METHOD FOR RECOVERING ALUMINUM COAGULANT FROM WATERWORKS SLUDGE BY ACIDIC EXTRACTION AND REUSE OF SLUDGE CAKE AS A DAILY LANDFILL COVER SOIL

摘要

PURPOSE: To completely recycle waterworks sludge so that waste is not generated at all by recycling aluminum as coagulant by recovering aluminum and using thickened sludge as substitute landfill cover soil after separating filtrate and thickened sludge from sludge generated from water treatment. CONSTITUTION: The method comprises a step of extracting aluminum and other metals existing in the waterworks sludge by acid treatment of waterworks sludge using sulfuric acid; a step of separating filtrate containing aluminum and acidified thickened sludge from the waterworks sludge by separately filtering the water treatment sludge; a step of extracting aluminum in the aluminum ion state from the filtrate containing aluminum using extractant of mono- and di-ethylhexyl phosphate; a step of recycling recovered aluminum as an alum coagulant in the water treatment process by regenerating aluminum from aluminum sulfate using sulfuric acid; a step of manufacturing dewatered cake by treating waste slaked lime onto acidified thickened sludge separated in the separation step so that the thickened sludge is neutralized, and dewatering the neutralized thickened sludge; and a step of recycling the obtained dewatered cake as a landfill cover soil.