What is the disadvantage of raw water disinfection by chlorine in RO desalination?
Chlorine will irreversibly damage a polyamide RO membrane, and as such, a chlorine residual cannot be allowed to contact the membrane. This means that once you dechlorinate, surviving bacteria will once again flourish, and dead bacteria wil...
Can Sulfuric acid or HCl be used with the addition of Citric acid for the control of iron and other scales in a reverse osmosis plant?
First and foremost, citric acid is a highly assimilable organic acid – this means that it would act as a carbon source for growth of microorganisms. In the few cases we’ve come across where citric acid was being dosed continuously int...
Is sodium metabisulfite an effective disinfectant for my RO system?
Sodium metabisulfite (SMBS) is not a disinfectant. SMBS dissolved in water converts to sodium bisulfite (SBS). It is effective as a preservative because it is an oxygen scavenger and therefore prevents growth of aerobic microorganisms. ...
How can I clean a membrane that has been clogged with suspended solids and sludge?
This is a very common problem and there is no single solution. Some suspended solids consist of natural organic matter (NOM) or dead bacteria, and can be removed by performing a high pH cleaning. Other suspended solids (such as limest...
Can hydrogen peroxide be used effectively in place of sodium bisulfite for dechlorination of seawater RO feedwater? We are concerned about dissolved oxygen levels in the concentrate that is disposed back into the sea…
Q: Can hydrogen peroxide be used effectively in place of sodium bisulfite for dechlorination of seawater RO feedwater? We are concerned about dissolved oxygen levels in the concentrate that is disposed back into the sea… Sodium sulfite ...
How can we determine whether the membranes in our Reverse Osmosis system are damaged?
There are various symptoms that can be associated with membrane damage: Loss in permeability that doesn’t recover even after aggressive cleaning: This is usually a sign of irreversible damage. It can occur as a result of membrane dehydr...
What filtration system will remove soluble iron, manganese and salt from bore water
Soluble iron and manganese can be removed by using a Manganese Greensand Filter. However, in order to separate salt from water, either Reverse Osmosis or Evaporation have to be used. See also: What filtration system will remove soluble iron...
Please suggest an appropriate antiscalant and dosage for use with feed water having a TDS of 1500 ppm
Antiscalant dosage cannot be determined by TDS (Total Dissolved Solids). The reason is that TDS can be made up entirely of sodium and chloride which do not have a scaling potential, or it could be made up entirely of calcium and sulfate w...
Can chlorine dioxide be used effectively in place of sodium hypochlorite for prechlorination of bore well water, RO feedwater and Permeate water?
Chlorine dioxide is a highly potent biocide that has a higher efficacy than hypochlorite in destroying protozoa, bacteria and viruses, without allowing them to build a tolerance. It is effective over a wide pH range as both a biocide and ...
If silica is not removed by ion exchange, does that mean it is colloidal silica?
It is not possible to have colloidal silica in your feedwater unless your silica concentration is above the solubility limit under those conditions, resulting in polymerization and hence colloidal silica formation. The difference between re...