Perfluorinated Compounds in Drinking Water:Risks, Considerations, & Solutions

Dustin Mobley, P.E.Process Engineer

Water Technology Group

April 17, 2019

Agenda

• Background

• Properties & Application

• Health Effects

• Contamination Routes

• Occurrence

• Regulatory Status

• PFAS Treatment

• Risks, Considerations, & Solutions

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PFAS Background

What is PFAS?

• Per- and Poly-Fluoro Alkyl Substances

• Synthetic Chemicals

• Persistent, bioaccumulative and some exhibit adverse health

effects

• Pervasive

• Ubiquitous

• Largely Unregulated

PFAS are commonly found in human and animal populations worldwide and are not metabolized

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Chemistry of PFAS

• C-F bonds

• Strong, Stable, Persistent

• Fluorinated carbon chain

• Water- and Oil Resistant

• Length contributes to persistence, bioaccumulation

• Functional Groups Yield Useful Properties

• Coatings

• Surfactants

• Dispersants

PFAS properties benefit a wide range of applications but promote migration through the environment

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PFAS Structures

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Over 3,000 PFAS in use today

PFAS History

As legacy PFAS are phased out, new short-chain PFAS are introduced.

2016 - EPA sets health advisory

for PFOA and PFOS of 70 ng/L.

2018 - EPA holds national

leadershipsummit for

PFAS.

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Polyfluorinated Compounds: Past, Present & FutureLindstrom et al., Env. Sci. & Tech.

Applications

Numerous pathways for contamination and human exposure

Firefighting Foams Non-stick Cookware Oil Recovery Food Packaging

Cosmetics Paints & Inks Coatings & Textiles Medical Devices

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Health Effects

• Readily adsorbed through ingestion

• Inhalation & dermal exposures not studied

• Not metabolized (long half-lives)

• Crosses placenta and into breast milk

• Known adverse effects:• Pregnancy complications

• Liver damage

• Increased risks of asthma, thyroid disease, infertility

• Increases in cholesterol (total, LDL)

• Suggestive evidence of additional adverse effects

Need analytical methods to perform health studies

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Common Contamination Routes

• Military Bases & Fire-Fighting Schools

• Use of Aqueous Fire-Fighting Foams (AFFF)

• Waste Disposal

• Runoff

• Landfill Leachate

• Manufacturing

• Air Emissions

• Wastewater Discharges

Preventing contamination at the source is key

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11Likely that contamination is grossly underestimated.

Regulatory Efforts

Regulatory Status (Federal Level)

• EPA Health advisories (2016):

• PFOA < 70 ng/L

• PFOS < 70 ng/L

• Measured individually or combined

• ATSDR Draft Toxicological Profile for PFAS

• PFOA, PFNA, PFHxS, PFOS

• Values up to 10x lower than current HAs

• EPA Draft Toxicological Profile for GenX & PFBS

Lack of health studies on PFAS makes rule-making difficult and slow.

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EPA PFAS Action Plan

Common theme is information gathering.

Key Actions:

• Begin MCL setting process for PFOA & PFOS

• Designate PFOA & PFOS as CERCLA hazardous substances

• Finalize outstanding toxicity assessments + more

• Repeat nationwide sampling (UCMR5)

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Issued February 2019

Regulatory Status (State Level)

Some states dealing with PFAS contamination have developed guidance values more stringent than EPA health advisories.

Information from www.itrcweb.org

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PFAS guidance

PFAS MCL

Federal• PFOA 70 ppt• PFOS 70 ppt

Michigan• PFOA 9 ppt• PFOS 8 ppt• PFNA 9 ppt• PFHxS 84 ppt• PFBS 1,000 ppt

New Jersey• PFOA 14 ppt• PFOS 13 ppt• PFNA 13 ppt (MCL)

PFAS Solutions

Problem Definition & Treatment Goals

Know Your Contaminants

• Measurable, not measurable

• Concentration

• Long-chain, short-chain

• Sulfonates, carboxylic acids

GenX, 6.3%

PFOA, 4.0%

PFOS, 1.6%

PFHpA, 8.4%

PFHxA, 14.0%

PFNA, 0.7%

PFBA, 1.1%

PFBS, 1.1%

PFPeA, 14.3%

PFPeS, 0.2%PFHxS, 1.4%

PFDA, 0.4%

Estimated Compounds

*, 46.5%

Selecting the treatment goal is perhaps as challenging as determining the most cost effective means to remove the contaminants.

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External Factors

Solutions must consider technical, political, public relations, and regulatory components.

• PFAS Regulations/Guidance

•Unknowns

•Available Health Studies

• Customer expectations

•Rates/Cost

• Level of removal (non-detect)

•Other desired outcomes

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Universe of PFAS Solutions

No one-size-fits-all solution for treatment of PFAS.

• Treatment (individual vs. regionalized)

•Granular Activated Carbon

• Ion Exchange

•Reverse Osmosis

• Purchase treated water

•New water supplies (well or surface)

• Blending

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Best Available Technology – GAC/IX

• Granular activated carbon – most widely applied

• Scheduled media replacement

• Staggered replacement yields lower cost

• Piloting recommended to evaluate:

• Media selection

• Expected PFAS removal

• Media replacement can impact operations

IX and GAC replacement driven by influent concentration and treatment goal. 20

Membrane Processes

• Applicable to reverse osmosis

• Near complete removal of all PFASs (95 percent removal)

• Can be combined with GAC or IX for greater removal

• Requires ~15% more raw water

• High levels of PFAS in concentrate stream

• Inland desalination very costly

• Need for pre- and post-treatment

RO becomes more favorable with high concentrations of PFAS

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Available Treatment Technologies

Technology CAPEX OPEX Pros Cons

GAC $$$ - $$

Varies withreplacement

• Removes wide range of organics

• Removes from environment• Re-useable media

• More frequency replacement• Low adsorption capacity• Early breakthrough of short

chain PFASs

IX $$$ - $$

Varies withreplacement

• Targeted removal of PFASs• Higher adsorption capacity• Removes from environment• Less frequent replacement

• Single use media• Removal of short chain PFASs• Removes few other

contaminants

RO $$$$$ - $$$

Varies with effluent goal

• High level of PFAS removal• Removes other contaminants• Indiscriminately removes all

contaminants

• Concentrated waste stream • Requires post treatment

stabilization

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• Breakthrough order based on

• Straight carbon length

• Sulfate or acid functional group

• Treatment validation/optimization

• Doubling the EBCT resulted in 70% improvement in GAC replacement

• Adjusting replacement provides flexibility in uncertain regulatory environment

Piloting provides certainty in the selected treatment method.

The Importance of Piloting

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Keys to dealing with PFAS:Knowledge + Communications

• Understand what compounds are present

• Develop reliable capital and cost models

• Evaluate various solutions

• Cost impact to consumer

• Flexibility if regulations change

• Proactive communication with stakeholders

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Dustin Mobley, P.E.Process EngineerBlack & VeatchMobleyDR@BV.com