Using Raw water in industry is an advantage, however, it has its challenges and difficulties too.
Treating raw water is a complex process, though it seems to be a simple process prima facie. If, due consideration of seasonal deviation in water quality, understanding and foreseeing the errors in pre-
treatment system, if not given, then the membrane system can create major issues in product quality, productivity, and energy usage. In this blog, we would like to mention our unique experience in one of
the cases.
To troubleshoot some crucial issues like product quality, productivity, and costly membrane
replacement, we, at Vipanan, received a call from a Power Plant situated in central India. This
organization decided to approach us for Membrane Autopsy, and a few membranes were sent to us
(Quantity, location, and packing of membranes were recommended by us.) We understood from
them that they are using a RO system for treating Raw water from the river to get feed water for their
boiler. They were having Pretreatment set up as follows
Chemicals used for the RO water treatment plant :
1. Chlorination
2. SMBS
3. Antiscalant
4. Biocide
Their RO cleaning frequency was twice a month. They noticed that the RO permeate was deteriorating in quality and quantity over the last two years drastically. Their problems increased enormously, especially after the rainy season. There was not only a steep drop in product quality, but system pressure was also reduced significantly.
This resulted in costly downtime and high membrane replacement costs. After receiving the
membrane, we had a Visual Inspection by our experts and came across some unusual and interesting
findings as mentioned below :
•Marks of harsh / panic cleaning were noticeable.
•There were symptoms of backpressure from the product side.
• A sticky/oily black colored substance was present on the membrane surface.
•Mineral deposition was visible.
•Maximum sheets of membrane were eroded.
•Glue lines were improper and damaged at different places.
Analytical findings and interpretation of foulants deposited on the membrane leaf are as follows:
1. An adequate amount of Microbial deposition was present on the membrane.
2. A positive Fujiwara test indicates the oxidation of the membrane surface by Halogens.
3. In chemical analysis, Calcium deposition was prominently observed, followed by Iron and Silica.
4. The main culprits found were Organic compounds, which are the major causes of Irreversible
damage. They were Alkyl halides, Alcohol, Hydrocarbons, Alkenes, and Amines. For example both
High and Low density polyethylene, Refined paraffin wax, Diene terpolymer poly(ethylene), 1-
Decanol, N-Decane, 10-Dichlorodecane .(thanks to our enhanced capacity to detect the
contamination on a carbon level.
It was unexpected to reveal such organic contamination on the membrane surface. This organic
Contamination plays an important role in most of the symptoms mentioned in visual inspection.
Organic matter is often quite reactive, and the risk that it poses as a foulant depends upon several factors, including its affinity for the membrane material.
While designing the RO Membrane system, Organic matter and organic substances are neglected. Some organic components may attack on membrane construction and alter its functionality.
Microbiological organisms grow on the membrane surface, releasing a protective substance
known as extracellular polymeric substance (EPS). Collectively, the microorganisms and EPS form a slimy gel layer known as biofilm. EPS and Saturated minerals & metals help each other to deposit on the membrane surface and further result in severe fouling.
Although COD is considered an organic contamination indicator, it doesn’t need to
cover all the functional groups in organic chemistry. If organic fouling is going to cause irreversible
damage to the membrane, then we have to be well equipped to face such contamination, which may
occur in the future.
Hence, assessment of soluble organic compounds in water is very much necessary. Further, it is
necessary to assess organic contamination in water, independently, for RO system design also.
This case study indicates that many times, we focus more on the known facts, which causes the
problems. However, while doing an Autopsy, one should not limit his thinking to knowing causes, but
should think ‘out of the box’, to find and check the various possibilities of the root cause of the
system failure.
Membrane Autopsy, if done well, is the best way to find out exact cause /causes of system failure.
We at Vipanan have developed such ‘Out of the Box’ thinking. #membraneautopsy
Vipanan Analytical Technologies LLP Lab: Flat 1-2, Nilay, Plot No. 23, Prathamesh Park, Baner, Balewadi Road, Baner, Pune 45
Email: lab@vipananlab.com
Tel no: 8149036220 /8793046221
Web: www.vipanan.co