Use of auxiliary electrode to prevent alkalinization of soil in electrokinetic remediation

We devised an improved electrokinetic remediation method in which an auxiliary electrode was placed at the cathode-side end of the soil to be treated. The electric potential difference between the anode and the auxiliary electrode was fixed constant while that between the cathode and the auxiliary electrode was controlled to make the auxiliary electrode function as a secondary anode. To test the performance of the method, we carried out a bench scale remediation experiment on cadmium-contaminated soil, in which the electrodes and soil etc. were arranged in the following order; anodelanolytelsoil-auxiliary electrodelelectrolytic diaphragmlH-saturated cation exchange resinlcatholytelcathode. During 112 h of the treatment, the net voltage applied to the soil could be maintained and the alkalinization of the soil could be prevented partly due to the acid-neutralization in the cation exchange resin, and partly due to the secondary anode. These results indicated the auxiliary anode was effective to improve the efficiency of electrokinetic remediation of heavy metals contaminated soils.