Influence of aqueous film forming foam containing per- and polyfluoroalkyl substances on the efficiency of activated sludge process and on the composition of the sludge microbiome

The research is part of a project aimed at testing a treatment train to remove per- and polyfluoroalkyl substances commonly known as PFAS, deriving from the foam produced by foam fractionation of aqueous film forming foams (AFFF) contaminated soils. Biological treatment is performed to improve the quality of the resulting foam before destructive treatment. The experimentation was carried out in duplicate in lab-scale bioreactors continuously fed on primary municipal wastewater spiked with increasing doses of AFFF. The results reveal distinct trends: the addition of AFFF did not adversely affect Chemical Oxygen Demand removal, while significantly affecting nitrification efficiency, with inhibition growing with increasing dose. The composition of the microbial community changed with time (especially for Comamonadaceae) and a gradual decline in biodiversity also occurred with time. A decrease in amoA gene bacteria copy numbers and in nitrification efficiency with increasing doses of AFFF were observed.