A well known military metal finishing operation in Pennsylvania was having trouble treating hexavalent chromate rinses that also had cadmium in them. Our team of experts set the system up to treat both the hex chrome and cadmium bearing rinses in the same tank. The Aquapure I300 was used for chrome reduction and the Aquapure™ P601 was used for treating cadmium to low levels and to ensure all chelated metals were reduced. This was achieved by simultaneously dosing both Aquapure™ I-300 and P 601 in the equalization tank. The pH is maintained at 6 in the equalization tank for best reduction of the hex chrome. The Aquapure™ P601 is used to treat chelated cadmium to low levels. The 2nd stage treatment tank was used for pH adjustment to 9.5 followed by the addition of a high strength, boosted anionic flocculant: Aquapure™ AS Plus. The solids are then sent to a standard inclined plate clarifier for settling and pressed out in a plate and frame filter press.
The Aquapure™ I-300 (added by simple ml/ gal dosing) not only reduces the hexavalent chrome at a pH of 6, it also eliminates the addition of bisulfite at a pH of 2 while adding weight to the flocculant formation to aid in quick settling in the clarifier.
The Aquapure™ P 601 (added by oxidation-reduction potential) is metered in simultaneously; next to with the Aquapure™ I-300 and caustic sodas used t maintain the pH at 6. The Aquapure™ P 601, a chelate breaker, insures the cadmium will be precipitated out at the low level required for discharge.
Aquapure™ AS PLUS, a boosted anionic flocculant is added as a standard 0.01% stock solution for quick settling.