Conclusions
Results of the parametric study of factors affecting ferrous iron oxidation show that the maximum conversion rate, which corresponds to the relative effectiveness of a given strain ofT. ferrooxidans on iron oxidation, is a function of initialpH, initial ferrous iron concentration, and cell number of inoculum size. However, the lag time, which corresponds to the time required to obtain the maximum conversion rate, is affected by initial ferrous iron concentration and initial cell number, but not by initialpH.
Measuring ferrous iron concentration during its oxidation in 9K medium is a quick and simple method for predicting the relative potential of various strains ofT. ferrooxidans in microbial leaching operations. However, according to Norris(16), developing better strains ofT. ferrooxidans may not improve leaching rates if mineral dissolution is slower than iron oxidation in solution. Therefore, as better iron-oxidizing strains of the bacterium are identified, other improvements in microbial leaching operations need to be developed.
Based on the data presented in this paper, a low initial ferrous iron concentration and a large inoculum volume (initial cell number) are recommended for comparative studies of various strains ofT. ferrooxidans. A low initialpH (1.8–2.0) is also recommended to prevent ferrous iron precipitation. In addition, before determining its maximum rate of oxidation of ferrous iron, each strain ofT. ferrooxidans grown for a comparative study should be washed thoroughly to obtain cell suspensions containing a minimum amount of ferric iron.
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Kang, S., Sproull, R.D. Iron Oxidation byThiobacillus ferrooxidans . Appl Biochem Biotechnol 28, 907–915 (1991). https://doi.org/10.1007/BF02922660
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DOI: https://doi.org/10.1007/BF02922660