Principles of Water Treatment
DOE-HDBK-1015/2-93
WATER TREATMENT PROCESSES
Rev. 0
CH-04
Page 3
WATER TREATMENT PROCESSES
One of the more common water treatment methods is the use of demineralizers
and ion exchange. This method will be discussed in this chapter.
EO 1.2
DEFINE the following terms:
a.
Ion exchange
e.
Polymer
b.
Demineralize
f.
Mixed-bed demineralizer
c.
Cation
g.
Affinity
d.
Anion
h.
Decontamination factor
EO 1.3
DESCRIBE the following:
a.
Resin bead
b.
Cation resin
c.
Anion resin
EO 1.4
DISCUSS the following factors of ion exchange:
a.
Relative affinity
b.
Decontamination factor
EO 1.5
WRITE the reaction for removal of NaCl and CaSO by a
4
mixed-bed ion exchanger such as one containing HOH resin.
Principles of Ion Exchange
Ion exchange is a process used extensively in nuclear facilities to control the purity and pH of
water by removing undesirable ions and replacing them with acceptable ones. Specifically, it is
the exchange of ions between a solid substance (called a resin) and an aqueous solution (reactor
coolant or makeup water). Depending on the identity of the ions that a resin releases to the
water, the process may result in purification of water or in control of the concentration of a
particular ion in a solution. An ion exchange is the reversible exchange of ions between a liquid
and a solid. This process is generally used to remove undesirable ions from a liquid and
substitute acceptable ions from the solid (resin).
The devices in which ion exchange occurs are commonly called demineralizers. This name is
derived from the term demineralize, which means the process whereby impurities present in the
incoming fluid (water) are removed by exchanging impure ions with H and OH ions, resulting
+
-
in the formation of pure water. H and OH are present on the sites of resin beads contained in
+
-
the demineralizer tank or column.
