Treatment Process

The treatment process for PFAS can be quite involved, due to the many chemistry challenges.

Many typical water purification techniques are not able to treat PFAS from water.  These ineffective techniques include bio-degradation, micron filtration, sand filtration, ultrafiltration, coagulation, flocculation, clarification, and oxidation by ultraviolet light, hypochlorite, chlorine dioxide, chloramine, ozone, or permanganate. None of these techniques will work. The only techniques that have been found to treat PFAS from water, are carbon adsorption, ion exchange, and reverse osmosis.  Also, some experimental techniques such as gas flotation are being tried with success.

Pretreatment

Before the PFAS treatment, the water must first be treated to remove suspended solids, particles, colloids, iron, manganese, Total Organic Carbon, oxidizing agents, bacteria, and various other contaminants, so that the carbon media, ion exchange media, or reverse osmosis unit can succeed in removing the PFAS. Thus the water is said to be pretreated prior to PFAS treatment. Such pretreatment may include many of the techniques mentioned above in the second paragraph:  micron filtration, clarification, etc.

PFAS Treatment

Once the water has been prepared, the selection of PFAS treatment technique is made. Finally, once the PFAS is treated by the carbon, ion exchange or reverse osmosis, it must be properly disposed of. Each of these technologies has many advantages and disadvantages. Learn more about which PFAS treatment technology is best for you by contacting us or downloading or brochure at the top of the page. 

Disposal

Typically disposal consists of either burning the PFAS in a high-temperature incinerator (best available technology) or disposed of in a suitable landfill.  With carbon, the carbon media may be recycled for use elsewhere after the PFAS is burned off.  With resin, the media is typically used once and incinerated.  Resin lasts a very long time, so the economics are attractive.  With reverse osmosis, the client must have a suitable destination for the concentrate water stream, which is termed RO Reject.  This stream can itself be further treated with carbon, or in some cases, ion exchange before discharge.  As the volume of reject water is small relative to the feed, the economics may succeed.    Any release would be subject to approval by the regulatory authorities.  The stream could also be deep well injected or treated by evaporation-crystallization followed by incineration or landfill. 

PFAS history

Perfluoro Alkyl substances come in many varieties. While there are an estimated 4700 (and growing) different types of these compounds, the ones of most concern are typically chains of 4-9 carbon atoms, fully saturated with fluorine, terminating in either a sulfonate or carboxylic moiety, or functional group. Some of the most common PFAS types and their abbreviations are: Sulfonic Acids/Sulfonates: - PFBS – perfluoro butanesulfonic acid - PFHxS – perfluorohexane sulfonic acid 8 - PFOS - perfluorooctane sulfonic acid Carboxylic Acids: - PFBA – perfluoro butanoic acid - PFHxA - perfluorohexanoic acid - PFHpA – perfluoro heptanoic acid - PFOA – perfluorooctanoic acid - PFNA - perfluorononanoic acid

This class of compounds has been around for over 60 years and was originally developed by organic chemists in search of better performing surfactants in certain applications. The three most common classes of applications are firefighting foams, surface-active agents in consumer products, and surface-active agents in manufacturing. Firefighting foams using PFAS form an excellent film for the suppression of liquid hydrocarbon-fueled fires. The foam coats the liquid fuel and smothers the fire. Consumer products use PFAS for oil resistance in food packaging, and for stain resistance in fabric and leather. Manufacturing applications include emulsifiers, wetting agents, and constituents of coating materials. The dual lipo-phobic and hydrophobic characteristics of the PFAS molecule confer superior performance in these applications.

Substitution of non-PFAS surfactant materials or alternately, a program of careful use, handling, recovery and destruction are warranted. Incineration of the material is the gold standard of treatment of material that is removed from water or sludge. If incineration is not possible, then concentration and a method of permanent sequestration are called for. Although landfill is still allowed in some jurisdictions, this practice is expected to reduce in frequency, in favor of more permanent and less risky alternatives. The key emerging areas of treatment are:

• legacy sites: Remediation of firefighting sites, Remediation of military sites, Remediation of industrial discharge sites
• ongoing use cases: Treatment of drinking water that has been contaminated with PFAS, Cleanup of municipal wastewater treatment water, prior to discharge (recycling back into the environment), Cleanup of industrial wastewater prior to being discharged into a receiving body, Treatment of the newer classes of PFASs that have not yet had their safety determined

Frequently asked questions about PFAS 

What is PFAS?

PFAS is an acronym for either Perfluoroalkyl Substances or Polyfluoroalkyl Substances. Typically, the term PFAS is used to refer to a broad range of man-made organic molecules containing a short to long chain of carbon atoms. The carbon atoms are bonded with fluorine atoms which is the key to the material properties. From a chemistry point of view, the substances are typically C4 to C9 (meaning 4 carbons or 9 carbons) usually straight chain, but sometimes branched chain of carbon atoms. PFAS materials are included within the much larger class of compounds called fluorinated organic molecules, or simply fluorocarbons. While it is estimated there are over 5000 types of PFAS molecules, there are approximately twenty types of most concern. These include the (now familiar) sulfonic acids and carboxylic PFAS compounds listed below, together with their number of carbon atoms:

• Sulfonic Acids/Sulfonates:
  • 4 - PFBS – perfluoro butanesulfonic acid
  • 6 - PFHxS – perfluorohexane sulfonic acid
  • 8 - PFOS - perfluorooctane sulfonic acid (or sulfonate)
• Carboxylic Acids:
  • 4 - PFBA – perfluoro butanoic acid
  • 6 - PFHxA - perfluorohexanoic acid
  • 7 - PFHpA – perfluoro heptanoic acid
  • 8 - PFOA – perfluorooctanoic acid
  • 9 - PFNA - perfluorononanoic acid

 

What is the difference between PFC (Perfluorocarbons) and PFAS (Perfluoroalkyl substances)

There are several differences:

• PFC compounds contain only carbon ( C ) and fluorine ( F ).
• PFAS compounds contain at a minimum, carbon, fluorine, and oxygen ( O ) , plus hydrogen ( H ) in the acid form, or if one or more of the original C-H bonds remains (i.e., has not been displaced by F).  Different PFAS compounds may also contain sulfur ( S ) and nitrogen ( N ).
• Both are human-manufactured, long-lived chemicals, typically not found in nature, which persist for decades in the environment, since they are not biodegradable.
• PFC compounds come in either volatile small molecules, such as CF4, or non-volatile plastics such as PTFE or Teflon.   If released, volatile PFCs harm the atmosphere, while the plastics do not.  Neither are considered toxic.  As a result, PFAS are treated as drinking water contaminants, while PFCs typically are not.
• PFAS molecules have specific functional groups that impart surfactant (soap-like) functionality, making them excellent for fire-fighting foams, among dozens of industrial uses. 
• Unfortunately, these functional groups often impart toxicity to the molecule.
• Since PFC compounds are generally either simple, small molecules, or chains or polymers, they are generally limited in terms of chemical structure.  PFCs do not typically contain a multiplicity of chemical functional groups such as carboxylic groups, sulfonate groups, amides, or ether structures. 
• PFAS do have some or several of these functional groups in different combinations; and, are therefore much more varied in structure, with over 4000 different PFAS compounds identified to data. 
• As a result of the multitude of chemical structures, PFAS are much more varied and complicated versus PFCs, in terms of manufacture, fate, transport, toxicity, environmental risk, breakdown pathways, treatment, remediation, chemistry, final destruction, testing, safety, and handling requirements & techniques.
• The most common PFAS are chains of carbon of between 3 to 12 carbons, normally, but not necessarily, saturated with fluorine, and terminating in either a carboxylate or sulfonate group (either COOH or SO3H or their respective salts).    

Why does PFAS exist?

This special class of compounds was invented about 60 years ago and found to confer superior benefits in a broad variety of applications.  The most important application has been as an active ingredient in fire fighting foams.  The product, when mixed with water, can suppress a hydrocarbon fueled fire better than any other known substance.  For endeavors that deal with high quantities of fuel, such as aviation, the military, fuel pipelines, and depots, a good firefighting foam is indispensable.  The molecule is both hydrophobic and paradoxically, lipophobic.  It does not “like” either water or oil.  Therefore in use, it immediately migrates to the interface between fuel and air, smothering and suppressing a fire.  Its foam spreads faster than any other known substance to suppress these fires.  Other applications include stain coatings for carpet, clothing, and outdoor gear, together with grease-resistant coatings for packaging

How do you treat PFAS?

PFAS can be treated in water by one of three techniques:  Selective Ion Exchange Resins, Carbon Adsorption, and Membrane separation called Reverse Osmosis or Nanofiltration.  Each technique has advantages and disadvantages, as outlined in the brochure table, shown nearby. Factors that will influence the approach will be water constituents, co-contaminants in the water such as suspended solids, organic contamination, other related fluorinated compounds, and the various dissolved solids; regulatory and discharge constraints; permitting concerns; removal media availability and suitability; footprint—space--availability; decisions around lease versus capital purchase; preferences for operating versus capital budget; energy availability and consumption, and more.

How do I know if my water has PFAS? 

To determine the level and type(s) of PFAS in a water supply, a careful sample must be sent to a lab with the equipment and processes to measure.  The US EPA has documented laboratory methods for analyzing PFAS such as EPA Methods 533 and 537.1.  Many labs in the US and around the world can perform the test.  Up to 25 PFAS compounds (the list is growing)  can be identified using this method, typically with a lead time of 1 to 2 weeks.  The lab method used is Liquid Chromatography followed by tandem Mass Spectrometry.  Results are typically reported in Parts per Trillion, or ppt.  Before testing, in the USA, it is worthwhile to check with the EPA web site devoted to the UCMR, or unregulated contaminant monitoring rule.  The site contains test results for thousands of locations around the USA and is in frequent use by Municipalities, the Military, and Industry as cleanup efforts are initiated

How do you dispose of and destruct PFAS?

The PFAS that are collected in treatment systems are concentrated and captured on special filtration media.  This media must be removed from service and shipped off site for proper disposal including properly permitted landfills and/or incineration facilities that can breaks down PFAS at high temperatures.  High-temperature incineration can break the carbon-fluorine bond, to treat the PFAS and turns the fluorine into a fluoride ion in a process called “mineralization”.   Once mineralized, the fluoride can be treated further as required.

Will pending legislation impact how PFAS can be treated?

Congress, the EPA and the European Union are actively working on new rules and laws that would limit the use and/or discharge of PFAS materials.  In many applications,  they will be replaced with compounds that are not per- or poly-fluorinated.  In situations where human life and safety require their continued use, such as dangerous liquid hydrocarbon fires aboard military ships and on land, we expect prudent use and careful cleanup is likely to be enforced to avoid subsequent environmental contamination.  In the meantime, the EPA, the Military, and State departments are actively assessing water supplies around the country to ensure that wherever the population is at risk, both immediate short and long term solutions are implemented to provide safe, clean water.  Fortunately, as we have seen with PFOA, and PFOS, which have been out of production for over 10 years, the concentrations in the blood serum of the population are coming down significantly, indicating that cleanup, though slow, is possible.

Veolia has extensive experience in the supply of equipment, chemicals and services to the remediation, cleanup, and drinking water markets. More specifically, we have applied media, resin and membrane technology to a variety of challenges in producing safe, clean potable water. We have developed and introduced a range of treatment technologies to address contamination in each of the industrial, military, and municipal applications encountered across the world. Our technologies include: