The Distribution Of Antibiotics In Wastewater Treatment Plant And Their Effects To Biological Treatment Process

The existence of antibiotics in pharmaceutical wastewater may inhibit metabolism ofmicrobes in activated sludge， which causes removal rate of conventional pollutants todecrease. Besides，the presence of antibiotics may induce the generation of antibioticresistant bacteria in wastewater. Antibiotic resistant bacteria are not easy to be removed byconventional wastewater treatment processes. When the antibiotic resistant genes aredischarged into the ecological environment， they may enter into pathogenic bacteria.Pathogens with antibiotic resistant genes will bring health risk to human beings.Therefore， doing research on the distribution and removal process of antibiotics in eachunit and making clear the effect of different antibiotics to activated sludge in biologicaltreatment unit and distribution of antibiotic resistant bacteria can provide basic data forcriterion values of antibiotics in discharge standards of water pollutants.Through the investigation on the production of pharmaceutical companies inindustrial zone and detection of water samples of the Shijiazhuang Liangcun wastewatertreatment plant with HPLC-UV, this research selected6kinds of antibiotics. Throughtesting oxygen uptake rate, this research measured inhibition of one antibiotic andmulti-antibiotics to activated sludge. Through training antibiotic resistant bacteria，thisresearch made clear the distribution and removal rate of antibiotic resistant bacteria in eachunit， which provides basic data for evaluating antibiotics’ potential risks to human health，and theories for further antibiotics’ control in pharmaceutical wastewater.The main results were as follows:(1) Set up the method to detect11antibiotics simultaneously with HPLC-UV. Withthis method， the distribution of6antibiotics-Sulfamethyldiazine、Trimethoprim、Tetracycline， Oxytetracycline， Sulfamethoxazole and Sarafloxacin in each unit weredetected. These6kinds of antibiotics mainly ranged from0.01μg/L to4.0μg/L. Theconcentrations of Trimethoprim and Oxytetracycline were higher than others. Both of themwere up to3.0μg/L in influent and the concentration of Trimethoprim was up to1.6μg/L in effluent. The concentrations of Tetracycline、Sulfamethyldiazine and Sarafloxacinwere mainly lower than0.5μg/L. Conventional treatment process could not removeantibiotics effectively. The concentrations of Sulfamethyldiazine、 Trimethoprim and Sarafloxacin appeared higher than those in former units，which showed that activatedsludge may recharged antibiotic into wastewater.(2) The inhibitory order of individual antibiotic to aerobic sludge OUR wasTetracycline> Oxytetracycline> Sulfamethoxazole> Sulfamethyldiazine> Sarafloxacin>Trimethoprim. Both EC50of tetracycline and oxytetracycline were <10mg/L，suggestingthe highly toxicity of tetracycline and oxytetracycline.6antibiotics were divided into twogroups in combined experiments. The first group showed that Tetracycline exertedsignificant inhibitory effect (P<0.05). The second group showed that Oxytetracyclineexerted significant inhibitory effect (P<0.01) while sulfamethyldiazine exerted significantinhibitory effect (P<0.05). The additive effect occurred in the Tetracyclines and Sulfamidessystem， while the interaction between other two antibiotics was antagonistic.(3) The total heterotrophic bacteria were above105CFU/mL in influent，regulate pooland anaerobic pool， were104CFU/mL in displaced beds and oxidation ditch， while was103CFU/mL in effluent. The heterotrophic bacteria in influent had strong resistance toSulfamethoxazole， Trimethoprim， Oxytetracycline. When the concentrations of these3antibiotics reached32mg/L， the number of antibiotic resistant heterotrophic bacteriawas still up to104CFU/mL. The resistant bacteria to Sarafloxacin were less， when theconcentration of Sarafloxacin was16mg/L or more， concentration of heterotrophicbacteria was almost zero. After anaerobic pool， the concentrations of resistantheterotrophic bacteria in displaced beds and oxidation ditch were reduced by two orders ofmagnitude. When concentrations of Sulfamethoxazole and Trimethoprim reached32mg/L， the concentration of resistant bacteria remained above102CFU/mL. Whenconcentration of Oxytetracycline was32mg/L， concentration of heterotrophic bacteriawas almost zero. The concentration of Sarafloxacin was more than8mg/L，concentration of heterotrophic bacteria was almost zero. Conventional wastewatertreatment process can remove some antibiotic resistant bacteria， but was not effectively.Under the conditions of low concentrations of antibiotics， resistant heterotrophic bacteriadecreased apparently after anaerobic treatment. In conclusion， heterotrophic bacteria weremore sensitive to Oxytetracycline and Sarafloxacin， while which had strong resistance toSulfamethoxazole and Trimethoprim， resistant bacteria could exist stability in highconcentration of these two antibiotics.The results of this research can be treated as basis of clean-for-production or the watercollection area management， which aims at improving the removal efficiency ofwastewater treatment plant， improving the quality of water environment and reducingpotential risk to human health.