Education

Research Description

Dr. Knappe's research focuses on physical-chemical water treatment processes and environmental analytical chemistry. Current research efforts include (1) developing and evaluating physical-chemical treatment processes for the control of organic micropollutants, such as per- and polyfluoroalkyl substances (PFAS), 1,4-dioxane, and pesticides, (2) assessing the fate of PFAS in natural and engineered systems, (3) identifying pathways by which people are exposed to organic micropollutants (e.g., water, diet, inhalation), and (4) 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. Funding agencies that have supported or are currently supporting his research include the U.S. Environmental Protection Agency, the National Institute of Environmental Health Sciences, the National Science Foundation, the Water Research Foundation, the North Carolina Water Resources Research Institute, and the North Carolina Urban Water Consortium.

Publications

Predicting per- and polyfluoroalkyl substances removal in pilot-scale granular activated carbon adsorbers from rapid small-scale column tests

Hopkins, Z. R., & Knappe, D. R. U. (2024), AWWA WATER SCIENCE, 6(2). https://doi.org/10.1002/aws2.1369

Removal of Per- and Polyfluoroalkyl substances by anion exchange resins: Scale-up of rapid small-scale column test data

Cheng, L., & Knappe, D. R. U. (2024), WATER RESEARCH, 249. https://doi.org/10.1016/j.watres.2023.120956

Degradation of imidacloprid by Phanerodontia chrysosporium on wood chips for stormwater treatment

Weaver, L. M. M., Alexander, N. L., Cubeta, M. A., Knappe, D. R. U., & Aziz, T. N. (2023), ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY, 9(12), 3333–3343. https://doi.org/10.1039/d3ew00545c

Estimation of the Half-Lives of Recently Detected Per- and Polyfluorinated Alkyl Ethers in an Exposed Community

Wallis, D. J., Kotlarz, N., Knappe, D. R. U., Collier, D. N., Lea, C. S., Reif, D., … Hoppin, J. A. (2023), ENVIRONMENTAL SCIENCE & TECHNOLOGY, 57(41), 15348–15355. https://doi.org/10.1021/acs.est.2c08241

Factors associated with per- and polyfluoroalkyl substances (PFAS) serum concentrations in residents of New Hanover County, North Carolina: The GenX exposure study

Cuffney, M., Wilkie, A. A., Kotlarz, N., Knappe, D., Lea, C. S., Collier, D. N., … Hoppin, J. A. (2023), ENVIRONMENTAL RESEARCH, 237. https://doi.org/10.1016/j.envres.2023.117020

Improved Darcian streambed measurements to quantify flux and mass discharge of volatile organic compounds from a contaminated aquifer to an urban stream

Nickels, J. L., Genereux, D. P., & Knappe, D. R. U. (2023), JOURNAL OF CONTAMINANT HYDROLOGY, 253. https://doi.org/10.1016/j.jconhyd.2022.104124

Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata): Recommendations for Methods Standardization

Ruyle, B. J., Pickard, H. M., Schultes, L., Fredriksson, F., Heffernan, A. L., Knappe, D. R. U., … Sunderland, E. M. (2023), ENVIRONMENTAL SCIENCE & TECHNOLOGY, 57(48), 20159–20168. https://doi.org/10.1021/acs.est.3c04560

Oxidation of Per- and Polyfluoroalkyl Ether Acids and Other Per- and Polyfluoroalkyl Substances by Sulfate and Hydroxyl Radicals: Kinetic Insights from Experiments and Models

Zhang, C., Tang, T., & Knappe, D. R. U. (2023, May 24), ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol. 5. https://doi.org/10.1021/acs.est.3c00947

Pilot-scale biofiltration of 1,4-dioxane at drinking water-relevant concentrations

McElroy, A. C., Ogles, M. E., Hyman, M. R., & Knappe, D. R. U. (2023), WATER RESEARCH, 231. https://doi.org/10.1016/j.watres.2023.119652

Predicting Concentration- and Ionic-Strength-Dependent Air-Water Interfacial Partitioning Parameters of PFASs Using Quantitative Structure-Property Relationships (QSPRs)

Stults, J. F., Choi, Y. J., Rockwell, C., Schaefer, C. E., Nguyen, D. D., Knappe, D. R. U., … Higgins, C. P. (2023, March 24), ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol. 3. https://doi.org/10.1021/acs.est.2c07316

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Grants

STC: Science and Technologies for Phosphorus Sustainability (STEPS) Center

National Science Foundation (NSF)(10/01/21 - 9/30/26)

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STC: Science and Technologies for Phosphorus Sustainability (STEPS) Center

Sponsor: National Science Foundation (NSF)

Start Date: 10/01/21

End Date: 9/30/26

Abstract

The Science and Technologies for Phosphorus Sustainability (STEPS) Center is a convergence research hub for addressing the fundamental challenges associated with phosphorus sustainability. The vision of STEPS is to develop new scientific and technological solutions to regulating, recovering and reusing phosphorus that can readily be adopted by society through fundamental research conducted by a broad, highly interdisciplinary team. Key outcomes include new atomic-level knowledge of phosphorus interactions with engineered and natural materials, new understanding of phosphorus mobility at industrial, farm, and landscape scales, and prioritization of best management practices and strategies drawn from diverse stakeholder perspectives. Ultimately, STEPS will provide new scientific understanding, enabling new technologies, and transformative improvements in phosphorus sustainability.

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Thermal Reactivation of Spent GAC from PFAS Remediation Sites

Strategic Environmental Research and Development Program (SERDP)(12/16/20 - 12/16/25)

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Thermal Reactivation of Spent GAC from PFAS Remediation Sites

Sponsor: Strategic Environmental Research and Development Program (SERDP)

Start Date: 12/16/20

End Date: 12/16/25

Abstract

The overarching goal of this research is to determine the fate of per- and polyfluoroalkyl substances (PFASs) during thermal reactivation of granular activated carbon (GAC) that had treated PFAS-laden water. Bench-scale studies will be conducted to determine reactivation conditions that release PFAS from spent GAC and lead to PFAS mineralization. To close the fluorine mass balance, this study will focus on laboratory-loaded GAC with known PFAS loadings. Limited experiments will be conducted with spent GAC from remediation sites with high PFAS levels.

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Non-Targeted Analysis of PFAS Impacted Multimedia Samples to Support NCDEQ???s Action Strategy for Addressing Existing PFAS Sources and Industries with Multi-Media Impacts through Collaboration and Coordination

NC Department of Environmental Quality (DEQ)(7/01/23 - 6/30/25)

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Non-Targeted Analysis of PFAS Impacted Multimedia Samples to Support NCDEQ???s Action Strategy for Addressing Existing PFAS Sources and Industries with Multi-Media Impacts through Collaboration and Coordination

Sponsor: NC Department of Environmental Quality (DEQ)

Start Date: 7/01/23

End Date: 6/30/25

Abstract

The objectives of this research are to (1) identify multimedia sampling locations in the state of North Carolina for non-targeted PFAS analysis, (2) conduct non-targeted PFAS analysis of multimedia samples, and (3) share results with the North Carolina Department of Environmental Quality.

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Center for Environmental and Health Effects of PFAS

National Institutes of Health (NIH)(2/28/20 - 1/31/25)

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Center for Environmental and Health Effects of PFAS

Sponsor: National Institutes of Health (NIH)

Start Date: 2/28/20

End Date: 1/31/25

Abstract

Per- and polyfluoroalkyl substances (PFAS) are emerging as a major public health problem in North Carolina and across the United States. PFAS comprise a class of over 5,000 compounds. Their unique chemical properties have been harnessed to make consumer and industrial products more water, stain, and grease resistant; they are found in products as diverse as cosmetics and flame-retardants. PFAS are resistant to degradation, move easily through the environment, and accumulate in living organisms. Exposure to PFAS has been associated with health effects including cancer and toxicity to the liver, reproductive development, and thyroid and immune systems. Despite widespread detection in the environment and evidence of increasing human exposure, understanding about PFAS toxicity, its bioaccumulative potential in dietary sources such as aquatic organisms, and effective remediation remain notably understudied. The recent discovery by this proposed Center??????????????????s Deputy Director, Dr. Detlef Knappe, of widespread PFAS contamination in the Cape Fear River watershed in NC underscores that these compounds are in need of immediate investigation.. The goal of our Center is to advance understanding about the environmental and health impacts of PFAS. To meet this goal we are employing a highly trans-disciplinary approach that will integrate leaders in diverse fields (epidemiology, environmental science and engineering, biology, toxicology, immunology, data science, and advanced analytics); all levels of biological organization (biomolecule, pathway, cell, tissue, organ, model organism, human, and human population); state-of-the-art analytical technologies; cutting-edge data science approaches; a recognized track record in interdisciplinary, environmental health science (EHS) training; and well-established partnerships with government and community stakeholders.

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Studying the Fate of PFAS through Sewage Sludge Incinerators

Hampton Roads Sanitation District (HRSD)(3/28/22 - 12/31/24)

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Studying the Fate of PFAS through Sewage Sludge Incinerators

Sponsor: Hampton Roads Sanitation District (HRSD)

Start Date: 3/28/22

End Date: 12/31/24

Abstract

Incineration can destroy per- and polyfluoroalkyl substances (PFAS), but the conditions required for destruction are not known. This research aims to elucidate the fate of these compounds through sewage sludge incinerators (SSIs), and thereby provide utilities and decision makers with an indication regarding the extent SSIs can reduce PFAS discharges to the environment which is important for informing PFAS handling strategies.

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Occurrence and Fate of Per- and Polyfluoroalkyl Substances (PFAS) in North Carolina Agricultural Systems

NC Department of Justice(1/01/21 - 12/31/24)

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Occurrence and Fate of Per- and Polyfluoroalkyl Substances (PFAS) in North Carolina Agricultural Systems

Sponsor: NC Department of Justice

Start Date: 1/01/21

End Date: 12/31/24

Abstract

The overall goal of this project is to identify the frequency of PFAS occurrence within swine sludge and biosolids to understand the risk of PFAS movement when these byproducts are applied to agricultural fields in the Cape Fear Watershed and other areas.

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Investigation of Treatment Alternatives for Short-Chain Poly- and Perfluoroalkyl Substances

Water Research Foundation(3/01/19 - 8/01/24)

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Investigation of Treatment Alternatives for Short-Chain Poly- and Perfluoroalkyl Substances

Sponsor: Water Research Foundation

Start Date: 3/01/19

End Date: 8/01/24

Abstract

Poly- and perfluoroalkyl substances (PFASs) are contaminants of emerging concern for drinking water providers nationwide. As concerns about adverse health impacts have risen for long-chain PFASs, fluorochemical manufacturers have shifted their production to short-chain PFASs. As a result the detection frequency of short-chain PFASs in drinking water sources is increasing. The overarching objective of this research is to develop effective water treatment approaches for the control of short-chain PFASs. Treatment technologies, such as activated carbon adsorption, anion exchange, and high-pressure membrane filtration will be evaluated in both surface and ground water treatment contexts. In addition, innovative sorbents and destructive processes will be explored. Data generated in this study will inform life cycle analysis and cost models and will provide guidance for drinking water providers impacted by short-chain PFASs.

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Collaborative Research: Cyclodextrin-Based 2D Materials for the Treatment of Legacy and Emerging Perfluoroalkyl Substances

National Science Foundation (NSF)(8/15/18 - 7/31/24)

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Collaborative Research: Cyclodextrin-Based 2D Materials for the Treatment of Legacy and Emerging Perfluoroalkyl Substances

Sponsor: National Science Foundation (NSF)

Start Date: 8/15/18

End Date: 7/31/24

Abstract

Development of water purification media for perfluoroalkyl contaminants via cyclodextrin grafted graphene oxide.

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PFAS Transport & Exposure from DW & Diet

US Environmental Protection Agency (EPA)(5/01/19 - 4/30/24)

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PFAS Transport & Exposure from DW & Diet

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 5/01/19

End Date: 4/30/24

Abstract

Per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants of global concern. Over 3,000 PFASs are on the global market, but for most PFASs we lack information about their properties, environmental fate and transport, bioaccumulation in foods of plant and animal origin, and human exposure. The overarching objective of the proposed research is to develop actionable information on the fate, transport, bioaccumulation, and relative exposures of understudied PFASs in PFAS-impacted communities. Information developed in this research is expected to enable risk managers to make informed decisions and reduce uncertainties related to human PFAS exposures.

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Novel Mass Spectrometry Approaches for the Identification of Pesticides and Per- and Poly-Fluoroalkyl Substances in North Carolina Drinking Water Sources

NCSU Water Resources Research Institute(3/01/21 - 11/30/23)

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Novel Mass Spectrometry Approaches for the Identification of Pesticides and Per- and Poly-Fluoroalkyl Substances in North Carolina Drinking Water Sources

Sponsor: NCSU Water Resources Research Institute

Start Date: 3/01/21

End Date: 11/30/23

Abstract

North Carolina drinking water sources are vulnerable to impacts from a unique set of emerging organic contaminants, including per- and poly-fluoroalkyl substances (PFAS), pesticides, and pesticide degradates. The impact of these contaminants on the private well community in NC remains understudied. In this proposal, we will use the combination of ion mobility spectrometry (IMS) and mass spectrometry (MS) to extend a multidimensional database of toxicants, create a rapid analytical method suitable for organic contaminants, and apply this method to up to 50 private wells in NC.

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