Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7n. PFAS Source and Forensic Considerations

Formatted Title:

Sources, Pathways, and Treatment Options for PFAS in Groundwater: An Example from Maryland

Background/Objectives:

Per- and polyfluorinated alkyl substances (PFAS) are now commonly found in groundwater in the US. In certain cases there are known or likely sources, but the occurrence of PFAS in groundwater is not always clearly linked to a local source. Here we review the available information on background PFAS from atmospheric deposition, and compare the relative concentrations expected from other diffuse sources such as biosolids and septic systems. This review of widespread PFAS distribution is then used to place context around detections of PFAS in community water systems across the state of Maryland that rely on groundwater. The objective of this analysis is to evaluate patterns in the spatial distribution of PFAS and the relative abundance of individual PFAS compounds.

Approach/Activities:

The approach of this study is to compile data from (1) literature for PFAS in atmospheric deposition, biosolids, and septic systems; and (2) community water systems in Maryland. The relative PFAS concentrations and fingerprints are compared among the widespread sources, which are then used to discuss spatial patterns and PFAS fingerprints in community water systems. A case study of a single community water system is presented, including a pilot PFAS treatment system that evaluates the effectiveness of granular activated carbon (GAC) and a cyclodextrin adsorbent.

Results/Lessons Learned:

PFAS are detectable in atmospheric deposition, but more comprehensive sampling with forensic-quality analytical data are needed to identify a consistent atmospheric background signature. Septic effluent and biosolids consistently have detections of PFOA, PFOS, PFHxS and PFHxA. Thus far in the analysis, it is clear that PFAS is a widespread problem for community water systems in Maryland that rely on shallow aquifer systems. In the coastal plain physiographic region, where drinking water is typically obtained from deeper, confined, aquifers, there are very few community water systems with PFAS detections. In the case study example, the detected PFAS fit the same pattern seen in widespread sources such as atmospheric deposition, biosolids, and septic effluent. The pilot treatment system was recently installed, and preliminary results show that both media were effective in removing PFAS to below detection limits.

Kathleen Mihm

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(Group 2, Poster Board #81) Sources, Pathways, and Treatment Options for PFAS in Groundwater: An Example from Maryland