Effects of single and combined copper/perfluorooctane sulfonate on sequencing batch reactor process and microbial community in activated sludge

Long-term exposure experiments with single and combined pollutants of copper (Cu)/perfluorooctane sulfonate (PFOS) were conducted to explore the influence on activated sludge in SBRs. Compared with the control, the removal of organics, nitrogen and phosphorus in the presence of PFOS exhibited no apparent difference, but reduced in different degrees when Cu and Cu/PFOS existed. PFOS exposure deteriorated the settling performance of activated sludge with SVI value and amount of extracellular polymeric substance (EPS) increasing, but posed little impacts on microbial activity (dehydrogenase, protease) and antioxidant activity (SOD, CAT). Under Cu and Cu/PFOS loading, dehydrogenase and protease activity were observed to decrease as well as SOD and CAT activity. The sequencing results revealed that bacterial richness and community diversity reduced under Cu and Cu/PFOS exposure. Overall, adverse effect of combined pollution was lower than that of single Cu in long-time due to antagonistic effect existed between Cu and PFOS.