| Antibiotics are widely used in human medical treatment and animal breeding due to their good antibacterial effect and low price.However,the large-scale use of antibiotics has brought great risks and challenges to the natural water body,especially the surface water environment.Therefore,it will be great significance for investigating the concentration of antibiotics in natural water bodies,assessing their ecological risks,and on this basis,researching reactors that efficiently degrade antibiotics and their resistance genes in water bodies.In this thesis,we selected 17 lakes and 8 rivers in the middle and lower reaches of the Yangtze River as the research area.The field samples were collected to investigate and evaluate the contents and risks of 10 typical antibiotics.The MBR-UV/NaClO system has studied the treatment effect of contaminated surface water containing 10 typical antibiotics.The research results obtained are as follows:（1）The survey results of typical antibiotics in the middle and lower reaches of the Yangtze River are as follows:1)7 and 5 target antibiotics were detected in lakes and rivers,respectively,with concentrations ranging from ND-1139.4 ng/L and ND-84.15 ng/L.Sulfadiazine（SD）,Sulfamethoxazole（SMZ）,Ofloxacin（OFX）,Erythromycin（ERY）,Roxithromycin（ROX）,Ibuprofen（IBU）detected in the lake under investigation And naproxen（NAX）concentration ranges are:0-24.84 ng/L,14.86-657.02 ng/L,0-106.04 ng/L,0-1139.4 ng/L,ND-23.49 ng/L,IBU,0.62-17.50 ng/L,0.44-3.74 ng/L;the concentration ranges of SD,SMZ,ERY,ROX,and NAX detected in the surveyed river are ND-6.33 ng/L,ND-84.15 ng/L,ND-11.80 ng/L,0.51-3.34 ng/L and 0.59-1.34 ng/L.In general,SMZ and ERY pollution is the most serious in the investigation water body.2)Correlation analysis of antibiotics in the water body of the survey area and some water quality parameters in the corresponding environment.The results show that there is a significant positive correlation between SD and ROX,OFX and NAX（p<0.05）,OFX and IBU have a very strong positive correlation（p?<0.01）,OFX and oxidation has significantly negatively correlated（p?<0.05）,NAX and conductivity were strongly positively correlated（p<0.01）,and IBU was significantly positively correlated with redox potential（p?<0.05）;in the study In river water,SMZ was significantly positively correlated with ERY and temperature（T）（p<0.05）,and also significantly positively correlated with NO3--N,NH4+-N and suspended particles（p?<0.01）;ERY was NO3--N was positively correlated（p?<0.05）;ROX was positively correlated with NH4+-N and suspended particulate matter（p?<0.01）.3)The ecological risk level and health risk level of antibiotics in the survey area were evaluated.The ecological risk assessment results show that SMZ has a high risk in all lakes and 6 rivers,and ERY high risk in 5 lakes;health risk assessment results show that different antibiotics pose health risks in different water bodies,and as the age group decreases,the health risk level of antibiotics increases.The occurrence of antibiotics in 5 lakes presents a high level of risk to humans.OFX,ROX and ERY are more likely to be at risk in each lake than other antibiotics.In the rivers under investigation,the overall risk of antibiotics to the human body is low or no risk.The risk assessment results show that antibiotics exist in the environment for a long time,which poses a huge potential danger to the ecology and human body,prevention and control measures should be controlled as soon as possible.（2）The MBR-UV/NaClO reactor is used to treat contaminated surface water.The results show that:1)The MBR system has a good long-term removal effect on CODMn and NH4+-N,and the removal rate ranges from 49.32%-92.68%and 44%-100%,respectively.The removal rate of UV254 is 2.22%-54.95%.MBR-UV/NaClO has a good effect on the removal of CODMnn and NH4+-N,and the removal of UV254 in the system is increased by 0.94%-42.22%relative to the MBR system.2)The detection concentration of each antibiotic in each part of the system is ND-379.37 ng/L.The overall removal rates of the MBR-UV/NaClO system for SMZ,ERY,ROX,NAX,IBU,ciprofloxacin（CIP）,OFX,tetracycline（TC）,oxytetracycline（OTC）and SD are 95.61%,87.57%,93.38%,93.80%,71.46%,50.54%,52.97%,33.57%,47.71%and12.18%,respectively.In each stage of treatment,different antibiotics have been reduced or accumulated.In general,most of OTC,ROX and IBU are converted and degraded in the MBR system;while CIP,OFX,TC,ERY and NAX are mostly removed by UV/NaClO;in this study,the MBR system has no removal effect on SD and SMZ,while The UV/NaClO system has a good removal effect on SMZ,the removal efficiency is 95.61%,but still has no obvious removal effect on SD,and the removal efficiency is only 12.18%.The removal rate and detected concentration of each antibiotic in the system may be related to the operating conditions of each part of the reactor such as pH,DO,etc.,and the structural properties of antibiotics such as hydrophilicity and hydrophobicity,molecular weight,etc.,and the water matrix in the system such as carbonate,Ammonia nitrogen,etc.3)The long-term existence of antibiotics in the environment will induce the production of antibiotic resistance genes（ARGs）.This study continued to add antibiotics to the MBR-UV/NaClO system and found that the detection concentration of sulfa antibiotic resistance gene sul1 was 10-0.458-105.659.659 copies/mL,each part of the reactor contributes differently to the removal of sul1.In the MBR stage,sul1is 102.997-105.603 copies/mL in the influent and 102.066-102.909.909 copies/mL in the MBR effluent.The removal effects of MBR and UV/NaClO on sul1 are 0.121-2.693 and 1.299-3.187 orders of magnitude,respectively.In general,MBR and UV/NaClO have good removal effect on low concentration of sul1 in this study.The removal of ARGs by the reactor may be related to the operating parameters of the reactor such as DO,the concentration of antibiotics and heavy metals in the water matrix such as the system,and the microbial community in the system. |
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