Removing heavy metal, especially nickel, ions from waste water in the metal processing industries by further treating the hydroxide precipitate with an excess of sulfide and then filtering and oxidizing the sulfide

摘要

Removal of heavy metal (especially Ni) ions from waste water, especially from metal working or metal surface treating processes comprises (i) conventionally precipitating the heavy metal ions as the hydroxide; and then (ii) subjecting the precipitate to a long-term sulfide precipitation of -5 hours using a sulfide excess of -50 mg/l; and finally (iii) subjecting the treated charge to transverse ultrafiltration and oxidizing the sulfide excess.