Moghadaseh Salehin - Department of Chemical Engineering, Tehran North Branch, Islamic Azad University, Tehran, Iran
Ali Asghar Rohani - Research institute of petroleum industry (RIPI), national Iranian Oil Company, Tehran, Iran
Mohsen Nosrati - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran

Oil refineries generate significant amounts of wastewater which have to be treated and processed before their discharge into water streams. The refinery wastewater treatment plants employ physicochemical processes to achieveeffluents of satisfactory oil content to be further treated by biological processes. In the present study, coagulation and flotation processes were optimized to reduce the concentrations of oil, grease and other contaminants using sodium aluminate as coagulant. The temperature was kept constant and was 25°C during the process. Different amounts of coagulant were added to the wastewater samples. Then each sample was stirred for 1 minute at 200 rpm and then for 15 minutes at the low speed of 10 rpm and then after 20 minutes of sedimentation, the analyses were made and results were obtained. Treatment efficiency was evaluated in terms of COD and turbidity. Sodium aluminate at pH=7 removed up to 83% COD and 99.99% turbidity.

coagulation, flocculation, sodium aluminate, refinery wastewater, chemical treatment