HEAVY METAL SEQUESTRANT

PROBLEM TO BE SOLVED: To obtain a heavy metal sequestrant that does not deteriorate in its ability to sequester heavy metals and is nonproblematic in scale formation even when it is in the form of a dilute aqueous solution by mixing a water-soluble or water-dispersible heavy metal sequestrant component having the property of forming an insoluble metal complex with a tartrate. SOLUTION: This sequestrant comprises a water-soluble or water-dispersible heavy metal sequestrant component having the property of forming an insoluble metal complex and 0.01-10 wt.%, based on the sequestrant component, tartrate. The sequestrant may be a solid type containing the active ingredient or a liquid type prepared by dissolving the ingredient in an aqueous solvent. The sequestrant is used in the state dissolved in an aqueous medium. The sequestrant is excellent in the performance of trapping and sequestering heavy metals, especially, mercury, cadmium, arsenic, lead, hexavalent chromium, selenium, copper, zinc, manganese, and iron or compounds thereof and can be advantageously used in treatment of waste water, waste liquor, waste gas and solid waste containing such heavy metals.