Comparative study of electrochemical oxidation system hybrid with photocatalytic system for the treatment of Al-Najaf petroleum refinery wastewater

In this work, the efficiencies of two combined anodic oxidation with photocatalytic processes (AO + UV/SnO2and AO + UV/TiO2) for treating petroleum refinery wastewater were evaluated and compared based on COD removal efficiency and energy consumption. Results revealed that increasing pH has adverse effect on the removal of COD as well as increasing the dosage of catalyst regarding to AO + UV/SnO2. The combined process using TiO2 was better than the combined with SnO2 or the process of photocatalytic using SnO2 alone. Dosage of SnO2 catalyst (0.1g/ L) was needed with initially adjusting the solution pH to 3 for getting a significant removal of COD (80.16%) during 150 min in which a specific energy consumption of 36.54kWh/m3was required for the AO + UV/SnO2 while using AO + UV/TiO2 gave better result in terms of removal (89.03%) at lower energy consumption (27.38 kWh/m3). This is an indication that TiO2 has better photocatalytic efficiency than SnO2. However, SnO2 considered as a more environment ecofriendly catalyst with possibility of reaching 90% removal in two cycle process.