Optimization of Continuous Electro-Fenton and Photo electro-Fenton Processes to Treat Iraqi Oilfield Produced Water Using Surface Response Methodology

Abstract

Considerable amounts of produced water (PW) is usually accompanied with the production of oil. Most countries with oilfields are generally water stressed countries. This study proposed electro-Fenton (EF) as alternative for the degradation of organic pollutants in PW. Continuous electro-Fenton processes was investigated using dimensionally stable anode Ti-RuO2/IrO2 and activated carbon fiber felt (ACFF) cathode. The effect of crucial process variables, namely, initial ferrous ions concentration (0.1-0.5 mM), current intensity (100-500 mA), and residence time (22-81 minutes) on the removal efficiency of COD was studied using contour and response surface plots. The experimental results were analyzed by analysis of variance (ANOVA). Multiple response optimization for continuous EF experiments reveals that at optimum conditions (initial ferrous ion concentration of 0.306 mM, current intensity of 156.6 mA, and residence time of 81.0 min) the COD removal efficiency was 73.33% and electrical energy consumption was 0.901 kWh/kg COD. Improvement of continuous EF process was investigated using UVA irradiation (Photoelectron-Fenton). It was found that COD removal efficiency for continuous EF was increased to 81.1% and 86.0% when using one and two UVA lamps (3 Watt each) respectively. It is concluded that EF is an effective process for treating produced water and further improvement can be achieved by photo assisting the process.