Abstract:

The complex of PVA solution and sodium alginate solution crosslinked by Ca(NO3)2 as entrapment medium was prepared. The mixture of Acidithiobacillus ferrooxidans suspension and the entrapment complex were extruded into a solution of Ca(NO3)2 to form beads, and then the beads were frozen at -20°C for 1~2d and thawed at room temperature. A maximum oxidation rate of 2.90g Fe2+ / (L•h) was achieved in a packed-bed bioreactor with immobilized cells at the dilution rate of 0.5/h. In addition, the operation of this method was very simple, and the gelation solution (calcium nitrate) used was of low toxicity and very cheap. Moreover, the oxidation activity of the beads obtained by this technique was excellent even under non-sterile conditions. So its application on a commercial scale would be practicable.