Estimating Chemical Doses for Water Stabilization

Abstract

A simple method for directly estimating the lime and carbon dioxide doses needed to produce water that is stable with respect to calcium carbonate has been developed. The procedures employed are readily applicable using either a straightforward graphical approach or a user‐friendly microcomputer program. The method is superior to Caldwell‐Lawrence diagrams and the various stability indices that have been proposed in that chemical doses are obtained directly, without a trial‐and‐error approach. The procedures are based on numerically solving the equations governing calcium carbonate (calcite) equilibrium. The only data required are the calcium hardness, alkalinity, pH, temperature, and total dissolved solids (or ionic strength) of the water to be treated.