ABSTRACT
Bioaccumulation organisms should be selected among species which are resistant to high loads of pollutants and do not have mechanisms which protect from excessive accumulation inside the cell. Biosorption can be defined as the passive uptake of pollutants by dead or inactive biological materials through different physicochemical mechanism. The biosorption kinetics plays an important role in selection and design of reactor systems as well as operations. Since heavy metal biosorption is metabolism-independent, it typically occurs rapidly, in particular for uptake of cationic metal ions. Biosorption equilibrium is highly dependent upon the water chemistry and the nature of heavy metal ions and the biosorbents. Higher cationic metal uptake occurs when pH is higher. However, better removal for anionic heavy ions can be obtained at lower pH. Ionic strength plays an important role in the biosorption. The process of heavy metal biosorption involves mechanisms such as ion exchange, complexation, electrostatic attraction, and microprecipitation.
