Principles of Water Treatment
DISSOLVED GASES, SUSPENDED SOLIDS, AND pH CONTROL
DISSOLVED GASES, SUSPENDED SOLIDS,
AND pH CONTROL
The presence of dissolved gases, suspended solids, and incorrect pH can be
detrimental to the water systems associated with a reactor facility. Therefore,
these conditions must be minimized or eliminated to reduce corrosion in the
systems of the facility. The way these conditions are controlled and the
difficulties in controlling them are discussed in this chapter.
EXPLAIN the three basic methods used to remove dissolved
gases from water.
LIST five filtration mediums used to remove suspended
solids from water.
EXPLAIN how mixed-bed ion exchangers may be used to
DISCUSS resin malfunctions, including the following:
Removal of Dissolved Gases
Dissolved gases result from different sources depending upon which system we examine. In the
following discussion, we will address makeup water, reactor coolant systems, secondary facility
water systems, the sources of dissolved gases, and methods used to reduce their concentrations
to acceptable levels.
Many facilities use raw water as a source for makeup water systems. Pretreatment of this water
is accomplished in various ways from distillation to a series of distinct processes as shown in
Figure 5. In a pretreatment system similar to that shown in Figure 5, a resin column containing
a cation resin (hydrogen form) is used to remove cations. The water entering the cation
exchanger contains numerous ions including sodium (Na ), bicarbonate (HCO ), and others
(HCO is one of the major impurities in many raw water systems). Na ions result from the
water softener located upstream in the pretreatment system. In addition to the HCO ions, raw
water contains large amounts of magnesium (Mg ) and calcium (Ca ), as well as small amounts
of other ionic impurities.