Applied Chemical Engineering

Assessment of Advanced Treatment Techniques for COD Removal from Industrial Wastewater in Baiji Refinery Using Chemical Coagulation, Ozonation, and UV/O₃ Technology

Rand Tariq khalaf1

Chemical Engineering Department, College of Engineering, Tikrit University, Tikrit, Iraq

Waleed M. Sh. Alabdraba

Environmental Engineering Department, College of Engineering, Tikrit University, Tikrit, Iraq

DOI: https://doi.org/10.59429/ace.v9i2.5858

Keywords: COD, oil refinery wastewater, chemical coagulation, flocculation, (AOPs), industrial water treatment

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Abstract

Chemical Oxygen Demand (COD) is considered one of the most important parameters that indicates the presence of organic pollution in industrial wastewaters. Refinery wastes represent complex heterogeneous, structurally, oily liquid that contains a very high load of organics. This study aims to assess the efficiency of refinery wastewater treatment by three methods, namely coagulation, ozonation, and a UV/O₃ hybrid system, and to determine the optimum operational conditions of each technique at the Baiji oil refinery complex.

The study started by applying a coagulation process using two types of chemicals, namely Al₂(SO₄)₃ and FeCl₃ at varying pH to evaluate the effect of conditions on COD removal. The second process was ozonation with a range of concentrations and finally the UV/O₃ system for enhancing the advanced oxidation of steel. The standard methods of measurement as approved by the labs of Baiji Refinery and Tikrit University were followed for each procedure. The two-way ANOVA was used to find out the high coefficient factors affecting removal efficiency.

The results demonstrated that chemical coagulation alone gives removal rates of 44–62%. The efficiency increased when the procedure was coupled with ozonation to reach 67–81%. The UV/O₃ going system was the best, with removal efficiencies of 92–97%, which confirms the important role of the •OH hydroxyl radicals in destroying the complex organics. The statistical analysis indicates that the type of process was the most influential factor affecting the removal efficiency and that the coagulant did not have any statistically important effect. It could be concluded that the integrated system Coagulation + O₃ + UV/O₃ is a promising solution to treat high organic load refinery effluents. It is also recommended to optimize UV reactor design and O₃ dosage to ensure a higher efficiency and lower energy consumption. Further studies should be conducted to assess the optimum level of this system and to perform an economic feasibility study to scale them up in Iraqi refineries.

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