Biosorption of Pb(II) and Cu(II) by activated sludge in batch and continuous-flow stirred reactors

Biosorption of Pb(II) and Cu(II) ions in single component and binary systems was studied using activated sludge in batch and continuous-flow stirred reactors. In biosorption experiments, the activated sludge in three different phases of the growth period was used: growing cells; resting cells; dead or dried cells. Because of the low adsorption capacity of the non-viable activated sludge especially in the case of Pb(II) ions, biosorption of the Cu(II) and Pb(II) ions from the binary mixtures was carried out by using the resting cells. The biosorption data fitted better with the Freundlich adsorption isotherm model. Using a mathematical model based on continuous system mass balance for the liquid phase and batch system mass balance for the solid phase, the forward rate constants for biosorption of Pb(II) and Cu(II) ions were 0.793 and 0.242 l (mmol min)−1, respectively.