Bioaccumulation potential of Aspergillus niger and Aspergillus flavus for removal of heavy metals from paper mill effluent.

ABSTRACT

In the present study Aspergillus niger and Aspergillus flavus isolated from paper mill effluent showed tolerance and accumulation of toxic metals Ni, Zn, Cd, Pb, Cr and Cu from synthetic medium and paper mill effluent. Physico-chemical and heavy metals characterization of industrially treated paper mill effluent showed insignificant reduction in BOD, hardness, TDS and heavy metals as compared to permissible limits of BIS and WHO. A.niger and A.flavus were treated with synthetic medium containing 100-1000 mg l-1 of six heavy metals. A.niger was able to tolerate and grow in 1000 mg l-1 Pb, 500 mg l-1 Cu, 250 mg l-1 Zn and 100 mg l-1 Cr, Ni respectively. No growth of A.niger was observed in 100 mg l-1 of Cd. A.flavus was capable to tolerate and grow in 1000 mg l-1 Pb, Zn and Ni, 100mg l-1 Cu. A.flavus growth was completely inhibited in 100 mg l-1 of Cd and Cr. The Cd, Zn, Cu and Pb reduction were found significant (p<0.05) in the paper effluent inoculated with A.niger and A.flavus biomass compared to industrial treated effluent. A.niger and A.flavus accumulated maximum of Pb (75. 82%) followed by Zn (49. 40%) > Cu (45. 34%) > Ni (25. 20%), while only 41% Cr was accumulated by A.niger from 100 mg l-1 of Cr solution.