PURIFYING METHOD OF SOIL CONTAMINATED WITH HEAVY METAL

摘要

PROBLEM TO BE SOLVED: To provide a purifying method of soil contaminated with heavy metals which washes contaminated soil with an aqueous solution of a chelating agent little causing secondary contamination even when left in soil and having biodegradability to extract the heavy metals as complexes and separates the heavy metals in the extract for reuse of the chelating agent to reduce treatment costs and environmental impacts. SOLUTION: The purifying method has a process (A) of treating heavy-metal-contaminated soil with an aqueous solution of a biodegradable chelating agent to prepare an extract containing heavy metals as complex, a process (B) of adding an insolubilizing agent for the heavy metals to the extract to make the heavy metals precipitate as insoluble substances and regenerate the chelating agent and a process (C) of carrying out solid-liquid separation of the liquid containing the insoluble substances to remove the insolubilized heavy metals from the liquid containing the insoluble substances so as to obtain a regenerated solution containing the chelating agent and circulating the regenerated solution to the process (A). COPYRIGHT: (C)2007,JPO&INPIT