The feasibility of using ozonation and adsorption for the post-treatment of biologically treated effluents of the pulp and paper industry has been studied. Equilibrium conditions, as well as the kinetics of both processes, have been determined. The COD, AOX (adsorbable organic halides) content and color were chosen as the main process parameters. General design of an ozone reactor and adsorption unit, as well as estimates of capital and operating costs for both processes, have also been presented. Some remarkable advantages of ozonation in comparison to PAC-adsorption have been emphasized: at the same purification cost ($/m3) ozonation can guarantee 7-8 times higher efficiency than adsorption. Destroying color bodies and toxic organochlorine compounds in the effluents from the pulp and paper industry with ozone has become very promising.