In this work, three advanced oxidation technologies have been studied to improve the quality of the effluents of a physicochemical process and of a combined physicochemical-biological process during the treatment of actual industrial wastes of wooden door-manufacturing factories. From the treatment point of view (neglecting costs), advanced oxidation processes can be successfully used to treat both, coagulated and biologically treated wastes. Conductive-diamond electrochemical oxidation (CDEO) was found to be the more effective technology because it can reduce completely the chemical oxygen demand (COD) (no production of refractory compounds) with a very high current efficiency. However, from the economic viewpoint, the direct treatment of the coagulated wastes can not be recommended because it is very expensive. Only Fenton oxidation or conductive-diamond electrochemical oxidation can be cost-efficiently used to refine the quality of the effluent of the biological process. (C) 2009 Elsevier B.V. All rights reserved.