| With the continuous advancement of my country’s urbanization,the scale of the printing,dyeing and textile industry has gradually expanded.At present,the status of the printing and dyeing textile industry in our country is constantly improving,accompanied by a large amount of printing and dyeing wastewater.There are a large number of heavy metal antimony,aniline compounds and various pollutants in the printing and dyeing wastewater,which brings great harm to the environment.In 2014,a heavy metal antimony incident occurred in a certain district of Suzhou,causing printing and dyeing enterprises in a large area to suspend production,causing huge losses to the local economy.Under the current general trend of the common development of economy and environment,the exploration of re-repairing the dyeing and printing standard tail water still cannot be stopped.This topic has determined the wetland fillers and plants that have the best removal effect on heavy metals antimony and aniline in the previous research.On this basis,this paper selects the printing and dyeing wastewater treatment plant in a certain district of Suzhou as the research object to study the law of repurifying the printing and dyeing compliance with the constructed wetland composed of specific plants and fillers,and adopts the return flow operation mode.Explore the effect of different reflux ratios on the enhanced removal of various pollutants in wastewater.After that,the enrichment and transportation of heavy metal antimony in plants after the end of the wetland operation was discussed.The specific research results are as follows:(1)Use anthracite as a filler,cattails,water onions,calamus,and canna as wetland plants to build a subsurface artificial wetland.Four recirculation methods of 0,70%,130%,and 200% were used to explore the removal effect of wetlands on various pollutants in printing and dyeing wastewater.The results showed that the four types of constructed wetlands have good removal effects on TN and TP.,The removal rate of the 4 types of constructed wetlands are arranged in descending order of 130% reflux ratio(84.3%)>70% reflux ratio(82.2%)>200% reflux ratio(80.3%)>no reflux(70.7%).For TP,the removal rate of the 4 types of constructed wetlands is in descending order: 70% reflux ratio(78.3%)>200% reflux ratio(69.5%)>130% reflux ratio(68.8%)>no reflux(65%)).The removal rate of heavy metal antimony and aniline compounds is about 50%,and reflux does not significantly improve the removal rate of these two pollutants.For heavy metal antimony,the removal rate is200% reflux ratio(57.43%)in descending order.130% reflux(54.57%)>70% reflux(53.27%)>no reflux(50.25%).For aniline compounds,the removal rate is 200%reflux(51.2%)>70% reflux(49.6).%)>130% reflux(49.14%)>no reflux(47.8%);the removal rate of COD in wastewater is about 40%,and the removal rate of COD in the4 types of constructed wetlands is 200% in descending order(46.56%)>130% reflux(41.95%)>70% reflux(41.26%)>no reflux(35.2%).The main target pollutants of this project are heavy metal antimony and aniline compounds.According to the requirements of the subject,the constructed wetland with a reflux ratio of 200% is the most suitable wetland for this test.(2)Select the plants harvested after the trial operation of the constructed wetland with a reflux ratio of 200% to study the enrichment and distribution of heavy metal antimony and aniline compounds in the body.The results showed that the concentration of heavy metal antimony in the four plants was cattail>changpu>water onion>canna in order,and the highest concentration could reach 23.411 mg/kg;the concentration of aniline compounds was from large to small The order was scallion>cattail> calamus> canna,and the maximum concentration was 604.77 mg/kg.Among the different parts of the four plants,the strongest accumulation of heavy metal antimony and aniline compounds is the root part.The concentration coefficients of the four plants for heavy metal antimony are all greater than 1,and the order of the enrichment coefficients is cattail> calamus> water onion> canna;the transport coefficients for heavy metal antimony are all less than 1,and the transport coefficients are ordered from large to small.It is cattail> canna> calamus> water onion.(3)According to the requirements of the subject,develop new composite materials to further improve the adsorption effect of Sb(V).The fourth chapter of this article adopts the alkaline hydrothermal-coprecipitation method to prepare three different Mg Fe-LDHs of 2:1,3:1,4:1 to be loaded on the surface of anthracite;use SEM,XRD and other characterization methods to characterize them,and pass The adsorption isotherm,kinetic and thermodynamic analysis,adsorption time,p H value,desorption and other experiments explore the effect of Mg Fe-LDHs modified anthracite on the adsorption effect of Sb(V).The results show that the adsorption capacity of Sb(V)by the modified anthracite is significantly improved.It has the best adsorption effect when the molar ratio of magnesium to iron is 2:1.The Langmuir model can describe the adsorption process of modified anthracite to Sb(V)more accurately than the Freundlich model.After calculation by the Langmuir model,Theoretically,the maximum adsorption capacity of the material reached 6.772mg/g.Before and after modification,the adsorption process of Sb(V)is closer to the quasi-second-order kinetic equation;when the p H value is 6-11,the removal rate of Sb(V)on the 2:1Mg Fe-LDHs modified anthracite gradually decreases;the desorption experiment shows that the modification can improve the utilization rate of anthracite.It can be seen from the thermodynamic parameters that the adsorption process of Sb(V)by the modified anthracite is a process of spontaneous heat absorption.With the increase of temperature,the adsorption rate becomes faster and faster.This study explores the new operation mode of constructed wetland,prepares new high-efficiency adsorption fillers,and studies the characteristics of plants to absorb and transport antimony and aniline compounds,with a view to upgrading and repairing low-concentration antimony and typical pollutants in the tail water of printing and dyeing standards in the future constructed wetlands.Provide theoretical support. |
