Effects of combined Fe-Al electrodes and groundwater temperature on arsenic removal by electrocoagulation

The removal of arsenic from groundwater by continuous electrocoagulation (EC) using combined Fe-Al electrodes at its natural temperature (16.1±0.2 °C) was comprehensively evaluated. The results obtained indicated that all studied Fe-Al electrode combinations were able to reduce As concentration below 10 μg/dm³. Nevertheless, the Fe-Fe-Al-Fe electrode combination was the most suitable due to its highest arsenic removal capacity (0.354 μg As/C) for the lowest charge loading 68.4 C/dm³. The consumption of Fe was 0.0339 kg Fe/m³ and of Al electrodes 0.0145 kg Al/m³. The operating cost was estimated at 0.182 €/m³. The increase of the groundwater temperature by 8 °C from its natural temperature influenced increase of the Fe and Al electrodes dissolution rate by 30% and 17%, respectively and that of As removal efficiency by 16%. The residual Fe and Al concentrations in 500 dm³ of treated groundwater were below WHO guideline values for drinking water. Long-term field operation of the pilot-scale continuous EC reactor is required to validate effectiveness, reliability and robustness of the EC technique for arsenic removal from groundwater confirmed in laboratory conditions.