Arsenic Removal from High-Arsenic Water Sources by Coagulation and Electrocoagulation

Abstract

Abstract In this work, the removal of arsenates from high-arsenic groundwaters, 20 mg As dm−3, by using coagulation and electrocoagulation is compared. Results show that pH plays a key role in both processes, which allow us to explain the huge differences observed between both technologies and also between the use of iron and aluminum as coagulants. Electrocoagulation was found to be the best technology, being capable of removing arsenic down to 10 µg dm−3, which is the limit fixed by most of health agencies around the world for drinking water. Regarding coagulation, the pH reduction caused by the dosage of chemicals during the coagulation process leads to a higher solubility of the arsenate compounds reducing the efficiency of the removal process and explaining the worse performance of coagulation, in comparison with electrocoagulation, in the removal of arsenic. Keywords: aluminumarseniccoagulationelectrocoagulationiron ACKNOWLEDGEMENTS This work was supported by the MCT (Ministerio de Ciencia y Tecnología, Spain) and by the EU (European Union) through projects CTM2010-18833/TECNO and CONSOLIDER-INGENIO 2010 (CSD2006-044).