Backgrounds and Objectives: The base structure of total petroleum hydrocarbons (TPH) is made of hydrogen and carbon. Widespread use, improper disposal and accidental spills of this compounds lead to long term remaining of contaminations such as organic solvents and poly aromatic hydrocarbons (PAHs) in the soil and groundwater resources, resulting in critical environmental issues. In this study, an oil-contaminated soil was washed using Tween 80 surfactant and the application of photo-Fenton process (UV/Fe²⁺/H₂O₂) for treatment of the produced wastewater was evaluated.
Materials and Methods: Tween 80 is a yellow liquid with high viscosity and soluble in water. In order to determine of the photo-Fenton process efficiency, we studied effective variables including Fe concentration, pH, H₂O₂ concentration, and irradiation time. The UV irradiation source was a medium-pressure mercury vapor lamp (400 w) vertically immersed in the solution within 2L volume glass cylindrical reactor.
Results: The results showed that efficiency of COD removal depends on the initial Fe concentration, pH, H₂O₂ concentration and irradiation time.
Under optimum conditions, (Fe: 0.1mM, H₂O₂: 0.43 mM, pH: 3 and UV light irradiation time: 2 hours) the removal efficiency of COD was 67.3%. pH plays a crucial role in the photo-Fenton process such that the removal efficiency increased with decreasing of pH.
Conclusion: According to the results of this study, under acidic condition, this process is an efficient method for COD removal from the wastewater studied.