| Reduced Throughput / Poor Effluent Quality |
| Possible Cause |
Solution |
| NOTE: Most comments for cation and anion apply to mixed-bed demineralizers and for best performance always use mixed-bed grade resin. |
| Poor primary exchanger performance |
| |
· Troubleshoot primary cation and anion exchangers
|
| Poor separation of mixed bed in first step of regeneration |
|
|
· Check flowrates and temperature of backwash water
· Check for proper resin vs mid-collector interface location
· Insure use of mixed-bed grade resin
|
| Interface too low because of loss of cation resin |
| |
· Add cation resin
|
| Interface too high because of separation and anion trapped within cation bed |
| |
· Check flowrates and temperature of backwash water
· Correct flowrates
|
| Interface too high because of overcharging of cation resin |
|
|
· Remove appropriate amount of cation resin
|
| Cross contamination |
| |
· Result of poor separation of the cation and anion resins, improper interface location due to los of overcharging of cation resin
|
| Acid in the anion zone which causes SO4 leakage and early anion exhaustion |
|
|
· Insure adequate blocking flow
|
| Caustic in the cation zone which causes Na leakage and early cation exhaustion |
|
|
· Insure adequate blocking flow
|
| Insufficient displacement rinse which results in resin cross contamination and high effluent conductivity |
| |
· Extend displacement rinse to achieve acceptable conductivity
|
| Insufficient mixinf after regeneration step caused by insufficient air flow |
| |
· Check and adjust air flow
|
| Improper draindown prior to air mix |
| |
· Check water level prior to air mix
· Adjust setting for water level
|
| Fluidization and reseparation of the bed during refill due to excess flowrate |
| |
· Perform a slow fill through the caustic distributor followed by a fast fill through the service inlet
|
| Excessive Final Rinse |
| |
· Poor resin separation (see above)
· Cross contamination (see above)
|
| Premature silica break |
|
· Silica precipitation due to contact with acid
|
· Start acid injection 20 minutes after start of caustic injection
|
