TREATMENT METHOD OF SLUDGE FROM A WASTEWATER TREATMENT SYSTEM FOR FLUEGAS DESULFURIZATION

PROBLEM TO BE SOLVED: To uniformize sludge and gypsum and to obtain a dehydrated cake high in commodity value as recovered gypsum by introducing a gypsum slurry and a sludge slurry into a stirring tank and adding a polymeric flocculant to the stirring tank under mixing and stirring before dehydrating the slurries by a dehydrator. SOLUTION: The gypsum slurry discharged from the gypsum thickener 1 of a lime gypsum method exhaust gas desulfurizer is introduced into a stirring tank 2 by a pump P1 while the sludge slurry discharged from the concn. tank 3 of the exhaust gas desulfurizing waste water treatment apparatus is also introduced into a stirring tank 2 by a pump P2 and the gypsum slurry and the sludge slurry are mixed and stirred in the stirring tank 2. A polymeric flocculant is added to the stirring tank 2 from a storage tank 4 by a pump P3 to perform flocculation treatment. The flocculation treatment slurry of the stirring tank 2 is fed to a dehydrator 5 by a pump P4 to be subjected to dehydration treatment and a dehydrated cake and a dehydrated filtrate are respectively discharged out of the system. As the polymeric flocculant, an anonic or nonionic polymeric flocculant is used.