Research On Removal Of Typical Antibiotics By Ozone Catalytic Oxidation Process In Drinking Water

The study discussed the removal of typical antibiotics by ozone catalytic oxidation process in drinking water. The removal efficiency of typical antibiotics by ozone under different working conditions was explored. Oxidation product and transformation way of typical antibiotics in the process of oxidation were examined and oxidation mechanism of antibiotics by ozone was explored. On this basis, pollution sources of typical antibiotics in the aquatic environment of a city in china were explored. Typical antibiotics concentration gradation change rules in the productive drinking water ozone-active carbon advanced treatment process and removal mechanisms of antibiotics in the process were researched.The results show that the different removal efficiency between sulfamethoxazole and erythromycin in water by ozone under different working conditions. Antibiotic molecular structure have an effect on ozone oxidation effective and sulfamethoxazole of sulfonamides containing the unsaturated bond are more easy degradation than erythromycin of macrolides, which were built of mostly saturated hydrocarbon structure. The minimum amount of ozone required for almost complete degradation of sulfamethoxazole and erythromycin are2mg/L and3mg/L in the neutral condition. Sulfamethoxazole are easier degradation at low pH, but the erythromycin more easily degradation at low pH. The removal efficiency of sulfamethoxazole and erythromycin by O3+H2O2, O3+UV, O3+H2O2+UV and O3+modified AC system are superior to alone O3, and sulfamethoxazole and erythromycin removal efficiency are best by O3+H2O2+UV and O3+modified AC. In O3/H2O2system, the excess H2O2will be free radical scavenger and reduce ozone oxidation effect. The maximum removal efficiency of sulfamethoxazole and erythromycin are99.0%and98.2%at mole ration of H2O2/O3=0.5by H2O2/O3process. In O3+modified AC system, the minimum amount of modified AC required for almost complete degradation of sulfamethoxazole and erythromycin are1.0mg/L. The removal efficiency of sulfamethoxazole and erythromycin by O3+modified AC are98.8%and97.9%. Different water quality have an effect on alone ozone oxidation sulfamethoxazole and higher removal efficiency of sulfamethoxazole with spiked water in source water than pure water. But the removal efficiency of sulfamethoxazole and erythromycin with spiked water in source water are lower than pure water by O3+H2O2, O3+UV, O3+H2O2+UV and O3+modified AC.The study on ozone oxidation mechanism of sulfamethoxazole show that the direct oxidation first when alone ozone oxidation and the direct oxidation is as important as the indirect oxidation when ozone catalytic oxidation. Tert-butyl alcohol partially inhibited the removal of sulfamethoxazole by ozone catalytic oxidation. When tert-butyl alcohol concentration was20mg/L and30mg/L, the removal efficiency of sulfamethoxazole remained about the same by alone O3,O3+H2O2, O3+UV, O3+modified AC and O3+H2O2+UV and60.3%,54.6%,55.4%,70.9%and53.9%respectively. The study on intermediate product of sulfamethoxazole by ozonation show that five oxidation products identified are3-Amino-5-methylisoxazole, hydroquinone,4-nitro-Benzenesulfonamide, p-Nitroaniline and4-amino-Benzenesulfonamide in single ozonation process. The original S element of the sulfamethoxazole is finally converted to SO42-and part of the N element is converted NO3-, NH4+and free ammonia.The study on pollution characteristic of typical antibiotics in the aquatic environment of a city in china show that except for erythromycin, other five antibiotics include sulfamethoxazole, sulfamethazine, amoxicillin, tetracycline and oxytetracycline are widespread in the aquatic environment. The wasterwater treatment plant process can not completely remove these antibiotics. Traces of antibiotics were detected in the water samples which were taken from the Yellow River and the Shiao-chang River in the city and Yellow river Reservoir. The antibiotics removal effect of conventional drinking water treatment process is not obvious. A productive process of a drinking water plant are analyzed, the results show drinking water advanced treatment process can effectively removal sulfamethoxazole, sulfamethazine, amoxicillin, tetracycline, oxytetracycline and erythromycin and the average concentrations of the six antibiotics in raw water ranged from1～43ng/L drop to0～6ng/L. The removal efficiency of total antibiotics reach91.4%, amoxicillin85.6%, tetracycline92.0% oxytetracycline86.3%, sulfamethoxazole, sulfamethazine and erythromycin approximately100%in the overall of the drinking water treatment plant. Coagulation sedimentation, sand filtration and chlorination contribute to remove total antibiotics are1.9%,1.0%and3.8%, respectively. Ozone oxidation and biological activated carbon contribute to remove total antibiotics reach65.2%and19.8%. Obviously, ozone-biological activated carbon advanced treatment process is the main step to remove antibiotics in the drinking water treatment plant.