PFAS are a concern due to their persistence, mobility and toxicity with widespread exposure. Exposure to higher concentrations have been linked to cancer. There is also evidence of effects from exposure in utero, infancy and early childhood, including immunosuppression and diminished vaccine efficacy, as well as an increased risk of infections, allergies, asthma and attention deficit.

At a recent workshop hosted by The Water Research Foundation (WRF) and the Global Water Research Coalition (GWRC), some important research findings for water utilities were shared about PFAS transportation, treatment and fate.

Source identification

Required monitoring is confirming predictions that PFAS is widespread in surface water in the U.S. The good news is that PFOS and PFOA concentrations in wastewater have been declining since 2000, when 3M voluntarily began phasing out long-chain PFAS. However, short-chain PFAS are on the rise and are more mobile than their long-chain counterparts, leading to concerns over the spreading of biosolids on agricultural land.

Research conducted in the U.S. confirmed that the most concentrated sources of PFAS in wastewater were from fire training, metal plating, airports, landfill leachate and textile manufacturing. A more surprising finding was that domestic wastewater contributed the most in terms of mass contribution to wastewater. Monitoring on the Trinity River in Texas showed that 90% of PFAS entering the second plant was from domestic sources, pointing to the need to remove PFAS from household cleaning products, non-stick cookware, cosmetics, personal care products and food packaging.

Treatment efficiency and cost

Research on effective treatment approaches has focused on membranes, ion exchange resins (IEX), resins (IEX), granular activated carbon (GAC) and powdered activated carbon (PAC). All approaches were effective in removing PFAS, but each option has different operational and capital costs:

  • Low-pressure reverse osmosis membranes were the most effective (90%) but require costs and environmental approaches to be managed.
  • Relevant results on GAC and PAC for PFAS removal were promising but come with higher operational costs to replace filters at 4X the usual frequency.
  • The University of Toronto evaluated GAC at two Ontario wastewater plants. Their research showed that for a 50 MGD facility, it would cost $16 million per year to remove PFAS.
  • One project found that capturing aerosols during aeration shows promise for long-chain PFOA removal, given that PFAS accumulates to 3X higher concentration in the foam during aeration vs. wastewater.
  • IEX was also seen as a viable technical solution.

Once PFAS are captured, the question of how to destroy them remains a major problem. Existing destruction methods like incineration have not been very successful to date, given the prohibitive cost and concerns over local contamination.

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