Per- and polyfluoroalkyl substances (PFAS): sources, potential health problems, remediation, and remediation challenges

Per- and polyfluoroalkyl substances (PFAS) are dangerous contaminants in the environment and have attracted much public concern. Because of their unique physicochemical properties including surface active behaviour and chemothermal stability, they have been extensively used in numerous sectors of the economy. Their extensive use and ubiquitous discharge into the environment pose a potential risk to the ecosystem in general, and human health in particular. PFAS may undergo biotransformation after discharge, which makes monitoring their occurrence and transportation challenging. Despite precautionary legislation, reducing PFAS concentrations in water and wastewater to below health advisory levels requires remediation. As a result, scientists studied treatment technologies, categorising them as non-destructive or destructive. Among non-destructive technologies, adsorption has been widely studied and in much detail. Activated carbon (AC) and matCARE^TM composite are shown to be potential options for PFAS adsorption. As a promising destructive technique, ultrasonication is a viable option. PFAS can be mineralised into non-persistent species under acoustic waves propagation. However, to achieve maximum performance, sample characteristics, ultrasonic frequency, power input, atmosphere condition, pH, and temperature must be considered. Ultrasonication is still associated with several challenges, including energy consumption and operative mostly in the laboratory, which calls for more research and is reviewed herein.