Simulation of Lime-Soda Softening

Abstract

A computer model for lime-soda softening has been developed based on the solution of simultaneous chemical equilibrium equations. The effects of ionic strength and temperature on the dissociation constants, solubility products, and activity coefficients are accounted for as well as the effect on magnesium on the solubility product of calcium carbonate. Synthetic waters with systematic variations in composition were lime softened in the laboratory. Qualitatively, the experimental data agree well with the results of computer simulation. Further research is necessary to improve the numerical accuracy of the model.