A process for removing metal sulfates from dilute aqueous solutions in which a
conductivity control solution is injected into the stream. The solution is selected
to increase the conductivity of the stream to a value wherein the ion state of
each metal is then modified by passing the stream between electrodes of each pair
of an array of pairs of electrodes. A voltage is imposed across each pair of electrodes,
selected according to a target ion state for each of the various contaminants.
The pH of the stream is then increased to a value where precipitate of metal hydroxide
of the metal sulfates are formed. The precipitated metal hydroxide is then removed
from the stream leaving a reduced amount of sulfate ions. A chemical is added to
the stream in sufficient concentration to precipitate remaining sulfate ions from
the waste stream which are removed by settling/filtering