Use of ozone-based processes for the removal of pharmaceuticals detected in a wastewater treatment plant.

Ozone (O3)-based processes (O3, O3/H2O2, and O3/UV) were investigated for the removal of pharmaceuticals in real wastewater using a bench-scale experimental setup. An ozone dose of 6 mg/L (contact time = 10 minutes) was found to reduce the concentration of most pharmaceuticals detected in secondary effluent. Caffeine, N,N-Diethyl-meta-toluamide (DEET), and cyclophosphamide were removed with efficiencies of 84, 89, and 46%, respectively, even with a contact time of 15 minutes (O3 dose = 6 mg/L). In the case of the ozone process alone, the concentration of bromate ion in the effluent increased with longer contact time. On the other hand, it was found that the O3/H202 and O3/UV processes can be used as alternative processes for effective removal of pharmaceuticals, while leaving a low residual concentration of dissolved ozone in the system, thereby preventing bromate formation. Water