Occurrence and fate of antibiotics in a wastewater treatment plant and their biological effects on receiving waters in Guizhou

Wastewater treatment plants (WWTPs) are not designed for the removal of antibiotics. Thus, several studies have been conducted to evaluate the fate of antibiotics in wastewater treatment processes. However, most of these investigations did not consider the antibiotic contamination in the receiving waters. This study investigated the occurrence and fate of antibiotics in a wastewater treatment plant and the ecological risks posed by surface water receiving the effluent discharge. The results indicated that the levels of 18 antibiotics in the influent ranged from 37.21 ng L⁻¹ to 2935.40 ng L⁻¹, and sulfamethizole (SMZ) was the major component among the 18 antibiotics; SMZ occurred most frequently and at the highest concentrations. Mass balance analysis was performed to explore the mechanisms of antibiotic removal, and the findings indicated that biotic and abiotic degradation are the major removal mechanisms; however, removal of quinolones is primarily ascribed to sludge adsorption. Because activated sludge consists of negatively charged colloidal particles, it is more inclined to adsorb quinolones, which contain positively charged nitrogen atoms. The resulting loading of antibiotics from WWTP effluent discharge into the receiving water of the Yangjie River may result in their uptake by aquatic organisms and thus poses a risk to human health. Copyright © 2017 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.