How effective is the hot process lime-soda softener in removing hardness?

The hot process lime-soda softener is designed to effectively reduce water hardness by precipitating calcium and magnesium ions, which are primarily responsible for hardness. This method takes advantage of elevated temperatures to enhance the solubility of lime (calcium hydroxide) and soda (sodium carbonate).

Typically, the hot process can effectively reduce hardness levels to around 10 to 30 ppm. This range indicates that while the process significantly decreases hardness, it does not remove it entirely. This residual hardness is often acceptable for various industrial applications where entirely soft water is not necessary.

The effectiveness of this method hinges on the equilibrium between the chemicals used and the temperature at which the process operates, contributing to the partial but significant reduction in hardness levels. Hence, maintaining a hardness level between 10 and 30 ppm is consistent with what can be expected from this process, making it an effective option within that context.

Other options present levels of hardness or efficiency that do not align with the typical outcomes of the hot process lime-soda softening method.