TREATMENT OF NOXIOUS SLUDGE

PURPOSE:To enable the speedy and stable treatment of sludge containing cyanogen and hexavalent chromium for inhibiting the ooze of dyanogen and hexavalent chromium, by adding converter slug, gypsum powder and one or more of ferrous sulfate and sulfides to the sludge, and blending and caking the mixture. CONSTITUTION:A converter slug binder is prepared by compounding converter slug with powdery gypsum, and reserved in a converter slug binder hopper 2a. The converter slug binder from the hopper 2a and hexavalent chromium-contng. sludge 1 are weighed and charged into a hopper 3. One or more of ferrous sulfate and sulfides are then added to the hopper, and the mixture is blended and caked. In this way, caking treatment can be done under the condition that a sufficiently low-hydrogen ion concentration range is formed to properly suppress the ooze of cyanogen and hexavalent chromium. The addition amount of the converter slug is 15% or more in general, preferably 20% or more, by sludge.