REMOVAL OF CONTAMINANTS FROM SOILS BY ELECTROKINETICS - A THEORETICAL TREATISE

Feasibility and cost-effectiveness of electrokinetic soil processing in the remediation of contaminated clayey soils has been demonstrated by bench-scale studies and limited pilot-scale studies. A review of the fundamentals controlling the process demonstrates that contaminant transport and removal by electrokinetics are dependent on several factors including electrode reactions, pH and surface chemistry of the soil, equilibrium chemistry of the aqueous system, electrochemical properties of the contaminants and hydrological properties of the soil medium. Chemical, hydraulic and electrical fluxes in electrokinetic processing are formalized. A theoretical model describing reactive solute transport is developed in a coupled system of differential/algebraic equations. Considerations for solutions are discussed. An important factor in the removal of contaminants is the transport of the acid front developed by the anode reaction. The basic equation describing the pH distribution resulting from electrode reactions is simplified and solved under specific assumptions pertaining to the boundary conditions. The results reasonably predicted the pH distribution across specimens tested under one-dimensional conditions.