Pre-treatment of high boron containing wastewater by electro-coagulation

The aim of this study is to evaluate the ability of the electro-coagulation (EC) process with aluminum electrodes for removing boron from process and ground waters prior to the reverse osmosis (RO) system. The effect of the operating parameters, such as pH, applied current density, inter-elec-trode distance (IED), and reaction time, were investigated to achieve a higher removal of boron from water. The obtained results showed that pH was an important parameter affecting removal efficiency. Boron removal efficiency increased with increasing pH from 4 to 10 for process waters (PW) while maximum boron removal has been obtained at pH 7 for groundwater (GW). The highest boron removal efficiency (48%) was achieved at a pH value of 10 within 60 min of treatment time for PW. On the other hand, the maximum boron removal efficiency (30%) was obtained at pH 7 within 90 min of treatment time for GW. In order to evaluate the current density effects on the removal of boron, four different currents (1.5–3.0 A) were applied in experiments. These experiments were con-ducted at a constant voltage (10 V), a constant IED (1 cm) and an optimized pH value. The maximum boron removal efficiency was obtained at 2 A current density and 1 cm IED for both types of water. The IED was experimented in order to investigate the effect of this parameter on boron removal. The highest boron removal efficiency was obtained at 1 cm IED for both waters. Boron removal efficiency was higher at GW depending on the effluent boron concentration. Boron removal efficiency decreases with increasing boron concentration as, consistent with the literature. It can be concluded that the EC application as pre-treatment prior to RO is effective in reducing the boron concentration.