Occurrence of Ciprofloxacin, Sulfamethoxazole, and Azithromycin in Municipal Wastewater Treatment Plants

The occurrence of ciprofloxacin (CIP), sulfamethoxazole (SMX), and azithromycin (AZI) was evaluated in various aqueous streams of four municipal wastewater treatment plants (WWTPs) in the Midwestern United States. Aqueous phase grab samples were collected from different locations in the WWTPs at four different times of the year. The target compounds were extracted using solid phase extraction, separated with high-performance liquid chromatography, and identified/quantified using ultraviolet and fluorescence spectroscopy (CIP and SMX) or mass spectrometry (AZI). Aqueous phase concentrations for CIP and AZI were similar to literature values while SMX concentrations were generally higher than those reported in the literature. The average aqueous phase concentrations for CIP, AZI, and SMX in the raw wastewater were 1.44, 1.11, and 18.3μg∕L, respectively, while the concentrations in the WWTP effluent were 0.59, 1.23, and 3.25μg∕L, respectively. AZI concentration was consistently lower in the winter. While some CIP and SMX removal from the aqueous phase was observed in the WWTP, such reductions were not seen for AZI. Composite sampling data indicated that CIP and SMX concentrations were significantly higher in summer than in winter.