I have a waste stream with metal sludge I need to settle in a cone basin. The effluent is to be drained to be treated. It is the aqueous solution result of an alkaline cleaner and a chromate solution.
Are there any rules of thumb for this, or articles etc?
I did not see any statement on whether this is batch or continuous. However, I would try some bench testing with the wastewater. At minimum, you will need some glassware, maybe a stirrer. If need be, you can check aditives to help the settling. Chrome-based wastes will settle slower than other metals.
Regarding additives to help the settling, perhaps contact your water treatment specialty chemcials and treatment programs vendor. You likely already use one at your water treatment or boiler plants, if you have one. (eg: Betz, Nalco).
You didn't supply details, but, of course, further analysis of fundamentals, such as pH (is it even precipitating?), existing process hydraulics (cone basin?.. clarifier?), etc, would be a good first step.
Good luck.
There are any number of chemistries available to enhance the settling/sedimentation of your chromite sludge. Please contact us at orendatech@earthlink.net if you would like to pursue this approach.