| Phthalate esters?PAEs?are endocrine-disrupting chemicals,among which six are listed in the priority pollutants list of US Environmental Protection Agency?EPA?and European Union,and also listed in the priority pollutants list of Chinese waters,and are limited the concentration of PAEs in water.In order to explore the types and distribution characteristics of PAEs in the main water treatment units of urban sewage treatment plants,obtain the basic data of PAEs removal effect,and provide a new scientific basis for the application of PAEs removal technology,this study established the pretreatment and gas chromatography-mass spectrometry test and analysis methods of PAEs in environmental samples,selected three sewage treatment plants in Baoding,collected water samples and sludge samples from different process stages of sewage treatment plants,and investigated the types and distribution characteristics of PAEs in sewage treatment plants.At the same time,the sewage treatment plants were obtained through a series of tests On this basis,the ecological risk assessment of effluent from sewage treatment plant is also carried out.The research results are as follows:?1?An analytical method for PAEs in sewage and sludge samples was carried out.By exploring the effects of different solid phase extraction columns and eluents on the recovery rate of PAEs in sewage samples,and exploring the effects of types and amounts of extraction solvents and adsorbents on the recovery rate of PAEs in sludge samples,a detection method for PAEs was established.The correlation coefficient R2of 16 PAEs in this method was greater than 0.995,and both the correlation coefficient and the minimum detection limit met the requirements of microanalysis.?2?The total concentration of PAEs in the influent of three sewage treatment plants was tested.It can be seen from the test results that the total concentration of PAEs ranges from9.69?g/L to 14.19?g/L,and DBP has the highest concentration in the influent of each sewage plant,with its concentration ranging from 5.71?g/L to 8.96?g/L.The final effluent from the three sewage treatment plants was up to the pollutant discharge standards of urban sewage treatment plants in China.?3?the concentration of PAEs in the sludge of the three sewage plants ranged from 16.45?g/g to 62.95?g/g.According to the total amount of PAEs in sludge from high to low,the three sewage treatment plants are W1,W3 and W2.Among the PAEs detected from the sludge of three sewage plants,DEHP content is the highest,and its concentration is 12.75?49.89?g/g,accounting for 77%?79.3%of.The second is DBP,and its concentration is1.69?6.98?g/g,accounting for 10%?11.4%of.DEP content is the lowest,and its concentration is 0.07?0.14?g/g.Generally speaking,the PAEs content in the sludge of W1and W3 sewage treatment plants is higher,while the PAEs content in the sludge of W2sewage treatment plants is lower.?4?The total removal rate of W1 sewage treatment plant is 71%;The total removal rate of PAEs in W2 sewage treatment plant is 75%.The total removal rate of W3 Wastewater Treatment Plant is 66%.The total removal rate of the three sewage plants is 66%?75%.There is little difference in treatment effect among the three sewage treatment plants,and the overall PAEs removal effect of W2 sewage treatment plant is the best.By comparing the removal efficiency of PAEs by the secondary treatment processes of the three sewage treatment plants,it is found that the removal rate ofby the three sewage treatment plants ranges from 49%to 66%.The removal efficiency of DMP and DEP is the best by secondary treatment in three sewage treatment plants.?5?The ecological risk order of the effluent from the three sewage treatment plants is W3>W2>W1.The risk entropy of the effluent from the three sewage treatment plants ranges from 1.14×10-7to 0.118,from which it can be seen that the PAEs compound with the highest risk entropy is DEHP,followed by DBP.Among them,DEHP caused moderate ecological risk to W3 Wastewater Treatment Plant.Other PAEs compounds have low ecological and environmental risks.The ecological risk of a single phthalate ester in sewage is DEHP>DBP>DIBP>other PAEs.Conclusion:When the p H of sewage sample is 7,4m L of mixed solution of ethyl acetate and dichloromethane=1:1 is used,the recovery rate of PAEs is better.When acetonitrile is used as extraction solvent and PSA and C18 are used as adsorbents,the treatment effect of sludge samples is better.The effluent of the three sewage treatment plants is mainly DBP,and the sludge is mainly DEHP.The removal of PAEs in the three sewage treatment plants is mainly secondary treatment,and DEHP has the highest risk entropy of ecological risk to aquatic organisms in the effluent.Therefore,the research on DEHP removal in secondary treatment process of sewage treatment plant should be increased to reduce the impact of PAEs in effluent of sewage treatment plant on environment. |
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