Pollution Characteristics And Treatment Engineering Technology Demonstration Of Antibiotics In Drinking Water Sources

The emerging pollutants are difficult to be degraded and have enormous potential harm.The research on the pollution characteristics and treatment technology of emerging pollutants in water has become a hot spot in the field of environment.Antibiotic is an important kind of the emerging contaminants.In this research,the distribution and pollution characteristics of antibiotics in drinking water sources of Dongguan city were studied by solid phase extraction combined with HPLC-MS.To explore the removal performance of typical antibiotics by adsorption and advanced oxidation technology of waste plant fibers.The engineering application of PS advanced oxidation technology for antibiotic removal was studied.The main research results are as follows:（1）Solid phase extraction（SPE）combined with high performance liquid chromatography-mass spectrometry（HPLC-MS）was used to detect and analyze antibiotic content in drinking water sources in different watersheds and reservoirs in Dongguan city.The distribution and pollution characteristics of antibiotics in drinking water sources of Dongguan city were discussed.The results showed that among the 45 target antibiotics,34 antibiotics were detected in drinking water sources and 35 in reservoirs.In 11 drinking water source sampling points,the detected antibiotic concentration range was ND-143.94 ng/L.The highest concentration detected was ODM（143.94 ng/L）.Except for TMP,CFX,SAR,ODM and CTM,the detection frequency of other antibiotics in drinking water sources was 100%.In the9 representative reservoir sampling points,the detected antibiotic concentration range was ND-729.59 ng/L,and the highest detected antibiotic was ETM-H₂O（729.59 ng/L）.Among the antibiotics detected,except SMZ,SMM,TMP,NFX,CFX,PFX,SAR,MT,ODM,MO,ETM-H₂O,CTM,NAR,RTM,the detection frequency of other antibiotics was 100%.（2）The distribution differences of antibiotics in different spatial targets were analyzed by analysis of variance,and the results showed that the differences of antibiotics in water source spatial targets in Dongguan were not statistically significant.PCA results showed that there were as many as three principal components explaining 63.5%cumulative variance in the antibiotics detected in the water source of the water plant,and the key evaluation indexes were SQX,SGD,RTM,CTM,CTC,PEF,LFX,etc.In the reservoir evaluation sample points,the accumulation of as many as three principal components explained 75.4%variance,and SMX,LIN,ETM-H₂O,PEF,DFX and other important evaluation indicators were detected in antibiotics.Among the antibiotics detected in each water source,only SMM,SDZ,PEF and CAR showed moderate correlation with NH₄⁺and SO₄^2-in the water,indicating that the pollution sources of these antibiotics may come from domestic sewage or other pollution sources.Among sulfonamides such as SGD and SMX,ETM-H₂O and CTM were significantly correlated with Cl^-and SO₄^2-.The common pollution source of sulfate ion is closely related to domestic sewage,so it can be judged that the pollution source of this kind of antibiotics may be related to domestic sewage.SMM,SDZ,PEF,etc.are moderately correlated with domestic sewage,but there are also other uncertain pollution sources.In the water source,the antibiotic with high risk was CTM、NOV、NFX,and the RQ of CTM reached as high as 4.78,which appeared in the water source of shilong xihu waterworks.Among the high risk antibiotics evaluated were TMP,NFX,SAR,LIN,OTC,NOV,ETM-H₂O,and CTM.The HQ values calculated by the maximum concentration of each antibiotic are all less than 1,and the measured antibiotics pose no risk to human health,which is within the acceptable range of human body.（3）The influencing factors of antibiotics in the adsorption process were studied by changing the amount of adsorbent,reaction time,temperature and pH value.The results showed that the best operating conditions considering the adsorption efficiency and operating cost was 24 h reaction time,50 mg/L initial concentration,pH=6,and the adsorbent dosage was 2g/L.The theoretical saturation adsorption capacity of SCB fiber to ETM-H₂O before and after modification was 25.90 and 41.15 mg g^-1,and the removal rate reached 81.21%and94.44%,respectively.The adsorption process is more in line with the pseudo-secondary kinetic model and the Langmuir isotherm adsorption model,and for SCB,1/n=0.544>0.5,indicating that the adsorption process is difficult to carry out,and for CSCB,0<1/n=0.484<0.5,indicating that the adsorption process is easy to carry out.Through the thermodynamic analys,it is found thatΔH>0 andΔS>0,indicating ETM-H₂O adsorption via sugarcane bagasse fiber is an endothermic reaction and the adsorption of ETM-H₂O on the fiber increases the chaos of the substance at the solid-liquid interface.The adsorption of ETM-H₂O by the unmodified bagasse fiber has both physical adsorption and chemical adsorption,but it is more physically adsorbed,andΔG>0,indicating that the adsorption process is non-spontaneous,but the reaction is carried out because the conditions in the actual experimental process are not standard.The adsorption of ETM-H₂O by CA modified bagasse fibers is physical adsorption,ΔG<0,and the adsorption process is spontaneous.It can be seen from the experimental results that the modification significantly improved the adsorption performance of the bagasse fibers,which makes it more advantageous in practical application.（4）The degradation effect of PS and Fenton oxidation system on antibiotics was studied by changing the dosage of catalyst,pH and oxidant.The results showed that the reaction time was 4h,the initial pH of the solution was 7,the Fe²⁺dosage was 100 mg/L,and the PS dosage was 8.4 mmol/L,which were the best operating conditions considering the degradation efficiency and operating cost.The reaction time was 4h,the initial pH of the solution was 3,the Fe²⁺dosage was 100 mg/L,and the H₂O₂dosage was 12.6 mmol/L,which were the best operating conditions for Fenton oxidation system.Under the optimal conditions,the degradation rate of erythromycin in the PS oxidation system reached 94.26%and 96.27%at 30℃and 40℃,respectively.Compared with the Fenton oxidation system,its removal effect was better.The first 30min of PS oxidation degradation of erythromycin was a rapid reaction stage,which was consistent with the first-order kinetic reaction model The second stage（60 min later）conforms to the second-order kinetic equation.The thermodynamics results show that the rise of temperature is conducive to the generation of sulfate radical and the rapid degradation of pollutants.ΔH>0 andΔS>0 shows that PS erythromycin degradation reaction is endothermic reaction,increase is propitious to promote the reaction temperature,reaction increased after the phase interface material degree of chaos.PS oxidation system still has a good degradation effect on erythromycin at low concentration,and the degradation rate can reach more than 95%.According to the experimental results,the degradation efficiency of PS oxidation system to erythromycin is far better than that of Fenton,and it has more advantages in practical application.（5）By controlling the dosage,erythromycin concentration in raw water and water matrix,practical engineering demonstration was carried out.Through response surface design and analysis,the process conditions are further optimized in practical engineering.The results showed that the degradation effect of erythromycin was best when Fe²⁺:PS=1:40.The degradation rate reached 99.88%after 6h reaction.When the initial concentration of erythromycin decreased from 100 g/L to 1 g/L,the degradation rate of erythromycin increased from 72.46%to 97.55%,indicating that the lower the initial concentration of the pollutant,the more favorable the removal of the pollutant.The results of kinetic fitting showed that the degradation of hypoerythromycin conforms to the kinetic model of secondary reaction.The above conclusion fully proves that PS oxidation system can effectively degrade erythromycin at low concentration in raw water in practical engineering.The response surface was designed with reaction time,temperature and pH as influence factors and erythromycin degradation rate as response value.The simulation results showed that the reaction time,temperature and pH had significant interaction.Through response surface optimization,the model predicted the maximum degradation rate of erythromycin to be 98.53%.The optimal operating conditions were reaction time 6h,40℃and pH=6.5.Based on the response surface method,the degradation rate of erythromycin was taken as the response value,and the order of significance between NaCl,NaHCO₃,NaNO₃and HA was NaCl>NaHCO₃>HA>NaNO₃.The optimal operating conditions were as follows:NaCl was 0mM,NaHCO₃was 1.44mM,NaNO₃was 0.44 mM and HA was 3.32 mg/L,and the predicted degradation rate of erythromycin was 96.48%.The research of this paper has important theoretical and practical value for eliminating the harm of emerging pollutants and ensuring the water environment safety of drinking water sources.