In lime-soda ash softening, what are used to help gather the fine calcium and magnesium precipitates into particles that will readily settle?

In lime-soda ash softening, what are used to help gather the fine calcium and magnesium precipitates into particles that will readily settle?

• A. Coagulants, floc
• B. Coagulants, fine calcium and magnesium precipitates
• C. Coagulant aids, precipitates
• D. Coagulants, floc

Answer: (B)

In lime-soda ash softening, the hardness-causing ions (calcium and magnesium) are removed by forming very fine precipitates. These tiny solids don’t settle well on their own, so a coagulant is added to help them come together into larger, settleable particles. The coagulant neutralizes charges and promotes aggregation of the fine precipitates into larger flocs that will settle in a sedimentation basin. So the combination of coagulants acting on the fine calcium and magnesium precipitates is what enables efficient settling.

In lime-soda ash softening, the hardness-causing ions (calcium and magnesium) are removed by forming very fine precipitates. These tiny solids don’t settle well on their own, so a coagulant is added to help them come together into larger, settleable particles. The coagulant neutralizes charges and promotes aggregation of the fine precipitates into larger flocs that will settle in a sedimentation basin. So the combination of coagulants acting on the fine calcium and magnesium precipitates is what enables efficient settling.