Electrokinetic soil remediation: Multiple anode electrode arrangement

9th International Conference on Environmental Science and Technology -- SEP 01-03, 2005 -- Rhodes Isl, GREECEWOS: 000237755500041Electrokinetic remediation experiments of metal contaminated soils (Pb, Zn, Cu) were performed by constructing a multiple anode electrode arrangement. In this arrangement, the electrokinetic unit was cylindrical and had three sections. The central cylinder was selected as the cathode well to minimize the extent of the basic environment by the cathode and the outer cylinder was selected as the anode to maximize the spread of the acidic environment generated by the anodes. Nine identical graphite rods were used as electrodes and eight of them were the anodes. The anode electrodes were placed in octagonal with respect to the cathode electrode. In the experiments, a constant potential difference of 250 volt was applied to the electrodes and maintained for about 30 hours. In order to determine the removal efficiencies of metals as a function of distance from the electrodes the soil was divided into four sections. The metal amounts in each section were evaluated by adding the metal amounts at different fractions of the soil (i.e., exchangeable, sorbed, carbonate, organic and residual) that were obtained from by using a sequential extraction method. Experimental results showed that metals that were present in different fractions of soil could be removed or redistributed in different fractions of soil by the help of electric field. Depending on the sequential extraction results, the overall removal efficiencies of lead, zinc and copper from the soil were evaluated as 29%, 18% and 18%. In order to identify effects of electrode geometry on efficiency the electrokinetic remediation experiment was repeated by using a parallel plate electrodes configuration. In this case, the electrokinetic unit was rectangular and two identical graphite plates were inserted into the electrode compartments as the anode and the cathode electrodes. For lead, zinc and copper, higher removal efficiencies were obtained; numerically, 32%, 37% and 31%, respectively. Even though in theoretical analysis, higher performance is expected from the multiple anode arrangement, the presence of inactive electric field areas in the soil could be the main cause for the decrease in the removal efficiency values.Global Network Environm Sci & Technol, Univ Aegean, Dept Environm Studie