UV/Chlorine-BAC treatment of antidepressant drug in drinking water: efficacy, process optimization, and microbiological characterization

The environmental pollution caused by psychotropic drugs harms human health and has prompted a stronger emphasis on research into water treatment measures. The UV/Chlorine-biological activated carbon (BAC) combined process was employed in this study to treat amitriptyline (AMT), a typical psychotropic drug, in slightly contaminated drinking water. The removal efficiency of AMT in drinking water by UV/Chlorine and the feasibility of combining it with BAC were determined. The results demonstrated that the removal efficiency of 1 μmol/L AMT could reach 98.5% of the 2.0 mg/L chlorine and UV treated for 30 min. A significant removal improvement of AMT was 10%–45% compared to UV alone, Chlorine alone, and other oxidants combined, especially the SOUR (Specific Oxygen Uptake Rate), which was 57%–90% compared to other oxidants combined. Secondly, the optimal process parameters for UV/Chlorine-BAC treatment of slightly contaminated drinking water were a combination of UV exposure, chlorine dosage of 2 mg/L, and reaction times of 15 min followed by 30 min of BAC treatment. The AMT degradation, COD_Mn removal efficiency, and NO₃⁻–N production was 88%, 65%, and 95%, respectively. There was no significant effect on the number of microorganisms in the BAC medium, ensuring good long-term operation. Furthermore, an investigation was conducted to assess the influence of optimal process operation on the microbial community structure within BAC. This analysis unveiled a positive feedback loop in the colony architecture after implementing ideal process parameters. This study provides significant inspiration for addressing residual antidepressant issues using traditional drinking water treatment processes.