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WWT reaction tank design.

1998

What is considered to be the upper concentration limit for chromium +6 in a given influent rate for proper chrome reduction using the standard low pH-bisulfite process? Once the metals have been pre-treated (Cr reduction, metallic cyanide oxidation), what is the upper concentration limit for metals in a given influent rate for proper hydroxide formation using the standard CaCl2, NaOH process?

Are there any good reference materials available on design of WWT process tanks, gravity settlers, etc?

Thanks,

John Kostura
MASCO

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I don't know that there is any such limit. I haven't personally treated chrome plating solutions with bisulphate, but I have treated chromating solutions (2 to 5 percent chromic acid-sodium dichromate) and the reaction is not a problem.

Similarly, I have batch treated fairly concentrated acid dumps and cleaner dumps, and the reaction is not a problem.

However, there can be a logistics problem with physical separation processes (clarifiers, sludge thickeners, filter presses) as huge loads of solids come into play. And chrome waste are difficult to filter.

I don't know of any current books on the subject, but you might try to find Clarence Roy's "Operation and Maintenance of Surface Finishing Wastewater Treatment Systems" [adv: this book on eBay, Amazon, or AbeBooks] or you might contact AESF (www.nasf.org) regarding the manuals from their waste ewater treatment training course.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey