PFOA and PFOS – Emerging Contaminants

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 PFOA & PFOS are the latest in the growing list of contaminants affecting drinking water.  I attended a Calgon Carbon seminar to catch up on the recent recommendations.

Here are some takeaways you might find helpful:

  • System Design for Optimal Removal of PFOA & PFOS

    • Empty Bed Contact Time – 10 minutes minimum.
    • Lead-lag design should be applied – test results take up to 5 weeks. It’s important to have a sample port between the lead and polishing tanks.
    • Initial backwash of the carbon should be with treated water whenever possible and practical.
    • After installing the carbon run the system for a couple days before taking retesting.

  • EPA Health Advisory Limit for PFOA & PFOS 

    Perfluorooctanesulfonic acid PFOS-PFOA
    Perfluorooctanesulfonic acid
    • EPA currently lists the limit at 70 ppt – that’s parts per trillion.
    • The limit varies by state so make sure you check before installing.
    • Some states have placed restrictions on arsenic (naturally occurring) which may come off the carbon. Consider this before making or specifying a carbon purchase.

  • Which carbon to use for removal of PFOA & PFOS.

    • Coconut based carbon is not very effective for the removal of PFOA and PFOS from water.  PFOA_Removal Test Results
    • Calgon has been successfully using coal based Filtrasorb-600 (F-600) for the removal of PFOA and PFOS for about 12 years.
    • Filtrasorb-400 (F-400) a 12×40 mesh coal base carbon, can also be used. It performs almost as well and has a better price point.

  • Waste & Handling of Spent Activated Carbon

    • The generator (homeowner) is responsible for the disposal of the spent carbon. However, you should consider talking with your Calgon Carbon supplier who can assist you in obtaining a Carbon Acceptance Number (CAN). There is cost associated with the testing and application but it is a green and sustainable means of handling the spent carbon.  The spent carbon is reactivated and reused.
    • There are no special handling requirements for the removal of the spent carbon. It is not a hazardous waste.  Handle as you would any other activated carbon rebed.  Gloves, dust mask and safety glasses.
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