Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors

The presence of pharmaceutical compounds, including iodinated contrast media (ICM), in aquatic systems poses significant ecological and health risks due to their biological activity at low concentrations. This study investigated the removal efficiency of three selected ICM—diatrizoate, iohexol, and iodipamide—from synthetic hospital wastewater using anaerobic membrane bioreactors (MBRs) operated at varying sludge ages of 40, 70, and 100 days. The results indicated that the performance of the MBRs in removing organic compounds improved with increased sludge age. Diatrizoate exhibited the highest removal efficiency, achieving 72% at a sludge age of 40 days and nearly 90% at 70 and 100 days, with no substantial differences between the two higher sludge ages. In contrast, iohexol and iodipamide demonstrated relatively low and inconsistent removal efficiencies, reaching a maximum of 40%, with no observable dependency on sludge age. The findings underscore the importance of optimizing sludge age in biological treatment processes for effective ICM removal.