Treatment of petroleum wastewater by electrocoagulation using scrap perforated (Fe-anode) and plate (Al and Fe-cathode) metals: Optimization of operating parameters by RSM

Abstract

This study focused on removing chemical oxygen demand and phenol from petroleum wastewater by employing the electrocoagulation (EC) process using scrap electrodes. In the study, in a unique way different from those reported in the literature, scrap cylindrical perforated iron (PS) and plate metals discarded by different industries were used as electrodes by recovery for EC. PS was used the anode, and plate electrodes made of two different materials (Al and Fe) were used as the cathodes. The electrodes were placed at the center of the EC reactor and PS. The effects of the main parameters, namely, initial pH (4−10), initial exposure time (5–45 min), and current density (2–28 mA/cm2), on the EC process were assessed and optimized by employing response surface methodology (RSM). A reasonable correlation between the experimental and predicted data was found through analysis of variance (ANOVA). The ANOVA results revealed that the coefficients of determination (R2) for COD removal and phenol removal were 91.18% and 91.46%, respectively. The maximum predicted removal efficiency rates were 96.18% and 94.02% for respectively COD and phenol under the optimum conditions of pH= 6.30, current density= 22 mA/cm2, exposure time= 39 min, and the Fe cathode. Furthermore, the results showed that the initial current density and exposure time were significantly effective on COD and phenol removal from petroleum wastewater. The total cost was calculated as $3.1/m3. There was no electrode cost in the study due to the usage of scrap metals. The results indicated that the EC process is an effective treatment method for COD and phenol removal from petroleum wastewater using scrap metals as electrodes.