Operating performance of sequential batch system with calcium-modified basalt fiber bio-nest exposed to two typical perfluoroalkyl compounds (PFOA and PFBA)

Abstract

The effects of per- and polyfluoroalkyl substances (PFASs) on the application of sequential batch system with basalt fiber as a biological carrier material have been rarely reported. This study explored the decontamination performance, extracellular polymeric substances (EPS) and microbial community structure of sequencing batch system with calcium-modified basalt fiber (Ca-MBF) bio-nest exposed to perfluorooctanoic acid (PFOA) and perfluorobutyric acid (PFBA). The results showed that 0.5 mg/L PFOA and PFBA both inhibited nitrification by 24.67 % and 19.47 %, while promoted denitrification by 16.54 % and 11.15 %, respectively. Overall, compared to PFBA, PFOA inhibited the removal of total nitrogen (TN) and total phosphorus (TP) by 11.27 % and 9.49 %, respectively. Further analysis of EPS showed that under PFOA exposure, the total EPS and polysaccharide (PS) content decreased by 34.57 % and 40.78 %, respectively. In addition, PFOA and PFBA exhibited a phenomenon of initially promoting by 89.21 % and 55.29 %, and subsequently inhibiting on protein (PN) content by 50.22 % and 51.37 %, respectively. Analyses of Illumina Miseq sequencing showed that PFOA and PFBA exposure for 50 days both inhibited the richness and diversity of microbial communities, and the inhibitory effect of PFOA was greater than that of PFBA. In addition, PFOA and PFBA respectively domesticated the resistant bacteria Meganema and Acinetobacter. These results may provide valuable information for ecological restoration and biodegradation of PFOA and PFBA.