What is the latest research on the removal of PFAS chemicals from water? Is ozone a possible solution?
Per-and polyfluoroalkyl substances (PFAS) are known as “forever chemicals”, a diverse group of synthetic chemicals that are resistant to grease, oil, water and heat. They contain elemental bonds of carbon and fluorine (C-F) which results in an extremely strong chemical substance that does not disintegrate in the environment or the human body and can accumulate over time.
Introduced in the 1940’s, PFASs are commonly found in Teflon products, water repellants, paints, packaging, firefighting foam and cleaning products. Current research has revealed many potential adverse health impacts including liver damage, thyroid disease, high cholesterol, decreased fertility, hormone suppression and cancer. Human exposure through contaminated drinking water is now an issue of paramount concern. A 2007 study by the US Centers for Disease Control and Prevention estimated that PFAS chemicals could be prevalent in 98% of the US population.
The US Environmental Protection Agency (EPA) has identified PFAS as contaminants of emerging concern (CEC’s). PFAS are resistant to most conventional chemical water treatment technologies. GAC adsorption, ion exchange and reverse osmosis removal technologies are not able to destroy these chemicals, and result in simply transferring PFAS from one phase to another and/or accumulating them.
The current body of science and laboratory scale trials suggest that breaking the chemical bond via oxidation may be the most promising solution for elimination of PFAS in tap water. Recent research findings also indicate that ozone alone is not sufficient to break this very strong C-F bond. Supplementation with an oxidation catalyst (advanced oxidation process, AOP) has been shown to create reactive radicals that can effectively degrade PFAS. For example, with the combination of an iron-oxide based catalysis and persulfate, ozone has demonstrated a 70 to 98% removal of PFAS in tap water. (V. Franke, M. D. Schafers, J.J. Lindberg, L. Ahrens, Removal of per-and polyfluoroalkyl substances (PFASs) from tap water using heterogeneously catalyzed ozonation., Envron, Sci: Water Res Technol, 2019, 5, 1887) Another prominent research study tested an AOP combination of UV and ozone. The UV/ozone combined treatment removed 73% PFAS. ( X. Dai, Z. Xie, B. Dorian, S. Gray, J. Zhang, Comparative study of PFAS treatment by UV, UV/ozone, and fractionations with air and ozonated air., Environ. Sci.: Water Res. Technol., 2019,5, 1897-1907)
Although there is considerable on-going research, current findings suggest that ozone AOP combinations currently offer one of the most effective solutions for the removal of PFAS in drinking water. As scientific knowledge on best practices for PFAS removal evolve and grow we will keep our readers posted.