In this study an experimental work was done to study the possibility of using aluminum rubbish material as a coagulant to remove the colloidal particles from oily wastewater by dissolving this rubbish in sodium hydroxide solution. The experiments were carried out on simulated oily wastewater that was prepared at different oil concentrations and hardness levels (50, 250, 500, and 1000) ppm oil for (2000, 2500, 3000, and 3500) ppm CaCo₃ respectively. The initial turbidity values were (203, 290, 770, and 1306) NTU, while the minimum values of turbidity that have been gained from the experiments in NTU units were (1.67, 1.95, 2.10, and 4.01) at best sodium aluminate dosages in milliliters (12, 20, 24, and 28) for oily wastewater of concentrations (50, 250, 500, and 1000) ppm of oil. Zeta potential and particle size measurements have been carried out to the samples of oily wastewater before treatment and during the coagulation- flocculation process at 2, and 22 minutes after the addition of the optimum coagulant doses in order to determine and investigate the operation conditions. The results were presented graphically in two dimensional co-ordinates showing particle size distribution and growth that have (greater intensity, largest volume, and greater surface area) as a function with time.