Removing PFAS is not enough; destruction is required, says Dr Elvin Hossen, research and development engineer at Claros Technologies.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) can be found everywhere in the world and are considered a public health threat. Designed to withstand heat, water, oil, and corrosion, PFAS also withstand natural degradation and traditional methods for eliminating toxic chemicals. Highly soluble, PFAS in wastewater is especially concerning, because it so easily contaminates the food chain and drinking water. However, taking four steps that utilise new technologies can eliminate “forever chemicals” in wastewater forever.

About 17,000 sites in the UK and Europe have been contaminated with PFAS, including at least 940 that exceed the UK drinking water guideline of 100 nanograms per liter (ng/l). Additionally,

about 1,900 samples of drinking water sources in England and Wales were found to contain PFOS or PFOA, two of the most common PFAS compounds, above the proposed US limit of 4ng/l. The real total is thought to be even higher.

The most common methods used to treat wastewater today do not meet growing the challenge of PFAS pollution because they focus mostly on removal of persistent toxic chemicals. Methods such as reverse osmosis, ion exchange resins, and granulated activated carbon (GAC) have difficulty removing short- and ultrashort-chain PFAS, especially in complex wastewater, and they do not destroy PFAS. Instead, spent filter media have been sent to landfills, regenerated using chemicals, or incinerated, which transfers PFAS into soils, air, and groundwater through leaching, smoke, and ash.

4 steps to eliminate PFAS in wastewater

The most effective way to fully rid wastewater of PFAS pollution is a four-step process that involves initial testing, PFAS removal, destruction, and ongoing testing. The first step is to get the most accurate and complete picture of a water sample. To account for all the PFAS in a sample, it is necessary to utilise three test types: targeted compound analysis, non-targeted analysis, and measurement of free fluorine.

Targeted compound analysis involves liquid chromatography-tandem mass spectrometry (LC-MS) tests that identify specific PFAS compounds such as PFOS and PFOA. However, these tests cannot detect all of the estimated 15,000 PFAS compounds created since they were first introduced in the 1940s. It’s only by also leveraging non-targeted analysis such as total organic fluorine (TOF) and measuring free fluorine and using the mass-balance equation that all of the fluorines in a sample can be accounted for.

The second step is removal of PFAS to prepare for destruction. There are a variety of traditional and new removal methods used in wastewater treatment. The most common traditional methods are GAC, membrane filters, and reverse osmosis. Some of the new technologies being optimized for targeting PFAS are foam fractionation and ion exchange resins. For the optimization of destruction and to manage costs, concentration steps like these can be used alone or in combination.

Removal alone is not enough. The third step is to use a PFAS-destruction technology, which is the only way to permanently address the PFAS problem and avoid cycling PFAS in the environment. New PFAS-destruction technologies are being developed to replace traditional disposal methods that are ineffective, costly, and unsafe. There are five especially promising new technologies. Supercritical water oxidation and hydrothermal alkaline treatment use hot, pressurized water to break the powerful C-F bond. Electrochemical oxidation and plasma-based water treatment use electricity and photochemical defluorination uses ultraviolet (UV) light to do the same.

We use a proprietary photochemical process that rapidly destroys long-, short-, and ultrashort-chain PFAS with low energy consumption. The process operates at room temperature and atmospheric pressure, keeping energy costs to a minimum. Most importantly, the process leaves behind only naturally occurring, nontoxic elements.

The fourth step utilises the same three testing methods to answer the pressing question of whether all PFAS compounds were permanently destroyed. The only way to prove total destruction is to determine what PFAS compounds were in samples before and after treatment using targeted compound analysis, non-targeted analysis such as TOF, and measuring free fluorine. Otherwise, there is a real risk that long-chain PFAS compounds such as PFOS and PFOA are broken up into short-chain or ultrashort-chain compounds that cannot be detected using only LC-MS tests.

Managing PFAS critical to a circular economy

A comprehensive PFAS management strategy is needed to safeguard human and environmental health. All the technologies needed to treat PFAS are new, which is why it is imperative to accurately measure PFAS before and after treatment. Such measurements can prove compliance with water safety guidelines and regulations and ensure the public is protected from these toxic chemicals.

There is a cost to PFAS management but the cost of doing nothing is far higher, considering the serious health, regulatory, legal, and reputational risks of PFAS. Effective PFAS management requires four steps and adoption of new technologies, but many are designed to be easily adopted and retrofitted into existing wastewater treatment systems. By employing the four steps, all facilities that manage wastewater can prove that they have fully destroyed PFAS and that they can operate successfully in a circular economy.

Dr. Hossen is a process engineer who oversees the scale-up and commercialisation team at Claros Technologies. He holds a PhD in Civil Engineering with concentration in Environmental Process Engineering from North Carolina State University. His expertise includes experimental and engineering design, technology development, and process optimisation for water/wastewater treatment. Elvin serves as an R&D engineer for Claros supporting research projects, technology development, and scale-up and commercialization for environmental applications.