There are many studies on the composition of alginate and its advantages to cell immobilization. Because the chemical composition of this polymer and as a consequence that the same reactions can be obtained in reaction, alginate gels are recommended for cells sensitive to environmental conditions. Recent studies of the diffusional characteristics of the immobilized system, have improved our understanding of the environment surrounding the immobilized cells, optimize protocols and improve the stability of alginate gels [60].

One of the matrices that have been used in metal recovery by both viable and non-viable cells is the entrapment in the matrix of insoluble Ca-alginate. Fluidized beds of Ca — entrapped cells of Chlorella vulgaris and Spirulina platensis were successfully used to recover gold from a simulated gold-bearing process solution containing AuCk, CuCh, FeCh and ZnCl2. The Ca-alginate immobilized cells of Chlorella salina also showed greater binding of cobalt, zinc and manganese than the free cells. Rhizopus arrhizus entrapped on alginate beads was successfully used for the removal of uranium over multiple biosorption and desorption cycles. Accumulation was also dependent on cell density in alginate beads with greater uptake of cobalt at the highest cell densities [57].