The general strategy of this study was based on evaluation of the possibility of applying coagulation by chemical coagulant for removal of residual oils from wastewater, as a preliminary treatment prior to biological oxidation. Determination of the optimum conditions for getting the best results for oil removal by studying the different parameters that affect the processes. These parameters are pH, chemical reagent dose and Initial concentration of oil in wastewater. The optimum dose needed for efficient coagulation is about 30-40 mg l-1 for alum, ferric chloride and ferrous sulphate. The maximum efficiency obtained between pH 5 and 7 and this matches with the literature. The higher removal efficiency is about of 81% for Ferric chloride in COD removal and about 91.6% of turbidity removal.