Any membrane system such as the RO system is naturally clogged by the presence of suspended substances, soluble solutes and microbial parameters in the feed water, which necessitates proper physical and chemical pre-treatment of the system.
The first possibility for the formation of scale in the raw water treatment system is when the solubility of each low soluble salt is increased. The mechanism of deposition on the membrane surface is related to a concentration gradient that occurs as water passes through the membrane continuously, leaving a large amount of soluble salts. This occurs a concentration on the surface of the separating membrane, which causes the formation of a boundary layer. An effect known as concentration polarization inside this boundary layer causes the salts to precipitate, and the suspended solids can also settle on the membrane surface and form scale particles, and scale layers into separated layers of membranes.
If the natural waters are not treated, the calcium carbonate will deposit on the membrane surface. Calcium sulfate is another common scale in natural water. Deposition usually begins in the next steps. This scale decreases the pressure and thus requires more pressure to maintain the stability of the water outlet. Antiscalants are used to reduce the effects of scale that clog the pores of reverse osmosis membranes with water-soluble salts.
Antiscalant has a great impact through the life span of reverse osmosis membranes and reduces the cost of replacing the annual consumable filters.
Calibration of Using Phosphonate Antiscalants:
|Introduce & Calibrate of Using Phosphonate Antiscalants|
|Dosage||Type of use||Antiscalant code|
|3-6 ppm||Membrane anti-scale for industrial use|
Use for waters with hardness less than 1000 ppm
Ducts with relatively freer pores
|3-10 ppm||Industrial anti-scale for hardness water|
Use for hardness water + 1000ppm to 4000ppm
Ducts that are almost capillary and have closed pores
|2-6 ppm||Industrial anti-scale|
Use for waters with hardness -1000ppm
|3-10 ppm||Specially for saline waters|
|3-8 ppm||Industrial anti-fouling|
Anti-sediment and industrial bio-pollutants
Suitable for systems with contaminated feed water