Removal of arsenic from a deep well by electrocoagulation in a continuous filter press reactor Available to Purchase

We investigated arsenic removal from groundwater by electrocoagulation (EC) using aluminum as the sacrificial anode in a continuous filter press reactor. The groundwater was collected at a depth of 200 m in the plateau region, in Central Mexico, (As 134 μg L⁻¹, Fe 0.3 mg L⁻¹, Cd 0.7 mg L⁻¹, Na 58 mg L⁻¹, pH 6.8). The influence of current density (J) and mean linear flow rate (u) on As removal was analyzed. EC revealed that u of 0.91 cm s⁻¹ (which gives a retention time of 53.4 s) at J of 6 and 8 mA cm⁻² yielded samples that met the Mexican standard for arsenic (≤25 μg L⁻¹). EC at 10 mA cm⁻² did not improve results any further owing to massive generation of gases and anode passivation. The partial EC removal of arsenic can be attributed to the mixture of HAsO₂, H₃AsO₃ and HAsO₄²⁻. HAsO₄²⁻ is more susceptible to removal by adsorption on Al(OH)₃ and Al₂O₃ flocs. The best EC result was obtained at 6 mA cm⁻² and 0.91 cm s⁻¹, with energy consumption of 0.89 kWh m⁻³, which decreased arsenic from 134 to 14 μg L⁻¹.