BIOSORPTION OF Pb2+, Cd2+, & Ni2+ FROM WATERS BY ...

Various methods are available that can be applied for the biomass
immobilization. The principal techniques that are available in literature for the
application of biosorption are based on adsorption on inert supports, entrapment in
polymeric matrix, covalent bonds in vector compounds, or cell cross-linking (Figure
1.2) (Vegliò and Beolchini 1997).
Adsorption on inert
supports
IMMOBILIZATION TECHNIQUES
Entrapment in
polymetric matrices
Covalent bonds to
vector compounds
Figure 1.2. Immobilization techniques
(Source:Vegliò and Beolchini 1997)
1.6.1.1. Adsorption on Inert Supports
Cross-linking
Sterilization and inoculation processes are applied with starter culture, and
the continuous culture are left inside for a period of time. Then, the microorganism
(biomass) is supported on the suitable matrices. Many microorganims have an ability
to be attached spontaneously to surfaces. Indeed, once a suspension of cells is brought
into contact with a surface, the definite amount of adsorption to the solid becomes
inevitably. This technique has been used by Zhou and Kiff, 1991 for the
immobilization of Rhizopus arrhizus fungal biomass in reticulated foam biomass
support particles; Macaskie, et al. 1987, immobilised the bacterium Citrobacter sp. by
this technique. Scott and Karanjakar (1992), used activated carbon as a support for
Enterobacter aerogens biofilm. Bai and Abraham (2003) immobilized Rhizopus
nigricans on polyurethane foam cubes and coconut fibres. Polyurethane and polyinyl
foams have been used as supports for immobilized cells (Olguin 2000).
19