The principal objective of this study was to quantify the effectiveness of combiningUV/H<sub>2</sub>O<sub>2</sub> and biological oxidation processes for the mineralization of the antimicrobialcompound sulfadiazine (SDZ). Specific objectives included: quantification of photolysisand UV/H<sub>2</sub>O<sub>2</sub> oxidation rates of SDZ; evaluate the effects of a lake water matrix onphotolysis and photooxidation rates of SDZ; and, quantify the mineralizationpotential of 14C-labeled SDZ oxidation products as a function of UV/H<sub>2</sub>O<sub>2</sub> oxidationconditions (UV fluence, H<sub>2</sub>O<sub>2</sub> concentration).Photolysis and UV/H<sub>2</sub>O<sub>2</sub> oxidation rates of SDZ were quantified with a quasi-collimatedbeam (QCB) apparatus (Bolton and Linden, 2003). The purpose of the QCB apparatus isto ensure that the UV rays reaching the sample are exactly perpendicular, which allowsfor accurate measurement of UV energy at the surface of the sample. Therefore, we canaccurately measure the UV fluence delivered to the sample. The QCB is equipped withfour low pressure (LP) UV lamps. The determination of the delivered UV fluence to thesample by the LP lamps was calculated with the method described by Bolton and Linden(2003). Tests were conducted at an initial SDZ concentration of 4 (±1) µM. Testsconducted in the presence of natural organic matter (NOM) were performed by spiking SDZ into Lake Wheelerwater (Raleigh, NC) that had been filtered through a 0.45-µm membrane filter. The TOCof filtered Lake Wheeler water was 5.0 mg/L, the pH was 7.85, and the total alkalinitywas 24 mg/L as CaCO<sub>3</sub>. Includes 8 references, tables, figures.
