What is the primary purpose of adding polyphosphates or sodium silicates to water before it is exposed to disinfectants?

What is the primary purpose of adding polyphosphates or sodium silicates to water before it is exposed to disinfectants?

• A. To improve taste
• B. To aid in sediment removal
• C. To promote sequestration
• D. To neutralize chlorine

Answer: (C)

The primary purpose of adding polyphosphates or sodium silicates to water before disinfection is to promote sequestration. Sequestration refers to the process by which these chemicals bind to and stabilize certain metals, such as iron and manganese, preventing them from precipitating out of solution or causing undesirable reactions during water treatment. By sequestering these metals, polyphosphates and sodium silicates help maintain water clarity and improve the effectiveness of the disinfection process, as the disinfectant can work more effectively without interference from metals. In addition, this practice can help prevent the formation of disinfection byproducts and reduce the risk of taste and odor issues that can arise from the presence of free metals in the water. While improving taste, aiding sediment removal, and neutralizing chlorine may have their own merits, they do not directly address the critical role that sequestration plays in treating water prior to disinfection, making it the correct response in this context.

The primary purpose of adding polyphosphates or sodium silicates to water before disinfection is to promote sequestration. Sequestration refers to the process by which these chemicals bind to and stabilize certain metals, such as iron and manganese, preventing them from precipitating out of solution or causing undesirable reactions during water treatment. By sequestering these metals, polyphosphates and sodium silicates help maintain water clarity and improve the effectiveness of the disinfection process, as the disinfectant can work more effectively without interference from metals.

In addition, this practice can help prevent the formation of disinfection byproducts and reduce the risk of taste and odor issues that can arise from the presence of free metals in the water. While improving taste, aiding sediment removal, and neutralizing chlorine may have their own merits, they do not directly address the critical role that sequestration plays in treating water prior to disinfection, making it the correct response in this context.