TREATMENT METHOD FOR FLUE GAS DESULFURIZATION DRAIN

PROBLEM TO BE SOLVED: To remove effectively noxious matters and keep the quality of treated water favorably for a long period of time by adjusting the pH of flue gas desulfurization drain to the specified value or under, bringing the water into contact with iron and then carrying out the flocculation treatment and solid- liquid separation. SOLUTION: In a pH adjustment tank 1, hydrochloric acid is injected into flue gas desulfurization drain to adjust the pH to 5 or under. Water to be treated after the completion of pH adjustment is fed into a reaction tank 2, and iron fine particles are added to turn iron into bivalent iron ions and eluted. Oxidized substances and a selenium compound in the water to be treated are reduced by the arrangement. Then the water is transferred to a sedimentation separation tank 3, and potassium hydroxide is injected therein to adjust the pH to approximately 8 or over, and flocculate iron ions as iron hydroxide. Then the solid-liquid separation is carried out to separate treated water and taken out. Also, if necessary, the treated water is transferred to the process of removing nitrogen or the like. The operation control of drain becomes simple and easy by the arrangement. Also the required iron amount can be reduced to approximately one-fourth.