Use of Electrocoagulation with Aluminum Electrodes to Reduce Hardness in Tunisian Phosphate Mining Process Water

Abstract

This study evaluated electrocoagulation using Al electrodes for removal of non-carbonate hardness in phosphate mining process water. Examination of process parameters identified optimal conditions for hardness removal at pH 7, a NaCl concentration of 4 g/L, a current density of 22.2 mA/cm2, an inter-electrode distance of 2 cm, a stirring speed of 450 revolutions per minute, and a treatment time of 30 min. Production of primary coagulant during electrolysis improved removal of both calcite and magnesium hydroxide. The optimized hardness removal was highly efficient, with an overall removal rate of 83.8 % at 30 min of retention time.