Occurrence and removal of 25 antibiotics during sewage treatment processes and potential risk analysis

Abstract

The occurrence and removal of 25 antibiotics, including ten quinolones (QNs), four macrolides (MLs), four tetracyclines (TCs) and seven sulfonamides (SNs), were analysed at two sewage treatment plants (STPs) with different treatment units in Guangxi Province, China. The results showed that 14 and 16 antibiotics were detected in the influent of the two STPs, with concentrations ranging from 13.7–4265.2 ng/L and 14.5–10761.7 ng/L, respectively. Among the antibiotics, TCs were the main type in the study area, accounting for more than 79% of the total concentration of all antibiotics. The antibiotic removal efficiencies of the different process units ranged from −56.73% to 100.0%. It was found that the SN removal efficiency of the multistage composite mobile bed membrane bioreactor (MBBR) process was better than that of the continuous-flow Intermission biological reactor (IBR) process, while the IBR process was better than the MBBR process in terms of removing TCs and MLs; however, there was no obvious difference in the QN removal efficiencies of these two processes. Redundancy analysis (RDA) showed a strong correlation between antibiotic concentration and chemical oxygen demand (COD). Risk assessments indicated that algae, followed by invertebrates and fish, were the most sensitive aquatic organisms to the detected antibiotics. HIGHLIGHTS Tetracyclines are the main types of antibiotics in the study area.; The removal efficiency of MBBR process for sulfonamides is better than that for IBR, but the opposite is true for tetracyclines.; There is a strong correlation between the concentration of antibiotics and COD in wastewater in the study area.;

Keywords

• antibiotics
• ecological risk
• removal efficiency
• sewage treatment plants