ABSTRACT
Accumulation of heavy metals in water or soil due to industrial activities is one of the main sources of environmental pollution. Immobilization of microorganisms is considered as a well-known technique that can enhance the chemical and physical performance of metal uptake from the environment. Immobilization provides more flexibility in the design of reactors compared with conventional suspension systems, along with higher cell density, no washout of cells, and better stability in operation. There are several methods for the immobilization of bacterial, fungal, and algal cells. Biofilm formation on natural or synthetic packing, entrapment of cells inside polymeric matrices, adsorption and covalent binding of cells to a surface, and encapsulation of cells are considered as the main immobilization methods applied in the metal removal processes. The characteristics of matrices have an important effect on the metal uptake process.
