Removal Of Typical Antibiotics In Dairy Farm Wastewater

In order to effectively control the residual amount of antibiotics in the wastewater discharged from livestock farming industry,this thesis,taking the wastewater in typical dairy farm in Shanghai as processing obj ect,studied the removal effect of Sulfonarmides and?-lactams in the wastewater by anaerobic-aerobic biological treatment process.In addition,advanced treatment technologies including activated carbon adsorption and ozonation had been assessed for the removal of four typical sulfonamides(i.e.,sulfadiazine(SD),sulfamethazine(SMZ),sulfamonomethoxine(SMM)and sulfamethoxazole(SMX))in dairy farm wastewater.The reaction conditions of activated carbon adsorption and ozonation had been optimized.The following conclusions could be drawn from this study(1)The total amount of sulfonamides and ?-lactams in dairy farm wastewater used in the experiment was about 1.6-26.2?g/L.(2)Anaerobic-aerobic process was adopted to treat daily farm wastewater.When the hydraulic retention time(HRT)of anaerobic and aerobic units were both 5 d,the combined process had a relatively stable degradation effect on conventional organic pollutants.The average removal rate of COD by the combined process was as high as 93.3%.However,the removal efficiency for antibiotics showed a significant fluctuation from 49.1%to 95.3%,which was sometimes lower than 60%(the assessment index agreed in the task contract of this proj ect).(3)Anaerobic-aerobic process was used to treat dairy farm wastewater added with 4 typical sulfonamides such as SD,SMZ,SMM and SMX(the concentration of each antibiotics was 1000?g/L).When the HRT of anaerobic and aerobic units were still both 5 d,the degradation effect of conventional contaminants was almost unaffected.However,the removal rate of each sulfonamides was greater than 98%.This showed that when the concentration of antibiotics in dairy farm wastewater was relatively high,the biochemical process was better for removing antibiotics.(4)When activated carbon was used to adsorb simulated wastewater prepared from deionized water and four sulfonamide antibiotics such as SD,SMZ,SMM and SMX(the concentration of each antibiotics was 1000 ?g/L),the appropriate adsorption conditions were as follows:powdered activated carbon 50 mg/L,pH=6.0,and contact time 2 h.Under the optimized conditions,the removal rates of SD,SMZ,SMM and SMX were 83.3%,94.5%,95.3%and 88.8%respectively.(5)When activated carbon was used to absorb simulated wastewater prepared from the effluent from anaerobic-aerobic biochemical treatment of dairy farm wastewater(referred to as secondary effluent of dairy farm,COD?410 mg/L)and 4 sulfonamide antibiotics such as SD,SMZ,SMM and SMX(the concentration of each antibiotics was 1000 ?g/L),the appropriate adsorption conditions were as follows:powdered activated carbon 200 mg/L,pH=6.0,and contact time 2 h.Under the optimized conditions,the removal rates of SD,SMZ,SMM and SMX were 92.0%,95.0%,96.5%and 92.3%respectively.The adsorption effects of two kinds of simulated antibiotic wastewater were similar,but the dosage of activated carbon in the latter was 4 times that of the former,which showed that the adsorption of trace antibiotics was inhibited by the high concentration COD remaining in secondary effluent of dairy farm.(6)The activated carbon adsorption method was used to treat the secondary effluent of the dairy farm to remove the residual antibiotics.Under the conditions of powdered activated carbon dosage of 200 mg/L and pH=6.0,the removal rate of residual antibiotics after adsorption for 2 h was about 61.8%.The whole anaerobic-aerobic biochemical treatment+activated carbon adsorption advanced treatment process had a removal rate of 83.8%for antibiotics in dairy farm wastewater,higher than the proj ect requirement of 60%.(7)When O3 oxidation method was used to treat simulated wastewater(the concentration of each antibiotics was 1000?g/L)prepared from deionized water and 4 sulfonamides such as SD,SMZ,SMM and SMX,the appropriate process conditions were as follows:pH=8.0,O3 dosage 8.75 mg/(L min),and reaction time 5 min.Under the optimized conditions,the removal rates of SD,SMZ,SMM and SMX were 91.2%,90.5%,90.6%and 90.3%respectively.(8)When O3 oxidation method was used to treat simulated wastewater(he concentration of each antibiotics was 1000?g/L)prepared from secondary effluent of dairy farm and 4 sulfonamide antibiotics such as SD,SMZ,SMM and SMX.the appropriate process conditions were as follows:pH=8.0,O3 dosage 8.75 mg/(L min),and reaction time 25 min.Under the optimized conditions,the removal rates of SD,SMZ,SMM and SMX were 96.3%.96.3%.94.5%and 96.2%respectively.The O3 oxidation effects of the two simulated antibiotic wastewater were similar,but the O3 dosage of the latter was 5 times that of the former,because the high concentration COD remaining in the secondary effluent of the daily farm competed with trace antibiotics for oxidant and consumed a large amount of O3.(9)Advanced treatment of secondary biochemical effluent from dairy farm by O3 oxidation method to remove residual antibiotics.Under the conditions of pH=8.0 and O3 dosage of 8.75 mg/(L min),the removal rate of residual antibiotics after ozonation for 25 min was about 46.7%.The whole anaerobic-aerobic biochemical treatment+O3 oxidation advanced treatment process had a removal rate of about 77.4%for antibiotics in dairy farm wastewater,which also met the requirement of the project.