PFAS in Water Systems: Sources, Challenges and Emerging Removal Technologies

Abstract

Per- and polyfluoroalkyl substances (PFAS) have emerged as one of the most critical classes of persistent organic contaminants threatening global water resources. Due to their exceptional chemical stability, resistance to degradation, and widespread industrial applications, PFAS are increasingly detected in groundwater, surface water, wastewater, and even drinking water supplies.

This article reviews the origin and environmental pathways of PFAS contamination, with a particular focus on aquatic systems. It also examines the principal analytical techniques currently used for PFAS detection and quantification in water matrices, including LC-MS/MS and high-resolution mass spectrometry. Furthermore, the study critically analyzes conventional and advanced PFAS removal technologies such as activated carbon adsorption, ion exchange resins, nanofiltration, reverse osmosis, advanced oxidation, plasma technologies, and electrochemical degradation. The advantages, operational limitations, and energy implications of each technology are discussed.

Special emphasis is placed on the challenges facing desalination-dependent regions such as the Middle East and North Africa (MENA), where water scarcity and emerging contaminants constitute interconnected strategic risks. The article concludes that integrated treatment approaches combining advanced monitoring, source control, membrane processes, and destructive technologies are essential for long-term PFAS management and water security.

Introduction

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic fluorinated compounds characterized by strong carbon-fluorine bonds, among the strongest chemical bonds in organic chemistry [1]. These compounds possess unique physicochemical properties including thermal stability, hydrophobicity, lipophobicity, and chemical resistance, which have made them indispensable in numerous industrial and commercial applications for more than seven decades [2].

PFAS have been extensively used in firefighting foams, non-stick cookware, food packaging, textile coatings, aerospace materials, electronics manufacturing, pesticides, and metal plating industries [3]. However, their remarkable stability has also resulted in extreme environmental persistence, earning them the designation “forever chemicals” [4].

Over the last decade, growing scientific evidence has demonstrated the widespread occurrence of PFAS in aquatic environments worldwide, including groundwater aquifers, rivers, lakes, wastewater effluents, seawater, and drinking water systems [5]. Their persistence and mobility raise serious concerns regarding environmental contamination, bioaccumulation, ecosystem disruption, and human health risks [6].

In arid and semi-arid regions such as the Middle East and North Africa (MENA), the issue becomes even more critical due to increasing dependence on desalination, water reuse, and highly stressed water resources [7]. Consequently, understanding PFAS contamination pathways, analytical detection methods, and efficient removal technologies has become a strategic priority for sustainable water management.

This article reviews the major sources and occurrence of PFAS in water systems, analyzes state-of-the-art analytical methods, and critically discusses existing and emerging technologies for PFAS removal and destruction.

Sources and Occurrence of PFAS in Water Systems

Industrial Sources

Industrial activities remain the dominant source of PFAS contamination in water environments. Significant emissions originate from fluoropolymer manufacturing facilities, electroplating industries, semiconductor production plants, and textile treatment operations [8].

Aqueous film-forming foams (AFFF), extensively used in airports, military bases, and firefighting training centers, are among the most documented contributors to severe groundwater contamination [9]. Studies have reported PFAS concentrations exceeding several µg/L in aquifers surrounding firefighting sites [10].

Municipal and Domestic Sources

Municipal wastewater treatment plants (WWTPs) represent secondary but significant PFAS sources. Conventional biological treatment systems are generally ineffective at degrading PFAS molecules due to their high chemical stability [11]. Consequently, treated effluents often discharge PFAS into rivers and coastal waters.

PFAS-containing consumer products such as cosmetics, waterproof textiles, food-contact materials, detergents, and household products also contribute to diffuse urban contamination [12].

Landfills and Leachates

Landfill leachates contain elevated concentrations of PFAS due to disposal of contaminated industrial and domestic waste. These leachates can infiltrate groundwater systems and persist for decades [13].

Several studies have identified municipal landfills as long-term PFAS reservoirs capable of continuously releasing contaminants into surrounding hydrological systems [14].

Occurrence in Drinking Water

PFAS contamination of drinking water has become a major global concern. Monitoring campaigns in North America, Europe, and Asia have detected PFAS in public water supplies serving millions of people [15].

The United States Environmental Protection Agency (EPA) recently established extremely low drinking water limits for PFOA and PFOS due to their toxicity and persistence [16].

Human Health and Environmental Impacts

PFAS exposure is associated with multiple adverse health effects. Epidemiological and toxicological studies have linked certain PFAS compounds to:

• endocrine disruption;
• immune system suppression;
• liver dysfunction;
• thyroid disorders;
• reproductive toxicity;
• developmental effects;
• elevated cholesterol levels;
• kidney and testicular cancers [17].

Some PFAS compounds exhibit biological half-lives ranging from several years to decades in humans [18]. Their bioaccumulative nature increases long-term exposure risks through drinking water and food chains.

Ecologically, PFAS can affect aquatic organisms, alter microbial communities, and disrupt trophic interactions within freshwater and marine ecosystems [19].

Materials and Methods: Analytical Techniques for PFAS Detection

Sampling and Sample Preparation

PFAS analysis requires strict contamination control because these compounds are present in numerous laboratory materials such as Teflon tubing and fluoropolymer containers [20].

Solid-phase extraction (SPE) is commonly employed for concentration and purification of water samples prior to instrumental analysis [21].

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is currently considered the reference analytical method for PFAS quantification in water matrices [22].

The technique provides:

• high sensitivity;
• low detection limits (ng/L);
• excellent selectivity;
• simultaneous multi-compound analysis.

EPA Methods 533 and 537.1 are widely applied for drinking water monitoring [23].

High-Resolution Mass Spectrometry (HRMS)

High-resolution mass spectrometry enables non-targeted screening and identification of unknown PFAS compounds [24]. HRMS has become increasingly important because thousands of PFAS molecules remain poorly characterized or unregulated.

Emerging Analytical Approaches

Recent advances include:

• total oxidizable precursor (TOP) assay;
• extractable organic fluorine (EOF) analysis;
• combustion ion chromatography;
• fluorine mass balance methods [25].

These approaches improve understanding of precursor compounds and total fluorinated organic content in environmental samples.

Results and Discussion: Technologies for PFAS Removal from Water

Granular Activated Carbon (GAC)

Granular activated carbon remains one of the most widely used PFAS treatment technologies in drinking water facilities [26].

Performance

GAC exhibits high adsorption efficiency for long-chain PFAS such as PFOS and PFOA, with removal efficiencies frequently exceeding 90% [27].

Limitations

However, shorter-chain PFAS demonstrate lower adsorption affinity, reducing treatment efficiency [28]. Media exhaustion and regeneration costs also represent major operational challenges.

Ion Exchange Resins

Ion exchange resins provide high PFAS removal capacities and rapid adsorption kinetics [29].

Studies have demonstrated removal efficiencies between 90–99% depending on water composition and PFAS characteristics [30].

Advantages

• higher capacity than activated carbon;
• efficient short-chain PFAS removal;
• compact system design.

Challenges

Resin fouling, regeneration complexity, and waste management remain critical concerns.

Nanofiltration and Reverse Osmosis

Pressure-driven membrane technologies currently provide the highest PFAS rejection efficiencies [31].

Performance

Reverse osmosis (RO) systems can achieve rejection rates above 99% for many PFAS compounds [32]. Nanofiltration membranes also demonstrate strong performance for high molecular weight PFAS.

Limitations

Despite their effectiveness, membrane systems generate concentrated brines containing elevated PFAS levels [33]. Managing these concentrates represents one of the major unresolved challenges in PFAS treatment.

Additionally, RO systems involve substantial energy consumption, particularly in seawater desalination applications.

Advanced Oxidation and Destructive Technologies

Conventional oxidation processes are generally ineffective against PFAS because of the strong C–F bond [34]. Consequently, research has shifted toward advanced destructive technologies including:

• electrochemical oxidation;
• plasma treatment;
• UV-persulfate systems;
• sonochemical degradation;
• supercritical water oxidation [35].

These technologies aim to mineralize PFAS rather than merely transfer contaminants to another phase.

Electrochemical Oxidation

Electrochemical oxidation has demonstrated promising PFAS degradation capabilities, particularly when using boron-doped diamond electrodes [36].

However, high electrical energy demand and electrode costs currently limit large-scale implementation.

Plasma Technologies

Cold plasma processes generate highly reactive radicals capable of breaking PFAS molecular structures [37].

Recent pilot-scale studies reported degradation efficiencies exceeding 95% under optimized conditions [38].

Nevertheless, operational scalability and energy optimization remain under investigation.

Challenges and Future Perspectives

Several critical challenges continue to hinder effective PFAS management:

Regulatory Complexity

More than 10,000 PFAS compounds exist, yet only a small fraction are regulated [39].

Analytical Limitations

Current analytical methods cannot comprehensively identify all fluorinated compounds present in environmental samples.

Concentrate Management

Membrane and adsorption systems often transfer PFAS into secondary waste streams requiring further treatment.

Energy and Sustainability Issues

Advanced destructive technologies remain highly energy-intensive and economically challenging for full-scale deployment.

Implications for Desalination Regions

In desalination-dependent regions such as the MENA region, PFAS contamination introduces additional complexity to water security strategies. Concentrated PFAS rejection in desalination brines may create emerging environmental risks for marine ecosystems [40].

Integrated approaches combining advanced monitoring, hybrid treatment systems, renewable energy integration, and source reduction policies will likely define the next generation of PFAS management strategies.

Conclusion

PFAS contamination has emerged as a critical global environmental and public health issue due to the persistence, mobility, and toxicity of these fluorinated compounds. Water systems are particularly vulnerable because PFAS are highly resistant to conventional treatment processes and can accumulate across aquatic environments.

Analytical advancements such as LC-MS/MS and HRMS have significantly improved PFAS detection capabilities, enabling trace-level monitoring in complex water matrices. Meanwhile, adsorption, ion exchange, nanofiltration, and reverse osmosis remain the principal technologies for PFAS removal from water.

However, most current technologies only concentrate PFAS rather than destroy them completely. Emerging destructive approaches including electrochemical oxidation, plasma treatment, and advanced oxidation processes show considerable promise but still face economic and energetic barriers.

Future sustainable PFAS management will require integrated multidisciplinary strategies combining source control, advanced analytics, hybrid treatment technologies, regulatory harmonization, and circular water management principles, particularly in water-stressed regions increasingly dependent on desalination and water reuse.

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