The Electrochemical Removal of Wastes

Factory wastewaters often contain metal ions of sufficient concentration, which makes their recovery worthwhile. 

Suppose there are several metals in the original solution. These can be deposited on the packed bed, holding it at an appropriate potential. Then, the potential of the packed bed is reversed and such metals present are dissolved out and deposited onto an electrode potentiostat at a potential negative to the reversible value of the specific material. In this way, 99% of the metals to be recovered can be taken out separately. (It is necessary for the reversible potentials of the various metals to be separated to ca. 0.3 V for this process to be practical.) 

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