Energy Efficiency Analysis Of Enhanced Electrokinetic Remediation On Cr Contaminated Soil

In order to clearly present the comprehensive removal benefits of electrokinetic remediation and to solve the problem of chromium backflow in the electrokinetic remediation of chromiumcontaminated soils and the low removal efficiency in the middle of the soil chamber,three enhanced techniques(acid modification,point addition of electrolyte and anolyte update)have been developed and eight sets of electrokinetic remediation on Cr contaminated soil experiments at constant voltage have been conducted with ultrapure water,0.1mol/L potassium chloride solution,0.1mol/L citric acid solution and 1mol/L citric acid solution as electrolyte,two different types of soil(actual contaminated soil and kaolin)and three enhanced technology.In addition,the energy distribution in the experiment have been demonstrated,and to evaluate experimental comprehensive removal benefits,the energy efficiency of experiments have been analyzed via percentage energy consumption and unit removal energy consumption.The experimental results and energy efficiency analysis show,that compared with water(6.59%)and 0.1 mol/L sodium chloride solution(-2.15%),0.1 mol/L citric acid solution(24.52%)as the electrolyte,the chromium removal efficiency is significantly improved.When citric acid is used as the electrolyte,1 mol/L may be too high because the cathode membrane is clogged,resulting in an excessively high energy ratio of the cathode membrane(7.71% of the total energy consumption).However,compared with 0.1 mol/L citric acid,1 mol/L citric acid as the electrolyte in the actual contaminated soil experiment(Exp.7)achieved the highest removal efficiency(44.67%).In the actual contaminated soil experiment,Exp.7(used 1 mol/L citric acid)achieved the best comprehensive removal benefit,instead of Exp.6(used 1 mol/L citric acid and acid modification technology simultaneously),because excessive citric acid resulted in crystallization of salt blocked the soil voids and the cathode membrane and a lot of consumed energy.The cathode membrane of Exp.6 consumed 22.77% of the total energy.Compared with the exp.3(not used),the distribution of energy of the soil chamber of exp.5(used point addition of electrolyte technology)is higher by 10.6%,and the chromium removal of third part of the soil of exp.5 increased by 5.02%.The use of anolyte update and point addition of electrolyte have achieved remarkable results in kaolin experiment which effectively reducing the backflow of chromium and improving the recovery of chromium(increased by 24.05%)and the distribution of energy in soil chambers is more average,evenly,energy analysis results are better.