Investigation on an electrochemical pilot equipment for water softening with an automatic descaling system: Parameter optimization and energy consumption analysis

Abstract

Electrochemical water softening (EWS) technology is considered to be a very promising descaling method due to its superiorities in clean, efficient and water-saving ability, although limited by the cleaning of cathode scale. Herein, an innovative EWS device coupled with an automatic descaling module was manufactured and applied to treat the industrial recirculating cooling water (RCW). Response surface methodology (RSM) analysis based on Box–Behnken design (BBD) was applied to optimize the combination effect of four important operation parameters, including initial hardness (1150 mg/L, as Ca2+), ratio of hardness and bicarbonate (0.5), current density (30 A/m2) and circulating water flow (20 m3/h). Next, a mathematical dynamic model was employed to reveal the relationship between the hardness removal percentage and the current density (ρ, A/m2) according to the RSM analysis results. Additionally, various configurations of the device were performed and demonstrated that the integration of automatic descaling system enabled a significant improvement on the descaling capacity (19.95 g/h/m2) and energy consumptions (27.1 kW h/kg CaCO3), which exhibited evident economic and environmental advantages compared to the chemical scale inhibitor method. This work provides a facile strategy for the development and industrial applications of EWS technology.