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 to 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.
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 replacement costs for the membrane. 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 the 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 their 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.
Quick Insight
Even when the source water appears clear and harmless, hidden contaminants like silica, iron, organics, or microbiological growth can create unexpected treatment challenges. What seems simple often requires advanced processes like coagulation, filtration, RO, or even membrane autopsy to ensure safe, reliable water.
Membrane Autopsy, if done well, is the best way to determine the exact cause (s) 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
FAQs: Complexities in Simple Raw Water Treatment
Q1. Why is raw water treatment considered “complex” even when the source seems clean?
A: Even when raw water appears clear, it may contain dissolved solids, microorganisms, organic matter, suspended particles, hardness ions, and seasonal contaminants. Each of these requires different treatment methods, making the overall process more complex than it initially appears.
Q2. Why does coagulant dosage vary even in the same plant?
A: Raw water characteristics such as turbidity, pH, alkalinity, and organic load change constantly hourly, daily, and seasonally. This variability makes coagulant dosage dynamic, requiring regular jar testing and operator experience.
Q3. Why is raw water treatment not just a “set-and-forget” process?
A: Raw water varies 24/7. Continuous monitoring, chemical adjustment, and equipment maintenance are essential to maintain consistent treated water quality. Automation helps, but operator expertise remains critical.