To prevent scale buildup, magnesium hardness should be reduced to what level through excess-lime treatment?

To prevent scale buildup in water, the target level for magnesium hardness through excess-lime treatment is indeed 40 mg/L. Magnesium hardness can contribute significantly to the formation of scale in various systems, including boilers and piping. By reducing magnesium hardness to this level, the likelihood of scale formation is minimized, which is crucial for the efficiency and longevity of water treatment processes and equipment.

Excess-lime treatment is a common method used to precipitate calcium and magnesium hardness from water. By strategically adjusting the concentration of lime, water treatment plants can manage hardness levels effectively. Keeping magnesium hardness at or below 40 mg/L ensures that the water remains within a desirable range that helps prevent scaling, while also maintaining water quality for various uses. This makes the choice of 40 mg/L the most appropriate from a water treatment perspective.