Study on immobilization of Acidithiobacillus ferrooxidans using PVA-Ca(NO3)2 method
PVA-Ca(NO3)2法包埋固定氧化亚铁硫杆菌研究

A new cell immobilization technique utilizing the complex of PVA solution and sodium alginate solution as entrapment medium is reported. The mixture of Acidithiobacillus ferrooxidans suspension and the entrapment complex were extruded into the solution of Ca(NO3)2 (1% - 5%) to form beads, then the beads were frozen at -20 degrees C for 1d and thawed at room temperature. This method can simultaneously eliminate the agglomeration of PVA beads and the biological toxicity of H3 BO31. A maximum oxidation rate of 2.45g Fe2+ /(L x h) was achieved in batch cultures by this immobilized cells. In addition, the operation of this new technique is very simple, and the gelation solution (calcium nitrate) used is of low toxicity and very cheap. Moreover, the mechanical strength and the oxidation activity of the beads obtained by this technique are better than those obtained by the other methods. So its application on an industrial scale would be more practicable.