New insights into the impact of ribavirin on enhanced biological phosphorus removal process efficiency

Abstract Ribavirin (RBV) is a quintessential antiviral medication frequently detected in wastewater. However, the impact of RBV on the biological treatment of wastewater has rarely been reported to date. This study investigates the influence of RBV on the enhanced biological phosphorus removal process by controlling the influent RBV concentration and elucidates the underlying mechanisms. The results indicated that low concentrations of ribavirin (below 0.05 mg/L) did not significantly affect the EBPR efficiency, while concentrations exceeding 0.1 mg/L significantly reduced the removal of chemical oxygen demand (COD) and soluble orthophosphate, with higher exposure concentrations leading to poorer EBPR performance. High concentrations of RBV decreased the concentration of organic matter in the sludge and its settleability. At an RBV concentration of 2.0 mg/L, the sludge volume index increased, but the volatile suspended solids concentration decreased to 3.25 ~ 3.41 g/L. Exposure to RBV increased the content of extracellular polymeric substances (EPS), with higher exposure concentrations leading to a more significant increase in EPS content, notably in the content of protein. RBV reduced the specific oxygen uptake rate of microorganisms, with higher exposure amounts resulting in a more pronounced decrease in specific oxygen uptake rate (SOUR). RBV also promoted the release of reactive oxygen species and lactate dehydrogenase, reducing microbial metabolic activity.