ELECTROKINETIC SOIL PROCESSING - COMPLICATING FEATURES OF ELECTROKINETIC REMEDIATION OF SOILS AND SLURRIES - SATURATION EFFECTS AND THE ROLE OF THE CATHODE ELECTROLYSIS

Electrokinetic soil processing is an emerging technology for decontami nation of certain radionuclides, heavy metals, or organic species from soils or slurries. Tests reveal that the process efficiencies in part ially saturated kaolinite samples (without contaminants) are high, sin ce water supplied at the anode eventually flushed across the specimens and saturated the deposits. Consolidation settlements are expected in the vicinity of anodes in fine-grained soils, even when both electrod es allow ingress of the water. Uranyl ion at 1000 pCi/g could be effec tively removed from kaolinite but the removal efficiency decreased clo se to the cathode due to the high pH in this region. A yellow uranium hydroxide precipitate was collected at the cathode. Thorium ion, even at 300 pCi/g, could not be efficiently removed throughout the cell bec ause of its high adsorptive capacity, facile hydrolysis, and the preci pitation of insoluble hydroxide. Methods are required to prevent hydro xide ion formation by the cathode reduction of water and thus enable e xtraction of these metal species in soluble forms.