| Reduced Throughput |
| Possible Cause |
Solution |
| Increased ionic loading |
| |
· Check influent water hardness
· Increase regenerant
· Add capacity
|
| Channeling, poor distribution |
|
· Suspended solids loading
|
· Check backwash extend if needed
|
|
· Broken or clogged distributors
|
· Repair
|
|
· Low flow
|
· Maintain minimum flow
|
| Premature break |
| |
· Check previous run throughput
· If normal regenerant does not restore capacity, double regenerate
· Adjust end point
|
| Regenerant concentration and quantity |
| |
· Check metering pumps, eductors, piping, etc.
· Regenerant dosage
· Do brine elution study (brine curve)
· Check dilution flows, time settings
· Apply correct amount at correct concentrations
|
| Resin loss |
|
· Excessive backwash
|
· Check temperature and flowrate
|
|
· Underdrain failure
|
· Check and repair (resin trap?)
|
|
· De-crosslinked resin
|
· See "oxidation"
|
|
· Flotation by dissolved gas
|
· Effluent flow control
|
|
· Normal bead attrition
|
· Topoff
|
| Resin Age |
| |
· Up to 5%/yr loss in capacity considered normal
· Analyze resin to determine remaining useful life
|
| Resin oxidation |
|
· Presence of oxidents (chlorine) and oxygen in presence of
catalysts (iron) causes de-crosslinking which reduces wet volume
capacity (eventually high ΔP)
|
· Chemical pretreatment of feedwater/activated carbon filter
· Replace resin when moisture content exceeds 65%
|
| Resin fouling |
|
· Iron, manganese, aluminum fouling and precipitates
|
· Check water supply (analysis)
· Check backwash
· Check regenerant chemicals for contaminants (analysis)
· Clean resin by air-scour and backwash and chemically if required
|
|
· Microbiological fouling
|
· Clean resin with appropriate cleaner (compatible with resin)
|
| Excessive rinsing |
| |
· Check end-of-rinse set points
· Readjust rinse time to suit
· Check for fouling (see above)
|
| Note: All of the items listed above for "Reduced Throughput" should also be checked regarding poor effluent quality |
| Poor Effluent Quality |
| Leaky valve |
| |
· Check bed sample vs. discharge pipe sample (before and after valving); special caution on backwash inlet valve
· Check limit stops on valve operators
· Check air pressure on pneumatic valves
· Check sealing gaskets on multiports
· Check for physical damage due to water hammer
|
| Flow rates too high |
|
· Insufficient reaction time (kinetics)
|
· Reduce flow
|
| Flow rates too low |
|
· Poor distribution, channeling
|
· Place one or more units in Standby to increase flowrate
· Recycle treated water to inlet
|
| Resin fouling |
| |
· See "Resin fouling" above under "Reduced Throughput"
|
| For counter-current regeneration: loss of inert (inactive) resin allows resin migration which, in turn, causes high leakage |
| |
· Check resin level and add resin as needed
|
| In counter-current regeneration, it is important to use soft water for regenerant dilution and displacement rinse |
| |
· Check resin level and add resin as needed
|
| High Pressure Drop |
| Bed compaction |
| |
· Check flow and temperature for sufficient backwash
· Air or mechanical scour prior to backwash
|
| Resin fines |
| |
· Remove with backwash
|
| Cation resin de-crosslink |
| |
· Analyze resin and replace if necessary
|
| Lower water temperature |
| |
· ΔP increases with higher water viscosity at lower temperature
|
| Increased flow rate |
| |
· ΔP increases with flow (do not exceed specified ΔP)
|
| Valve partially closed |
| |
· Check and adjust all valves
|
| Internal distributor blockage |
|
· With resin, iron, debris
|
· Inspect strainers and clean
· Repair / clean distributors
|
| Flow rates too high |
|
· Insufficient reaction time (kinetics)
|
· Reduce flow
|
| Plugged underdrain |
|
· Resin or subfill in collectors outlet strainers
|
· Inspect internals
|
| Increased suspended solids loading in influent |
| |
· Mid-cycle backwash
|
| Resin fouling |
| |
· See "Resin fouling" above under "Reduced Throughput"
|
| Low Pressure Drop |
| Note: Low pressure drop is not necessarily a problem in itself; however, it may be a symptom of a problem |
| Leaky valve |
| |
· Check bed sample vs. discharge
|
| Reduced flow |
| |
· ΔP decreases with flow
|
| Increased temperature |
| |
· Lower viscosity - check backwash rate at higher temperature
|
| Resin loss, reduced bed depth |
|
· Underdrain failure
|
· Check for loss to sewer during backwash and rinses
|
|
· Resin attrition
|
· Inspect and repair
|
|
· Resin loss
|
· See "Resin loss" above under "Reduced Throughput"
|
