Biosorption of heavy metals by Rhizopus arrhizus and Aspergillus niger

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

Manuscript received 31 August 2001, revised 15 February 2002, accepted 23 April 2002

Biosorption of four heavy metals Pb, Cd, Ni and Cr by Rhizopus arrhizus and Aspergillus niger 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, R. arrhizus showed maximum biosorption (45.54%) in case of Pb whereas, A. niger showed maximum biosorption (59.67%) in case of Cd. A strain of R. arrhizus adapted to 100 mg/I Pb absorbed 57.77% of Pb and that of A. lager 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 R. arrhizus and 60-65% of Cd asso­ciated with the cell surface of A. niger.