basin, PFEAs 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 fluorochemical manufacturer, the mean concentration of hexafluoropropylene oxide dimer acid (HFPO-DA, also known as GenX) was 631 ng/L (n=37). Six other PFEAs were detected with three exhibiting chromatographic peak areas up to 100 times that of GenX. At this DWTP, PFEA removal by coagulation, ozonation, biofiltration, and disinfection was negligible. Implications of these findings on policy will be touched upon.