Occurrence, Fate, and Removal of Selected Antibiotics in Advanced Biological Urban Wastewater Treatment Plant

Abstract

Wastewater treatment plants (WWTPs) are considered as one of the most important point sources for releasing antibiotics into the natural environment. In this study, the occurrence, fate, and removal of three antibiotics, ciprofloxacin (CIP), sulfamethoxazole (SMX), and azithromycin (AZI), belong to quinolone, sulfonamide, and macrolide groups, respectively were investigated seasonally in a large-scale urban WWTP. While the occurrence concentrations of the investigated antibiotics in raw wastewater were found between about 0.26 and 0.73 μg/L in the summer season, it was determined in the range of approximately 0.41 and 4.6 μg/L in the winter season. Although the removal efficiencies obtained for antibiotics in the pre-treatment stage of the studied advanced biological WWTP were not very high, the most treated compound in the pre-treatment stage was determined as CIP (up to 23.8%). Total removal efficiencies of the investigated antibiotics in the WWTP varied mainly based on the biological treatment stage of the WWTP. At the same time, removal efficiencies of the antibiotics obtained in the biological treatment also changed considerably depending on the seasons. Among all the investigated antibiotic compounds, it was determined that AZI was the compound that was least affected by the seasons in terms of the total removal efficiency obtained in WWTP. According to the annual average total removal efficiencies, it was determined that SMX (25.7%), CIP (71.3%), and AZI (89.2%) were treated poorly, moderately, and highly in WWTP, respectively. However, advanced biological WWTP was determined to be insufficient for the complete removal of total antibiotics.