Fremgangsmåde til behandling af spildevand fra röggasafsvovling

A process for treating waste water of flue gas desulfurization comprising adjusting pH of the waste water to 5 or less, bringing the waste water into contact with iron, treating the waste water for flocculation, removing formed flocks from the waste water by solid-liquid separation, and optionally, bringing the remaining waste water into contact with a resin for COD adsorption, successively. Hazardous substances, such as oxidative substances, peroxosulfuric acid, iodic acid, heavy metals such as copper and lead, and non-metallic substances such as selenium compounds and fluorides, can be removed simultaneously and efficiently from waste water of flue gas desulfurization containing these hazardous substances by using a simplified waste water disposal system. Water having an excellent quality for a long time can be obtained by the process because deterioration of a resin for COD adsorption by oxidative substances such as peroxosulfuric acid and iodic acid can be prevented. Thus, an easy and efficient process for treating waste water of flue gas desulfurization can be provided.