Oil refinery wastewater treatment by coagulation with ferric chloride and dissolved air flotation

Oily wastewater produced in refineries and petrochemical industries contain variant contaminants. So these are needed to be treated before reuses or charging into water source. In this experimental study coagulation and flocculation with ferric chloride as coagulant, were used for Isfahan oil refinery wastewater treatment as well as dissolved air flotation. Coagulant dose, pH, recycle ratio and residence time were considered as effective factors. Experiments were designed and done according to general factorial methods. Results showed that pH was the most effective factor in turbidity reduction process and ferric chloride achieved more than 50% turbidity removal in optimum condition. It was included of 32ppm, pH equal to 6.2, 75% recycle ratio and 20 minute residence time.