Removal of PFOA by Carbon Treatment in a Public Water System: A Ten-Year Case Study
Thursday, June 20, 2019: 3:20 p.m.
Linda Aller, CPG
,
Bennett & Williams
Kerry Zwierschke, PhD, PE
,
Bennett & Williams, Westerville, OH
When the Little Hocking Water Association, a rural public water supply in southeastern Ohio, first learned about contamination of their wellfield by perfluorooctanoic acid (PFOA) in 2002, little was known about the chemical. Even less was known about potential treatment methods. Field investigations revealed that production wells in the wellfield had concentrations of PFOA as high as 22,000 ppt and that monitoring wells had concentrations as high as 78,000 ppt. In addition, soil concentrations were measured to be as high as 52,800 ppt.
A pilot study indicated that food grade activated carbon would remove these levels of PFOA. In November 2007, a treatment system using two vessels in series containing 20,000 pounds of food grade carbon was placed online and has been successfully operated since that time. This presentation will review the concentrations of influent PFOA over time, the effectiveness and replacement frequency of the carbon, and the long-term implications for treatment cessation.
Linda Aller, CPG, Bennett & Williams
For over 25 years, Ms. Aller has been actively involved in both the management and technical aspects of groundwater supply, protection and investigations. She has worked extensively with local, state and federal officials and legislators providing technical information on policies and regulations that affect groundwater. She is the author of several state-of-the-art publications including DRASTIC and design of groundwater monitoring wells. She has been involved in perfluorinated investigations for over 15 years.
Kerry Zwierschke, PhD, PE, Bennett & Williams, Westerville, OH
Kerry is a professional engineer with experiences related to water supply, source water protection, treatment technology, hydraulic modeling and GIS integration with a variety of engineering applications. In addition, she has a Ph.D. in engineering from the Ohio State University and has experience related to the statistical analysis of environmental data, solid and hazardous waste landfill design and monitoring, wetland treatment systems, and contamination assessment. Kerry is an organizer of the Ohio Rural Water GIS User group that meets quarterly and provides training on desktop GIS and ArcGIS Online applications.
