Degradation and Fate of Pharmaceutically Active Contaminants by Advanced Oxidation Processes

Abstract

The purpose of this review is to investigate the use of advanced oxidation processes (AOPs) including ozonation, UV photolysis, Fenton-type processes, UV/H2O2, and other photocatalytic processes to degrade persistent pharmaceutically active contaminants in water. The review focuses on four common pharmaceuticals carbamazepine (CBZ), diclofenac (DCF), sulfamethoxazole (SMX), and trimethoprim (TMP) which are used as exemplars. Insights into the removal efficiency of each compound by AOPs under various applied conditions are systematically elucidated. This review also investigates the fate of these pharmaceuticals during treatment by advanced oxidation treatment. The effectiveness of AOP processes for the degradation of pharmaceuticals varies significantly, depending on factors such as the nature of the process itself, operating conditions, and the target compound. Ozone can completely remove all four pharmaceuticals. By contrast, direct UV photolysis was effective for the removal of DCF and SMX, whereas the combination with H2O2 was essential to improve CBZ and TMP removal. In addition, a large number of transformation products were frequently detected during the degradation of the selected pharmaceuticals by AOPs. In addition, it has been confirmed that several transformation products were more resistant toward the applied AOPs than their original parent compounds. A major challenge with the use of AOPs for the degradation of the selected pharmaceutically active contaminants is the formation of by-products that are often more persistent than the original contaminants. Therefore, the existence of transformation products must be essentially investigated after the treatment of target pharmaceutical contaminants by AOPs in order to evaluate the effectiveness of the applied technique.