Water supplies meeting treatment requirements

Water Treatment & PFAS

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PFAS

 

Lake Superior

Summary

  • PFAS are a class of thousands of persistent chemicals from the manufacturing of consumer goods, firefighting foam, and landfills which can contaminate drinking water sources and cause increased human health risks
  • Regulation for maximum contaminant levels of PFAS vary depending on jurisdiction and type
  • Drinking water can be treated to remove PFAS with technologies such as granular activated carbon, ion exchange resins, and high-pressure membranes such as reverse osmosis

What is PFAS?

Per-and polyfluoroalkyl substances (PFAS) are a group of environmentally persistent chemicals that have been used in industrial processes and manufacturing.[1] PFAS bioaccumulate in human bodies, leading to increased health risks.[2]

Where does it come from?

PFAS can contaminate both surface and groundwater drinking water sources, often originating from consumer goods legacy contamination, disposal of landfill leachate, and the use of firefighting foam. [2,3

What are the contamination standards?

Maximum contaminant levels (MCL) for PFAS vary between the U.S. and Canada, [4] between states, and for different types of PFAS. For example, the MCL ranges between 6-400,000 parts per trillion (ppt) for various PFAS types in the state of Michigan.[5] The U.S. Environmental Protection Agency has announced the release of non-regulatory health advisories for four PFAS. These include 0.004 ppt for PFOA, 0.02 ppt for PFOS, 10 ppt for GenX chemicals, and 2,000 ppt for PFBS.[6]

How is drinking water treated to meet applicable standards?

Drinking water in homes and water treatment facilities can be treated with certain technologies to effectively remove PFAS. These technologies include granular activated carbon, ion exchange resins, and high-pressure membranes such as reverse osmosis.[1] Blending contaminated water with other sources to reduce the contamination level is not considered a treatment but is enacted for some water systems as a cost-effective measure.[7]

Granular Activated Carbon (GAC) has been shown to be a common and more than 90% effective treatment for long-chain PFAS contamination.[7,8] Several base materials are used for GAC and studies show that bituminous-based products demonstrate higher effectiveness for PFAS removal.[7] GAC is used in treatment plants, ranging in costs from $80,000 to $3 million in facility construction costs.[7,9] Operational costs such as power and inspections, the cost of carbon (estimated at $1.50 per pound), and disposal costs must also be considered.[7] Purolite estimates the cost of their system to be $0.45/1000 gallons of treated water.[10] GAC adsorbs longer chain PFAS[1] better than shorter chain PFAS and GAC media can be disposed of through landfilling or incineration[7]. Powdered Activated Carbon (PAC) uses the same material as GAC but with a smaller diameter form, meaning that it is added directly to contaminated water and then removed in a later stage of clarification. PAC is not as economical or effective as GAC when used in this way and the waste must still be disposed of properly. [1,7]

Anion exchange systems involve the use of resins to exchange ions and capture contaminants such as PFAS.[7] Costs will vary depending on the type of treatment system and resin;[1] although ion exchange system upstart costs are usually more expensive than GAC, the costs may be less over the project period due to their higher adsorption capacity.

Membrane technologies such as reverse osmosis and nanofiltration are a more than 90% effective method to treat PFAS contaminated water.[7] Reverse osmosis will create waste streams of water totaling between 20-25% of the original flow. This rejected water must be managed to reduce chance of further contamination, meaning smaller water volumes are optimal for reverse osmosis such as home use. [1,7] A further limitation is that this process also strips beneficial minerals from drinking water.

Newer PFAS treatment technology is being tested and certified including a group of engineered adsorption media development which have high adsorption capacities such as CETCO’s Fluoro-sorb and Cyclopure’s Dexsorb+.[11]

References

 

  1. EPA, Reducing PFAS in Drinking Water with Treatment Technologies (2018) Accessible online: https://www.epa.gov/sciencematters/reducing-pfas-drinking-water-treatment-technologies
  2.  Association of State Drinking Water Administrators, Per- and Polyfluoroalkyl Substances (PFAS) Source Water Protection Guidance Project (2020) Accessible online: https://www.asdwa.org/pfas/
  3.  ITRC, History and Use of Per- and Polyfluoroalkyl Substances (PFAS) found in the Environment (2020) Accessible online: https://pfas-1.itrcweb.org/wp-content/uploads/2020/10/history_and_use_508_2020Aug_Final.pdf
  4. Government of Canada, Guidelines for Canadian Drinking Water Quality – Summary Table (2020). Accessible online: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/water-quality/guidelines-canadian-drinking-water-quality-summary-table.html
  5. State of Michigan, Michigan PFAS Action Response Team (2022) Accessible online: https://www.michigan.gov/pfasresponse/drinking-water/mcl
  6. U.S. EPA, Drinking Water Health Advisories for PFOA and PFOS (2022). Accessible online: https://www.epa.gov/sdwa/drinking-water-health-advisories-pfoa-and-pfos
  7. Cummings, L., Matarazzo, A., Nelson, N., Sickels, F., Storms, C., Recommendation on Perfluorinated Compound Treatment Options for Drinking Water (2015) Accessible online: https://www.state.nj.us/dep/watersupply/pdf/pfna-pfc-treatment.pdf
  8.  ITRC, Treatment Technologies and Methods for Per- and Polyfluoroalkyl Substances (PFAS) (2020) Accessible online: https://pfas-1.itrcweb.org/wp-content/uploads/2020/10/treatment_tech_508_Aug-2020-Final.pdf
  9. EPA Office of Ground Water and Drinking Water, Addressing PFAS in Drinking Water with the Drinking Water State Revolving Fund (2019) Accessible online: https://www.epa.gov/sites/default/files/2019-03/documents/pfas_fact_sheet_and_case_studies_final.pdf
  10. Association of State Drinking Water Administrators, PFAS Treatment Options and Considerations for Drinking Water Utilities (Webinar) (2018) Study by Purolite. Accessible online: https://www.asdwa.org/past-events-webinar-recordings/?mgs_158=pfas&mgi_158=14529/pfas-treatment-options-and-considerations-for-drinking-water-utilities
  11. Orange County Water District, PFAS Phase I Pilot-Scale Treatment Study Final Report (2021). Accessible online: https://clu-in.org/download/contaminantfocus/pfas/ocwd-pfas-pilot-i_finalreport.pdf