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

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
specific 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.