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Sea water Desalination Chemical Packages

Thermal Desalination

Seawater Reverse Osmosis (SWRO)





The types of scaling species, such as CaCO3, Mg(OH)2, and CaSO4, that are commonly present in seawater evaporators exhibit an inverse solubility behavior, where their solubility decreases as the temperature increases.

To prevent the buildup of hard scale in seawater desalination plants, the Scaffix SI series, a co-polymer with a low molecular weight, has been developed. This product is designed to effectively inhibit the deposition of CaCO3 and Mg(OH)2 scale and functions as a crystal inhibitor that can increase the solubility of dissolved salts at higher temperatures.

To use Scaffix SI series, it should be added continuously to the feedwater line, upstream of the heat recovery section, at a rate of 2-5 ppm proportionate to the makeup flow rate.



SCAFFIX series polymer inhibits scale buildup on surfaces through at least three mechanisms:

  • Solubility enhancement or threshold effect, which reduces precipitation of low solubility inorganic salts.

  • Crystal modification, which deforms the growing inorganic salt crystals to give small, irregular, readily fractured crystals that do not adhere well to surfaces.

  • Dispersing activity, which prevents precipitated crystals or other inorganic particles from agglomerating and depositing onsurfaces.







Foaming occurring in the evaporator can lead to a deterioration of the distillate quality.  This cause of a solid carryover problem cannot be economically corrected through adjustment of water balance or the installation of additional external treatment equipment.  The use of antifoam chemical is mandatory.

The recommended chemical as antifoam is Melasil EO-125, containing block co-polymer like other poly-glycols which weaken the walls of foam bubbles, causing them burst quickly at the water surface.  This prevents the formation of high volume stable foam, which can carryover with vapor in the MSF evaporators, leading to increase solids in the distillate.

Melasil EO-125 should be fed continuously against feedwater line, upstream of the heat recovery section with the dosage: 0.1 - 1.0ppm in proportion to the makeup flow rate.





Vanicide NX-550 is a top-performing biocide and surfactant, utilizing decylisononyldimethylammonium chloride as its active ingredient. Harvest Chemical, a leader in the field of amine chemistry, has developed this highly effective and cost-efficient product.

Laboratory studies have demonstrated Vanicide NX-550's exceptional control of macrofoulants, including Zebra mussels and Asiatic clams, with mortality rates of 100% achieved in the latter at active levels below 5 ppm. Additionally, Zebra mussel control was highly effective with an LT50 of less than 2 hours at a 10 ppm active level and an LC50 of only 0.7 ppm active after 96 hours.

Vanicide NX-550's low-foaming quat formulation makes it a superior choice, effectively eliminating unsightly foam buildup in certain applications. During shake tests, foam heights of less than 1 cm at 15 ppm active were observed, and equilibrium foam heights in recirculation tests were only 2 cm.


Notably, Vanicide NX-550's short exposure time for controlling macro-fouling provides a range of environmental, performance, and cost benefits over chlorine and other oxidizers

These include:


· Less chemical released to the environment

· Completely biodegradable

· Non-foaming

· Safe to handle

· Capital cost on the dosing systems is insignificant compared to chlorine gas dosing systems.

· These non-oxidizers are powerful cationic surfactants in cleaning of bio-slime.

· Non-corrosive

· Product concentrations can be monitored and verified during the entire application.

· Reduced risk of under-deposit corrosion and pitting attack on yellow metal metallurgy since

  Vanicide NX-550 does not induce corrosion.

Please consult with our expert regarding your requirement, please send us an email to


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