Influent concentration, conductivity, or
Effluent concentration, conductivity, or radioactivity
15 ppm Cl
0.1 ppm Cl
2.8 × 102 µCi/ml
1.0 × 104 µCi/ml
WATER TREATMENT PROCESSES
Principles of Water Treatment
The ion exchange process is reversible. If too much solution is passed through the ion
exchanger (that is, the capacity of the resin has been exceeded) the exchange may reverse, and
undesirable ions or other substances that were previously removed, will be returned to the
solution at the effluent. Therefore, it is necessary to periodically monitor the performance of
the ion exchanger and either replace or regenerate the resin when indicated. Ion exchanger
performance is measured by comparing the solution concentration, conductivity, or radioactivity
at the influent and effluent. The parameter measured depends upon the purpose of the ion
exchanger. The term normally applied to ion exchanger effectiveness is decontamination factor
(DF), which is defined as a ratio of the concentration (or activity) of the fluid at the inlet
compared to the concentration (or activity) at the effluent, which expresses the effectiveness
of an ion exchange process.
An ion exchanger influent contains 15 ppm chloride (Cl). Effluent chloride is measured
at 0.1 ppm. What is the DF of this ion exchanger?
Reactor coolant activity entering the purification ion exchanger equals 2.8 x 10 µCi/ml
gross activity. Ion exchanger effluent activity taken at the same time and conditions is
measured at 1.0 x 10 µCi/ml. What is the DF?