Emerging regulatory requirements and restrictions for per- and polyfluoroalkyl substances (PFAS) will see stricter limits on permitted levels in industry emissions. This brings distinct challenges for companies with water-intensive operations. Even if PFAS are not used directly in process media, contamination may occur within the fluid handling and wastewater infrastructure.
For some businesses, PFAS restrictions for wastewater will have significant consequences, so a systematic response is key. There are four key aspects to this: identifying the presence of PFAS and replacing upstream sources where feasible, then detecting and removing PFAS before discharge when replacement isn’t an option.
Managing PFAS is complex. There are thousands of distinct compounds and harmful effects may be associated with extremely low concentrations. Accurate detection and effective mitigation present significant technical challenges which may take time to resolve, so an early, well-informed response will minimize the risk of disruption later.
Identify where PFAS exist in wastewater
The first step is to determine whether wastewater contains PFAS. If so, the PFAS type/s and quantities must be identified, as well as where, why and how they are introduced. This is rarely straightforward and can take months to resolve, so steps must be taken to identify both direct and indirect sources of PFAS sooner rather than later.
Testing is widely used to obtain this knowledge, which takes time and can be costly, especially for companies with multiple facilities and waste streams. Nevertheless, it can yield specific, reliable data on chemicals and concentrations. To ensure results are accurate and meaningful, sampling and analysis strategies must be carefully designed to ensure they are representative and robust.
Engaging with suppliers to obtain information on PFAS in raw materials, process chemicals, and equipment across the supply chain can inform testing and help manage costs. Strategies for supply chain surveys and data gathering are determined case by case and usually need support from the procurement team as well as regulatory affairs and product stewardship experts.
Gathering information from suppliers can be a slow, resource-intensive process, particularly when complex systems and/or multi-tiered supply chains are involved. Close liaison and an educative approach may be required to bring suppliers onboard, and confidential business information must be respected and managed with care.
Replace upstream sources of PFAS
PFAS chemicals are used for a variety of reasons, and replacement is more problematic for some uses than others. Nonetheless, all sources will be in the firing line, so investment is needed to stay ahead of regulations.
Take fluoropolymers, such as PTFE (found in many corrosion resistant pipe coatings) or FKM (routinely used to make O-ring seals). It’s often the case that a fluoropolymer’s full scope of properties is not necessary for a given application and an alternative with ‘just enough’ properties might be adequate. A relatively common, commercially available alternative may already exist, or design changes might avoid the need for a direct alternative.
Some sectors have made rapid progress towards solving the PFAS replacement issue, with large percentages of the market already using commercially available alternatives.
For other sectors, replacement is not so simple. The development and testing of alternatives can take months, possibly even decades, especially when PFAS provides a performance- or safety-critical function. Rigorous testing is needed at a material, component, and system level to demonstrate that all necessary criteria are satisfied before an alternative is qualified and introduced.
In any replacement project, increased cost is a primary challenge. Fluorinated polymers are relatively cheap not because they’re easy to manufacture, but because largescale production has been a priority. A choice may have to be made between waiting for the scale-up of alternatives or taking the early adoption route and banking on them getting cheaper as use becomes more widespread.
Ideally, a PFAS replacement should facilitate global regulatory compliance. This avoids the need for multiple product specifications, simplifies regulatory strategy, and supports free flow of products from common manufacturing processes and facilities to different markets. As regulatory authorities around the world place greater emphasis on chemicals, and divergence between and within markets escalates, an understanding of the global landscape will enable well-informed decisions about substitution.
Detect PFAS levels in line with regulatory limits
When it comes to measuring PFAS content in water, liquid chromatography-mass spectrometry (LC-MS) is the current gold standard. This technique is expensive, in terms of the equipment and expertise required. Proper calibration is needed for each PFAS compound of interest. So, while some organizations are developing in-house capabilities, most send samples to specialist PFAS test houses. However, this has a high per-sample cost and longer turnaround times (usually a matter of weeks), which limits currency and efficacy.
At present, the number of laboratories with expertise in PFAS testing is limited. PFAS sampling presents challenges too, with specialist expertise needed to gather and process samples to avoid cross-contamination.
Meanwhile, sensor technologies for PFAS detection1 in water are emerging. The two key properties of any sensor are sensitivity (the ability to detect low concentrations) and selectivity (the ability to detect specific PFAS species).
Electrochemical sensors with a PFAS-selective adsorptive layer on the surface (usually a molecularly imprinted polymer) are one area of interest. Since PFAS are unreactive, these sensors generally employ a separate redox probe (for example oxygen or ferri/ferrocyanide).
Optical sensors are also attracting a lot of attention. These utilize PFAS’ interactions with various dye molecules to generate detectable color changes. They are interesting from a cost management perspective, but have high limits of detection. Other sensor-based approaches which may hold potential include fluorescence-based methods and those based on bacteria or protein binding.
While these sensor technologies hold promise, they all have limitations. For example, in complex mixtures PFAS detection is prone to interference from similar components, such as other surfactants or organic acids. Cross-sensitivity between different PFAS molecules is a major challenge too, as is measuring some of the more difficult PFAS at all. At their current level of development, existing sensor technologies may only be useful for a subset of applications.
Remove and destroy PFAS found in wastewater
Greater emphasis on the control and removal of PFAS from wastewater is to be expected in the future. Various emerging and competing removal methods exist, each with their own advantages and disadvantages.
Conventional PFAS removal methods involve absorbents such as activated carbon. This can be effective, but it lacks specificity, so equipment quickly fills up with any organic substances that are present. Newer technologies such as foam fractionation are more specific for surface-active molecules. However, they can struggle with the removal of short-chain PFAS molecules.2
Most separation techniques must be combined with a destruction technique to truly remove the PFAS from environmental circulation. For example, concentration methods such as foam fractionation may be combined with adsorption, while membrane separation methods like reverse osmosis require dual consideration of PFAS destruction and membrane upkeep.
Combining either of these methods with techniques such as plasma, UV, or oxidation (electro- or supercritical water) can fully destroy concentrated PFAS compounds by separating them into inorganic fluoride and carbonaceous material. Adsorption methods like activated carbon or ion exchange may require destruction of the adsorptive material to destroy the PFAS.3
Deciding which removal technique to use is situation specific. For example, if it is known that a process only produces one or two PFAS species at stable concentrations, a simpler method may be adequate. If a full spectrum of PFAS is produced and/or different PFAS’ concentrations change significantly with time, complex multi-stage separation may be required. PFAS removal is not a ‘set and forget’ process. Efficacy must be tested, and continuous monitoring may be necessary.
As PFAS rules tighten, early preparation is key
Given the technical challenges of PFAS management and the fast-moving regulatory landscape, many companies are unsure how to proceed. However, some organizations are already collaborating on knowledge development and communications to avoid duplicated effort or mixed messages. Working collectively at industry sector level – through associations and working groups, with suppliers and customers, and with policy makers – could accelerate innovation and commercial development. If you’re concerned about PFAS levels in your organization’s wastewater, there is no time to lose.
REFERENCES
- R. Menger et al, Sensors for detecting per- and polyfluoroalkyl substances (PFAS): A critical review of development challenges, current sensors, and commercialization obstacles (PubMed Central, August 3 2023) https://pmc.ncbi.nlm.nih.gov/articles/PMC10398537/
- A. We et al, A review of foam fractionation for the removal of per- and polyfluoroalkyl substances (PFAS) from aqueous matrices (Science Direct, March 5 2024) https://www.sciencedirect.com/science/article/pii/S0304389423024664
- F. Sabba et al, PFAS in landfill leachate: Practical considerations for treatment and characterization (Science Direct, January 5 2025) https://www.sciencedirect.com/science/article/pii/S0304389424032667?pes=vor&utm_source=scopus&getft_integrator=scopus
