Inhibitory effects of biofilms on the adsorption of per- and polyfluorinated alkyl substances by biological activated carbon in practical drinking water treatment plants

Although activated carbon filters are thought to be the best way to remove per- and polyfluorinated alkyl substances (PFAS), it is yet unknown how biofilms affect PFAS removal. This study first examined how the removal of PFAS in full-scale drinking water treatment plants (DWTPs) was impacted by biofilm from biological activated carbon (BAC) of varying depths and carbon ages. PFAS desorption from BAC was visible, but at this point, BAC could still remove dissolved organic matter (DOM) efficiently. Studies have demonstrated that the use of activated carbon filters can dramatically lower the content of PFAS in water, with the amount of PFAS reducing as the filter's depth grows and its use duration increases. Additionally, pore-clogging becomes more noticeable as the biofilm ages, which reduces BAC's capacity to eliminate PFAS and hinders PFAS desorption. Furthermore, the adsorption process of PFAS may be impeded by the secretion of biofilms, which are composed of proteins and polysaccharides. Based on the analysis above, it can be the adsorption of PFAS by BAC is significantly inhibited by biofilms, according to another research. This provides theoretical direction for improving the removal effectiveness of PFAS in DWTPs.