Colloid interaction and coagulation of dye wastewater with extra applicatio- n of magnetites

The feasibility of treating direct dye wastewater by coagulation is investigated herein. The theoretical development of colloid interactions for coagulation is also reviewed. Ferric chloride and its combination with hydrated lime [Ca(OH)2] is used as a coagulant. Treatment for high strength dye wastewater is preferred and better than medium strength wastewater which showed slow settling velocity and long settling time. The effect of magnetic powder on ferric chloride coagulation system reveals an obvious improvement in settling, particularly for medium strength direct dye wastewater. In addition, increasing magnetite (Fe3O4) dosages enhances the treatment efficiency of settling.