Metal finishing Q&As since 1989

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Resin Fouling in demineralized water plant

 

In my plant we have water treatment system of capacity 20 m3/hr demineralized water. We get clarified water in Demineralize Plant from pretreatment system that is River Water- Clarifier - Pressure Filter - Carbon Filter. In Demineralization Plant we have Cation Exchanger, Degassifier, Anion Exchanger and Mixed Bed Polisher(MBP) System. After MBP outlet water conductivity should be 0.5 micro-S/cm. When water quality fall down, we regenerate the MBP and it become good condition. Anion / Cation bed regeneration is based on Anion bed outlet conductivity that is 5 micro-S/cm. Last month our MBP resin become fouled because the conductivity of MBP outlet was not going down by regeneration. We like to know how the resin become fouled and how the fouled resin can be regenerated. Thanks in advance.

Nazrul Islam
- Dhaka, Bangladesh

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From your query it is not clear Why you are using term fouling. I think that fouling of mixed bed resin is not a common phenomenon.It would have been helpful if you had provided the pH of effluent of MB unit. If it is in acidic side, it may be due to improper regeneration of anionic part(Chloride leakage) and if it is in alkaline side it may be due to improper regeneration of cationic resin(Na leakage).There may also be disproportion of resin quantities due to resin loss.

Dr.Rajesh Tiwari
electricity board - Korba, CG, India
 

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Dear Mr. Islam

While your problem could have a number of causes, from what you report, it sounds like organic fouling, especially because of the presence of the carbon filter.

A quick test would be to feel inside the outlet of the backwash line from the filter. If it is slimy then organics from it will be affecting the entire system down stream.

Remove the carbon. chlorinate the tank overnight and replace the carbon. In the meantime, follow somebody's defouling procedures for all ion exchange units.

Good Luck,

Dave Peairs

Dave Peairs
- Santa Ana, California USA
February 15, 2011

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Q. How to avoid the resin loss during the bed regeneration because we are even losing resin during chemical injection.

Robert Loolo
- Kuwait
January 28, 2012

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We have 20000 liters per hour capacity of dm plant with counterflow regeneration method and injection time is 40 minutes, now we are decided to done the regeneration by both co-flow and counterflow method,after some line modification (first half of the injection period to be given by co-flow method and second half to be counterflow method). Is it correct method or not, please explain.

Kandasamy Suriyanarayanan
- Tuticorin, Tamilnadu, India
March 13, 2012