This paper presents results of kinetic and equilibrium studies of the removal of heavy metals (Cr, Cu, Cd, Ni and Pb) from the sewage sludge using a new technique of solid-liquid-solid extraction with the adsorption-diffusion column filled by the zeolite. The metal extraction onto the zeolite from aqueous solution of the clinoptilolite and the sludge composition is characterized by three stages: intensive extraction, inversion and stabilization with the moderate extraction increase. Addition of 25% of the zeolite provides extraction efficiency of cadmium and lead of about 84%, chromium, copper and nickel of 66%, 61% and 50%, respectively. The estimated values of Gibbs free energy change Delta G show that the metals extraction by the clinoptilolite may be considered as a physical adsorption. The negative values of Delta G testify to an exothermic nature of the process. The difference between energetic potentials of the components is a driving force of the metal redistribution in the system "clinoptilolite-water-sludge". (c) 2008 Elsevier B.V. All rights reserved.