Electrocoagulation (EC) treatment of water brings in the advantages of Chemical coagulation (CC) and adsorption media, currently the processes of choice. Electrocoagulation is a novel and innovative technique which uses a sacrificial anode to dose the water electrochemically and no chemical addition is needed.

During electrocoagulation, ferrous ions are generated from zero-valent iron at the anode. These ferrous ions hydrolyze to produce iron hydroxides, which strongly adsorb arsenic depending on pH and the kind of hydroxides formed. The amount of iron dose is generated by electrolysis of iron rods rather than addition of coagulants, and addition of base is not needed in EC. Therefore, it appears that EC has some advantages over CC and would be a better choice. The removal efficiency of arsenic by CC with ferric salts is compared with EC and the study on the oxidation of As(III) is discussed. Finally, the effects of pH and competing ions on both processes are compared.            As(V) removal was pH dependent in both CC and EC, and the efficiency increased with decreasing pH. Proper optimization of the EC unit is needed in order to ensure complete oxidation of Fe(II) produced. The adsorption capacity was almost the same with CC and EC at pH 7.5 and 8.5, while at pH 6.5, CC showed a better adsorption capacity. A comparison of As(III) removals showed better removals during EC which was pH dependent, compared to CC, which was pH independent. However their was no significant oxidation of As(III) during electrocoagulation as reported. However a two-stage process with the use of graphite followed by iron rod was effective in As(III) oxidation and removal. The competing ions, silica and phosphate did affect the adsorption of arsenic in both CC and EC and the effect was dependent on the presence and absence of other competing ions.