Which compound is utilized to sequester iron and/or manganese in water treatment?

Sodium polyphosphate is commonly used in water treatment to sequester iron and manganese. These metals can cause staining and other aesthetic issues in water. When sodium polyphosphate is added to water, it forms a complex with iron and manganese ions, effectively keeping them in solution and preventing them from precipitating out as solid particles. This process avoids the formation of unwanted sediments and maintains the clarity and consistency of treated water.

The efficacy of sodium polyphosphate in water systems is essential for both potable water and industrial applications because it helps in controlling metal levels without requiring extensive filtration or additional treatment steps. Additionally, its role in preventing scale formation and corrosion makes it valuable in maintaining the longevity of pipes and plumbing systems.

In contrast, other compounds listed may serve different purposes in water treatment. Calcium carbonate primarily acts as a mineral for adjusting pH and carbonate hardness, while potassium permanganate is primarily used as an oxidizing agent for the treatment of taste and odor control or to maintain residuals in water systems. Chlorine dioxide is primarily utilized for disinfection rather than sequestering metals, focusing on pathogen control instead.