The recycling of domestic wastewater is an effective means of coping with the water shortage in Tunisia. After hydrogen peroxide oxidation, the refractory organic substances in wastewater were decomposed. COD, offensive odor and foaminess in the effluents were reduced with increasing dose. Hydrogen peroxide oxidizes both organic and inorganic pollutants which contribute to BOD and COD. The Oxidation of sulfides into sulfates by H2O2 may be applied directly to aqueous wastes containing these odorants. Inactivation efficiencies of bacteria in the secondary effluents by H2O2 oxidation was investigated. The number of total coliforms exponentially decreased with increasing dose and fell to low levels at the dose of 2.5 ml/L. (c) 2006 Elsevier B.V. All rights reserved.