METHOD FOR CLARIFYING SOIL

摘要

A method for clarifying a contaminated soil containing a heavy metal, which comprises: (a) an extraction step of contacting the soil with an extracting agent to extract the heavy metal as a heavy metal ion and prepare an extract [a] containing the soil and the heavy metal ion, (b) a solid-liquid separation step of subjecting the extract [a] to solid-liquid separation to provide a clarified soil and an extract [b] containing the heavy metal ion, (c) a precipitation step of adjusting the pH of the extract [b] to 3 or higher in the presence of an iron ion, to thereby precipitate the heavy metal together with iron and provide an extract [c] containing precipitates of iron and the heavy metal, and (d) a heavy metal recovering step of foaming the extract [c] in the presence of a surfactant, to thereby allow foams generated to capture precipitates of iron and the heavy metal, and recovering them. The method can be employed for removing a heavy metal from a contaminated soil containing the heavy metal with good efficiency.