A process for continuous countercurrent ion exchange comprises piping a
contaminated feed stream into a closed loop ion exchange contactor. The
contactor is an ion exchange bed that has three or more reaction
segments. The segments are comprised of at least an adsorption segment
for treating the contaminated feed stream, a regeneration segment for
stripping the contaminant ions from the resin bed, and a pulse segment
for advancing the resin bed. Simultaneously, the feed stream is moved
through the contactor in the same direction as the regeneration stream.
Measuring the quality of this treated feed stream after it exits the
contactor monitors the treatment capacity of the resin bed. In response
to this quality measurement, the regenerated resin bed is advanced in the
pulse segment of the contactor. The spent brine is recycled back to the
contactor until the final effluent brine is highly concentrated. After
the resin stops advancing, the feed stream and regeneration stream resume
flow. Process water is recycled in four different steps of the ion
exchange process, for the dilution of acid, as resin rinsing water, for
back wash and during the resin pulsing stage.