Tech Hub for Cutting-Edge Ion Exchange Resins Types

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Trouble Shooting

1. Low output between regenerations (OBR)

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Sr. No.	Cause	Remedial measures
1	Increase in ionic load	Check and verify. OBR is inversely proportional to ionic load.
2	Change in water characteristics	For WAC : Check TH/M Alk For SAC : Check Na/TC & Alk/TC For WBA : Check SO4/EMA For SBA : Check SO4/EMA & SiO2/TA And verify the effect of the above from resin literature.
3	Lower resin volume	Check bed depth and verify. OBR is directly proportional to resin volume.
4	Improper regeneration	Check the quantity of regenerant. Use specified quantity. Check quality of regenerant. Regenerant to IS spec to be used. For HCl – IS 265 For NaOH – IS 252 Check injection & rinse flow rates. Maintain as specified. Check regenerant injection concentration. Maintain as specified. Check for channelling. Rectify defects in distribution and / or collecting systems. Clean resin bed and remove resin fines.
5	Incorrect termination of unit	In case of WAC, unit is generally terminated to Alkalinity end point of 30 ppm CaCO3. In certain cases ( WAC – SAC system ) unit is terminated to Hardness end point. So, check and verify. Often anion unit is terminated due to high conductivity of water.The high conductivity of water may be due to cation exhaustion also. So, check pH at anion outlet to verify Which unit has exhausted. Low pH indicates anion exhaustion High pH indicates cation exhaustion.
6	Dirty resin	Give extended backwash or open manhole backwash to clean the resin. Air scour also if required. Ensure proper operation of upstream clarifiers, dosing systems and filters.
7	Resin fouled by Iron or Organic matter	Treat Iron fouled resin with HCl and organically fouled anion resin with Alkaline brine solution. Follow Recommended methods of treatment. 2. Correct pretreatment operations such as chlorination, coagulation and flocculation.
8	Resin deteriorated	Collect resin samples for analysis and verification. Change resin if suggested by the report.
9	Channeling of water in the bed	Check distribution and collecting systems and rectify. Check if bed is dirty and clean. Check for resin fines in the bed and remove by open – manhole backwash and scraping the top layer.
10	Intermittent usage of unit	Operate unit continuously as possible.
11	Insufficient displacement of regenerant i.e., less volume of slow rinse in counter flow (CCR) units	Maintain 1.5 to 2 BV for cation resin. Maintain 2 to 3 BV for anion resin.
12	Slow rinse flow rate higher than injection flow rate in CCR units	Slow rinse must be less than or equal to injection flow rate. Ensure Injection and slow rinse flow rate is 5m/h minimum.
13	Over run of previous cycle	Operate to specified water quality or rated OBR whichever comes first.

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2. Fall in treated water quality

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Sr. No.	Cause	Remedial measures
1	Resin bed exhausted	Regenerate the unit.
2	Inadequate rinse	Continue rinse to satisfactory quality.
3	Leaky backwash inlet valve	Check and rectify.
4	Resin in MB not mixed uniformly	Air mix and rinse to satisfactory quality.
5	Channeling of water in the bed	Check distribution and collecting systems and rectify. Check if bed is dirty and clean. Check for resin fines in the bed and remove by open – manhole backwash and scraping the top layer.
6	Excessive or low flow rates	Maintain the flow rate between the minimum and maximum specfied.
7	Improper regeneration	Check the quantity of regenerant. Use specified quantity. Check quality of regenerant. Regenerant to IS spec to be used. For HCl – IS 265. For NaOH – IS 252. Check injection & rinse flow rates. Maintain as specified. Check regenerant injection concentration. Maintain as specified. Check for channeling. Rectify defects in distribution and / or collecting systems. Clean resin bed and remove resin fines.
8	Change in influent water quality	For WAC : Check TH & M.Alk. WAC takes up temporary Hardness completely but leaks permanent hardness totally. For SAC : For coflow units, check Na/TC. Higher the ratio, higher is the Na slip. For WBA: Check Na slip from SAC. Higher Na slip will give higher chloride slip. For SBA : I) Check Na slip from SAC. Higher Na slip will give higher pH, conductivity and Silica slip. II) Check SiO2/TA. Higher ratio will give higher silica slip for coflow units.
9	Dirty resin	Give extended backwash or open- manhole backwash to clean the resin. Air scour also if required. Ensure proper operation of upstream clarifiers, dosing systems and filters.
10	Resin fouled by Iron or Organic matter	Treat Iron fouled resin with HCl and organically fouled anion resin with alkaline brine solution. Follow recommended methods of treatment. Correct pretreatment operations such as chlorination, coagulation and flocculation.
11	Resin deteriorated	Collect resin samples for analysis and verification. Change resin if suggested by the report.

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3. Long rinse of units

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Sr. No.	Cause	Remedial measures
1	Resin bed exhausted	Regenerate the unit.
2	Low rinse flow rate	Maintain specified flow rate.
3	Leaky backwash inlet	Check and rectify.
4	Inadequate mixing of resins in MB	Air mix and rinse to satisfactory quality.
5	Improper regeneration	Check the quantity of regenerant. Use specified quantity. Check quality of regenerant. Regenerant to IS spec to be used. HCl – IS 265, NaOH – IS 252. Check injection & rinse flow rates. Maintain as specified. Check regenerant injection concentration. Maintain as specified. Check for channeling. Rectify defects in distribution and / or collecting systems. Clean resin bed and remove resin fines.
6	Regenerant hide-out	Check unit internals (especially man-hole nozzles) and rubber lining.
7	Organically fouled anion resin	Treat resin with alkaline brine solution. Follow recommended procedure. Correct pretreatment operations such as chlorination, coagulation and flocculation.
8	Resin deteriorated	Collect resin samples for analysis and verification. Change resin if suggested by the report

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4. High pressure drop across unit

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Sr. No.	Cause	Remedial measures
1	High flow rate	Maintain rated flow. Verify pressure drop with rated flow from resin literature.
2	Sulphate precipitation in cation bed	Dissolve precipitate by soaking in 5% w/v HCl. Maintain the correct concentration of H2SO4 during injection. For SAC : Check Ca/TC and refer resin literature for injection concentration For WAC : Maintain injection concentration 0.8 % w/v H2SO4.
3	Silica precipitation in WBA unit. This can occur when caustic is thoroughfared from SBA to WBA	Dissolve precipitate by soaking in 5% w/v NaOH. Maintain the correct concentration of NaOH during injection into SBA and WBA. Maximum injection concentration : SBA - 4%w/v, WBA - 2%w/v. Minimum injection concentration : SBA - 2%w/v, WBA - 1%w/v.
4	Excessive resin fines	Remove resin fines from the bed by open – manhole backwash and scraping 1 to 2 inches of top layer.
5	Choking of strainers in collecting systems	Determine source of choke – dirt, precipitate, resin fines & follow the appropriate procedure mentioned above.
6	Throttled or defective valves in the circuit	Check and rectify.
7	Bulging of rubber lining in pipes	Replace the defective rubber lined pipes.
8	Decrosslinking of resin due to oxidative attack & presence of Heavy metals like Iron	Ensure free chlorine & iron are absent in feed water to the unit and the regenerant chemicals.Check pretreatment plant for removal of iron & ensure dechlorination by ACF / Na2SO3 dosing. Use chemicals to IS specifcation. Sample resin and check moisture content. Replace resin if advised in the report.

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5. Low flow rate during service

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Sr. No.	Cause	Remedial measures
1	Pump malfunction	Check and rectify
2	Dirty resin bed	Give extended backwash or open- manhole backwash to clean the resin. Air scour also if required. Ensure proper operation of upstream clarifiers, dosing systems and filters.
3	Excessive resin fines	Remove resin fines from the bed by open – manhole backwash and scraping 1 to 2 inches of top layer.
4	Throttled or defective valves in the circuit	Check and rectify.
5	Bulging of rubber lining in pipes	Replace the defective rubber lined pipes.
6	Choking of strainers in collecting systems	Determine source of choke – dirt, resin fines & follow the appropriate procedure mentioned above.
7	Increased ‘head’ of the system due to above or other reasons	Check and rectify.

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6. Loss of resin from unit

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Sr. No.	Cause	Remedial measures
1	High backwash flow rate	Maintain design flow rate.
2	Lower water temperature	Reduce backwash flow rate to maintain design bed expansion. Refer resin literature.
3	Failure of collecting system	Check and rectify.
4	Evolution of CO2 in bed during backwash (This occurs in WAC,SAC & WBA units)	Carry out a pressurised backwash to keep CO2 in solution.

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7. Back pressure during regeneration

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Sr. No.	Cause	Remedial measures
1	Passing of valves	Check unit inlet, outlet and backwash inlet valves.
2	Chokage of strainers in collecting system	Check and clean strainers.
3	Resin fines present in bed	Remove resin fines by open manhole backwash and scraping of the top layer.
4	Middle collector not flushed	Carry out flushing operation before injection.
5	Dirty resin bed	Backwash bed thoroughly. If required give extended backwash or open manhole backwash. Air scour if necessary. Ensure clean water quality from pretreatment plant.
6	High regeneration flowrates	Check down flow, power water & injection flow rates. Maintain design values.
7	Collecting system inadequate	Check design ie, header size, number and size of laterals: and number and size of strainers.
8	Throttled or defective valves in the circuit	Check & rectify.
9	Bulge in rubber lining of pipes	Check and replace pipes.
10	Sulphate precipitation In cation bed	Dissolve precipitate by soaking in 5% w/v HCl. Maintain the correct concentration of H2SO4 during injection. For SAC: Check Ca/TC and refer resin literature for injection concentration. For WAC: Maintain injection concentration 0.8 % w/v H2SO4.
11	Silica precipitation in WBA	Dissolve precipitate by soaking in 5% w/v NaOH. Maintain the correct concentration of NaOH during injection into SBA and WBA. Maximum injection concentration: SBA - 4%w/v WBA - 2%w/v. Minimum injection concentration: SBA - 2%w/v WBA - 1%w/v.

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8. Ejector not working.

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Sr. No.	Cause	Remedial measures
1	Low power water pressure	Maintain minimum pressure of power water at 2 kg/cm2 g.
2	Excessive backpressure from unit	Refer measures recommended under 'back pressure during regeneration' indicated above.
3	Air lock in the unit	Ensure unit is full of water after backwash / middle collector flushing.
4	Ejector defective	Replace ejector.

9. High sodium slip at SAC outlet

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Sr. No.	Cause	Remedial measures
1	Improper regeneration	Carry out regeneration as per recommended procedure.
2	High Na/TC - This affects coflow units	Use higher regeneration level soak bed in acid after injection.
3	High sodium in degassed water - This affects CCR units	Ensure sodium content in degassed water is below 1 - 2 ppm CaCO3.
4	CCR unit backwashed	Use double quantity of acid.
5	Unit overrun	Operate unit to rated capacity and quality.
6	Channeling of water in the bed	Check distribution and collecting systems and rectify. Check if bed is dirty and clean. Check for resin fines in the bed and remove by open – manhole backwash and scraping the top layer.

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10. High conductivity & pH at anion outlet.

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11. High Silica at SBA outlet

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Sr. No.	Cause	Remedial measures
1	Improper regeneration	Carry out regeneration as per recommended procedure.
2	High SiO2/TA - This affects co flow units	Use higher regeneration level soak bed in alkali after injection.
3	High silica in DM water used for regeneration - This affects CCR units	Ensure silica content in DM water is below 0.1 - 0.2 ppm SiO2.
4	CCR unit backwashed	Use double quantity of caustic.
5	High sodium slip from cation	Use double quantity of caustic.
6	High sodium slip from cation	Refer measures for 'High sodium slip at SAC outlet.'
7	Channelling of water in the bed	Check distribution and collecting systems and rectify. Check if bed is dirty and clean. Check for resin fines in the bed and remove by open – manhole backwash and scraping the top layer.

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12. Low pH at MB outlet.

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Sr. No.	Cause	Remedial measures
1	pH measured off line	Online measurement of pH is mandatory for MB.
2	Inadequacy of pH measuring device	Select pH sensor & instrument suitable for low conductivity (1 microsiemens/cm ) DM water.
3	Improper mixing of resin	Air mix as specified. Subsequent operations of settle bed, refill & final rinse must be done quickly & effectively.
4	Resins not separated after backwash	Backwash at higher flow rate and for a longer period.
5	Improper regeneration	Ensure down flow/up flow operations are maintained during injection & rinse stages.
6	Organics in water	Ensure proper operations of pretreatment plant.
7	Defective collecting system	Check & rectify.

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Complaint – Higher fines content:

Fines content especially in cation resins is reported to be high by the clients. It is a very common and frequent complaint in the new supplies.

The operators of DM plants draw sample from top of the drums and after visual inspection they report that the fines content in the resin, as supplied is very high.

The resin beads can appear to be fines when the above method is employed. The resin beads present at the top of the drum can be half dried and shrunk, because of transit and storage time at the site and hence, it appears as fines.

How to resolve this complaint:

Draw a representative sample of resin and soak the resin in a beaker containing water for nearly an hour. The resin beads will regain their original shape and the beads will be normal in shape.
In case the client is still not convinced, then send the representative sample to our Ankleshwar Q.C. laboratory with a request letter for Fines content analysis.

Note: Reasons for fines not being present in the fresh supply:

The percentage fines passing through 300 microns mesh size is maintained well below the specification limit of 1% maximum, at our factory.
The effective size range as per the earlier specification was 0.4 – 0.5 mm and it has been revised upwards to 0.45 – 0.55 mm since 1999 - 2000. So, the possibility of the presence of higher fines content in the fresh supply is ruled out.