Education

Research Description

Dr. Knappe has conducted research on water treatment processes for over 25 years. Current research efforts focus on (1) developing and evaluating physical-chemical treatment processes for the control of disinfection byproduct precursors and trace organic compounds (taste and odor causing substances, carcinogenic volatile organic contaminants, 1,4-dioxane, per- and polyfluoroalkyl substances, endocrine disrupting chemicals, antibiotics, and other pharmaceutically active compounds), 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. Funding agencies that have supported or are currently supporting his research include the U.S. Environmental Protection Agency, the National Science Foundation, the Water Research Foundation, the North Carolina Water Resources Research Institute, and the North Carolina Urban Water Consortium.

Publications

Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFASs)

Herkert, N. J., Merrill, J., Peters, C., Bollinger, D., Zhang, S., Hoffman, K., … Stapleton, H. M. (2020), ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS, 7(3), 178–184. https://doi.org/10.1021/acs.estlett.0c00004

Degradation Model for the Tensile Strength of PVC and Rubber Gasket Materials Exposed to Benzene and PCE-Saturated Aqueous Solutions

Hosseini, P., Alhomair, S., Faeli, Z., Pour-Ghaz, M., Gabr, M., Knappe, D., & Parker, C. (2020), TRANSPORTATION RESEARCH RECORD. https://doi.org/10.1177/0361198120906126

Elevated levels of per- and polyfluoroalkyl substances in Cape Fear River Striped Bass (Morone saxatilis) are associated with biomarkers of altered immune and liver function

Guillette, T. C., McCord, J., Guillette, M., Polera, M. E., Rachels, K. T., Morgeson, C., … Belcher, S. M. (2020), ENVIRONMENT INTERNATIONAL, 136. https://doi.org/10.1016/j.envint.2019.105358

GAC to BAC: Does it make chloraminated drinking water safer?

Cuthbertson, A. A., Kimura, S. Y., Liberatore, H. K., Knappe, D. R. U., Stanford, B., Summers, R. S., … Richardson, S. D. (2020), WATER RESEARCH, 172. https://doi.org/10.1016/j.watres.2019.115432

1,4-Dioxane in drinking water: emerging for 40 years and still unregulated

McElroy, A. C., Hyman, M. R., & Knappe, D. R. U. (2019), Current Opinion in Environmental Science & Health, 7, 117–125. https://doi.org/10.1016/j.coesh.2019.01.003

Does Granular Activated Carbon with Chlorination Produce Safer Drinking Water? From Disinfection Byproducts and Total Organic Halogen to Calculated Toxicity

Cuthbertson, A. A., Kimura, S. Y., Liberatore, H. K., Summers, R. S., Knappe, D. R. U., Stanford, B. D., … Richardson, S. D. (2019), ENVIRONMENTAL SCIENCE & TECHNOLOGY, 53(10), 5987–5999. https://doi.org/10.1021/acs.est.9600023

Effects of Co-occurring Species Present in Swine Lagoons on Adsorption of Copper on Eggshell

Hess, B. J., Kolar, P., Classen, J. J., Knappe, D., & Cheng, J. J. (2019), INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH, 13(4), 613–622. https://doi.org/10.1007/s41742-019-00203-x

Fate of Per- and Polyfluoroalkyl Ether Acids in the Total Oxidizable Precursor Assay and Implications for the Analysis of Impacted Water

Zhang, C., Hopkins, Z. R., McCord, J., Strynar, M. J., & Knappe, D. R. U. (2019), Environmental Science & Technology Letters, 6(11), 662–668. https://doi.org/10.1021/acs.estlett.9b00525

High Temperature Co-pyrolysis Thermal Air Activation Enhances Biochar Adsorption of Herbicides from Surface Water

Kearns, J. P., Shimabuku, K. K., Knappe, D. R. U., & Summers, R. S. (2019), ENVIRONMENTAL ENGINEERING SCIENCE, 36(6), 710–723. https://doi.org/10.1089/ees.2018.0476

Evaluation of Waste Eggshells for Adsorption of Copper from Synthetic and Swine Wastewater

Hess, B. J., Kolar, P., Classen, J. J., Knappe, D., & Cheng, J. J. (2018), Transactions of the ASABE, 61(3), 967–976. https://doi.org/10.13031/trans.12599

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Grants

Development of a Perfluoroalkyl Substances (PFAS) Systems Analysis Tool (SAT) to Assist in Prioritization of Destruction Research and Management Decisions

US Environmental Protection Agency (EPA)(6/11/20 - 9/30/20)

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Development of a Perfluoroalkyl Substances (PFAS) Systems Analysis Tool (SAT) to Assist in Prioritization of Destruction Research and Management Decisions

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 6/11/20

End Date: 9/30/20

Abstract

The objective of this project is to develop a comprehensive systems analysis tool (SAT) to estimate PFAS release associated with management alternatives for a wide range of PFAS-containing wastes. Through this project, we will establish an analytical framework to rigorously describe alternatives for the management of individual PFAS-containing wastes, estimate PFAS release and the receiving medium (air, surface water, groundwater, land).

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Field Evaluation of Hardening Methods for Subsurface Utilities and Drainage Pipes

NC Department of Transportation(8/01/19 - 7/31/21)

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Field Evaluation of Hardening Methods for Subsurface Utilities and Drainage Pipes

Sponsor: NC Department of Transportation

Start Date: 8/01/19

End Date: 7/31/21

Abstract

The North Carolina Department of Transportation (NCDOT) routinely performs road improvement projects where a portion of the right-of-way might be contaminated. Based on the field evaluations carried out by NCDOT, at times subsurface utilities including water and/or drainage pipes are present, or need to be installed, in environments where soil and groundwater contamination exists. The currently funded project (RP 2017-08 with end date on July 31, 2019), is focused on the laboratory evaluation of contaminant migration through concrete pipes, as well as evaluation of the effect of contaminants on the mechanical performance of PVC pipe and three gasket materials (Neoprene, Buna-N, and Viton) when exposed to contaminated water. In addition, modeling of hardening methods and evaluating their efficacy is conducted as a part of the ongoing project.

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Center for Environmental and Health Effects of PFAS

National Institutes of Health (NIH)(2/28/20 - 1/31/21)

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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: 1/31/21

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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An Electroactive Point-of-Use Filter for Per- and Polyfluoroalkyl Contaminant Removal

US Environmental Protection Agency (EPA)(10/01/19 - 9/30/20)

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An Electroactive Point-of-Use Filter for Per- and Polyfluoroalkyl Contaminant Removal

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 10/01/19

End Date: 9/30/20

Abstract

Emerging contaminants are widely present in raw and treated drinking water and present an ongoing threat to human health, prosperity, and the planet. Per- and polyfluoroalkyl substances (PFAS), a broad class of fluorinated chemicals compounds used in a variety of industrial products, such as food packages, and household products, have been detected in drinking water across the country, including locally in Wilmington, North Carolina. Many PFAS are known or suspected carcinogens and pose a risk to humans even at trace levels (ng/L to ug/L). Moreover, they present a risk to the planet because they poorly degrade in the environment. The profound health risk of PFAS has therefore created an urgent need to develop viable methods and technologies to remove PFAS from water resources. The proposed technology in this project directly addresses the three aspects of sustainability because it will result in a cost- and energy-efficient PFAS removal method that can be readily adopted in households across the US. Furthermore, this project will provide an excellent opportunity for educating the public, especially school students in the regional community, many of which have been exposed to PFAS-contaminated waters. To broaden our dissemination of our project and the concepts of sustainability, we will attend and present our results in regional science fairs, such as at the NC Science Festival.

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

Water Research Foundation(3/01/19 - 3/01/22)

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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: 3/01/22

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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PFAS UNITEDD: U.S. National Investigation of Transport & Exposure from Drinking Water & Diet

US Environmental Protection Agency (EPA)(5/01/19 - 4/30/22)

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PFAS UNITEDD: U.S. National Investigation of Transport & Exposure from Drinking Water & Diet

Sponsor: US Environmental Protection Agency (EPA)

Start Date: 5/01/19

End Date: 4/30/22

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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Impacts of GenX (2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate) on reproductive function and transcriptome signature in Caenorhabditis elegans

NCSU Center for Human Health and the Environment(6/01/18 - 3/31/20)

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Impacts of GenX (2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate) on reproductive function and transcriptome signature in Caenorhabditis elegans

Sponsor: NCSU Center for Human Health and the Environment

Start Date: 6/01/18

End Date: 3/31/20

Abstract

Perfluoroalkyl substances (PFASs) are a diverse group of synthetic chemicals used in a wide variety of industrial processes and consumer products. The short-chain PFAS GenX (2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate) has been detected in drinking water from NC’s Cape Fear River downstream of a facility that generates GenX at an average concentration four times higher than the estimated safe level. Currently, little or nothing is known about the potential health effects of exposure to GenX. The overarching goal of this pilot project is to address this gap employing the nematode Caenorhabditis elegans (C. elegans) to identify toxic effects in reproduction upon exposure to this compound. We hypothesize that exposure of C. elegans to environmentally relevant concentrations of GenX will result in impaired reproductive function and alterations in transcriptome profile. To test this hypothesis the following two specific aims will be conducted 1) Characterize effects of exposure to a range of environmentally relevant concentrations of GenX on reproductive function including brood size, egg hatching rate, gonadal development, permatogenesis and oogenesis. and 2) Evaluate effects of GenX exposure on gene expressions by transcriptome profiling and qRT-PCR confirmation. Based on aim 1) one GenX treated group will be selected for transcriptome profiling and compared with control. This study will identify potential health effects of exposure to GenX that will guide future analysis of mixtures, guide validation studies in vertebrate animals and inform translation into exposed human cohorts.

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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 - 7/31/21)

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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: 7/31/21

Abstract

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

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Occurrence of Pesticides in North Carolina Private Drinking Water Wells and Identification of Point-of-Use Treatment Options

NCSU Water Resources Research Institute(3/01/18 - 12/31/20)

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Occurrence of Pesticides in North Carolina Private Drinking Water Wells and Identification of Point-of-Use Treatment Options

Sponsor: NCSU Water Resources Research Institute

Start Date: 3/01/18

End Date: 12/31/20

Abstract

Approximately 3.3 million North Carolinians (35% of the population) rely on private wells as their primary source of drinking water.1 Well water quality is not regulated at the state or federal level, despite several studies illustrating a link between well water contamination and adverse health outcomes.2,3 Moreover, well water can contain harmful organic contaminants such as pesticides, but occurrence data are sparse.4 Key goals of the proposed research are to characterize pesticide contamination in private well water across the state and develop information for the selection of effective home treatment devices.

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Assessing impact of drinking water exposure to GenX (hexafluoropropylene oxide dimer acid) in the Cape Fear River Basin, North Carolina

National Institutes of Health (NIH)(11/01/17 - 10/31/20)

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Assessing impact of drinking water exposure to GenX (hexafluoropropylene oxide dimer acid) in the Cape Fear River Basin, North Carolina

Sponsor: National Institutes of Health (NIH)

Start Date: 11/01/17

End Date: 10/31/20

Abstract

GenX is a perflourinated compound used and generated in the production of non-stick coatings. This chemical has been detected in the Cape Fear River in North Carolina, upstream of where the Cape Fear Public Utility Authority obtains drinking water for the City of Wilmington (population ~250,000), Brunswick County and Pender County, NC. In June 2017, community concern about this chemical in drinking water resulted in multiple public meetings of citizens trying to obtain information about their potential exposure and resulting health effects associated with consumption of drinking water. As a result of community concern, the chemical plant has reportedly stopped discharging GenX into the river. However community concern still exists. This project is designed to help address community concerns about GenX exposure and health effects. Little is known about how GenX is stored in the body, the toxicity of GenX, or how long the chemical will remain in the environment. To address these questions, we plan to conduct a community-based study of Wilmington area residents who are served by public utility water. We will work with community partners of the Cape Fear Riverkeeper and the New Hanover County Department of Health to help identify a representative sample of residents, to collect biological samples, and to keep the community informed about what is known about GenX and what the study finds. We plan to recruit ~400 Wilmington area residents (100 men, 100 women, 100 boys, 100 girls) to provide blood, urine, and drinking water samples and to complete a questionnaire on their water use history. We plan to analyze blood, urine, and drinking water for GenX and related perflourinated chemicals; blood and urine samples will also be used for clinical tests (lipid profile, thyroid function, liver function, and urinalysis). All results from the study will be shared with both the community as a whole and each individual participant. We will have a community advisory panel for the study to help advise about study protocols, methods of reporting back results to participants, and provide guidance on ongoing or new community concerns about GenX. This project leverages the expertise of NC State’s Center for Human Health and the Environment to respond to an emerging community concern.

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