Evaluation of Direct Anodic Oxidation Process for the Treatment of Petroleum Refinery Wastewater

Abstract

This paper investigates the treatment of real petroleum refinery wastewater (PRW) using an electrochemical oxidation process. Direct anodic oxidation, an effective advanced electrochemical oxidation process (AEOP), was applied with different electrodes using a parallel-plate batch electrochemical reactor. The petroleum refinery wastewater originated from a national oil refinery for producing fuels, lubricants, and intermediates. Experiments treated wastewater samples of 500–510 mg/L initial chemical oxygen demand (COD) concentration effluent flowed directly from the refinery to a physical treatment unit. Direct anodic oxidation, which is characterized by the generation of a hydroxyl radical (OH•), can potentially destroy a wide range of organic pollutants. This paper studies several parameters: current density, initial pH, temperature, and the type of electrode. The kinetic study shows that high COD removal efficiency can be achieved following a pseudo-first-order reaction rate. The rate constants of oxidative degradation of organic pollutants by OH• radicals are determined for different anode materials. Results reveal that the COD removal efficiency of 84.8% is obtained at pH 4.0, 25°C, and 50 mA cm−2 using PbO2 anode, whereas COD removal efficiency of 86.3% is obtained at pH 7.0, 50°C, and 50 mA cm−2 current density using a carbon felt anode. However, the highest COD removal is predicted at pH 4 and 55°C for most electrodes.