Arsenic removal from naturally arsenic contaminated ground water by packed-bed electrocoagulator using Al and Fe scrap anodes

•Both Al and Fe scrap anodes reduced the residual As level to WHO standard.•Overal, Fe scrap anodes performed much better than Al electrodes.•Electrogenerated Al or Fe-hydroxides showed satisfactory As removal capacity. In this work, feasibility of electrocoagulation (EC) process with Al and Fe scrap anodes for treatment of groundwater contaminated with arsenic (As) was examined as a cheaper treatment alternative for affected remote communities. EC experiments were carried out in a batch packed-bed EC reactor and the effect of applied current (0.010–0.100 A), type of scrap electrode (Fe and Al), packed-bed density (0.1–0.4 kg/m3 for Fe and 0.02–0.08 kg/m3 for Al) and EC time were investigated. Optimum operating conditions to obtain maximum contaminant level (MCL) of 10 μg /L for total As (>93% removal) in groundwater samples were determined as 8 min and 0.05 A for Fe scrap anodes. Whereas for Al scrap anode, 30 min and 0.10 A were the optimums. The operating cost, energy and electrode consumptions at these optimums were calculated as 0.017 US $/m3, 0.070 kW h/m3 and 0.052 kg/m3 for Fe anodes and 0.181 US $/m3, 0.876 kW h/m3 and 0.067 kg/m3 for AL anodes respectively. The As removal slightly decreased with decrease in anode bed density. Moreover, Fe scrap anodes exhibited better As removal than the Al scrap anodes at all tested conditions. The scanning electron microscopy (SEM) of the electro-coagulated sludge revealed irregular and porous particles with amorphous structure. The Fourier-transform infrared spectroscopy (FTIR) showed bonding between Fe(III) - As(V), and AsO bond, confirming As removal by co-precipitation and adsorption, respectively in the EC process.