Application of High Voltage Impulse for Desalination of Hard Water

High voltage impulse (HVI) has been gained attention as an alternative technique that could control the CaCO3 scale problems encountered in water main, pipe, cooling tower, and heat exchanger vessels. The aim of this study was to investigate the effect of electric field (E) and contact time (t) of HVI on the reduction of Ca 2+ concentration at two different temperatures of 25°C and 60°C. A kinetic model on the effect of E and t was investigated too. As the E and t increased, the Ca 2+ concentration decreased more than that of the control (= no HVI). The Ca 2+ concentration decreased up to 81% at 15 kV/cm at 60°C, which was nearly 2 times greater than the control. With this experimental data-set of reduction of Ca 2+ concentration under different E and t, the kinetic model was developed. The relationship between E and t required to reduce the concentration of Ca 2+ by 30% was modeled at each temperature. The empirical model equations were; E 0.83 • t = 60.3 at 25°C and E 0.08 • t = 1.1 at 60°C. These equations state the products of E n and t is always constant, which means that the required contact time can be reduced in accordance with the increment of E and vice versa.