The optimum conditions for biosorption of Pb(II) and Ni(II) from aqueous solution were investigated, by using living and nonliving Pseudomonas fluorescens and Bacillus pumilus isolated from wastewater treatment plant. It was found that the optimum pH for Pb(II) removal by living and nonliving cells was 6.0, while 7.0 for Ni(II) removal. At the optimal conditions, metal ion biosorption was increased as the initial metal concentration increased. The binding capacity by living cells is significantly higher than that of nonliving cells at tested conditions. The maximum biosorption capacities for lead and nickel by using Ps. fluo-rescens and B. pumilus were 77.6, 91.4 and 65.1, 73.9 mg/g, respectively. The results of bio-sorption time and desorption experiments suggested that Pb(II) and Ni(II) uptake by the living bacterial biomass might be enhanced by intracellular accumulation.
