Biosorption of heavy metals by Rhizopus arrhizus and Aspergillus niger

Abstract

Department of Chemical Technology, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India Department of Chemical Engineering, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India <em>Manuscript received 31 August 2001, revised 15 February 2002, accepted 23 April 2002</em> Biosorption of four heavy metals Pb, Cd, Ni and Cr by <em>Rhizopus arrhizus </em>and <em>Aspergillus niger </em>during their active growth was observed to develop strains to remove heavy metals from industrial waste waters. Among four metals tested for biosorption from synthetic growth media containing 1 mg/I of the metals, <em>R. arrhizus </em>showed maximum biosorption (45.54%) in case of Pb whereas, A. <em>niger</em><em> </em>showed maximum biosorption (59.67%) in case of Cd. A strain of <em>R. arrhizus </em>adapted to 100 mg/I Pb absorbed 57.77% of Pb and that of <em>A. lager </em>adapted to 100 mg/I Cd absorbed 91.59% of Cd during active growth. EDTA extraction studies showed that 78-85% of Pb was associated with cell surface of <em>R. arrhizus </em>and 60-65% of Cd asso­ciated with the cell surface of <em>A. niger.</em>