COD, BOD, Oil Content and Heavy Metals Removal from Wastewater Effluents by Coagulation - Flocculation Process

Wastewater effluents from the refineries are considered the major sources, which pollute the environment. Several efforts were carried out to study the possibility of treatment oily wastewater using new materials, to remove contaminates and prevent or minimize its impacts on the environment at low cost. The present study deals with the treatment of the oily wastewater effluents, from El-Nasr Petroleum Company, Suez - Egypt by coagulation flocculation processes. The reagents used in this study were cationic type flocculent of moderate molecular weight Zetag57, kaolinite and modified kaolinite (blended kaolinite with alum) as coagulants. The obtained results showed that kaolinite and modified kaolinite are highly efficient in removal of the contaminants (COD, BOD, Oil content and Heavy Metals) from the oily wastewater. Valuable results were obtained under the following optimal conditions: 3g/l kaolinite; 15 mg/l flocculent Zetag 57 and pH of 7.5. At these conditions, turbidity decreased from 180 to 8 NTU with removal percentage of 95.6%, COD decreased from 4800 to 150 mg/l with removal percentage of 96.9 %, BOD decreased from 1800 to 14 mg/l with removal percentage of 99.2% and Oil content decreased from 1800 mg/l to 0.0 with removal percentage of 100 %. Pb decreased from 14.7 to 0.55 mg/l with removal percentage of 96.3%, Cu decreased from 9.4 to 0.5 mg/l with removal percentage of 94.7%, Zn decreased from 11.5 to 1 mg/l with removal percentage of 91.3%, Fe decreased from 6 to 0.5 mg/l with removal percentage of 91.7% and Cd decreased from 0.2 to 0.0 mg/l with removal percentage of 100%.