Removal of pharmaceuticals using combination of UV/H₂O₂/O₃ advanced oxidation process

Water and wastewater effluents contain a vast range of pharmaceutical chemicals. The present study aims to determine the potential of the advanced oxidation technology UV/H₂O₂/O₃ and its sub-processes (i.e. UV, UV/H₂O₂, UV/O₃, O₃ and H₂O₂/O₃) for the degradation of the antibiotics ciprofloxacin (CIP) and trimethoprim (TMP), and the antineoplastic drug cyclophosphamide (CPD) from water. Creating AOP conditions improved in most cases the degradation rate of the target compounds (compared with O₃ and UV alone). H₂O₂ concentration was found to be an important parameter in the UV/H₂O₂ and H₂O₂/O₃ sub-processes, acting as ^•OH initiator as well as ^•OH scavenger. Out of the examined processes, O₃ had the highest degradation rate for TMP and H₂O₂/O₃ showed highest degradation rate for CIP and CPD. The electrical energy consumption for both CIP and CPD, as calculated using the E_EO parameter, was in the following order: UV > UV/O₃ > UV/H₂O₂/O₃ > O₃ > H₂O₂/O₃. Whereas for TMP O₃ was shown to be the most electrical energy efficient. Twelve degradation byproducts were identified following direct UV photolysis of CIP.