FACTORS AFFECTING THE ULTIMATE QUALITY OF DEIONIZED WATER

Many other factors, besides the type of anion resin used affect the ultimate quality of deionized water as well as the quantity of deionized water produced by the system. The factors that affect the performance of the cation and anion resin columns are as under:

CATION RESIN:
EXCHANGE CAPACITY:
The exchange capacity of each cubic foot of cation resin is affected by:
The amount of chemical used to regenerate each cubic foot of resin (regeneration level)
The ratio of sodium to total cations in the untreated water
The ratio of alkalinity to total anions in the untreated water

LEAKAGE:
The amount of sodium in the decationized water that will pass into the anion resin column is affected by:
The amount of chemical used to regenerate each cubic foot of resin (regeneration level)
The ratio of sodium to total cations in the untreated water
The ratio of alkalinity to total anions in the untreated water

ANION RESIN:
EXCHANGE CAPACITY:
The exchange capacity of each cubic foot of anion resin is affected by:
The amount of chemical used to regenerate each cubic foot of resin (regeneration level)
Temperature of the regenerant chemical
The ratio of the silica (SiO2) to total anions in the untreated water
Influent sodium level,
Flow rate through the resin column (GPM/FT3)

LEAKAGE:
The total amount of dissolved minerals that pass into the product water is affected by:
The amount of chemical used to regenerate each cubic foot of resin (regeneration level)
Temperature of the regenerant chemical
The ratio of the silica (SiO2) to total anions in the untreated water
Sodium leakage from the cation resin column

OTHER FACTORS:
Other factors, such as the influent water temperature, chlorine content, turbidity, including both colloidal and filterable solids, organic content, iron content, etc, will also influence the performance of the system. However, the latter factors can be eliminated or controlled with the use of proper pretreatment.
The ultimate water quality may be improved by the use of a third exchanger (polisher) downstream of the anion exchanger. This exchanger will remove a portion of the leakage through the first two exchangers.
The data, calculations and projections show that proper pretreatment for the removal of the above interfering factors before the influent water contacts the ion exchange resins improves the ultimate quality of deionized water.