20th Annual EPA Drinking Water Workshop: Session 6B
Per- and Polyfluoroalkyl Substances (PFAS)
Track B: Source, Treatment, and Operations
Presentation summaries and speaker and moderator biographies for Session 6B of the 20th Annual EPA Drinking Water Workshop.
September 13, 2023 from 10:45 a.m. to 12:30 p.m. ET
See the full workshop agenda for all sessions.
Moderator:
Thomas F. Speth, Ph.D., P.E. | EPA Office of Research and Development
Tom serves as senior science advisor for EPA’s Center for Environmental Solutions and Emergency Response in the Office of Research and Development. He is a professional engineer who has worked in the field of water treatment research at EPA since 1986. At EPA, Tom has served as branch chief of EPA’s Treatment Technology Evaluation Branch from May 2005 to January 2009. From January 2009 to March 2018, he served as division director of EPA’s Water Supply and Water Resources Division. During this time, from September 2015 to December 2016, he served in a detail with EPA’s Office of Ground Water and Drinking Water’s Standards and Risk Management Division as a senior engineering advisor assigned to the Flint Enforcement Team. From March 2018 to April 2023, he served as the associate director for science for the Center for Environmental Solutions and Emergency Response. Tom is a member of AWWA, ASCE, and ACS. He has served as trustee for AWWA's Water Quality and Technology Division, an associate editor for ASCE's Journal of Environmental Engineering, a member of Journal AWWA’s Editorial Advisory Board, and as a trustee and chair of AWWA’s Water Science and Research Division. Tom has a Ph.D. in environmental engineering from the University of Cincinnati, an M.S. in civil/environmental engineering from Michigan Technological University, and a B.S. in chemical engineering from Michigan Technological University.
GAC Uptake of PFAS: Assessment of Rapid Small-Scale Column Test Scaling Assumptions
This presentation will cover U.S. EPA’s research to investigate the baseline adsorption kinetics and capacity of three commonly used granular activated carbons (GACs) towards nine selected PFAS compounds. Through a series of single solute batch adsorption studies, the study systematically evaluates the effect of PFAS properties and GAC particle size on the batch adsorption kinetics and equilibrium. Research findings offer a baseline for estimating the fundamental adsorption parameters for adsorption of PFAS from drinking water and provide a quantitative assessment of rapid small-scale column test (RSSCT) scaling assumptions and potential implications. The availability of such information can facilitate an informed and streamlined design of GAC treatment systems.
Gulizhaer Abulikemu, M.S., P.E. | Pegasus Technical Services (Contractor to EPA, Office of Research and Development)
Gulizhaer is an environmental engineer at Pegasus Technical Services and provides on-site contract support to EPA. She has 11 years of research experience, with a recent focus on GAC adsorption of natural organic matter and emerging contaminants, such as VOCs, cyanotoxins, and PFAS from drinking water. Her previous research areas include ultrafiltration treatment of refinery process cooling water and oil spill treatment in marine environment and salt marshes using chemical dispersants and oil wicking agents. Gulizhaer is a Ph.D. candidate in environmental engineering at the University of Cincinnati. She holds an M.S. in environmental engineering from the University of Cincinnati and a B.S. in environmental engineering from the Harbin Institute of Technology.
PFAS Treatment: Granular Activated Carbon Adsorption and Ion Exchange
Granular activated carbon (GAC) adsorption and ion exchange (IX) are readily implementable PFAS treatment methods, but factors determining GAC and IX use rates are poorly understood. In this research, the removal of 23 PFAS was investigated using rapid small-scale column tests (RSSCTs) to (1) develop scale-up approaches to predict PFAS removal in full-scale GAC and IX contactors and (2) investigate factors controlling GAC and IX use rates, including the impact of PFAS properties and water matrix constituents.
For GAC, RSSCTs designed with a proportionality factor (X) of 0.25 effectively predicted pilot-scale PFAS removal. Influent PFAS concentration and co-occurring PFAS had a negligible effect on normalized breakthrough curves, while increasing TOC concentration had a strong adverse effect on GAC use rates. Pretreatment to remove and/or transform dissolved organic matter prior to GAC treatment lowered GAC use rates. Increasing empty bed contact time (EBCT) was beneficial in some cases but had a negligible impact in others.
For IX resins, constant diffusivity RSSCTs (X=0) effectively predicted pilot-scale PFAS removal kinetics, but PFAS uptake capacity was dependent on hydraulic loading rate as expressed by the Sherwood number. Similar to GAC, influent PFAS concentration and co-occurring PFAS had a negligible effect on normalized breakthrough curves. Increasing TOC concentration had a negative impact on IX use rates, but the effect was not as pronounced as for GAC. Nitrate also adversely impacted PFAS uptake capacity while chloride, sulfate, and bicarbonate at concentrations up to 3 mEq/L had negligible effects. IX use rates were not measurably impacted by EBCTs in the 1.5-3 minute range.
Results from this research will support the design of future GAC and IX treatment processes in the context of PFAS remediation and drinking water treatment.
Detlef Knappe, Ph.D. | North Carolina State University
Detlef is the S. James Ellen Distinguished Professor of Civil, Construction, and Environmental Engineering at North Carolina State University. He joined the NCSU faculty in 1996 after receiving a Ph.D. in environmental engineering from the University of Illinois at Urbana-Champaign. Detlef’s research interests broadly encompass drinking water quality and treatment, and he has conducted research on per- and polyfluoroalkyl substances (PFAS) since 2010. Detlef is a member of the North Carolina’s Secretaries’ Science Advisory Board, is deputy director of NCSU’s Superfund Center for Environmental and Health Effects of PFAS, and serves as associate editor of the AWWA Water Science journal.
PFAS Sampling Efforts in Indiana
Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic organic chemicals that consist of carbon-fluorine chains of varying length. More than 3,000 unique PFAS compounds have been manufactured since the 1940s. Many PFAS compound have useful chemical properties that have resulted in their use in both industrial and consumer products. Though U.S. production of some of these chemicals has declined, PFAS are highly resistant to degradation, and they have earned the moniker “forever chemicals” for their persistence in the environment. U.S. EPA considers PFAS compounds to be emerging contaminants in the environment.
Beginning in February 2021, the Indiana Department of Environmental Management (IDEM) facilitated PFAS monitoring at all Community Public Water Systems (CWS) throughout the state of Indiana. The purpose of the sampling program is to evaluate the occurrence of 18 common PFAS compounds in CWS across the state and determine the efficacy of conventional drinking water treatment for PFAS. IDEM partnered with labs (the Indiana Department of Health and Pace Analytical) to distribute PFAS sampling bottles and kits to the operators at the CWSs that have agreed to participate in the program. This project is funded by an Emerging Contaminant grant from U.S. EPA.
This presentation will highlight the PFAS sampling project, which is being implemented in three phases: Phase 1, the sampling of CWSs that serviced between 3,300 and 10,000 people, was completed in 2021; Phase 2, the sampling of systems serving less than 3300 people, was completed at the beginning of 2023; and Phase 3, sampling of systems serving more than 10,000 people is currently underway. Samples are collected by the drinking water operator at all raw water (i.e., wells and intakes) and finished (after treatment) water points in a CWS’s supply and shipped overnight to the contract lab. Sampling results will be shared with the CWSs and posted on the project’s website for public viewing.
Kevin Spindler, M.S. | Indiana Department of Environmental Management
Kevin has 18 years of experience with the Indiana Department of Environmental Management in the Office of Land Quality and the Drinking Water Branch at Office of Water Quality, where he currently serves as the project manager for the Statewide Ground Water Monitoring Network and the PFAS Sampling Initiative. Kevin holds an M.S. in geological sciences from Indiana University-Bloomington and a B.S. in geology and geophysics from the University of Missouri-Rolla (now Missouri S&T).
Disclaimer: The views expressed in these presentations are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency. Any mention of trade names or commercial products does not constitute EPA endorsement or recommendation for use.