Development of pilot-scale electrokinetic remediation technology for uranium removal

The original pilot-scale electrokinetic equipment suitable to soil contamination characteristics of Korean nuclear facility sites was manufactured for the remediation of soil contaminated with uranium. During the experiment with the original pilot-scale electrokinetic equipment, lots of metal oxides were generated and were stuck on the cathode plate. The uranium removal capability of the original pilot-scale electrokinetic equipment was almost exhausted because the cathode plate was covered with metal oxides and did not conduct electricity properly. Therefore, the original pilot-scale electrokinetic equipment was improved as follows. First, an immersion-washing device was manufactured for washing the metal oxides from the cathode plate. Second, a metal oxide separator for removal of metal oxide particles below 0.075 mm was manufactured. Third, a circulation system for pH control and waste-solution movement was manufactured. The circulation system controls the pH in the cathode room at 1–2, to prevent the generation of metal hydroxide and circulates waste-solution in a cathode room to prevent the increase of metal oxides due to its stagnancy. After the remediation experiment for 25 days using improved pilot-scale electrokinetic equipment, the removal efficiency of uranium from the soil was 96.8%, and its residual uranium concentration was 0.81 Bq/g. When the initial uranium concentration of the soil was 50 Bq/g, the electrokinetic remediation time required to remediate the uranium concentration below clearance concentration of 1.0 Bq/g was about 34 days. When the initial uranium concentration of soil was 75 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was about 42 days. When the initial uranium concentration of soil was 100 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was 49 days.

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► During operation of original electrokinetic equipment, lots of metal oxides were generated.
► Original pilot-scale electrokinetic equipment was improved for removal of metal oxides.
► Immersion-washing device, metal oxide separator, and circulation system were manufactured.
► After 25 days, the removal efficiency of uranium from the soil was 96.8%.