Separation of pollutants from tannery effluents by electro flotation

Treatment of tannery effluent samples by electroflotation technique was studied. Effects of current density and electrode material on the removal of suspended solids, sulphides, chromium, COD and other pollutants have been discussed. Soluble anodes such as aluminum and iron were found to be very effective for the removal of suspended solids compared to stable electrodes such as titanium coated with Ir/Ta/Ru oxides and graphite. It was observed that the colloidal size suspended solids are coagulated in the presence of aluminum and iron anodes. Electroflotation has been found to be very effective especially for the elimination of pathogenic bacteria and colour of the effluent. The kinetics of flotation of suspended solids by electrolytically generated bubbles was also studied and found to obey first order rate expression. (C) 2004 Elsevier B.V. All rights reserved.