Deciphering the effects of long-term PFOA stress on system performance, microbial communities, and functional gene in denitrifying phosphorus removal processes

This research explored the long-term impact of perfluorooctanoic acid (PFOA) on the denitrifying phosphorus removal (DPR) system and its underlying mechanisms. Removal efficiency of phosphorus and nitrogen decreased by 14.70 % and 8.30 % at 0.10 mg/L PFOA. Meanwhile, synthesis and degradation of polyphosphate, glycine, and polyhydroxybutyrate reduced by 62.81 %, 65.40 % and 80.09 %, respectively. Extracellular polymeric substances multiplied from 40.29 to 177.96 mg/g VSS with PFOA increasing from 0 to 0.10 mg/L, conducing to mitigation the PFOA-induced damage. Moreover, the relative abundance of Thauera was promoted by 184.92 %, while most of functional bacteria was inhibited. Metagenomic analysis revealed that the relative abundance of genes responsible for carbon synthesis, nitrogen metabolism , and phosphorus cycling decreased, leading to a reduction of metabolic capacity in the DPR system. This study elucidated mechanism of PFOA effects in DPR systems, offering scientific insights for wastewater treatment plants handling PFOA-contaminated wastewater. • PFOA at 0.10 mg/L reduced nitrogen and phosphorus removal by 6.34 % and 21.63 %, respectively. • Long-term PFOA stress suppressed poly-P, Gly and PHB synthesis and degradation. • Thauera , Flavobacterium , and Bacteroides showed high tolerance to long-term PFOA stress.