Effect of O3 Dose on the O3/UV Treatment Process for the Removal of Pharmaceuticals and Personal Care Products in Secondary Effluent

A municipal wastewater treatment plant (WWTP) is a melting pot of numerous pharmaceuticals and personal care products (PPCPs) together with many other substances. The removal of PPCPs using advanced oxidation processes within a WWTP is one way to reduce the amount of PPCPs that potentially enter an aquatic environment. The aim of this study was to examine the effectiveness of the ozone (O-3)/UV treatment process, especially, the effects of O-3 dose and reaction time, on the removal of PPCPs in the secondary effluent of a WWTP. Experiments were conducted using a pilot-scale treatment process that consisted of two flow-through reactors connected in series. Each reactor was equipped with three 65 W lamps (UV65W). The experimental variables were ozone dosage (1, 2, 3, 4, and 6 mg L-1) and hydraulic retention time (HRT; 5 and 10 min). On the basis of the PPCP concentrations after O-3/UV65W treatment and their limit of detection (LOD), 38 PPCPs detected in the secondary effluent were classified into 5 groups ranging from the category of "sensitive" to O-3/UV65W or "unstable" in the O-3/UV65W process to the category of "insensitive" to O-3/UV65W or "very stable" in the O-3/UV65W process.