Journal of Hazardous Materials B101 (2003) 315–322 Pre-oxidation of an extremely polluted industrial wastewater by the Fenton’s reagent Nora San Sebastián Mart´ ınez, Josep F´ ıguls Fernández, Xavier Font Segura, Antoni Sánchez Ferrer ∗ Escola Universitària Politècnica del Medi Ambient, Rbla Pompeu Fabra 1, Mollet del Vallès, 08100 Barcelona, Spain Received 2 March 2003; received in revised form 27 May 2003; accepted 29 May 2003 Abstract The pre-oxidation of an extremely polluted pharmaceutical wastewater (chemical oxygen demand (COD) value of 362,000 mg/l) using the Fenton’s reagent has been systematically studied using an experimental design technique. The parameters influencing the COD removal of the wastewater, namely temperature, ferrous ion and hydrogen peroxide concentrations have been optimized to achieve a COD global reduction of 56.4%. The total range of the proposed experimental design, however, could not be tested because under some conditions (hydrogen peroxide concentration over 5 M) the Fenton’s reaction became violent and could not be controlled, probably due to the high exothermic effect associated with COD oxidation. For the tested conditions, the optimal values of hydrogen peroxide and ferrous ion concentration were 3 and 0.3M, respectively, whereas temperature only showed a mild positive effect on COD removal. In addition, during the first 10 min of Fenton’s reaction, more than 90% of the total COD removal can be achieved. Fenton’s reaction has proved to be a feasible technique for the pre-oxidation of the wastewater under study, and can be considered a suitable pre-treatment for this type of wastewaters. © 2003 Elsevier B.V. All rights reserved. Keywords: Advanced process oxidation; COD removal; Experimental design; Fenton’s reagent; Industrial wastewater 1. Introduction Generation of wastewaters in industrial processes is sometimes unavoidable and in most cases a process to reduce the organic load and other contaminants must be employed ∗ Corresponding author. Tel.: +34-93-5796784; fax: +34-93-5796785. E-mail address: asanchez@eupma.uab.es (A.S. Ferrer). 0304-3894/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0304-3894(03)00207-3