Prediction of scale formation in calcium carbonate aqueous phase for water treatment and distribution systems

Accurate estimation of scale formation in distribution systems for drinking water and water treatment technologies is of utmost importance. A novel and simple method is presented here to predict the formation of calcium carbonate scaling as a function of pH, temperature, ionic strength of the solution, calcium cation, and bicarbonate anion concentrations, in order to evaluate the effect of solution conditions on precipitation tendency. The proposed simple method covers concentrations of calcium cations and bicarbonate anions up to 10,000 mg/L, temperatures up to 90°C, pressures up to 500 kPa, total ionic strength up to 3.6, and pH values ranging between 5.5 and 8. The predicted values are found to be in good agreement with the reported data with average absolute deviations being less than 2.6%. Predictive tool presented in the paper can be of immense practical value for engineers and researchers to have a quick check on the formation of calcium carbonate scaling at various conditions without opting for any experimental measurements. In particular, personnel dealing with water treatment and distribution systems would fi nd the proposed method to be user-friendly with transparent calculations involving no complex expressions.