Evaluation of the removal efficiency of perfluoroalkyl substances in drinking water using electro chemical oxidation

Sammanfattning

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic organic compounds that have been widely used since the 1950s due to their desirable chemical properties. Their water-, grease, and dirt-repellent characteristics, combined with chemical stability and heat resistance, have made them useful in everything from firefighting foams (AFFF) and food packaging to textiles and non-stick coatings. These properties, along with their strong carbon-fluorine bonds that provide PFAS with high stability, make them highly resistant to degradation. As a result, PFAS are found in all parts of the environment, including water, soil, air, and living organisms, as well as in humans worldwide. Because PFAS are generally persistent, bio-accumulative and toxic, drinking-water exposure is a major public-health concern. One of the major exposure pathways for humans is drinking water, making effective treatment techniques crucial for reducing PFAS contamination in groundwater as conventional treatment methods have proven insufficient. Studies suggest that combining advanced non-conventional techniques in treatment trains provide more effective results. As part of the SIDWater (Sustainable Innovative Drinking Water Treatment Solutions) project, this study was conducted to evaluate the degradation efficiency of PFAS through electrochemical oxidation (EO) using boron-doped diamond (BDD) electrodes as the final step in a treatment train. Water samples pre-treated with reverse osmosis (RO) or foam fractionation (FF) were subjected to EO under controlled laboratory conditions. The results show that EO effectively reduces the concentration of perfluorosulfonic acids (PFSAs), while perfluorocarboxylic acids (PFCAs) and PFAS precursors exhibited lower removal efficiencies, with some of these compounds increasing in concentration. These findings indicate that the degradation process had begun thus complete degradation of PFAS was not yet achieved under the current treatment conditions. For achieving more efficient degradation longer treatment time are required and higher current densities.