RO water has virtually no buffering capacity found in natural waters. As a result minor alterations have a great impact on the pH of the water. The most likely cause is the loss of soluble carbon dioxide due to pressure. The loss of CO2 from the water causes a rise a in pH
Please confirm that rise in pH is along with rise in conductivity. If so then you need cleaning or replacement of membrane. If not then check the quality of feed water. pH of permeate depends on the composition of feed water. For further details please contact on rvsveipl@gmail.com. Prof. Rajendrakumar V Saraf, Chairman Viraj Envirozing India Pvt. Ltd. Pune, India
Yes, similar to the sentiments of Mr. Lipshultz. The loss of membrane rejection is an indication of increasing permeate conductivity and subsequently a typically higher pH of the permeate water. To regain rejection efficiency, a potential membrane cleaning may work or a membrane replacement would be required if the cleaning is not sufficient.
- Changes in the feed water. - Fouling, indicating necessity of chemical cleanings. - Damage of the membranes increasing the salts passage. - Improper dosage of conditioning chemicals, antiscalant for instance.
If membranes need cleaning or replacement it will also show changes in permeate EC and flows. If everything is fine then, Try lowering pressure and increasing reject flow to get desired pH. Increased pH in permeate has also dependency on antiscalent used. Please do check antiscalent properties.
If the membranes are showing proper rejection however, the pH is increasing and / or same as source water, it is a sign the membrane rejection will soon reduce requiring cleaning or replacement.
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