Can we send the CIP solution to our deep injection well after cleaning our Reverse Osmosis membranes?
No, if a high pH RO cleaning solution is mixed with RO brine, it would result in severe scaling. Always consult with your hydrogeologist before sending any solution to the deep injection well. See also: What is the procedure for cleaning ...
Our RO plant doesn’t have a neutralization tank for our spent CIP solution. Can we just neutralize while circulating through the membrane system?
That is not recommended. A high pH cleaning solution is designed to dissolve membrane foulants and scales that are soluble in basic conditions. A low pH cleaning solution is designed to dissolve membrane foulants and scales that are sol...
Can we send our CIP solution direct to the waste water treatment plant after cleaning our Reverse Osmosis System?
No, pH extremes can be very disruptive to bacteria and can upset the operation of the wastewater treatment plant. The RO cleaning solution should always be neutralized prior to sending to a wastewater treatment plant. The solution is us...
Why does the RO permeate pH rise when the water passes through a degasifier? Does that higher pH really stabilize the RO permeate to help prevent corrosion in the distribution system?
Bicarbonate is in equilibrium with carbonic acid, and carbonic acid is in equilibrium with carbon dioxide. [1] $${HCO{_3}{^-} \Leftrightarrow CO{_3}{^2}{^-} + H^+}$$ [2] $${H_2CO_3 \Leftrightarrow HCO{_3}{^-} + H^+}$$ [3] $${CO{_2}{_(}{_...
A few weeks ago, we pickled all RO membranes in our trains with sodium metabisulfite for long term storage. Our membrane manufacturer recommended that we change the solution once the pH drops below 3. We measured a decrease in pH for the first two weeks, but then on the third week, the pH increased. Can you explain why the pH increased instead of decreasing?
When you mix sodium metabisulfite in water, you form a sodium bisulfite solution: $${Na_2S_2O_5 + H_2O \Leftrightarrow 2NaHSO_3}$$$${NaHSO_3 \Leftrightarrow Na^+ + HSO{_3}{^-}}$$ Bisulfite is in equilibrium with sulfite and sulfurous acid (...
We recently installed new RO membranes in our system and observed that the permeate water tested positive for coliform bacteria. Is it possible in your experience that RO membranes could be damaged during installation and cause contamination of the water distribution system by bacteria and pathogens?
It’s unlikely that the RO membranes were damaged inadvertently during installation. While it’s possible for there to be manufacturing imperfections that allow pathogens such as viruses and bacteria to pass through, it’s not common. In...
What is the procedure for cleaning RO membranes? What CIP chemicals should be used?
RO membrane cleaning should be performed with high and low pH CIP chemicals. The high pH cleaning should always be performed first to penetrate and disperse biological or organic foulants. Specialty high pH cleaning chemicals more effective...
Does reverse osmosis desalination of sea water remove viruses from the product water?
Yes, viruses are substantially removed by reverse osmosis membranes. However, studies performed have shown varying viral removal efficacy, varying from 2 log removal (99% rejection) to 5.9 log removal (99.99987% rejection). This is believed...
What is the maximum Calcium Sulfate (CaSO4) level in brine side that A-102 plus can deal with?
A-102 Plus can handle up to 300% calcium sulfate saturation on the brine side. CaSO4 saturation will vary according to concentrations of dissolved calcium and sulfates, temperature and salinity. If you already have high sulfate levels, avoi...
How do I determine anti-scalant dosage for a 2300 gpd R/O unit, when CaCO3 is 255 gpg?
When calculating antiscalant dosage, inhibition of all scales must be considered. Potentials scales that can form are: Calcium carbonate Calcium phosphate Calcium fluoride Calcium sulfate Barium sulfate Strontium sulfate metal hydroxides (i...