On the design of laboratory scale apparatus for electrokinetic soil decontamination under open-flow condition

We devised an experimental apparatus to simulate the electroosmotic and hydraulic flow of water during electrokinetic soil decontamination process. The apparatus is an open box with electrode compartments at the both ends and a central compartment in which soil sample is packed. A laminated wire gauze-nylon net was used as cathode-cum-separator. The opening of the wire gauze should be > 1 mm to let evolved gas escape freely. The cathode compartment was filled with water and a graphite rod immersed wherein was used as the anode. The draining conduit was attached to the cathodic end at a position lower than the water table in the anode compartment. Under this setup, the electroosmotic and hydraulic flow contributes to the water flow through the soil. To evaluate the electroosmotic flow, the flow under zero electric field was subtracted from the total water flow. Experiments with a soil with mixed mineralogy showed the subtraction method gave fairly reproducible results with respect to the rate of electroosmotic flow.