Kinetics of the liquid‐phase oxidation of acid ferrous sulfate by the bacterium Thiobacillus ferrooxidens

The kinetics of the batch‐wise liquid‐phase oxidation of ferrous sulfate by the organism Thiobacillus ferrooxidans has been studied over a range of temperatures from 20°C to 31°C and in the presence of an abundant supply of oxygen, carbon dioxide, and other nutrients. The rate of oxidation was found to be accurately described by the equation\documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{dS}}{{dt}} = \frac{{\mu _m SX}}{{Y(K + S)}} $$\end{document}where t = time hr, S = concentration of ferrous ions g Fe ++ /1., μ m = maximum specific growth rate of bacteria, hr −1 . Y = mass of bacteria produced per gram of iron oxidized g/g, K = saturation constant, g Fe ++ /l., and X = concentration of bacteria g/1. The value for the maximum specific growth rate, μ m , was found to vary from 0.12 hr −1 at 20°C to 0.20 hr −1 at 31°C, while the value for the saturation constant K varied randomly between 1 and 2 g/1. A method has also been described which permitted evaluation of the relevant rate constants μ m and K without direct knowledge of the bacterial population. This method was found to yield values of μ m and K which agreed with values determined accurately by a statistical regression analysis of the experimental data.