Behavior and Removal of Ciprofloxacin and Sulfamethoxazole Antibiotics in Three Different Types of Full-Scale Wastewater Treatment Plants: a Comparative Study

Abstract

Due to the inadequate removal rates of drug residues in wastewater treatment plants (WWTP), the transition of these compounds into the environment has become a serious environmental problem for ecosystems and public health. In this study, occurrence, fate, and removal of widely consumed two antibiotics, ciprofloxacin (CIP) and sulfamethoxazole (SMX), selected from fluoroquinolone and sulfonamide groups, respectively were investigated in three different types of full-scale WWTPs located in Turkey. In this context, three WWTPs consisting of advanced biological treatment (large-scale), wastewater stabilization pond (WSP) (medium-scale), and constructed wetland (CW) (small-scale) were selected. While the detected influent concentrations of CIP in WWTPs ranged between the 218.6 and 2733.5 ng/L, maximum influent concentration for SMX in the same plants was determined as 179.7 ng/L. On the other hand, although it was detected at higher concentrations in raw wastewater, CIP was significantly removed in all WWTPs with a removal efficiency ranging from >77.1 to >98.2%. However, SMX showed quite different behaviors depending on the applied wastewater treatment processes in WWTPs in terms of total removal achieved. While treated in WSP well enough (>72.2%), a serious negative removal efficiency (-133.4%) was achieved for SMX in the WWTP having advanced biological treatment. Best removal performance obtained for the both antibiotic compounds among the investigated WWTPs was the medium-scale WSP consisting of anaerobic and facultative stabilization ponds, consecutively. This situation also supported the idea that WWTPs which are operated with higher solid retention time (SRT) and hydraulic retention time (HRT) contribute positively in the removal of antibiotic compounds.