Influence Factors Of Electrokinetic Remediation For Nitrate-polluted Kaolin

In recent years, with the development of industry and agriculture, groundwater and soilpollution of nitrate becomes more and more serious. People pay attention to the technology ofnitrate pollution soil remediation. The experimental study was done on electrokineticremediation for nitrate-polluted Kaolin and the purpose is to improve the removal efficiency.Use the frame type electric device, frame type and PRB combined electric device,built-anoderadiation type electric device for test. The effects of pH, operating time, applied voltage,EK+PRB combined and electrode arrangement on removal efficiency were mainly studied.The experimental results were as follows:(1) Under the effect of electromigration positively charged nitrate ion migrated to theanode. Under the action of electrodialysis part of the nitrate ion migration to the cathode. Asmall amount of nitrate nitrogen near the cathode reduce to nitrite nitrogen and ammonianitrogen.(2) When use acetic acid and sodium hydroxide solution to keep pH of cathode andanode neutral respectively, nitrate nitrogen removal rate increased significantly. For kaolin oftest, the soil pH for neutral, repair voltage30v, repair time for10days, the removal efficiencyof nitrate nitrogen can be as high as99.25%.(3) And the removal efficiency can be improved as the operating time and applied currentincreased. According to the removal efficiencies and electric energy consumptions the bestoperating time and applied voltage for the studied soils are4days and0.7~1.0V/cmrespectively. When the operating time and applied voltage are4days and1.0V/cmrespectively, soil nitrate nitrogen removal rate is87.67%and the power consumption is335.2kW·h·g-1.(4) In the EK+PRB system, NO3–was reduced by Fe and the main product is NH4+. Dueto the decline of iron scraps reducibility and nitrate ion quickly passing PRB, the vast majorityof NO3–through PRB continue to move toward the anode. This lead to lower ofNO3–removal efficiency. compared with EK system.(5) When used built-anode radiation type electric device for test, no control of the pH, repair voltage10V, repair time for6days, removal efficiency of nitrate nitrogen was47.66%.It is obvious that removal efficiency was relatively low, built-anode radiation type electricdevice don’t had advantage compared with frame type electric device.