Per-and polyfluoroalkyl substances (PFAS) removal from water by aeration

Abstract

Conventional water treatment plants do not completely eliminate emerging contaminants that, although they occur at low concentrations, can be harmful. Among them, per- and polyfluoroalkyl substances (PFAS), present in many everyday products, can provoke adverse health effects. Due to the growing concern, it is necessary to develop new technologies for their elimination. The main objective of this work is to evaluate the effectiveness of the removal of these contaminants by aeration. To date, this technology, which commonly consists of exposing water to an air flow in order to volatilize contaminants, has been scarcely investigated for the treatment of PFAS. To this end, a literature review related to the aeration process for the removal of PFAS from water was conducted, resulting in the identification of seven research articles. First, two removal mechanisms were proposed, volatilization-stripping and aerosol formation. In addition, the effects of the main factors in the aeration process on the removal of PFAS from water were analysed. The main results indicated that, at low concentrations, PFAS can be effectively removed. However, when a certain concentration threshold is exceeded, foams are formed which decrease the efficiency of the process. In addition, it was observed that the removal efficiency improves with increasing compound chain length, ionic strength and air flow rates. Regarding the pH of the aqueous medium, no conclusive conclusion was obtained due to the ambiguous results obtained in the different studies reviewed. Although other parameters were less investigated, such as the effect of temperature and the coexistence of other substances, were also investigated since they could influence the efficiency of the process. In conclusion, the aeration process is presented as a promising alternative for the removal of PFAS from the aqueous medium