Poly- and perfluoroalkyl compounds (PFAS) are synthetic substances introduced onto the market in the 1960s. The most well-known PFAS are perfluoro octane sulfonic acid (PFOS) and perfluoro octane acid (PFOA). The substances have been used to provide water and oil repelling features in textiles, clothing, carpets, glues and paper. Another large-scale application of PFAS was foam forming extinguishing agents. These types of extinguishing agents were used for decades in firefighting worldwide. The function of PFAS in these agents was to decrease the surface tension of the water and foam, thus allowing rapid spreading of the extinguishing agent over inflammable liquids – and rapid extinction of the fire. All over the world, virtually all airports and numerous industrial sites are affected by PFAS contamination. PFAS production sites have also contributed to the spreading of PFAS in the environment by (permitted) discharges.
Over the past decades, PFAS have proven to be harmful for humans and the environment. Various research reports have shown that these substances are highly persistent in the environment, because they do not biodegrade and are toxic. It was also shown that widespread dispersion of PFAS occurred in the ecosystems by bio-accumulation. PFOS were even found in polar bears at the north pole. The use of extinguishing foams in fire fighting and fire fighting drills has caused soil and groundwater contamination at many sites.
Until now, the only well-established technique for the degradation of PFAS is thermal decomposition at a temperature exceeding 1,200°C. PFAS removal is therefore a very costly and relatively inefficient process. Nowadays the use of PFAS is banned for most applications and the use of firefighting foams containing PFOS has been banned since June 2011. The use of lesser known PFAS applications has been under investigation in recent years.
PFAS are difficult to remove from soil and groundwater. Techniques that work for one compound may not be effective for others. Arcadis In-Situ Technieken has created a worldwide network of specialists involved in dealing with PFAS issues. In this network all information is shared, from toxicity and monitoring values to the remediation of PFAS. In the Netherlands, a PFAS expertise center has been created together in order to share technical, toxicological, legal and policy-based know-how and information on these compounds and remedial techniques. The PFAS expertise center is an initiative by Witteveen+Bos, TTE Consultants and Arcadis. For more information, click here.