A Study On Toxicity And Antimicrobial Resistance Of Antibiotic Wastewater And Control Technologies

In order to control the toxicity and the induction of antibiotic resistance tomicroorganism caused by antibiotic wastewater discharge, the toxicities of differentkinds of antibiotic wastewater influents and effluents were investigated; besides, theantibiotic resistance levels of bacteria isolated from the municipal wastewater,cephalosporin wastewater, integrated pharmaceutical wastewater, and surface water ofthe receiving river were investigated in this paper. The approaches of bacteria to aquireantibiotic resistance in antibiotic wastewater were analyzed. The suitable advancedtreatment technologies for treating antibiotic wastewater based on biosafety assurancewere tested. The results indicated that:(1) Both of the toxicities of wastewater to Scenedesmus obliquus and to Vibriofischeri could be effectively reduced in most of the16antibiotic wastewater treatmentplants investigated. The acute toxicities of the effluents from10out of the16antibioticwastewater treatment plants exceeded the discharge limit. Most of the organicsubstances and toxic substances were degraded in the aerobic biological treatmentprocess. The results of Spearman rank correlation analysis indicated that the toxicitieswere positively correlated with both COD and NH3-N among the different kinds ofantibiotic wastewater.(2) Enterobacteriaceae of lactose fermentation type (E-LF) isolated fromcephalosporin wastewater were highly resistant to β-lactam antibiotics, with the averageresistant rate of55.1%in the influent and82.5%in the effluent. The quantities ofantibiotic resistant E-LF and antibiotic resistant gene could be reduced after wastewatertreatment. However, the antibiotic resistant rate of microorganisms and the aboundanceof antibiotic resistant gene among the microorganisms were promoted during thewastewater treatment process. The multi antibiotic resistant index (MAR Index) ofE-LF in the effluent of municipal wastewater was as1.5times as in the influent, whileMAR Index of E-LF in the effluent of cephalosporin wastewater was as1.4times as inthe influent.(3) The central pharmaceutical wastewater treatment plant receives the treatedantibiotic wastewater from antibiotic manufacture plants. The E-LF isolated from theinfluent and effluent of central pharmaceutical wastewater treatment plant were highly resistant to gentamicin(GTM), ampicillin(AMC), amoxicillin (AMC), cefuroxime(CXM)and ceftriaxone (CTR). The order of the MAR Index of E-LF isolated from both theinfluents and effluents were: integrated pharmaceutical wastewater> cephalosporinwastewater> municipal wastewater. The quantity of antibiotic resistant E-LF, the MARIndex of E-LF and the concentration of blaTEM-2gene increased by0.71-log,3timesand1000times respectively in the downstream receiving river resulting from integratedphamceutical wastewater discharge.(4) Bacteria could acquire antibiotic resistance by the induction and culture ofpharmaceutical wastewater. Escherichia coli (E. coli) could become resistant to CTRand AMC after contact with CTR. The minimal inhibition concentrations of E. coli toboth CTR and AMC were linearly correlated to the product of CTR concentration andcultivation time. The blaTEM-2gene could be horizontal transferred from Salmonella toE. coli. Measurements should be taken to remove the antibiotics, antibiotic resistantbacteria and antibiotic resistant genes from antibiotic wastewater in order to control thespreading of antibiotic resistance among microorganisms.(5) COD and acute toxicity of cephalosporin wastewater could beeffectively removed by both ozonation and Fenton oxidation. Moreover, theremoval efficiencies of cephalosporins, antibiotic resistant E-LF and blaTEM-2gene were more than97%,3-log and1-log respectively by both ozonation andFenton oxidation. Ozonation and Fenton oxidation were suitable in the advancedtreatment of antibiotic wastewater based on biosafety assurance.