| Reduced Throughput |
| Possible Cause |
Solution |
| Increased ionic loading |
| |
· Check influent water analysis
· Increase regenerant
· Add capacity
|
| Channeling, poor distribution |
|
· Suspended solids loading
|
· Check backwash, extend if needed
|
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· Broken or clogged distributors
|
· Repair
|
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· Low flow
|
· Maintain minimum flow
|
| Premature break |
| |
· Check previous run throughput
· If normal regeneration does not restore capacity, double regenerate
· Adjust end point
|
| Regenerant concentration and quantity |
| |
· Check metering pumps, educators, piping, etc.
· Regenerant dosage
· Check dilution flows, time settings
· Apply correct amount at correct concentrations
|
| If degasser (decarbonator) is used |
| |
· Check CO2 at the outlet of the clearwell: should be less than 5 ppm. If not:
· Check air filter on blower; replace if dirty
· Inspect packing (rings) in column. If dirty or slimed, replace packing.
|
| Resin loss |
|
· Excessive backwash
|
· Check temperature and flowrate
|
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· Underdrain failure
|
· Check and repair (resin trap?)
|
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· De-crosslinked resin
|
· See "oxidation"
|
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· Flotation by dissolved gas
|
· Effluent flow control
|
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· Normal bead attrition
|
· Topoff
|
| Resin Age |
| |
· Up to 5%/yr loss in capacity considered normal
· Analyze resin to determine remaining useful life
|
| Resin degradation |
|
· Resin exposed to excessive temperature
|
· Do not exceed 120°F anytime for type I styrenic strong base anion resins
· Do nto exceed 95°F anytime for type II styrenic or type I acrylic strong base anion resins
|
| Excessive rinsing |
|
· Organic fouling (organics tend to hold on to sodium as they contain weak sites which retain sodium)
|
· Partial restoration of resin with a brine squeeze
· Analyze resin for strong base capacity and replace resin if necessary
· Incorporate routine brine squeezes into operation of plant.
· In the case of weak base anions, consider regeneration with ammonia
· Recycle rinse water to reduce water usage
· Adjust rinse end-point
· Check caustic concentration (higher concentration requires more rinse water)
· For high TOC waters, consider the installation of an organic trap
|
| Presence of cation resin in anion bed |
|
|
· Analyze resin
· Check for presence of cation resin in anion bed
· Identify cause of presence of cation resin (leaky or broken strainer or lateral) and repair
|
| Resin fouling |
|
· Silica precipitation
|
· Lower caustic strength (2.5% suggested)
· Thoroughfare regeneration (strong base anion/weak base anion) dump first portion of strong base eluate before feeding residual caustic to WBA resin
|
| If degasser (decarbonator) is used |
| |
· Check air filter on blower; replace if dirty, damaged or missing
|
| Note: All of the items listed above for "Reduced Throughput" should also be checked regarding poor effluent quality |
| Poor Effluent Quality |
| High conductivity or pH in treated water |
|
· Ran past cation breakpoint
|
· Check cation effluent
· If cation effluent is within acceptable range, check anion resin
|
| Chemical precipitation |
|
· Hardness in regenerant dilution and / or rinse waters
|
· Check for calcium and magnesium in cation and anion effluent
· Insure that dilution and rinse waters are hardness-free
|
| Hardness in treated water |
| |
· Check cation performance
· Check for hardness in all waters used for regeneration to eliminate precipitates
|
| Chloride or silica in treated water |
| |
· Check regenerant specs for chloride and silica content (mercury cell or rayon grades of caustic are acceptable)
· Check for leaking regenerant (caustic) valve
|
| 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
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
|
| Lower water temperature |
| |
· ΔP increases with higher 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
|
| Plugged underdrain |
|
· Resin or subfill in collectors outlet strainers
|
· Inspect internals
|
| 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 |
| 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 abnd rinses
|
|
· Resin attrition
|
· Inspect and repair
|
|
· Resin loss
|
· See "Resin loss" above under "Reduced Throughput"
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