Biosorptive performance of an Escherichia coli biofilm supported on zeolite NaY for the removal of Cr(VI), Cd(II), Fe(III) and Ni(II)

One of the major environmental concerns of nowadays is the presence of heavy metals in industrial effluents. Aiming a solution for this problem, various efforts have been made towards research and implementation of economic and easily adaptable processes to remove heavy metals. The ability of a biofilm of Escherichia coli supported on NaY zeolite to biosorb Cr(VI), Cd(II), Fe(III) and Ni(II) was investigated in batch experiments aiming the treatment of wastewater with low metal concentrations. The biosorption performance, in terms of uptake, followed the sequence: Fe(III) > Ni(II) > Cd(II)> Cr(VI). The equilibrium data in batch systems were described by Langmuir, Sips and Toth isotherms. The best fit for chromium was obtained with the Toth model isotherm and for cadmium and nickel the best fit was the obtained with the Sips model. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion, was confirmed by FTIR. The whole study showed that the biofilm tested is very promising for the removal of metal ions from effluents. (C) 2009 Elsevier B.V. All rights reserved.