Study On Removal Of Typical Antibiotics And Antibiotic Resistance Genes By Catalytic Ozone Ozonation Technology

Five selected antibiotics?ETM?SMX?SD?TC?OTC?in water were detected along the water treatment process in a drinking water treatment plant in a city,and their fates were analyzed;Long-term excessive antibiotics continuous emissions into the environment resulting in a high antibiotics selection pressure and inducing the microorganism to produce a antibiotic resistance genes?ARGs?.A large number of studies have shown that ARGs are widely found in soil,surface water and even groundwater.To ensure the safety of drinking water,analyzed the pollution and removal of four sulfonamide and tetracycline resistance genes,namely,sul?,sul?,tetA and tet G in this drinking water treatment plant with the method of real time PCR?SYBR Green?;Selected Sulfadiazine as the target antibiotic,investigated the removal efficiency of the antibiotics by different catalytic Ozone ozonation technology.Moreover,the different oxidation technology were evaluated by investigating the biodegradability and toxicological changes of sulfadiazine during the degradation process.The results showed that the raw water contains all kinds of five target antibiotics in the samples and the highest concentration of SMX reached 59.40 ng/L,the lowest concentration of ETM was 0.87 ng/L.The content of antibiotics was decreased obviously in the finished water,two kinds of antibiotics were not detected,and the other antibiotics' concentrations were below 7ng/L.The antibiotics can effectively be removed in this plant,and the total removal efficiency of the antibiotics in the integrated water treatment process was 89.9%.The units of Ozonation and biological activated carbon were demonstrated to be the most effective techniques for the antibiotics removal,the total removal efficiency of the antibiotics was 71.2% and 13.1%,respectively.And the unit of sediment?sand filter and chlorine disinfection showed a low removal efficiency of the antibiotics.The unites of Ozonation and biological activated carbon were the advanced processes of the plant,others were traditional.From the results,it can be seen that the advanced treatment processes are better than the traditional treatment processes for the removal of antibiotics.Samples were collected from the source water of the plant and finished water of each unites.For each sample,extracted DNA and the quantified by PCR detection.The results showed that the raw water contains all kinds of four ARGs in the samples,the concentrations of sul??sul??tetA and tetG were 2.54×10³ copies/ml?1.36×10³ copies/ml?1.47×102 copies/ml and 0.064×102copies/ml,respectively.The concentration of ARGs were decreased first and the increased and then decreased again along the processes.Among them,the units of Ozonation and chlorine disinfection were the lowest point of ARGs,almost no ARGs.the effluent of biological activated carbon unit was another peak of ARGs,the concentrations of sul??sul??tetA and tetG were1.12×10³copies/ml?0.18×102copies/ml?0.05×102copies/ml and 0.14×102copies/ml,respectively.Different processes have different effects on the removal of antibiotics.Taking sulfadiazine as the target antibiotic,compared the removal efficiency of alone O₃?O₃/H₂O₂?O₃/UV and O₃/UV/H₂O₂.The results showed that the four technology had well removal effect on the sulfadiazine at medium pH.When the Ozone dosage was 10 mg/L,the removal rates of SD by the O₃/UV/H₂O₂ process were nearly 100%,82.5%?91.7% and 98.6% by the other processes.The Ozone dosage increased to 12 mg/L,O₃/UV process can also completely remove the SD.Therefore,the removal efficiency of SD by the four processes was O₃/UV/H₂O₂>O₃/UV>O₃/H₂O₂>O₃ alone.O₃ alone showed a low removal efficiency of TOC.When the ozone dosage increased to 10 mg/L,the removal efficiency of TOC by O₃ alone was19.6%,the other three were 34.60%?46.54% and 55.87%,respectively.It can be seen that catalytic Ozone ozonation processes of mineralization of the solution is higher than O₃ alone.In order to evaluate the four catalytic Ozone oxidation technology,the biodegradability dissolved organic carbon?BDOC?and the acute toxicity of the luminescent bacteria of the solution were determined before and after oxidation.The bio-sand to which the active bacteria were attached was inoculated into the SD solution before and after oxidation and determined the BDOC after 9 days.The results showed that when the Ozone dosage increases from 0 mg/L to 12mg/L,the BDOC concentration increases from 0.107 mg/L to 0.875 mg/L?from 0.107 mg/L to1.007 mg/L?from 0.107 mg/L to 1.046 mg/L and from 0.107 mg/L to 1.29 mg/L by O₃ alone?O₃/H₂O₂?O₃/UV and O₃/UV/H₂O₂,respectively.It can be seen from the results,the solution of SD can be more biodegradable after catalytic Ozone ozonation.Adding luminescent bacteria to the SD solution before and after oxidation,the luminescence intensity of the luminescent bacteria was measured after 15 min.SD solution showed a well linear relationship with the luminescence inhibition rate of luminous bacteria before oxidation,with EC20 value of 562.7 mg/L and EC50 value of 1235.35 mg/L.The results show that the inhibition of luminescent bacteria increases withthe oxidation time.when the oxidation time was extended to 140 min,the luminescence inhibition rate of SDZ solution to luminous bacteria were 95.55% ?96.34%?91.6% and nearly 100% by the O₃ alone?O₃/H₂O₂?O₃/UV and O₃/UV/H₂O₂ processes,respectively.