1 Arsenic removal from groundwater using iron

10 11 We demonstrate that electrocoagulation (EC) using iron electrodes can reduce arsenic 12 below 10 µg/L in synthetic Bangladesh groundwater and in real groundwater from 13 Bangladesh and Cambodia while investigating the effect of operating parameters that are 14 often overlooked, such as charge dosage rate. We measure arsenic removal performance 15 over a larger range of current density than in any other single previous EC study (5000 16 fold: 0.02 – 100 mA/cm 2) and over a wide range of charge dosage rates (0.060– 18 17 ___________________________ 18 20 2 Coulombs/L/min). We find that charge dosage rate has significant effects on both 21 removal capacity (μg-As removed/coulomb) and treatment time and is the appropriate 22 parameter to maintain performance when scaling to different active areas and volumes. 23 We estimate the operating costs of EC treatment in Bangladesh groundwater to be 24 $0.22/m 3. Waste sludge (~ 80 – 120 mg/L), when tested with the Toxic Characteristic 25 Leachate Protocol (TCLP), is characterized as non-hazardous. While our focus is on 26 developing a practical device, our results suggest that As[III] is mostly oxidized via a 27 chemical pathway and does not rely on processes occurring at the anode.