METHOD FOR RECOVERING HEAVY METAL FROM AQUEOUS WASTE SOLUTION

摘要

PROBLEM TO BE SOLVED: To provide a method by which heavy metals contained in an aqueous waste solution are separated with a reduced amount of sludge, and heavy metals are separated and recovered from the sludge. SOLUTION: This method for recovering dissolved heavy metals from an aqueous waste solution containing the same is composed of steps of (i) insolubilizing heavy metals in which alkaline substance and a flocculation accelerator are added to the waste solution to control the pH of the waste solution to 7 to 13 to insolubilize the dissolved heavy metals to form precipitates, (ii) separating the precipitates from the waste solution as sludge, and (iii) recovering heavy metals from the sludge containing the same. The ratio between the heavy metals and the alkaline metals contained in the sludge satisfies the following inequality (1): M/(M+A)>=0.2 (1) (wherein; M is the molar amount of the heavy metals contained in the sludge, and A is the molar amount of the alkaline metals contained in the sludge).