Biosorption of Cd and Ni by inactivated bacteria isolated from agricultural soil treated with sewage sludge

In this study, the capacities of the bacterial biomass in binding simultaneously two metals, Cd and Ni, isolated from soils subject to long-term sewage-sludge applications in Ahvaz, were investigated. Three strains of bacteria were isolated based on their resistance to these metals; namely, Actinomycete sp., Streptomyces sp. and Bacillus sp. The inactivated forms of these bacterial cells were investigated. Actinomycete sp. was the most tolerant isolate to Cd and Ni ions. Freundlich isotherms indicated that the sorption capacities on the biomass surfaces increased with increasing initial metals concentration of both metals. Generally, the biosorption of Ni was slightly higher than that of Cd. These results suggest that native bacteria in polluted area are competent candidates for bioremediation and improving soil quality for agricultural purposes.