PFAS

Summary

• PFAS are a class of thousands of persistent chemicals in consumer and industrial products as well as firefighting foam which can contaminate drinking water sources and cause increased human health risks
• Regulations for maximum contaminant levels of PFAS in drinking water vary depending on jurisdiction and type, with both the U.S. and Canada proposing new regulations for comment early in 2023
• 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. PFAS bioaccumulate in human bodies, leading to increased health risks.

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. 

What are the drinking water requirements?

The U.S. and Canada have proposed different enforceable standards for PFAS in drinking water. In March 2023, the U.S. Environmental Protection Agency announced a proposed rule to establish an enforceable limit for six PFAS chemicals. These include a maximum contaminant level (MCL) of 4 parts per trillion (ppt) for PFOS and PFOA, and a hazard index limiting any mixture containing one or more of PFNA, PFHxS, PFBS, and/or GenX chemicals. Additionally, in February 2023, Health Canada proposed a draft objective of 30 ppt for the sum of all PFAS found in drinking water to protect public health while official guidelines are in development.

In addition to these proposed federal standards, several U.S. states have different MCLs for PFAS in drinking water. See the chart below to understand how these MCLs compare to the proposed federal standards.

Table 1: Enforceable PFAS standards by jurisdiction (in ppt)

*Wisconsin’s MCLs are set at 70 ppt for PFOS and PFOA individually or combined

Although their guidelines for PFAS in drinking water are non-enforceable, Illinois, Indiana, Minnesota, Ohio, and Ontario are also taking meaningful action to protect public health.

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. 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.

Granular Activated Carbon (GAC) has been shown to be a common and more than 90% effective treatment for long-chain PFAS contamination. Several base materials are used for GAC and studies show that bituminous-based products demonstrate higher effectiveness for PFAS removal. GAC is used in treatment plants, ranging in costs from $80,000 to $3 million in facility construction costs. Operational costs such as power and inspections, the cost of carbon (estimated at $1.50 per pound), and disposal costs must also be considered. Purolite estimates the cost of their system to be $0.45/1000 gallons of treated water. GAC adsorbs longer chain PFAS better than shorter chain PFAS and GAC media can be disposed of through landfilling or incineration. 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.

Anion exchange systems involve the use of resins to exchange ions and capture contaminants such as PFAS. Costs will vary depending on the type of treatment system and resin; 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. 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.  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+.

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. U.S. EPA, Per- and Polyfluoroalkyl Substances (PFAS) (2023). Accessible online: https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas
5. Government of Canada, Draft objective for per- and polyfluoroalkyl substances in Canadian drinking water: Overview (2023). Accessible online: https://www.canada.ca/en/health-canada/programs/consultation-draft-objective-per-polyfluoroalkyl-substances-canadian-drinking-water/overview.html
6. 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
7.  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
8. 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
9. 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
10. 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