Ahmad Azari

The toxic and dangerous wastewater from the petrochemical industry should be effectively treated before it is discharged into the environment. In this study, the electro-Fenton (EF) process was performed as a pre-treatment for petrochemical wastewater that resulted from olefin, methanol, aromatic, ammonia, and urea units. The effects of the solution pH, electric current, hydrogen peroxide (H2O2) concentration, and reaction time on chemical oxygen demand (COD) removal and sludge volume index (SVI) values were investigated. The treated wastewater of an EF process was used as feed for an integrated fixed-film activated sludge (IFAS) process. The effect of the ratio of the inlet wastewater volume to the activated sludge in the aeration tank and the influence of the fixed media and retention time on the IFAS system capacity were evaluated. The results showed that an increase in the electric current and H2O2 concentration led to an improvement in the COD removal while increasing the pH had a negative effect on the wastewater treatment. Furthermore, the initial pH of 3, electric current of 160 mA, H2O2 concentration of 65 mM, and reaction time of 30 min were introduced as optimum conditions for the subsequent stage of the treatment. Finally, the IFAS system demonstrated better performance than the conventional activated sludge (AS) method.