Copper(II) and nickel(II) adsorption by Rhizopus arrhizus in batch stirred reactors in series

In this research, the adsorption of copper(II) and nickel(II) ions on Rhizopus arrhizus, a filamentous fungus, was investigated in three batch stirred reactors operated in series. The adsorption in multistage reactors can be considered as multistage equilibrium operation, which depends on two constraints: that of equilibrium and that of mass balance. The sorption phenomenon was expressed by the Freundlich adsorption isotherm developed for optimum adsorption conditions. At a given ratio V₀/X₀ of volume of waste water containing heavy metal ions to quantity of fungus, this expression was used to calculate the residual metal ion concentration C_{eq, r} or adsorbed metal ion concentration C_{eq, xr} at equilibrium in the solution leaving each stage. Experimental C_{eq, r} and C_{eq, xr} values were compared with calculated values. High metal ion quantities per unit mass of dried biomass were removed by using low V₀/X₀ ratios. When aqueous solutions containing copper(II) at a concentration of 99.9 mg l⁻¹ and nickel(II) at a concentration of 97.9 mg l⁻¹ were fed to the first reactor, 65.7 mg of copper per gram of dried biomass and 90.2 mg of nickel per gram of dried biomass were removed in the solution, leaving a third reactor, at a chosen V₀/X₀ ratio of 1.00.