76-13: Electrochemical Destruction of Chromate and Zinc From Cooling Tower

Chromates are generally destroyed to trivalent chromium by addition of chemical reducing hydroxide sludge that can be readily removed from the waste stream. Sulfur dioxide and ferrous sulfate are the reducing agents that are commonly used. Alkalis, such as slaked lime, sodium carbonate, or sodium hydroxide, are commonly used for precipitating trivalent chromium. Other methods reported in the literature for the destruction, removal, recovery, or reuse of hexavalent chromium from aqueous industrial waste effluents include : ion exchange, reverse osmosis, electrodialysis, ion flotation, and organic complexation.