Granular activated carbon‐based treatment and mobility of per‐ and polyfluoroalkyl substances in potable reuse for aquifer recharge

Abstract

Hampton Roads Sanitation District recently initiated an indirect potable reuse project to recharge the Potomac Aquifer in southeastern Virginia, USA. Source control and granular activated carbon (GAC) treatment are employed to minimize per-and polyfluoroalkyl substances (PFAS) content in this water. Final purified water maintained low long-chain perfluoroalkyl acids (PFAAs; <8 ppt sum of PFOA, PFNA, PFDA, PFHxS, PFOS) and moderately low short-chain PFAAs (<118 ppt of sum PFBA, PFPeA, PFHxA, PFHpA, PFBS). High mobility of low concentrations of five PFAS (PFBS, PFPeA, PFHxA, PFHpA, PFOA) in the Potomac Aquifer was observed. Despite low concentrations relative to current guidelines, PFAS breakthrough and mobility support strict source control and the use of surrogates like total organic carbon to guide GAC operation at the installation.

Poly- and Perfluoroalkyl Substances in Municipal Wastewater Treatment Plants in the United States: Seasonal Patterns and Meta-Analysis of Long-Term Trends and Average Concentrations

“…Certain PFAS such as PFPeA, PFHxA, PFHpA, and PFOA biotransform from polyfluorinated precursors, such as n :2 fluorotelomer alcohols and 6:2 fluorotelomer sulfonic acid (FTSA), which have been observed in wastewater. ,,, 6:2 FTSA is known to biotransform from polyfluorinated substances in aqueous film forming foam (AFFF). ,, The Virginia WWTP has a zero discharge policy toward AFFF, and discharges of AFFF to sewers in general would be unlikely. Nevertheless, it was suspected that 6:2 FTSA might biodegrade from related higher-molecular weight polyfluorinated substances in wastewater.…”

“…Twenty-seven PFAS were monitored every 2 weeks from May 2019 to May 2020 in the secondary effluent of a WWTP in Virginia using published methods ( n = 24). , This WWTP has a design flow of 110000 m 3 /day (30 MGD) with a five-stage Bardenpho process, and its sewershed has a landfill as a known PFAS source.…”

“…On the basis of this scope, aqueous data were analyzed from 20 peer-reviewed articles, ,,,,− ,− ,− one Water Research Foundation (WRF) technical report, one 3M report, and one state government report . Original data were also included for six WWTPs managed by a single utility in Virginia.…”

“…However, because PFOS and PFOA were gradually phased out by different producers from 2002 to 2015, these two studies may have occurred too soon to observe any resulting changes in PFAS in biosolids. , Houtz et al found two short-chain PFAS, perfluorobutanoic acid (PFBA) and perfluorohexanoic acid (PFHxA), increased in the effluent of WWTPs in the San Francisco Bay Area between 2009 and 2014, but the sample size was limited ( n = 6) . Arvaniti and Stasinakis thoroughly reviewed occurrence studies for PFAS in wastewater and biosolids in 2015, but new data have emerged in the six years since. ,,− …”

PFAS are forever? The state of the science and research needs for analyzing and treating PFAS‐laden water

“…GAC was determined to be the critical process for removing both PFAS and TOC, and the study shows the treatment trade‐offs in a water reuse operation. Likewise, Gonzalez et al (2021) present a project at Hampton Roads Sanitation District (HRSD), which recently initiated an indirect potable reuse project to recharge the Potomac Aquifer. The results show source control and GAC treatment maintained low concentrations of long‐chain PFAAs (<8 ppt sum of PFOA, PFNA, PFDA, PFHxS, PFOS).…”