Understanding Different Types of Scale in Water Treatment and How Soltellus™ Polymers Remove Them

Water treatment is a vital process across various industries, including cooling towers, desalination, and oilfield operations. One of the key challenges in maintaining efficient water treatment systems is understanding and managing scale formation. This understanding empowers professionals to prevent reduced efficiency, increased maintenance costs, and equipment damage. This comprehensive guide explores the different types of scale encountered in water treatment and the solutions provided by Lygos’s Soltellus™ products, focusing on the underlying mechanisms of scale inhibition.

Types of Scale in Water Treatment

Calcium Carbonate Scale

Calcium carbonate scale, prevalent in cooling towers and boilers, forms when calcium ions (Ca²⁺) in water react with carbonate ions (CO₃²⁻) to produce calcium carbonate (CaCO₃). This reaction typically occurs in environments where water temperatures are elevated, which increases the tendency for calcium carbonate to precipitate out of solution. This scale can manifest as hard, crystalline deposits that adhere strongly to metal surfaces, impairing heat transfer and reducing the efficiency of heat exchangers.

Calcium Sulfate Scale

Found in desalination plants and industrial processes utilizing sulfate-rich water, calcium sulfate scale forms when calcium ions combine with sulfate ions (SO₄²⁻). This type of scale, with its low solubility, especially in high-salinity environments, poses significant operational challenges. The precipitation of calcium sulfate can lead to scaling on membranes and heat exchange surfaces, highlighting the urgency of addressing scale formation.

Barium Sulfate Scale

In oilfield operations, particularly in the formation waters that accompany crude oil extraction, barium sulfate scale is a critical issue. It forms when barium ions (Ba²⁺) in the formation water react with sulfate ions, leading to the precipitation of highly insoluble barium sulfate (BaSO₄). This scale tends to form dense, hard deposits that can obstruct oil well pipes and equipment, leading to decreased production efficiency and increased maintenance costs.

Strontium Sulfate Scale

Similar to barium sulfate, strontium sulfate scale forms in environments rich in sulfate ions, such as in seawater desalination systems. Strontium ions (Sr²⁺) react with sulfate ions to form strontium sulfate (SrSO₄). This scale can severely disrupt operations by clogging filters and membranes, thereby impacting the desalination process efficiency and the longevity of the equipment.

Halite (Sodium Chloride) Scale

Halite, or sodium chloride (NaCl) scale, is typically found in high-salinity water sources like brine or seawater used in desalination processes. It forms when the concentration of dissolved sodium chloride reaches a point where the salt can no longer remain dissolved and begins to precipitate. This type of scale is particularly challenging in cooling systems and on heating surfaces where it can lead to corrosion and reduced thermal efficiency.

Iron and Silica Scale

Iron and silica scales are formed from contaminants in water sources. Iron scale can form when ferrous iron is oxidized to ferric iron in the presence of oxygen and then combines with water to form ferric hydroxide, which deposits as a scale. Silica (SiO₂), on the other hand, tends to precipitate as a scale when waters with high concentrations of dissolved silica experience changes in temperature or pH. These scales are problematic in boiler systems and cooling towers, where they create dense layers that insulate heat transfer surfaces, reducing efficiency and increasing energy costs.

How Soltellus Addresses Scale Formation

To effectively combat the pervasive issue of scale formation in water treatment systems, Lygos has engineered Soltellus, a solution that harnesses the power of polyaspartate. This innovative product leverages chemical mechanisms to mitigate scale buildup, which can impede operational efficiency and increase maintenance demands across various industrial applications. Here, we explore the mechanisms by which Soltellus addresses scale formation.

Crystal Modification

Polyaspartate interacts with scale-forming minerals like calcium carbonate, distorting their crystal structure. This modification leads to the formation of less adherent, irregular crystals that do not easily deposit on surfaces. This process is commonly referred to as crystal distortion or modification, where the scale inhibitor adsorbs onto the active sites of scale crystals, preventing the formation of a regular morphology and crystalline lattice​.

Dispersion

Polyaspartate also acts as a dispersant. It adsorbs onto micro-crystals, imparting a charge that repels other particles. This electrostatic repulsion keeps the particles suspended in the solution, preventing them from clumping together and adhering to surfaces. This mechanism is crucial for maintaining flow and preventing the formation of hard scale deposits​.

Conclusion

Scale formation poses a significant challenge in water treatment systems, but understanding the different types of scale and utilizing effective inhibitors like Soltellus can greatly improve system performance. Soltellus products offer a versatile, environmentally friendly, and efficient solution that not only prevents scale but also enhances the operational longevity of water treatment systems.