External Treatment Terminology

Cycle: A complete course of ion exchange operation; from backwash through brining rinsing and back to operation.

Effluent: The solution which emerges from an ion exchange column.

Elution: The stripping of adsorbed ions from an ion exchange material by the use of solutions containing other ions in relatively high concentrations.

Exhaustion: The state in which the resin is no longer capable of useful ion exchange; the depletion of the exchanger’s supply of available ions. The exhaustion point is determined arbitrarily in terms of: (a) a value in parts per million of leakage; (b) the reduction in quality of the effluent water determined by some test parameter such as conductivity.

Flow Rate: The volume of solution passing through a certain quantity of resin within a given time. Usually expressed in terms of gallons per minute per cubic foot of resin, or as gallons per minute per square foot of bed area.

Hydrogen Cycle: A complete course of cation exchange operation in which the active regenerant used is hydrogen based, such as sulfuric acid.

Raw Water: Untreated water from wells or surface sources.

Regenerant: The solution used to restore the activity of an ion exchange. Acids are employed to restore a cation exchanger to its hydrogen form; brine solutions may be used to convert the cation exchanger to the sodium form.

Rinse: The operation which follows regeneration; a flushing out of excess regenerant solution.