INDION Resin

Operating exchange capacity
Figures 1, 2, 3 and 4 give operating exchange capacity of INDION 225 H when used in co-flow regeneration mode. Operating exchange capacity of INDION 225H in counter current mode depends on :
- Regeneration level
- Alkaline content of feed water
- Sodium content of feed water
- Active bed-depth
Figures 5, 6, 7 and 8 give operating exchange capacity and correction factor of INDION 225 H in counter current regeneration mode.
Regeneration
Co-flow regeneration The concentration of hydrochloric acid used in regeneration is 4-5 % w/v.
Counter current regeneration
The concentration of hydrochloric acid used in regeneration is 2.5 to 5 % w/v. For acid dilution and rinsing, decationised water must be used. To prevent the disturbance of the resin bed during upward acid injection and uprinse, use of down flow of water is employed. Alternatively, a downward air pressure can also be used for the same purpose. Backwashing of complete bed, during every regeneration is not desirable and only subsurface wash must be employed.
Whenever the counter current unit is backwashed, higher than the normal quantity of regeneration has to be used in subsequent injection operation.
Thoroughfare regeneration
When the alkaline hardness is high, use of INDION 236 weak acid cation exchanger preceding INDION 225 H is recommended. In such cases, the regeneration can be conducted first through strong acid cation exchanger, followed by weak acid cation exchanger. The waste acid from the
strong acid cation exchanger is utilised to regenerate the weak acid cation exchanger. This process improves the utilisation of acid and minimises the effluent while obtaining highest quality treated water. This process is commonly referred to as “thoroughfare regeneration”.
Treated water quality
Leakage of sodium ions in treated water from strongly acidic cation exchanger depends on:
- Sodium content of feed
- Regeneration level employed
Refer to Figure 10 for leakage characteristics of INDION 225 H in co-flow regeneration mode. The exchange capacities of INDION 225 H in counter current mode of regeneration are shown in Figure 5. These are based on end point of one ppm of sodium slip expressed as CaCO . For sodium slip less than 3 one ppm, consult us.
Mixed bed de-ionsing
When used as the cation exchanger in a mixed bed unit, variation with feed water composition in operating exchange capacity is less than that, in two stage deionising. For practical purposes, feed water may be classified as - Ion exchange softened or demineralised
- Low ionic load influent.
In both cases, INDION 225 H may be regenerated with hydrochloric acid of 5% concentration. Figure 9 gives operating exchange capacity when used in a mixed bed unit.