Combined electrodialysis and electrocoagulation as treatment for industrial wastewater containing arsenic and copper

Wastewater produced by mining activities often exceeds the limiting concentrations of different contaminants established by local authorities. For this reason, in Chile a treatment to lower the concentrations of the contaminants in order to fulfill the limits established by Chilean standard D.S. No90/00 is necessary [1]. Currently, the used treatment to reduce the concentration of inorganic contaminants in mining wastewater is based on the addition of chemical reagents, such as lime slurry that facilitates the precipitation of the different metals by an pH increase of the wastewater, together with an eventual flocculant and coagulant addition. This procedure generates high economical costs due to the reagent consumption and the large volume of generated sludge, which requires further processing. Moreover, processes for recovery of valuable metals are not implemented and the waste is only disposed [2-4].