METHOD FOR CLEANING HEAVY METAL CONTAMINATED SOIL USING CHELATING AGENT AS CLEANING AGENT

摘要

PROBLEM TO BE SOLVED: To provide a method for inexpensively and efficiently cleaning heavy metal contaminated soil which maintains a cleaning capacity and realizes a high circulating efficiency by re-utilizing a recovered chelating agent for cleaning contaminated soil through highly effectively recovering the chelating agent by acid precipitation directly using hydrochloric acid without performing removal of heavy metals after the contaminated soil is cleaned by using the aqueous solution of the chelating agent and the heavy metals are extracted as complexes. SOLUTION: The method for cleaning heavy metal contaminated soil comprises the following processes: (A) a process of obtaining an extracting solution containing the heavy metals as the complexes by cleaning the contaminated soil with the heavy metals by the chelating agent; (B) a process of recovering the chelating agent by solid-liquid separation and washing by water after precipitating the chelating agent as the complexes formed by acid precipitation using hydrochloric acid of 5-20 wt.% from the extracting solution containing the heavy metals as the complexes; and (C) a process of preparing a chelating agent aqueous solution for cleaning soil by using the recovered chelating agent. COPYRIGHT: (C)2007,JPO&INPIT