Per- and polyfluoroalkyl substances (PFAS), nicknamed “forever chemicals” because of their persistence in the environment, are one of the most pressing challenges facing the water industry today.
These synthetic compounds, once renowned for their non-stick and water-repellent properties, have been identified as persistent pollutants in raw water sources across England and Wales.
The Department of Drinking Water Inspection (DWI), in collaboration with leading researchers from Cranfield University, has completed an effectiveness study on the removal of PFAS in drinking water using conventional treatment methods. Previously published literature reviews indicate that a significant amount of research has been conducted on PFAS removal technologies.
Understanding the PFAS threat
PFAS compounds present unique challenges due to their exceptional chemical stability. The strong carbon and fluorine bond makes it useful in fire extinguishing foams, non-stick cookware, stain-resistant fabrics, and more. It is also more durable in the environment.
Once released, they can accumulate in water bodies and remain indefinitely. What makes this particularly difficult is the diversity of PFAS compounds. There are thousands of different variations, each with distinct characteristics that affect how it is removed from the water.
Forty-eight different PFAS compounds have been detected in water sources in England and Wales, ranging from short-chain molecules like perfluorobutanoic acid (PFBA) to long-chain compounds like perfluorooctane sulfonic acid (PFOS). This diversity requires strategically designed treatment processes based on a risk-based approach that incorporates a clear understanding of the source water being treated.
Reducing contamination risk
The DWI study focused on understanding how different water sources in England and Wales (groundwater, upland surface water, and lowland surface water) respond to different treatment technologies.
This approach recognizes that water quality has a significant impact on treatment effectiveness, but this factor is often overlooked in international studies.
The research team evaluated six major treatment approaches: granular activated carbon (GAC) adsorption, surface modified clay (SMC) adsorption, ion exchange (IEX), membrane filtration, advanced oxidation processes, and coagulation. Each technology was tested against 15 different PFAS compounds, providing unprecedented insight into therapeutic efficacy.
An important discovery reveals that long-chain PFAS compounds are generally easier to remove than shorter-chain variants. This is critical because short-chain PFAS, especially four-carbon compounds like perfluorobutanoic acid (PFBA), have proven to be very difficult to treat using traditional methods. This study demonstrated that PFBAs breached treatment systems almost immediately, highlighting the need for a strategic approach when addressing PFAS contamination. Most water treatment processes require coagulation and filtration as part of the standard process.
DWI innovations to eradicate PFAS in drinking water
DWI’s systematic approach identified four technologies with the highest potential for full-scale implementation. Advanced ion exchange resins, membrane filtration, granular activated carbon, and new surface-modified clay materials.
Ion exchange technology has emerged as particularly promising for long-term PFAS removal. This study demonstrated that a specialized PFAS-selective resin achieves sustained removal of most long-chain compounds over extended operating periods, although short-chain compounds such as PFBA and PFBS remain difficult in all treatment methods tested.
However, this study highlights important economic considerations, as maintaining effective treatment may require frequent media changes and regeneration cycles, especially when dealing with diverse PFAS contamination profiles.
Membrane technologies using nanofiltration or reverse osmosis have shown remarkable versatility. In this study, more than 90% removal was achieved for most PFAS compounds, and more than 80% removal was achieved even for problematic short-chain variants. Importantly, nanofiltration requires lower operating pressures than reverse osmosis, making it economically viable for widespread implementation.
Perhaps most importantly, this study reveals that an integrated treatment approach can address the limitations of individual techniques. The study demonstrated that membrane technology provides “better overall removal of a variety of PFASs with fewer limitations and selectivity issues” compared to the use of adsorption or ion exchange technologies individually.
However, the study notes that “these technologies, when used in conjunction, can be an effective treatment process for removing PFAS compounds.”
A pilot-scale study completed in April 2025 provided important real-world validation. Long-chain PFAS compounds were consistently removed more efficiently than short-chain variants, and selectivity for sulfonated PFAS over carboxylic acid compounds was improved. While confirming the universal applicability of nanofiltration membranes, making them a strong option for water bodies with diverse PFAS contamination profiles, the study emphasized that the cost implications for capital and operational expenditures must be fully considered for proposed treatment facilities.
Engineering solutions for implementation
The study provides a detailed cost analysis for different processing scales, from small-scale rural supplies (3.8 megalitres per day) to metropolitan systems (380 megalitres per day). Capital investments range from £1.2m for a small ion exchange system to £57.9m for a large scale membrane facility, with corresponding operational costs reflecting the complexity and intensity of each treatment approach.
Importantly, this study addresses the challenges of waste management. PFAS removal technologies concentrate rather than destroy contaminants, creating a waste stream that must be handled carefully.
This study found that although traditional flocculation processes are not effective for primary PFAS removal, significant concentrations of PFAS migrate into water treatment sludge, potentially impacting disposal options and management strategies. This once again highlights the need for a strategic approach when addressing PFAS contamination.
I’m looking forward to it
DWI research represents a paradigm shift from one-size-fits-all solutions to customized approaches based on specific water properties and PFAS profiles. This precision approach recognizes that effective PFAS management requires understanding the local context and implementing the appropriate technology mix.
The findings of this study will inform regulatory approaches and guide water companies in selecting appropriate treatment technologies. As PFAS regulations continue to evolve globally, this research puts England and Wales at the forefront of practical, evidence-based solutions to one of the water industry’s most challenging problems.
The study also highlights the importance of continuous innovation. Although current technology can effectively address many PFAS compounds, the challenge of short-chain PFAS remains, and the fight against eternal chemicals requires sustained scientific efforts, as the development of new PFAS compounds is ongoing.
As water treatment professionals around the world grapple with PFAS contamination, a comprehensive assessment of DWI provides a roadmap for effective interventions. This research demonstrates that by combining rigorous science with practical engineering solutions, even the most stubborn environmental pollutants can be tackled through systematic innovation and targeted technology deployment.
The fight against persistent chemicals is far from over, but thanks to DWI’s groundbreaking research, water treatment professionals now have the tools and knowledge they need to protect public health while managing the technical and economic challenges posed by these persistent compounds.
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