Screening and selection of indigenous metal tolerant fungal isolates for heavy metal removal

Heavy metal removal efficiency of indigenously present metal tolerant fungal isolates obtained from a scrap dumpsite was assessed in this study. Four fungal isolates were selected based on their ability to grow in multi-metal supplemented media. Minimum inhibition concentrations of these four isolates were determined against individual metals; lead (II) (50-400 mgL−1), cadmium (II) (50-400 mgL−1), arsenic (III) (10-100 mgL−1) and mercury (II) (10-100 mgL−1). Their ability to remove metals from synthetic aqueous medium was tested and the heavy metal-fungi combination which showed the highest removal efficiency was selected. Live biomass of the selected isolate dispensed in lead solution with concentrations of 50 mgL−1, 100 mgL−1 and 150 mgL−1 showed a removal of 92.27%, 92.73% and 89.36% respectively at the end of the 40th h. Scanning Electron Microscopy with Electron Dispersive X-ray (SEM-EDX) of the treated biomass confirmed the biosorptive ability of the isolate for lead when compared with the control biomass. Fourier Transforms Infra-red (FTIR) Spectroscopy showed the probable involvement of amide, carboxylic acid, hydroxyl and isocyanate groups in the adsorption of lead from the synthetic metal solution.