METHOD FOR CLARIFYING SOIL

摘要

A process for cleaning contaminated soil containing a heavy metal, comprising: (a) an extraction step where extracting the heavy metal contained in the soil as a heavy metal ion by bringing an extracting reagent into contact with the soil to obtain an extract "a" containing soil and the heavy metal ion; (b) a solid-liquid separation step where carrying out the solid-liquid separation of the extract "a" to obtain cleaned soil and an extract "b" containing the heavy metal ion; (c) a precipitation step where adjusting the pH of the extract "b" to 3 or more in the presence of an iron ion to precipitate the heavy metal together with ion so as to obtain an extract "c" containing iron and heavy metal precipitates; and (d) a heavy metal recovery step where foaming the extract "c" in the presence of a surfactant and collecting the iron and heavy metal precipitates by bubbles to recover them. The process can remove a heavy metal from the polluted soil containing the heavy metal efficiently.