| This thesis presents an investigation into various kinetic aspects, related to the cultivation of a Leptospirillum ferriphilum-dominated culture. This bacterium recently came to the attention of the scientific community as an important iron oxidizing microorganism with various practical applications. The present research was catered towards the Biogenerator - a novel energy generation device, working as a microbial fuel cell which can convert chemical energy directly into electricity. In order for the Biogenerator to work efficiently it requires operation at high iron concentration and low pH, hence the need for this study.;In the second part of the research, the continuous cultivation of the bacterium was studied for both suspended and immobilized cultures in two types of airlift reactors and a spouted bed reactor. It was found that at high iron concentration, the pH changed significantly between the feedstock and the reactor, which caused unstable operation, particularly in the case of suspended cell cultivation. To better describe the system, a model for the pH change was developed based on thermodynamic principles. The operation with immobilized cells showed that biofilm reactors tend not to be very stable at low pH due to the observed poor mechanical strength of the L. ferriphilum biofilm. At pH 0.56 the biofilm disintegrated completely, and the culture, which until then was dominated by L. ferriphilum shifted towards another acidophilic iron oxidizing microbe: Ferroplasma acidarmanus. Then, a kinetic study for the effect of the pH on the Ferroplasma behaviour was conducted, and biological activity was detected at negative pH of -0.25.;Keywords: Leptospirillum ferriphilum, Ferroplasma, ferrous iron oxidation, kinetics, airlift reactor, spouted bed reactor, microbial fuel cell, acidophiles, negative pH, pH modelling;A series of batch experiments were conducted. First, the dependences of the cell growth and biooxidation rate on the temperature and the pH of the medium were investigated. Then, a study was undertaken at five different total iron concentrations ranging from 5 to 40 g Fe/L. A new kinetic equation, which includes the effect of the total iron concentration, was developed. The final batch study was on the effect of the presence of different reformate gases (hydrogen, methane and carbon monoxide) on the cell growth and oxidation rates. |
