Tradable Pollution Discharge Permitting for Industrial Users | home
Segregation of Wastestreams
Treatment of Segregated Metal Wastestreams
Treatment costs are reduced by wastestream segregation. Chrome, cyanide, oily waste, or precious metals sources must be identified and treated separately in order to be combined and treated with source wastestreams of common metals, before being discharged to the municipal WWTP.
Treatment Method: Purpose/Comments
1. Oxidation/sulfur dioxide: Chrome Reduction
from hexavalent Cr6+ to trivalent state Cr3+, through pH decrease/alkaline precipitation; pH critical
2. Oxidation/sodium: Cyanide to cyanate
then, cyanate to carbon dioxide and nitrogen hypochlorite gas; pH critical
3. Evaporation, ion exchange: Precious metals recovery
after cyanide removal
4. Demulsification: Oily waste separation
process coolant/lubrication centrifugation, ultra-filtration, reverse osmosis; removal of free oils, water soluble oils and grease
5. Aeration, carbon adsorption: Control of toxic organics
which are more soluble in oil and grease, therefore removal of oil and grease will reduce toxics
6. Sulfide precipitation: Break complexing metal
solution and allow chemical reduction, precipitation and settling for treatment
