A gravity fed water bath process treats waste water from spray rinses containing compounds of copper and like heavy metal  For displacing heavy metal, such as copper, the bath has a substantially pure metal with an electrode potential greater than the heavy metal contained in the rinse water. A system for controlling the pH level of the water bath treatment and for supplying acid at the beginning of the bath, and alkaline material at the bath's end provides a highly acidic pH level for the water bath and heavy metal removal chamber, and adjusts the pH level of the discharged water for satisfactory deposit in municipal sewer systems.

A method for displacing the heavy metal from the compound in solution requires exposing the heavy metal compound to a substantially pure metal having an electrode potential greater than the heavy metal of the compound, in an acidic bath whose pH level is controlled. The control of the pH is accomplished by acid sensing probes connected in circuit with a valve control which injects and mixes acid in the bath of a treatment chamber. 

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