The omnipresent per- and polyfluoroalkyl substances (PFAS), have quietly permeated our world and infiltrated every corner of our environment. As a result of their cross-industry application over the years and their environmental persistence, PFAS can be found everywhere across the globe, even in drinking water sources.
With new studies unearthing the potential negative impacts of excessive exposure on human health, the EU persistent organic pollutants (POPs) regulation and other legislations are restricting the use and emission limits of these molecules, among others, in industrial wastewater.
Several techniques exist to capture PFAS, but activated carbon is one of the best available technologies (BATs), proven to remove them efficiently.
Subscribe to PII and receive:
Our long-established bi-monthly digital magazine *Process Industry Informer*, featuring exclusive articles, news and updates across the Process Industries, plus commentary from our three industry experts:
Sean Moran
Gavin Smith
Dave Green
PLUS:
- Process Industry Update — our weekly e-newsletter
- PII Podcast
- Special messages from our advertising partners
DESOTEC – leading provider of mobile filtration solutions – has a secure and POP-compliant purification method that enables manufacturers to permanently and sustainably address the persistent challenge of these chemicals.
What’s The Fuss About PFAS?
PFAS belong to a group of thousands of man-made chemicals. In 2021, the Organisation for Economic Cooperation and Development (OECD) defined PFAS as fluorinated substances that contain at least one fully fluorinated methyl or methylene group.
Because of their high thermal and chemical resistance, manufacturers across many sectors have tapped into these compounds to achieve water and dirt resistance. Food packaging and preparation, cosmetics, textiles, firefighting foam. You name it.
However, their industrial functionality has turned into an environmental legacy. If production wastewater is not properly treated, PFAS may enter both surface and ground water, where they break down very slowly or not at all. That’s why they are dubbed as ‘forever chemicals’.
Recent studies revealed the presence of PFAS in tap water across the US as well as over 17,000 contaminated sites around Europe. To address this widespread concern, regulations on the use and emissions of PFAS are becoming increasingly stringent.
The Regulation Landscape
The EU was a global pioneer on PFAS control. The POPs regulation has restricted the use of perfluorooctane sulfonate (PFOS), one of the most widely applied forever chemicals, since 2009.
EU regulators have then widened the legislation scope to include other PFAS such as perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS). In February 2023, the European Chemicals Agency (ECHA) changed gear by proposing to ban 10,000 PFAS.
Once approved, this landmark regulation will affect both EU-based producers and their non-EU suppliers for PFAS use on their own, in mixtures, and in products. Waiting for PFAS to be eradicated by European industrial processes forever, the EU revised its Drinking Water Directive to introduce a limit of 0.5 µg/l for all PFAS. On top of that, the European Commission proposed to add a series of PFAS among the controlled chemicals released both in groundwater and surface water.
US legislators are scrutinising general PFAS emission. In 2021, the Environmental Protection Agency (EPA) released a PFAS Strategic Roadmap to limit their pollution. In particular, companies discharging PFAS-tainted wastewater must comply with an emission limit which mostly depends on the quality standards of the receiving water. In the USA, the reactivation of PFAS-containing activated carbon has been promoted by the American Department of Defense (DoD) to effectively destroy PFAS.
Considering this regulatory scenario and the low PFAS removal efficiency of conventional wastewater treatments, firms have to look into more adequate purification technologies.
How To Remove PFAS From Wastewater
According to both researchers and regulators, the three most ready-to-use technologies to decontaminate water from PFAS include membrane separation, anion exchange resins (AER), and activated carbon.
Membrane Separation
Membranes are a solid porous media that can separate a certain pollutant from a liquid phase. Based on PFAS properties (e.g., molecule size), reverse osmosis (RO) and nanofiltration (NF) are one of the most suitable separation processes.
Previous studies found these methods to be effective at removing PFAS from water. On the other hand, they require an upstream pre-treatment (e.g., activated carbon filtration) to prevent membrane fouling and extend their lifespan.
Anion Exchange Resins
As the name suggests, this purification route entails swapping the negatively charged PFAS ions dissolved in water with some other anions (e.g., chlorides) embedded into a polymeric resin bed. This exchange occurs through an adsorption mechanism.
Resins exhibit great adsorption capacities and effectively remove a wider range of PFAS. Nonetheless, being a less mature technology, its cost was estimated to be three times higher than that of activated carbon.
Activated Carbon filtration
In this case, PFAS are adsorbed on the highly porous inner structure of activated carbon. The superior surface area of these sorbents is created via the high-temperature treatment (i.e., activation) of either coal or renewable feedstock-based chars. While being able to trap a broad array of PFAS within their pores, activated carbon’s adsorption performance increases with the contaminant chain length.
Being able to work as a stand-alone technology makes activated carbon filtration more cost-efficient than the above mentioned techniques. This is particularly true when renting plug-and-play mobile filters rather than buying fixed installations upfront.
Furthermore, activated carbon filtration can be moved to a closed-loop solution if the PFAS concentration on the activation carbon is below the POPs regulation thresholds and the activated carbon can be reactivated.
Other benefits from this type of filtration are that pollutants are not handled on site, the solution is flexible and has a minimal cost of ownership, which is in the current economic and financial environment more than a benefit.
A Law-Proof & Eco-Friendly Activated Carbon Filtration
After years of research and development, DESOTEC has the expertise to select the most appropriate type of activated carbon and filters to optimise the purification of wastewater containing a limited amount of PFAS.
As reported by a third-party organisation, DESOTEC’s granular activated carbon (GAC) was found to be effective at purifying groundwater and firefighting wastewater. GAC was also recommended as BAT for removing PFAS from drinking water by the EPA in its recent regulation proposal.
To ensure full compliance with the stringent EU POPs regulation, DESOTEC has devised a validated method to accurately measure the level of PFAS adsorbed on activated carbon. Also, DESOTEC has put in place an environmentally conscious procedure to irreversibly destroy the contaminants.
In particular, if the PFAS concentration on the spent carbon is below the established and safe limits outlined in the European POPs Regulation, the saturated carbon will be subjected to a thermal reactivation process at DESOTEC’s facilities.
This route reactivates the carbon while breaking PFAS down completely and safely, thus avoiding their release in the environment. However, when the PFAS concentration exceeds the EU POP limit, the activated carbon will not be reactivated on DESOTEC’s sites in Europe but will be transported to a specialised external party, ensuring safe and compliant treatment.
The End (Of PFAS)
Countries around the world have already implemented strategies to reduce PFAS contamination risk. While POPs and other regulations are tightening PFAS emission limits, new purification technologies are popping up.
However, the design of a truly sustainable solution should go beyond the removal step and offer a definitive yet green elimination of “forever chemicals”, considering the whole lifecycle of the purification technology.
By using a safe, law-compliant, and environmentally responsible technology, DESOTEC is helping the process industry get rid of these chemicals, forever.
About the authors:
Dr. Annemie Houben, PhD, is a R&D leader specializing in adsorption technology. With a dedicated focus on PFAS from both analytical and legislative perspectives, Annemie brings her expertise as Senior R&D Manager at DESOTEC. Her background in Chemistry and extensive experience make her a notable contributor to advancements in purification technologies.
Dr. Dirk Reichert, owns a doctorate in Chemistry from Karlsruhe University, Germany. He worked in chemistry research at Sydney University, Australia, and Freiberg University, Germany until 2013, leading to Engineering & Development Management functions in EMEA and Asia at Johnson Matthey between 2013 and 2021. Since 2021, he’s working as Business Development Manager – global, at DESOTEC.
Bérengère Lemaire, is a chemical engineer specialised in B to B marketing. Her engineer background coupled with marketing experience led her to occupy several marketing functions in the industry. She’s been working at DESOTEC since 2019 in the marketing department.
