The contaminated soil used in this study was prepared by adding heavy metals to non-contaminated soil. The heavy metals chosen were Pb, Cd and Cu, because they are potential contamination sources used in components, printed circuit boards and soldering materials in electrical and electronics industries. The chelating agents selected were citric acid and N,N-dicarboxymethyl glutamic acid tetrasodium salt (GLDA), which were used alone and mixed together in order to examine purification of the contaminated soil. It was found that by mixing the soil and the chelating agent, soil purification is completed with a smaller amount of the chelating agent. Reaction in the ball mill proceeded quickly, reaching equilibrium in about 15 min. A flowchart was produced for soil purification in the mill: leaching in the mill, filtration, and washing with water. Treatment of the washing water, which contains heavy metals and chelating agent, was then examined. It was found that sulfide precipitation is a suitable method to remove heavy metals from the waste solution containing chelating agents and heavy metals.