Process for immobilizing arsenic waste
AssigneePaques Bio Systems B.V.
InventorsRenate Ruitenberg, Cees Jan Nico Buisman
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Abstract
The invention provides a process for removing and immobilizing arsenic from an arsenic-containing waste. It comprises oxidizing the arsenic to pentavalent arsenic in an aqueous medium, contacting the pentavalent arsenic with trivalent iron to form an insoluble iron-arsenic compound and separating precipitated iron-arsenic compound from the aqueous medium. The oxidation of arsenic is effected using oxidizing bacteria at a pH between 0.5 and 4 and at a temperature between 20 and 90° C. in the presence of a mineral catalyst such as pyrite.
Claims16
A process for removing and immobilizing arsenic from an arsenic-containing waste comprising:
- (a) oxidizing the arsenic to pentavalent arsenic in an aqueous medium using oxidizing bacteria at a pH between 0.5 and 4 and at a temperature between 20 and 90° C. in the presence of a mineral catalyst;
- (b) adding to the arsenic between 0.9 and 1.8 mole of iron per mole of arsenic, the iron being trivalent iron or being oxidized to trivalent iron, and allowing said pentavalent arsenic and said trivalent iron to form a crystalline scorodite (FeAsO4.2H2O) precipitate at a pH between 0.5 and 4;
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- (c) continuously separating precipitated scorodite from the aqueous medium.
Dependencies are inferred from the claim text.