Treatment Effect and Ecological Risk Assessment of Typical Antibiotics in Wastewater from Large-scale Dairy Farms in Tianjin

Abstract

To obtain the content level and treatment efficiency of typical antibiotics in wastewater treatment in large-scale dairy farms in Tianjin, the SPE-UPLC-MS/MS (ultra-high performance liquid chromatography tandem triple quadruple mass spectrometry combined with solid-phase extraction for pretreatment) technology was utilized to investigate and monitor seven typical antibiotics in wastewater from 12 large-scale dairy farms in Tianjin. Antibiotic residues were detected in 12 large-scale dairy farms before and after wastewater treatment. In the wastewater before treatment, the detection rates of tilmicosin (TIL), oxytetracycline hydrochloride (OTC), sparfloxacin (SPA), sulfathiazloe (STZ), ofloxacin (OFL), and sarafloxacin hydrochloride (SAR) were all 100%, whereas the detection rate of sulfadiazine (SDZ) was 83.33%. Among them, TIL and OTC were the main antibiotic components in untreated wastewater, the concentrations were 25.21 μg·L-1 and 9.87 μg·L-1, respectively. The detection rates of SDZ and OFL in the treated wastewater dropped to 25.00% and 41.66%, respectively. The main components were TIL and OTC and the concentrations were 11.30 μg·L-1 and 3.71 μg·L-1, respectively. There were significant decreases in the concentrations. The treatment effect on antibiotics from different farms ranged from 24.95% to 81.05%. The comprehensive treatment effect of the anaerobic-anoxic-oxic (AAO) treatment process was better than that of the anoxic-oxic (AO) treatment process. OFL, SAR, and OTC were the main high-risk pollutants in treated wastewater. Each large-scale dairy farm contained one or more antibiotic with RQs>1, and their emissions pose an ecological risk to the environment.