PFAS detection and removal in wastewater treatment plants

Per- and polyfluoroalkyl substances (PFASs) are a large group (± 5,000) of synthetic, highly fluorinated chemicals. They are regarded as ‘forever chemicals’ due to their high thermal and chemical resistance. Because of their volatility, they are easily dispersed into the environment (air, water and soil).

Even at low concentrations, these micropollutants have a negative effect on a population’s well-being and health, as well as on the quality of the ecosystem. To reduce their impact, intervention at the source is the first step.
Moreover, a high level of public awareness needs to be achieved.
Through water treatment plants, for example, our environment is exposed to these waste substances. To bring and keep our environment in harmony with water, Aquafin, although not required to do so, tries to discharge as few micropollutants as possible into surface water. Very little is known today about the presence of PFASs in wastewater, let alone how to remove them. Analyses commissioned by Aquafin and the VMM for some 30 wastewater treatment plants (WWTPs) show that there are large differences between the WWTPs, but also within the results from one and the same plant. As the reason for this is not yet known, a comprehensive dataset is needed to make informed statements. One further observation: if low levels are measured in a WWTP’s effluent, this does not mean that there is no PFAS problem at that location. Indeed, we find that wastewater also contains non-measurable precursors, i.e., building blocks converted by biological reactions to measurable components of the PFAS family. Thus, even if we measure low PFAS concentrations in the effluent, we may still be overlooking non-measurable precursors.
Given the large number of PFAS components, building up sufficiently large datasets to base conclusions on is not easy. In our study, we are therefore examining which types of PFAS occur and how they react in the different treatment steps in a WWTP.
Detection is one thing, but their removal is a completely different story. Though there are currently no standards for discharging WWTP effluent into surface water, we want to be prepared for any future standardisation. We are therefore actively participating in projects with other companies to explore techniques for their elimination.