[Removal Efficiencies and Mechanism Research on Four Sulfonamides and Their Acetyl Metabolites in a Wastewater Treatment Plant].

Acetyl metabolites are the major metabolites of sulfonamides. In order to investigate the removal mechanism of four commonly used sulfonamides and their metabolites in wastewater treatment plants, sulfonamides and their corresponding acetyl metabolites in wastewater and sludge in a wastewater treatment plant equipped with A/O in Xiamen City were sampled. Sample selection was based on the hydraulic retention time. Solid phase extraction followed by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was applied to analyze the target compounds. Results showed that six out of eight of the target compounds were detected in the wastewater, while five were detected in the sludge. Based on the removal efficiencies overall and of the different compartments, the concentration of sulfamethazine was almost unchanged during wastewater treatment plant (WWTP) processes, the other sulfonamides were removed with different removal efficiencies. Removal efficiencies varied for every compartment. The potential removal pathways were analyzed based on the mass balance of the target compounds. The removal pathway of sulfamethazine was sludge adsorption, while the potential removal mechanism of sulfamerazine, sulfadiazine, and sulfamethoxazole was biodegradation.