Biosorption of Pb(II) and Zn(II) by the growing strain/dry biomass of a resistant fungus: optimization and mechanism studies

Abstract:

[Objective] The aim of this study is to screen lead-zinc tolerant fungus for the bioremediation of heavy metal pollution in Zixing, Hunan. [Methods] The fungus J3 which was isolated from the local tailing of lead-zinc deposit was used. Orthogonal test was carried out for studying adsorption conditions optimization and biosorption mechanism was discussed by kinetics simulation. And morphological characteristics and 18S rRNA gene sequence analysis were used for identification. [Results] Under the optimal conditions, the results showed that the removal rate of Pb2+ and Zn2+ by growing strains reached 92.2% and 87.7%, while the removal rate of Pb2+ and Zn2+ by dry biomass was 72.6% and 23.8%. The results of kinetics study indicated that the absorption by growing strain was affected by the concentration of Pb2+ and Zn2+. The intra-particle diffusion was the main rate-controlling step for the adsorption of Zn2+. The adsorption of Pb2+ by dry biomass may be affected with membrane diffusion and intra-particle diffusion at the same time. And the adsorption process of Zn2+ was controlled by membrane diffusion. According to the morphological characterization and phylogenetic tree, J3 was preliminarily identified as Verticillium insectorum. [Conclusion] The growing strain had better adsorption effect than the dry. The result which fitted to the second-order equation can provide the basis and guidance for bioreactor settings.