Removal of heavy metals from waste water
AssigneeMiyoshi Yushi Kabushiki Kaisha
InventorsMasafumi Moriya, Kazuo Hosoda, Akira Nishimura, Takao Imachi
Life of this patent
Estimating the term…
Abstract
A heavy metal can be removed from waste water, in which the metal is contained as ions, by adding to the waste water a metal scavenger together with at least one of sodium monosulfide, sodium polysulfides and sodium hydrogensulfide to form a metal ion containing floc. The resulting floc is then removed from the waste water by filtration. The metal scavenger contains at least one carbodithio group and/or at least one carbodithioate salt group as N-substituents per molecule.
Claims8
A process for removing heavy metal ions in waste water comprising adding a metal scavenger containing at least one carbodithio group, at least one carbodithioate salt group or at least one carbodithio group and at least one carbodithioate salt group as N-substituents per mole and at least one sodium sulfide selected from the group consisting of sodium monosulfide, sodium polysulfides and sodium hydrogensulfide in a weight ratio of metal scavenger to sodium sulfide of from 20:80 to 98:2 to heavy metal ion containing waste water in an amount of from 0.7 to 4 mole equivalents based on the total amount of heavy metal ions in the waste water, adjusting the pH of the waste water to a pH of 4-9, forming a metal ion containing floc, and removing the floc by filtration.
Dependencies are inferred from the claim text.