Principles of Water Treatment
DISSOLVED GASES, SUSPENDED SOLIDS, AND pH CONTROL
Dissolved Gases, Suspended Solids
And pH Control Summary (Cont.)
Dissolved gases are removed from reactor facility systems to limit corrosion by
any one of the following methods or combinations of methods:
Aeration - The spraying of the water to physically release the entrained
gasses, then venting the gas.
Deaeration - The heating of the water to a slow boil, then vents the gas
usually to a condenser so the moisture is not lost.
Addition of scavengers - Examples are hydrogen, hydrazine, and
morpholine, the scavenger combines with the gas and removes it
Channeling in an ion exchanger occurs when there is a direct flowpath for the
water that decreases the resin-water contact. Channeling may occur in the resin
bed as a result of improper filling or malfunction of the inlet connection.
Resins are susceptible to damage by overheating. Although a resin contains a very
large number of exchange sites, the number is finite and the resin exchange
capability is eventually depleted. The first indication of depletion is breakthrough,
which occurs when impurity ions begin to appear in the solution after it has passed
through the resin.
When the concentration of impurities is the same before and after the solution
passes through the resin, the resin has reached a state of exhaustion.
Suspended solids are removed by the use of mechanical filters. The two basic
categories of mechanical filters are gravity flow and pressure flow filters. The
pressure flow filters are more likely to be used because there are better control
capabilities. Numerous materials are used as filter media and include sand,
activated charcoal, anthracite, diatomaceous earth, and to some extent the resin
in an ion exchanger