Demin regen problem
Demin regen problem
(OP)
Our plant has two demin trains, anion and cation type. Beads are 1 year old in one unit and 2 months old in the other. When we regen our units, we measure the SiO2 in the effluent to determine if the regen has been successful. Recently, we have had trouble with our regens in regards to getting the SiO2 readings down after doing one. I am not a chemist, but do have a basic understanding of what is happening here. My question, for lack of further understanding, is: From which unit does the SiO2 come from? (We may be working on the wrong unit) Is it "flushed" from the cation, thru the anion and out? Or does it come directly from the anion, or both, as in sodium leakage?





RE: Demin regen problem
http://www.hungerfordterry.com/condensate.htm
These two links may be helpful to you.
RE: Demin regen problem
RE: Demin regen problem
Silica levels in feed water can vary quite a bit. You should monitor the incoming silica levels too.
S. Bush
www.water-eg.com
RE: Demin regen problem
Is your anion resin type I or II? Type II resins are damaged irreversibly if the water or regenerant temperature exceeds 95 degrees F. Type I are damaged above 120 degrees F.
What is the pH of the anion rinse water at the end of your normal rinse time? If it is still high, then Na leakage from the cation could be part of the problem.
If you are operating packed beds or one of the counter-current designs you could be disrupting the bed during regeneration. These units depend on having 3" - 6" of fully regenerated resin at the bed outlet. You shouldn't over run your beds either because it will take a 2X or 3X regenration to restore the polishing section.
And the obvious problem is: are you getting sufficient regenerant into the bed to regenerate the resin?
RE: Demin regen problem
I also have a question on what is the best way to deal with RO membrane biofouling? I have a chemical softening/coagualtion/flocculation system followed by Sand Filters, AC filters and cartridge filters.
Best regards to all
rami cremesti