Study On Removal Of Antibiotics From Wastewater By Electrochemical Advanced Oxidation Technology

In terms of the treatment of medical wastewater,pharmaceutical wastewater,animal husbandry wastewater and aquaculture wastewater in China,due to the lack of standards for the discharge content of drugs and antibiotics in water,the discharge indexes of ordinary sewage plants are still used.However,when COD,ammonia nitrogen,total nitrogen and total phosphorus meet the standards,antibiotics and other drugs are discharged into rivers and discharged into the ecological environment without complete degradation.In recent years,the existence of antibiotics has appeared in the investigation reports of various basins.Due to the toxicity and poor biodegradation of antibiotics and other drugs,the long-term accumulation of antibiotics in animals and plants can easily cause unpredictable ecological risks.When antibiotics exceed the standard in the water environment,it is easy for bacteria to develop resistance,and even lead to the occurrence of gene mutation,which has a continuous threat to human health and the ecological environment.The existence of antibiotics makes the ecosystem have a serious security hidden danger.In recent years,with the improvement of people’s living standard,this kind of safety risks affecting health have been widely concerned.It is worth exploring to establish efficient and effective treatment method of antibiotic wastewater,and make such organic matter completely oxidized without secondary pollution.The advantages of electrochemical advanced oxidation technology are obvious.In this study,levofloxacin was selected as the target pollutant,and the influence factors,degradation products and pathways in the degradation process of levofloxacin were comprehensively studied by electrochemical oxidation technology,and the following conclusions were drawn:（1）The liquid phase detection conditions of levofloxacin were defined,and the specificity,repeatability,linearity and other aspects of the detection method were verified.The feasibility of the method was determined by data analysis.（2）Three kinds of coating electrodes based on titanium plate were selected to characterize the electrode materials by XRD and SEM,and the oxide structure and surface morphology characteristics of the electrolytic surface were clearly understood.The advantages and disadvantages of the structure for electrochemical oxidation reaction were analyzed according to the morphology of the electrode.After preliminary screening of the electrode plate,the performance of the electrode was tested.The experimental results show that the existence of Sn O₂ oxide can improve the oxygen evolution potential of the electrode,reduce the generation of oxygen evolution side reaction,and improve the reaction efficiency of the electrode.（3）In the study of the optimal conditions for the electrochemical oxidation of levofloxacin,a single factor experiment was conducted by the control variable method in view of four influencing factors,such as different current intensity,plate spacing,solution electrolyte concentration and initial p H of the solution.Combined with the analysis of energy consumption and removal rate in the process of experiment,the optimal conditions were obtained by orthogonal experiment:current intensity of 0.9A,distance between plates of 2 cm,electrolyte concentration of 4 g/L,and initial p H of the solution of 6.Under these conditions,the removal rate of levofloxacin was 94.65%after 120 min of electrochemical oxidation.（4）The molecular probe experiment of adding the capture agent to the reaction process shows that the reaction process is mainly involved with hydroxyl radicals,and the strong oxidation of hydroxyl radicals provides energy for the breaking of molecular chemical bonds.At the same time,the degradation process was analyzed according to the change of TOC and p H of the solution during the experiment,which provided the basis for inferred the mechanism.Finally,four intermediate products of levofloxacin were analyzed by liquid chromatography-mass spectrometry,and two possible degradation pathways were proposed for the electrolysis process.