0
$\begingroup$

I am facing a challenge since long ago, but have not been able to find a suitable solution for it. Please share your thoughts if you have the knowledge or experience in this area.

I am running an RO system at 90% recovery, where the feed concentration of Bicarbonate in the RO is 69 mg/L. For certain reasons, I am not allowed to reduced the pH of the feed water to get the desired level of bicarbonate in the permeate (18 mg/L). However, I have 55 - 90 mg/L of HCO3 in my permeate water (which is not a desired concentration in the permeate).

As acid dosing is not an option, what do you think are other options that I can reduce the HCO3 to below 18 mg/L?

I am worried if the CO2 concentration in the feed is quite high, when it passes with permeate water (gas), it is making the equilibrium with bicarbonate again. Which means although the bicarbonate is removed by the RO membrane, in the permeate CO2 changes to HCO3 to make the equilibrium.

Measurement of CO2 practically have not been done yet, as is quite rare to do.

My feed water pH is 6.04.

Improve this question
$\endgroup$
3
  • $\begingroup$ Explain what you are doing ! What is a RO system ? What is recovered at 90% ? Why do you use bicarbonate ? What is the meaning of "permeate water (gas)" ??? What is a RO membrane ? What is a feed water ? $\endgroup$
    – Maurice
    Commented Jun 17 at 19:20
  • $\begingroup$ It sounds like the membrane is not rejecting CO2 and HCO3-; check the specifications. 90% is a high thruput ratio. $\endgroup$
    – jimchmst
    Commented Jun 17 at 20:12
  • $\begingroup$ One is tempted to say the membrane is ruptured and RO does not work any more. $\endgroup$
    – Poutnik
    Commented Jun 18 at 5:47

0

Reset to default