To understand the pollution characteristics and removal effect of antibiotics in the wastewater treatment process of large-scale pig farms in Guizhou, solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS) was used to investigate the removal of ten veterinary antibiotics from the influent and effluent of each treatment unit during the wastewater treatment process in two large-scale pig farms (named Farm A and Farm B). The results showed that the removal rates of conventional pollutants[including chemical oxygen demand (COD), NH4+-N, total nitrogen (TN), and total phosphorus (TP)] in Farm A and Farm B were above 88.10%. The antibiotics concentrations detected in the influent and effluent ranged from ND-120842.74 ng·L-1. The main antibiotics were sulfamonomethoxine (SMM), sulfamethoxazole (SMD), oxytetracycline (OTC), and ofloxacin (OFL), and the SMM concentration was highest at 120842.74 ng·L-1. The removal rate of the ten antibiotics was 99.23%-100.00% in Farm A and Farm B. In the wastewater treatment process of Farm A, the treatment section "USR+2A/O+disinfection pond+oxidation pond" removed antibiotics in wastewater effectively, with the total removal rate of SMM, SMD, and OTC reaching 100.00%. In the wastewater treatment process of Farm B, the treatment section "ultrafiltration (UF)+nanofiltration (NF)" removed antibiotics effectively by more than 99.23%. However, the concentrations of antibiotics investigated in the effluent were higher than the EU water environment antibiotic threshold (10 ng·L-1). Finally, through redundancy analysis, it was found that conventional indicators (COD, NH4+-N, TN, TP, and pH) in wastewater were related to the degradation of some antibiotics.
Keywords: pollution characteristics; redundancy analysis; removal effect; swine wastewater; veterinary antibiotics.