PFAS

Perspectives and Insights > PFAS

Introduction

PFAS, or Per- and Polyfluoroalkyl Substances, comprise a complex family of more than 10,000 synthetic chemicals that are widely used in everyday products due to their resistance to water, grease, and stains. These chemicals have been utilized for decades in a range of applications, including non-stick cookware, water-repellent fabrics, and firefighting foams.

Though highly valuable for these purposes, growing evidence points to potential health risks associated with PFAS exposure and their persistence in the environment. As they are commonly referred to as “forever chemicals,” due to their inability to break down naturally, concerns over their impact on both human health and the environment have led to increased scrutiny and regulation.

Top Takeaways PFAS Drinking Water Regulation

What are PFAS Chemicals?

Per and Poly Fluoroalkyl Substances
Group of over 10,000 fluorinated organic chemicals
Emerging Contaminant
Become engrained in almost everything we use

Where are PFAS Used?

Used to make products more heat resistant, stain-resistant, waterproof and/or nonstick as well as help reduce friction in certain products.

Fire-fighting foams
Fabric surface protectants
Upholstered furniture & carpets
Cleaning products
Pesticide formulations
Non-stick cookware
Electronic devices
Some food takeout containers
Paint & building materials

Potential Health Impacts

Reproductive effects
Developmental effects
Effects on the immune system (antibody production)
Increased risk of cancer
Increased cholesterol/risk of obesity

Accumulate and stay in the body.

Impacts can occur at fairly low concentrations.

Final Regulation

The United States Environmental Protection Agency (EPA) has finalized the first ever drinking water regulations for six PFAS chemicals. The final rule sets a maximum contaminant level goal (MCLG) of zero and a maximum contaminant level (MCL) of 4.0 Parts per Trillion (ppt) for both PFOS and PFOA. The rule also sets individual MCLGs and MCLs of 10 ppt for PFHsS, PFNA, and HFPO-DA (GenX).

EPA also proposed a Hazard Index approach, as described below, toward the regulation of a mixture of four PFAS chemicals: PFHxS, HFPO-DA (GenX), PFNA, and PFBS. The finalized regulatory framework is based on running annual average of samples, which is similar to the compliance methodology for disinfection by-products.

Hazard Index

Health Based Water Concentration (HBWC)

Levels protective of health effects over a lifetime of exposure, including sensitive populations and life stages.

Hazard Quotient

Ratio of potential exposure to a substance and the level at which no health effects are expected (HBWC).

Hazard Index (HI)

Sum of component Hazard Quotients (HQs), which are calculated by dividing the measured regulated PFAS component contaminant concentration in water by the associated Health Based Water Concentration.

A hazard index calculation greater than 1 would trigger a violation and corresponding regulatory enforcement action.

Treatment Technologies

Considerations for selecting a treatment solution:

• Space available

• Pretreatment requirements

• Removal effectiveness

• Capital investment

• Operating costs

• Disposal of waste/media

Granular Activated Carbon (GAC)

Removal Mechanism:

PFAS compounds absorb to the porous carbon particles

Most proven PFAS treatment technology
Removal effectiveness affected by other water quality parameters such as Total Organic Carbon (TOC)
GAC is typically a single use product and requires disposal once breakthrough has occurred
Less effective for some PFAS, such as short-chain
GAC regeneration and carbon disposal is a potential pollution concern
Regenerated GAC can not be utilized in drinking water
Relatively large equipment footprint

Ion Exchange (IX)

Removal Mechanism:

Positively charged resins/polymers bind the negatively charged PFAS (and other) compounds

Can be specialized for specific PFAS compounds
Most IX resins used for PFAS are single use media due to difficulties achieving effective regeneration
Other IX resins are being promoted as effective for onsite regeneration using proprietary regeneration processes
Proprietary resins and limited suppliers can increase costs
Reduced equipment footprint

Reverse Osmosis (RO)

Removal Mechanism:

Contaminated water is pressurized and forced through a semipermeable membrane that filters out PFAS (and other contaminants)

Best broad spectrum PFAS removal but most costly treatment solution
The PFAS is concentrated into a brine waste stream
Moderate equipment footprint
Increased energy and chemical costs
Disposal of waste brine stream can be difficult

Treatment Residuals Issues

PFAS accumulating in treatment residuals also presents challenges. Options for treatment residuals are provided below:

GAC – Spent Media Incinerated/Landfilled
Ion Exchange – Spent Media Incinerated/Landfilled
RO – Brine Sent to Sanitary Sewer or Landfilled

Future regulatory actions not under the Safe Drinking Water Act (SDWA) may have a bearing on future disposal options.

PFAS Resources

The Update is a monthly newsletter exclusively focused on U.S. water news, encompassing regulatory compliance and political developments.

PFAS Articles from The Update

AE2S is Advanced Engineering and Environmental Services

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Nate Weisenburger, PE, P Eng, ENV-SP
(406) 268-0626