Improvement of Two Iranian Petrochemical Complexes’ Wastewater Biodegradability from 2015 to 2017 Using H2O2/ Fe2+ and Optimization of the Conditions by RSM

Background: Petrochemical wastewaters are a critical environmental challenge in industrial zones due to the amount of pollutants they release into the environment. Therefore, finding a solution for treatment of the wastewater has become the priority of the researchers. The main objective of this research is improvement of petrochemical wastewaters’ biodegradability using Fenton oxidation process and defining the effective parameters on the efficiency of this technique. Methods: In this research, the capability of Fenton method for promoting the biodegradability of hardly-decomposable wastewaters of petrochemical complexes was studied. The actual wastewater of Karoon and Maroon petrochemical complexes were used in this research. Design of the experiments and also the analysis of the experimental results were carried-out using Response Surface Methodology (RSM) with four variables and four parameters. A rector with sizes of 60, 20 and 20 cm was designed and built. The ranges of CODin, H2O2 concentration, Fe2+ dosage, and TDS variation were 1000-2500 mg/L, 1000- 4000 mg/L, 500-3000 mg/L, and 4500-11500 mg/L, respectively, and the average ratio of BOD/COD in the inlet stream was 0.09. Results: The range of BOD/COD in the outlet stream was 0.19-0.37 which decreased with the COD growth. The trend of biodegradability promotion with increase in H2O2 concentration and Fe2+ dosage was ascending, while the effect of TDS on biodegradability was not noticeable. Conclusion: The optimum conditions for achieving maximum efficiency of the reactor were COD=1375 mg/L, [H2O2]=2509.27 mg/L, [Fe2+]=1753.49 mg/L and TDS=8622.9 mg/L and the BOD/ COD ratio was 0.32.