To determine the removal efficiency of typical antibiotics in Guiyang wastewater treatment plants (WWTPs) and the impact of effluent on aquatic organisms in receiving waters, nine antibiotics in the influent, effluent, and receiving water of two WWTPs in Guiyang City were investigated. The concentrations of antibiotics in the influent and effluent ranged from 0 to 835.60 ng·L-1 and 0 to 286.60 ng·L-1, respectively, and the concentration of ofloxacin (OFX) was highest. Its concentration in the influent was 835.60 ng·L-1 and 539.00 ng·L-1 and in the effluent was 11.74 ng·L-1 and 286.60 ng·L-1, respectively. The removal rate of antibiotics in the WWTPs ranged from -42.29% to 100%, and tetracycline (TC) was completely removed. The concentrations of antibiotics in the influent and effluent of the WWTPs in Guiyang City was less than in other regions of China and in other counties. Through the analysis of the antibiotics in the receiving waters, it was found that the concentrations of OFX were higher than other antibiotics, and the WWTPs effluent was one source of antibiotics in the receiving waters. OFX showed a high risk (RQ>1) for aquatic organisms in the receiving waters, as determined by an ecological risk assessment.
Keywords: antibiotics; ecological risk; pollution level; receiving water; wastewater treatment plant.