PFAS (Per- and Polyfluoroalkyl Substances) are a large group of synthetic chemicals that have been widely used in industrial processes and consumer products since the 1940s. These substances are valued for their resistance to heat, water, grease and chemicals, but the same properties also make them highly persistent in the environment.
Because PFAS break down very slowly, they are often referred to as “forever chemicals”. Once released into soil, groundwater, lakes or rivers, they can remain for many years and may accumulate in both wildlife and humans.
Where do PFAS come from?
PFAS can originate from many different sources, including:
- Firefighting foams
- Industrial manufacturing processes
- Surface treatments
- Textiles and outdoor clothing
- Food packaging
- Non-stick coatings
- Landfills and waste sites
- Wastewater treatment plants
- Contaminated groundwater
In some areas, historical use of firefighting foams has resulted in significant PFAS contamination of groundwater and drinking water resources.
Example PFAS molecular structure
One of the most well-known PFAS compounds is PFOA (Perfluorooctanoic Acid). Simplified structure:
CF3-(CF2)6-COOH
Another common PFAS compound is PFOS (Perfluorooctane Sulfonate):
CF3-(CF2)7-SO3H
Why are PFAS so persistent?
PFAS molecules contain chains of carbon atoms where most or all hydrogen atoms have been replaced by fluorine atoms. The carbon–fluorine (C–F) bond is one of the strongest chemical bonds in organic chemistry. This makes PFAS highly resistant to biological degradation, oxidation, heat, sunlight and natural environmental processes. As a result, PFAS can persist in water, soil and sediments for many years and are often called forever chemicals.
F F F
| | |
— C — C — C —
| | |
F F F
PFAS chemistry, PFOA structure, PFOS structure and the carbon–fluorine bond explain why conventional treatment is often insufficient and why PFAS are called forever chemicals.
Key characteristics of PFAS
| Property | Effect |
|---|---|
| Strong C–F bonds | High chemical stability |
| Water and oil repellent | Useful in industrial products |
| Resistant to degradation | Long environmental persistence |
| Mobile in water | Can spread through groundwater |
| Difficult to remove | Often requires advanced treatment |
Why are PFAS a concern?
PFAS are environmentally persistent and can travel long distances in water systems. Some PFAS compounds have been associated with potential effects on human health and have therefore become the subject of increasing regulatory attention around the world.
- Persistence in the environment
- Bioaccumulation
- Contamination of drinking water sources
- Difficult and expensive remediation
- Increasing regulatory requirements
How can PFAS be removed from water?
PFAS are among the most challenging contaminants to remove from water because of the extremely strong carbon–fluorine (C–F) bonds that make these compounds highly stable and resistant to natural degradation. Conventional water treatment processes such as sedimentation, sand filtration, UV disinfection and chlorination are generally ineffective at removing or destroying PFAS.
A range of specialized technologies has therefore been developed to either remove PFAS from water or destroy the PFAS molecules themselves.
PFAS removal technologies include:
- Activated carbon (GAC)
- Ion exchange resins
- Zeolites and other selective adsorption media
- Reverse osmosis (RO)
- Nanofiltration (NF)
- Flotation
- Specialized adsorption technologies
These technologies primarily separate PFAS from the water, producing either a concentrated waste stream or a spent treatment media that must be managed appropriately.
PFAS destruction technologies include:
- Advanced oxidation processes (AOPs)
- Specialized AOPs and hybrid treatment systems
- Electrochemical oxidation
- Plasma-based treatment technologies
- Radiation-based treatment methods
- Sonolysis (ultrasound treatment)
- Other emerging physical and chemical destruction technologies
Unlike removal technologies, destruction processes aim to break the carbon–fluorine bonds within PFAS molecules, reducing them to smaller compounds and ultimately mineralizing them into less harmful substances.
The most appropriate treatment strategy depends on many factors, including PFAS concentration, water chemistry, the presence of co-contaminants, regulatory requirements and the intended use of the treated water. In many cases, a combination of removal and destruction technologies provides the most effective solution.
See also PFAS Removal, Activated Carbon, Ion Exchange, Reverse Osmosis, Water Reuse and Water Analysis.
PFAS and water reuse
PFAS should always be considered when evaluating water reuse, especially where industrial process water, landfill leachate, wastewater or impacted groundwater are involved. Risk assessments, water analysis and appropriate treatment barriers are often required before water can be safely reused.
Open the water reuse risk assessment tool →
Quick facts
- What does PFAS stand for?
- Per- and Polyfluoroalkyl Substances.
- Why are PFAS called forever chemicals?
- Many PFAS compounds degrade extremely slowly and may persist in the environment for decades.
- Can PFAS be removed from water?
- Yes, but specialized treatment technologies are generally required.
- Are all PFAS the same?
- No. PFAS is a large family consisting of thousands of different compounds with varying properties and behaviour.