What exactly are PFAS?

Stefano Bruzzano: PFAS form a group of more than 10,000 chemicals first being used in the 1950s. Their design as fluoro-organic surfactants is both hydrophilic and hydrophobic. Thanks to these properties they are used as additives in countless products.

Please give us examples of where to find them.

Stefano Bruzzano: One prominent example is Aqueous Film Forming Foam, a so-called AFFF- agent for extinguishing very effectively high-energy liquid fires as e. g. in the petrochemical industry or on airplanes. Also, household products such as baking paper or pizza boxes, in impregnating sprays and lubricants contain PFAS. However they are also relevant for electromobility – as an integral component in batteries. It can be stated that, over time, the widespread distribution of PFAS products has become almost out of control.

Why are PFAS so heavily criticized?

Stefano Bruzzano: They have a carbon-fluorine bond. On the one hand, their high resistance to heat, for example, is an advantage; on the other hand, as a result, PFAS do not degrade in the environment. Depending on their chemical structure PFAS have different effects on humans and on the environment. Certain compounds have been proven to have carcinogenic properties. Others are toxic to the liver or show hormone-like effects. Many PFAS compounds used in practice have not yet been investigated in detail, which is why a ban on production and use currently makes sense as a precautionary measure. Some PFAS have already been banned or severely restricted in the past. These include perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA).

Are there any alternatives to PFAS?

Stefano Bruzzano: As a start, I would like to point out that the properties of PFAS are purpose-made depending on the characteristics of fluorine in the molecule. Hence, a simple replacement by a combination of other elements is not possible. Some alternative molecules with comparable properties, for instance based on silicon, have been developed. However, most of them are not yet at the stage to being commercialized. Time is needed here to develop proper and marketable alternatives.

So, you are taking a critical view on an extensive ban. What would be a better approach?

Stefano Bruzzano: According to economic experts, a widespread ban on PFAS would paralyze entire branches of industry and might even eliminate several modern technologies. This is one of the reasons why we need a more differentiated regulation. One important point is a minimized release of PFAS to the environment in a targeted and controlled manner. Regulated, substance-specific interim periods lead to a reduction in the variety of substances. Products with direct and uncontrollable emissions of PFAS, on the other hand, should be banned in a timely manner. Furthermore, it always has to be scrutinized whether there is a specific necessity for PFAS use, such as safety related reasons, or whether there are other solutions at hand. In the case of foam extinguishing agents, the development of fluorine-free alternatives began because of several EU regulations that stipulate a limit on individual PFAS substances and some PFAS groups. The EU had granted transitional periods that allowed extinguishing agent manufacturers and users to take action. Nevertheless, various users may not be able to meet the set deadlines. In this case, those responsible must rely on a combination of treatment and proper, traceable disposal.

How important is it to take a comprehensive look at the PFAS compounds in circulation?

Stefano Bruzzano: The market surrounding the "PFAS -challenge" is currently divided into three important market segments. Analytical services are one of them. Firstly, we need to know where contamination occurs in the first place. To obtain knowledge of this, we must detect all emitted substances that contain PFAS. Secondly, there is the site assessment, which includes the development of societally necessary and economic solutions. Where and how PFAS or products with their properties are to be used and adequately disposed of? Thirdly, a further segment covers treatment and decontamination and builds on the other two segments. With a view to the current market, analytical services and site assessment are representing the lion's share while PFAS treatment still has room for expansion.

And that is exactly where you are active. How long has Fraunhofer UMSICHT been involved in PFAS treatment?

Stefano Bruzzano: I have been involved in the PFAS research for about 15 years. I started collaborating with Cornelsen Umwelttechnologie GmbH very early on, directly after joining Fraunhofer UMSICHT. As part of our first joint project, we aimed at producing a specific biosorbent to separate short-chain PFAS compounds from water. For this, we took cellulose substrates such as wood chips, hemp stalks and coffee grounds, modified their surface and developed a sorbent for aqueous media contaminated with PFAS. Basically, this worked out very well. However, the complex synthesis was challenging in particularly with respect to the resulting production costs. Therefore, we transferred the chemistry of the process – which took place on the surface of the sorbent – into the water phase by provoking a precipitation process. In doing so, we consistently used biodegradable molecules as active ingredients.

This was the origin for the PerfluorAd^® process.

Stefano Bruzzano: That's how it is. The result was PerfluorAd^® as an easy-to-handle solution. An aqueous solution of the active ingredient developed by Fraunhofer UMSICHT and Cornelsen is added to the PFAS contaminated water, which triggers the precipitation of these pollutants. The resulting PFAS-sludge can be separated and typically incinerated afterwards. Alternatively, the sludge may be mineralized using other processes, but their feasibility has yet to be proven. The process of precipitation can be combined with other PFAS treatment technologies downstream to ensure that the removal of PFAS is almost complete (polishing). In our process, we use commercially proven, safe, and available components that are already in use in other applications, for example in the personal care or home care sector. These chemicals already certified and very well characterized facilitated the market entry of our product formulation into a new field of application. PerfluorAd^® has now been on the market for five years across Europe and North America.

Where does the PerfluorAd^® process show its strengths?

Stefano Bruzzano: PerfluorAd^® scores particularly high at elevated levels of PFAS and is largely independent of organic contamination in the water, unlike most other commercial processes. Let's take activated carbon as an example – it is predominantly used in Germany, and it displays only moderate adsorption activity for PFAS. Hence, highly contaminated water also requires a large quantity of activated carbon. PerfluorAd^® can be used here as pre-treatment to boost the overall process performance. As already mentioned, PerfluorAd^® ensures that a very large proportion of the PFAS precipitates right away. To bring the PFAS content in the water below the regulatory thresholds, a treatment with a small amount of activated carbon after the PerfluorAd^® process is performed. This way, the overall amount of process agents as well the amount of waste is significantly minimized, and less energy is required than for using only activated carbon. For high levels of PFAS it is both a huge economic and ecological advantage – which we have verified -by comparative life cycle assessments.

You mentioned the collaboration with Cornelsen. How is it organized?

Stefano Bruzzano: Fraunhofer UMSICHT contributes its expertise in chemistry, analytics as well as via IP generation and property rights. Cornelsen develops process engineering solutions next to process efficiency improvements for future and actively implements the application for the customer.

Who are the customers?

Stefano Bruzzano: The PerfluorAd^® service addresses companies that are working in the field of maintenance of sprinkler systems, fire engines and fire pumps. The landfill sector is expected to become a large market in the future as well. In the USA, PFAS are increasingly leaking from landfills of consumer goods. This way PFAS from electrical appliances are entering the environment. Soil remediation and the treatment of leachate will be correspondingly important here. Just as industrial wastewater from fluoro-plastics production, groundwater in the vicinity of other PFAS emitters can be contaminated, too.

This issue is also becoming increasingly relevant to the energy industry, for example in the production of green hydrogen, via electrolysis where a very high quality of water is required. The fact that PFAS are so omnipresent means that methods to ensure this quality may be necessary in the future.

What are the next steps?

Stefano Bruzzano: Together with Cornelsen, we will continue to optimize the PerfluorAd^® process. One aim is to increase the dry content of the sludge produced during precipitation to reduce the water content in the subsequent combustion process at the same time. We are also going to improve the specific separation of short-chain PFAS. And finally, increasing the number of sales channels is an activity field that needs to be worked on. We are looking for further partners who would like to expand their product portfolio technologically offering flexible and efficient solutions for the purification of PFAS-contaminated water. Ideally, these are large companies that are active in the wastewater or water sector, for instance companies that develop or offer complementary treatment technologies such as activated carbon and membranes.