CETP (common Effluent Treatment Plant) located in one of the well-known textile industry zones in
Gujarat has an RO Membrane system for treated water recycling. In, comparatively shorter span of In
two years, management has to replace all the membranes forcefully due to deterioration of the product
quality, quantity, and a rise in unscheduled CIP frequency.
Deterioration of product quantity was by 35%, and the change in quality was also quite significant.
Before the replacement of membranes, CETP management made a call to perform a membrane autopsy
to diagnose the reason for membrane failure and contacted.
Based on our recommendation, they have selected the RO membrane for autopsy and sent it to us
with the recommended packing. We studied this case and came up with very interesting facts.
So, let’s see the case and its findings.
Chemicals used for the Effluent water treatment plant :
1. Ferric Chloride
Chemical used for RO feed treatment :
1.Non-phosphate base antiscalant
2. Non-oxidising biocide
3. Chlorination
4. SMBS
All these chemicals were common and standard chemicals that are available on the market.
After receipt of the membrane while carrying out the autopsy, we came up with very valuable
observations and findings, which are listed below :
1. Evidence of panic and harsh cleaning was observed.
2. Evidence of back pressure from the product side was observed.
3. The membrane was delaminated.
4. Reject spacer was partially choked.
5. Two membrane leaves with a reject spacer were stuck together.
6. Some sticky or oily, or glue-like black coloured substance was observed on the membrane.
Reject the Carrier stuck to the membrane sheet
Delamination observed
Some of our analytical findings and interpretation of foulants deposited on membrane leaf
are as follows:
1. In chemical analysis, calcium deposition was prominently observed, followed by iron and silica.
Apart from this halogen group, alcohol, alkyl halide,s and hydrocarbons were found.
2. An adequate amount of microbial deposition was observed.
3. The Fujiwara test was positive at various locations.
4. Uncontrolled dosage of chlorine and SMBS has oxidised the membrane.
5. Uncontrolled dosage of ferric chloride at ETP has created irreversible damage to the membrane.
We were surprised to observe a sticky or oily or glue-like substance on the membrane sheet, which
was a unexpected experience for us and a challenge to investigate. After a deep and
very time-consuming investigation, we could understand that alkene has reacted with some
of the halogen group and formed a sticky or oily, or glue-like substance. Considering the
quantity of that particular substance on the membrane, contamination of alkyl halides in the feed
water could be a few ppm or ppb also. But that minute contamination has damaged the membrane
completely.
Vipanan Analytical Technologies LLP Lab: Flat 1-2, Nilay, Plot No. 23, Prathamesh Park, Baner, Balewadi Road, Baner, Pune 45
Email: lab@vipananlab.com
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