Experimental Study On Rehabilitation Of Uranium Contaminated Soil By Electro-mechanical Coupled Permeation Reaction Wall

In Soil is the foundation of human existence.In the process of industrialization of human society,soil environment is gradually polluted and destroyed.Uranium tailings reservoir refers to the place where a dam is built to intercept the valley mouth or enclosure to queue up tailings or other industrial wastes after ore separation of uranium mines.Although the safety of uranium tailings has been fully considered in the design,construction,operation and disposal after decommissioning,radionuclides in uranium tailings will migrate to the soil environment with the passage of time and unpredictable geological movements and climate changes.The prevention and remediation of uranium-contaminated soil has become one of the research hotspots in uranium mining and metallurgical industry.In this study,the contaminated soil around uranium tailings reservoir was selected as the research object.EK-PRB technology was applied to the remediation of uranium-contaminated soil.The remediation effect of EK and EK-PRB technology on uranium-contaminated soil was systematically discussed.By comparing the changes of current intensity during the remediation process of the two technologies,the distribution of soil pH before and after remediation and the distribution of uranium residue in the soil after remediation,the scanning electron microscopy(SE)was M)The PRB fillers before and after remediation were characterized and analyzed,and the remediation mechanism of uranium contaminated soil remediated by EK-PRB technology was deduced.The mainconclusions are as follows:(1)In the process of single EK and EK-PRB combined repair,the current increases first,then decreases,and finally tends to be stable.The peak value of EK group was slightly higher than that of EK-PRB group,reaching 170 mA,while that of EK-PRB group was 165 mA.After that,the current decreases gradually and tends to be stable.Finally,the current of EK group is stable at 20 mA and that of EK-PRB group is stable at 10 mA.(2)After remediation,the soil pH changed obviously,the anode pH decreased and the cathode pH increased.Compared with the single EK repair experiment,there was no significant difference in the trend of pH change in the EK-PRB combined repair experiment,which was acidic near the anode side and alkaline far from the anode side.However,the pH of EK-PRB group near the cathode side was slightly higher than that of EK group alone,apparently due to the existence of PRB,and other ions affecting the pH were blocked.(3)Uranium residues in soil of EK-PRB group and EK group alone are higher in cathode sampling area and less in anode sampling area,showing a trend of increasing gradually from anode to cathode.However,the residual uranium in each sampling area of EK group was significantly higher than that of EK-PRB group,reaching a peak of 92.8 in the cathode sampling area,while the uranium concentration in EK-PRB group reached a peak of 55.6 in the same sampling area,which was much lower than that in EK group alone.This is because the presence of PRB absorbed some uranium ions,resulting in the decrease of uranium concentration.(4)The principle of EK-PRB technology for remediation of uranium-contaminated soil is that the external electric field is used to promote the movement of uranium ion to the cathode end.When the uranyl ion moves to PRB,it reacts with the filler in PRB to form hydrogen and oxygen precipitates ofuranium,so as to achieve the purpose of remediation of soil contaminated by uranium.