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FLUX RATE IN UF SYSTEM

2005

We are having CED process in our plant. During our recent block closure we have cleaned the F module (OSMONICS ED7) with following procedure:

1 Recovery of paint from module using permeate.
2.Circulated DM water(ph 5.5-6.5)through system in normal flow direction for 6 days with temp max 40 deg. Draining & refilling DM water every 2 hrs 3.On last day we flushed the system BG+acetic acid [on eBay or Amazon](87%Dm water+8% BG+5%acetic acid )as per procedure with room temp (no heating done for chemical) during flushing & flow direction was opposite to normal flow.

After normalising the system, we observed that lux rate of the UF system is dropped to 5.8 cum/hr from 6.5 cm m /hr. We again did cleaning of the modules with 0.5% nitric acid . But still flux rate is not improving. We want to know that what are the probable causes of sudden drop in the flux rate. is there problem in the procedure which we followed during block closure. Please help.

Dhananjay Joshi
Mahindra& Mahindra Ltd - Nasik, Maharashtra, India

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2005

Dear Dhananjay:

You have not mentioned the permeate flux before you started the cleaning. You alse need to mention clearly the permeate flux after cleaning and then after 24 hours or later.

If you compare the permeate flux during cleaning and after that, you will end up with a incorrect comparison since the composition of the cleaning liquid and the CED paint bath are very very different.

To be able to analyse, the following should me mentioned clearly:
Permeate flux before starting the cleaning
Permeate flux immediately after finishing the cleaning
Permeate flux after 24 hours of paint circulation

Once these figures are available the matter can be looked at afresh.

Best regards.

Gurvin Singh
Mohali, Punjab, India

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Dear Sir

Thanks for your input

Flux before the cleaning was 5.1

Flux immediately after cleaning was 6.5

Flux after 24 hrs is 5.2

So we want to know what has cause the flux to drop so drastically.

Dhananjay Joshi
Mahindra&Mahindra - Nasik, Maharashtra, India
2006

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2006

Looking at the information provided by you, prima facie,I do not see any reason for concern.

The first inference that can be drawn is that the UF module is operating at its optimal level and while the cleaning procedure MIGHT prolong its life has no effect on its current performance.

The flux immediately after the cleaning is not the steady state flux and should not be considered for comparison.

For a wider perspective, you have to assess the flux in comparison to what it was when the system was started, how the flux has changed over a period of time and how long the system has been in operation.

I hope this will help.

Gurvin Singh
Mohali, Punjab, India