Monitoring of bio-oxidation process of ferrous ion by using piezoelectric impedance analysis

A new method of monitoring the bio-oxidation process of ferrous ion in the presence of Thiobacillus ferroxidans was proposed by piezoelectric impedanc e analysis. The time courses of the responses of impedance parameters for a quartz crystal in a culture system were simultaneously obtained and discus sed. It was found that the frequency shift response originates mainly from the adsorption of bacterial metabolites on the surface of gold electrode. E xperiments also examined the effect of culture temperature on the bio-oxida tion process. Combined with the growth situation of the bacterium, an imped ance response model reflecting the process was established. By fitting Delt af vs. time curves toward the proposed model, we obtained and discussed the bacterial growth parameters. The results showed that the proposed method c ould provide real time and multidimensional information to monitoring of th e bio-oxidation process.