This study refined the hardness removal (together with chemical oxygen demand (COD) and turbidity) from the
produced water by a pilot-scale electrocoagulation (EC) system to mitigate the scaling and fouling of Reverse
Osmosis (RO) membranes. In preliminary studies, effects of initial pH, current density and electrolysis time on pollutant removal were investigated. Response surface method (RSM) was employed further to evaluate individual/
interactive influences of parameters on pollutant recovery. Analysis of Variance (ANOVA) showed a satisfactory
agreement of the predicted and experimental data. The refined operating conditions were pH of 7.36, current
density of 5.90 mA/cm2, and reaction time of 30.94 min to maximize the hardness removal at 85.81%, COD at
66.64%, and turbidity at 93.80%. The equivalent coagulant dose was 23.76 mg/L (as Fe3+). The permeate flux
was around 22 L/(m2 h) and the water recovery rate reached 87.83%. The operating refinement of EC processes
by RSM was a promising alternative for the pretreatment of produced water prior to RO membranes. The product
water from the batch EC–RO system was suitable for reinjection or beneficial reuse