Treatment of wastewater by a combined technique of adsorption, electrocoagulation followed by membrane separation

Abstract

In this study, a combined lab-scale purification system was set up to treat wastewater from the National Iranian Oil Company. The combined system was composed of three main sections: pre-filtration using activated carbon filter (ACF), electrocoagulation (EC) system, and a filtration section (MF followed by RO). The performance of the treatment system was evaluated by measuring heavy metals, BOD, COD, TDS, TSS, and O&G. The results showed that pre-filtration using ACF could lead to the removal of the BOD, COD, TDS, TSS, and O&G by 24.6%, 21.12%, 31.07%, 36.9% and 8.49%, respectively; the heavy metals were removed significantly. In the EC section, heavy metals were rejected by more than 98% using both the Al and Fe electrode, except for the Cr ions that were mostly removed with Fe electrodes. The removal of BOD, COD, TDS, TSS, and O&G using the Al and Fe electrode was 95.6%, 96%, 91%, 76.6%, and 98.6% and 93.2%, 92.1%, 76%, 83% and 99%, respectively. EC followed by MF/RO filtration led to a remarkable purification performance, and the rejection rate of all pollutants was obtained over 99% after this section. The experimental results indicated that the optimum time for ACF and EC processes were 20 and 50 minutes.

Keywords

• wastewater treatment
• produced water
• electrocoagulation
• filtration
• hybrid treatment