Study On Characteristics And Screening Of Organic Pollutants In Wastewater From β-lactam Antibiotics

China is a major manufacturing and export country of antibiotic active pharmaceutical ingredient.The pollutant emission from pharmaceutical manufacturing process is one important sources of antibiotics in the environment.Although the pharmaceutical wastewater is treated before discharging,antibiotic residues and their metabolites can still be detected in surface water,groundwater and soil,which poses potential threats to the environment and human health.Therefore,it is of great importance to monitor the characteristic pollutants in antibiotic pharmaceutical wastewater.However,it is difficult and the research is yet not complete because the wastewater has complex composition.The research on its pollution factors and removal characteristics is not yet complete.Based on this,systematic research on its detection methods and pollution characteristics of three typicalβ-lactam antibiotics,i.e.,meropenem（MERO）,procaine penicillin（PROP）,and cefazolin sodium（CFZS）are studied.A solid phase extraction-high performance liquid chromatography-ultraviolet detector（SPE-HPLC-UVD）method was established for the simultaneous detection of three antibiotics,i.e.,MERO,PROP,and CFZS.The conditions affecting recovery rate,peak shape and sensitivity in SPE and HPLC-UVD were optimized.The optimized SPE condition is p H of 4,extraction column of HLB ultrapure water eluate volume of 10 m L,and methanol eluate volume of 10 m L.At the optimized SPE condition,the recovery rate in blank water is 53.2%～98.67%,and the relative standard deviation（RSD）is 0.06%～5.65%.Meanwhile,the recovery rate in actual wastewater is 74.67%～106%,and RSD is 0.3%～6.34%.The optimized HPLC condition is column type of EXTEND C18 column,ammonium acetate-acetic acid as the water phase and acetonitrile as organic phase with a percentage of 90%:10%,and the UV absorption wavelength of 285 nm.The correlation coefficient（R²）of the three antibiotics between 0.2 mg/L and 20mg/L all reached 0.999,showing a good linear relationship.The limit of quantification is3.26～7.25μg/L when the substrate is blank;and the limit of quantification is 2.65～5.87μg/L when the sewage is the substrate.This method has high recovery rate and low quantification limit,and can be used to analyze trace antibiotics in waste water.A complete analysis of conventional water quality indicators,residual antibiotics and organic pollutants in the effluent of a sewage treatment plant of a large domestic pharmaceutical company was carried out.The"hydrolysis acidification-anoxic-aerobic"process adopted by the sewage treatment plant played an important role in the organic pollutant degradation.The removal rates of COD,TOC,NH₄⁺-N,and TN were 87.43%,89.33%,98.66%and 40.91%,respectively.Meanwhile,the concentrations of MERO,PROP and CFZS in the effluent were6.98μg/L,9.92μg/L,18.45μg/L,respectively.The pretreatment unit and the hydrolysis acidification unit account for a higher proportion of acid esters,amides,amines and heterocyclic organics in the wastewater.The proportion of hydrocarbons in the effluent of anoxic and aerobic units is relatively high.Besides,the relative abundance of some pollutants,such as triethylamine,tetrahydrofuran,phenol,1,2-dichloroethylene,5-methyl-3H-1,3,4-thiadiazole-2-thione,2,6-dimethylpyridine,eicosane,butyric acid are relatively high,and these pollutants are not currently included in the relevant emission standards,which has certain toxicity and potential environmental risks.In order to evaluate the potential environmental impact of organics in wastewater,priority pollutants for environmental management and monitoring are screened.Based on the possibility of pollutant exposure and the consequence,a screening method for characteristic pollutants in antibiotic industrial wastewater has been established using environmental exposure,toxicity,bioaccumulation,and persistence as indicators.A priority pollutants list is established,which contains bis（2-ethylhexyl）isophthalate,eicosane,（Z）-docos-13-enamide,2,4-dimethylbenzaldehyde,2,2’-methylenebis（6-tert-butyl-4-methylphenol）,meropenem,cefazolin sodium,procaine penicillin.The relevant research results of this paper can provide basic data and support for antibiotic wastewater pollution control and environmental management.