The addition of a new plating line posed economical and environmental opportunities for a hard chrome plating facility. A new wastewater treatment system deisgn eliminates discharge to the sewer via rinse water recycling and chromium recovery and putification. Objectives included exceeding environmental regulations and reducing costs associated with plating bath disposal and replacement. Technical issues to be overcome includes: Balancing the volume of water added to the system for rinsing with evaporation water loss; determining the contaminant build rate to establish the chrome purification process rate; and establishing a cleaner replacement rate to provide clean parts without excessive disposal costs. The final design provides multiple operational benefits: Recovered chromium from rinses is returned to plating tanks for resue; chromium plating baths are purified, eliminating bath disposal; ion exchange recycles rinse water and provides DI water for rinses; and evaporation further concentrates liquid wastes for disposal. The only discharge to the city swer are the dissolved solids that enter the plant with the city water. nearly all the chromium in the rinse water is recovered and returned to the plating bath.
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