The Study On The Transport Of DOM And Chromium During The Waste Water Underground Storage

The heavy metal ions in waste water pollution is one of the important factors to affect its recycling.The heavy metal ions in waste wateris difficult to remove.It always cause serious pollution of underground aquifer in its transferring process.Dissolved organic matter,whose surface has more adsorption sites,can adsorb so much heavy metal ions.Regenerated wastewater will eventually enter the groundwater circulation.As a bearer of heavy metal ions,DOM has an important influence on the migration and accumulation of heavy metal elements in the aquifer.Therefore,in order to solve the heavy metal pollution of groundwater and make regenerated wastewater transfer safely in the aquifer,it is of great significance to study on the DOM and of the interaction between the heavy metal ions and coordination of migration behavior.This research use static adsorption experiment to study on the adsorption behavior and mechanism of adsorption of Cr6+ by DOM in wastewater.and i choose the simulation column experiment to analyze the cooperated migration behavior of Cr6+and DOM.The main research results are as follows:(1)Using the suction filter combined with freeze drying method to extract the DOM from secondary treated wastewater.Through chemical analysis method and Fourier infrared spectrum,the three dimensional fluorescence spectra,the combination of the electronic scanning electron microscopy and other technical means,analyze the DOM samples before and after adsorption Cr6+.The results show that the main part of the DOM in secondary treated wastewater is humic acid and a small amount of protein.After adsorption of Cr6+,there are a large number of irregular granular structure appearing on DOM and mesh surface,mainly because of the functional groups such as carboxyl and amide group in the DOM and Cr6+ reaction results.In DOM dosing quantity of35 mg/L,the DOM on the adsorption of Cr6+ rate reached the highest point.(2)Measure the DOM and Cr6+ mixture of Zeta potential value can get these results: When we choose the Ca Br2 and Na Br respectively to be the background electrolyte solution,increase the intensity of ions in the solution will increase the number of positive charge,at the same time,it reduce Zetapotential values solution.With Ca Br2 and Na Br as electrolyte solution together,the experiment use Sodium Adsorption Ratio to value the different solution ions.Under the condition of the same ionic strength,when the increase of SAR values,Zeta potential value of the solution will increase.The main reason is that the decrease of Ca2+ content lead to the decrease in the number of positive charge in the mixture and enhance the electronegativity.(3)Compared the Freundlich isotherm adsorption curve and Langmuir adsorption isotherm curve with the experimental data fitting effect,indicates that the Langmuir adsorption isotherm curve predicts more accurately under the condition of p H = 5.0,25 ?.(4)By the column simulation experiment we study how the ions construction or ionic strength change influences the cooperated migration patterns on DOM and Cr6+.The experimental results show that: under the condition of no electrolyte,DOM can effectively promote the Cr6+ migration in the aquifer medium model.When Ca Br2 and Na Br as background electrolyte solution respectively,when the ionic strength increases,it will lead to the increase of discharged ratio of Cr6+ and make the initial discharge time disappears early.And the effect of Ca2+ adsorbs Cr6+ is better than Na+.Under the condition of coexistence of DOM and background solution,cation exchange adsorption can effectively restrains the DOM on the migration of Cr6+ at the beginning of the experiment.But with continuous infusion solution,DOM and Cr6+ collaborative moved gradually from sand column.At the same time the increase of ionic strength can enhance the ability to migrate of DOM and Cr6+ in the aquifer medium.(5)With the constant ionic strength solution,we mix Ca Br2 and Na Br to be background solution.When the SAR increase,the discharge flow ratio will reduce and the initial discharge time will delay.When DOM and electrolyte solution injection,DOM can effectively inhibit the migration of Cr6+.And the increase of SAR will weaken the ability of coordinated migration of DOM and Cr6+.