Study On Removal Of Antibiotics By Catalytic Ozonation From Factory Marine Aquaculture Wastewater

Florfenicol?Florfenicol,FF?and tetracycline?Tetracycline,TC?were commonly used as antibiotics in mariculture processes.Due to farmers'blind pursuit of benefits and prevention of fish diseases,unscientific and excessive addition of FF and TC in the production process led to a large number of antibiotic residues in the circulating culture water.The residual antibiotics were difficult to remove by conventional treatment methods,leading to pollution of cultured circulating water and the breeding of resistant bacteria bring serious harm to the cultured economic products.Based on this background,this paper mainly carried out the following work.Firstly,Catalytic ozone oxidation technology was used to remove FF from simulated marine aquaculture wastewater.Using?-Al₂O₃ supported by different metal oxides as a catalyst,and FF as a target pollutant.The removal efficiency of different catalysts was investigated,and the catalyst suitable for degrading FF was screened out.The effects of process parameters such as ozone concentration and catalyst dosage on FF removal were investigated.The response surface method was used to investigate the optimal reaction conditions of FF.The effects of potassium permanganate index(COD_Mn)and ammonia nitrogen concentration on the removal rate of FF in seawater were investigated,and the concentration of bromate formed in FF simulated wastewater after reaction was also detected.The changes of three-dimensional fluorescence characteristics before and after FF simulated wastewater reaction were studied by three-dimensional fluorescence spectroscopy was used to study,and the removal rate of TOC after FF simulated wastewater reaction was detected.The FF degradation intermediates were qualitatively analyzed by liquid chromatography-mass spectrometry?LC-MS?to speculate the FF degradation pathway.Finally,the toxicity of wastewater was investigated by the acute biotoxicity test of luminescent bacteria.The results showed that S-Mn-CeO_x/?-Al₂O₃ was suitable for the degradation of FF in cultured circulating water,and the degradation rate was consistent with the mixed first-order reaction kinetics.The increase of ozone concentration and catalyst quality would promote the removal efficiency of FF.According to the analysis results of the response surface method,the optimal degradation conditions of FF:the dosage of ozone was 14.77 mg/L,the dosage of catalyst was159.78 g,and the reaction time was not less than 19.46 min.With the increasing of COD_Mnn and ammonia nitrogen concentration,the removal efficiency of FF decreased,and the removal of FF also degraded ammonia nitrogen.The concentration of bromate formed after the reaction of FF simulated wastewater was 0.2 mmol/L.During the degradation of FF,the reaction system had a certain degree of degradation effect on aromatic protein and arginine in simulated wastewater with FF.After the reaction,the TOC removal rate of FF simulated wastewater was 55%.In the process of FF degradation,the benzene ring of FF was attacked by·OH,and then gradually became a small molecule,CO₂ and H₂O.The relative luminescence intensity of bright fag luminescent bacillus increased,indicating that the simulated wastewater was treated by catalytic ozone oxidation process,and the biotoxicity of the water after the reaction was significantly lower than that before the reaction.The TC in the simulated wastewater was removed by catalytic ozonation,using?-Al₂O₃supported by different metal oxides as catalysts.First,the catalysts suitable for degrading TC were screened by the removal effect of TC by different catalysts.The effects of process parameters such as ozone concentration and catalyst dosage on TC removal were investigated.The response surface methodology was used to investigate the optimal reaction conditions of TC.The effects of potassium permanganate index(COD_Mn)and ammonia nitrogen concentration on the removal rate of TC were investigated,and the concentration of bromate formed in the simulated wastewater of TC was measured.The changes of three-dimensional fluorescence characteristics before and after the reaction of TC simulated wastewaterwas studied by three-dimensional fluorescence spectroscopy technique,and the removal rate of TC simulated wastewater in the system was investigated.The degradation pathway of TC in the degradation process of the system was investigated by LC-MS.The toxicity of simulated wastewater was investigated by using the acute toxicity test of luminescent bacteria.The results showed that D-Mn-CeO_x/?-Al₂O₃ was suitable for the degradation of TC in cultured circulating water,and the degradation rate of D-Mn-CeOx/?-Al₂O₃ was consistent with the mixed first-order reaction kinetics.The increase of ozone concentration and catalyst quality would promote the degradation of the target pollutants in the reaction system.According to the analysis results of the response surface method,the optimal degradation conditions of TC:the dosage of ozone was 4.46 mg/L,and the dosage of catalyst was 186.67 g.The catalytic time was no less than 3.27 min.TC removal rate decreased with the increasing of COD_Mn and ammonia nitrogen concentration,demonstrated that the system could remove ammonia while removing TC.The concentration of bromate formed after the end of the TC simulated wastewater reaction was 0.0103 mmol/L.During the degradation of TC,many refractory humic acids with complex structures were occurred in TC simulated wastewater of D-Mn-CeO_x/?-Al₂O₃ catalytic ozonation system.After the reaction,TC simulated wastewater The TOC removal rate was 71.6%.The TC underwent a dipolar addition reaction,a molecular rearrangement reaction,etc.as the C-C double bond attacked by·OH,and finally converted into CO₂ and H₂O.The relative luminescence intensity of bright fag luminescent bacillus T₃increased,indicating that the water quality of TC simulated wastewater increased after the catalytic ozone oxidation process.Finally,the catalytic ozone technology was applied to treat the wastewater of sea cucumber seeding base,and the effects of S-Mn-CeO_x/?-Al₂O₃ and D-Mn-CeO_x/?-Al₂O₃ on the actual aquaculture wastewater were investigated.In the research of nursery wastewater treatment,the residual seedling wastewater containing 3.13 mg/L FF and 3.62 mg/L TC was obtained in different culture areas,and the optimal reaction conditions of FF and TC was obtained by response surface method,changes of water quality before and after the reaction were compared.Finally,the three-dimensional fluorescence characteristics of the tailwater containing FF and TC were analyzed.The experimental results showed that the optimal removal condition of tailwater containing FF sea cucumber was 17.13 mg/L,the dosage of catalyst was 170.57 g,and the reaction time was no less than 4.74 min.The degradation rate of FF was 100%,and the water quality after the reaction was in compliance with the safety standards for sea cucumber seedling water.The optimum removal conditions for TC-containing wastewater were 12.96 mg/L for ozone,172.52 g for catalyst,and no less than4.85 min for reaction time.The TC removal rate was 86.2%under this condition.The water quality was in accordance with the safety standards of sea cucumber seedlings;S-Mn-CeO_x/?-Al₂O₃ had a good removal effect on fulvic acids,tryptophans,and humic acids in FF sea cucumber seedling wastewater.D-Mn-CeO_x/?-Al₂O₃ had a good removal effect on proteins and complex humic acids in TC sea cucumber seedling wastewater.