Modeling methane utilization by methanotrophs in groundwater: Applications for groundwater bioremediation

A model was developed to predict substrate concentrations for bacterial growth in a groundwater system. The model coupled substrate transport and oxidation by cells with bacterial growth. A reactor was designed that could test the model's ability to correctly predict the biological and physical phenomena governing the reactor setup. In order to design the reactor, I needed a methanotroph strain capable of attaching well to sand contained in the reactor. I found that Methylomicrobium albus BG8 cells attached strongly to the pretreated Ottawa sand used for the reactor solid phase. I also analyzed the effect of copper on methane utilization kinetics for this strain because prior evidence suggested copper may influence kinetic parameters. I found that copper did not have a statistically significant effect on methane utilization kinetics under the experimental conditions used. I also found that the mathematical model worked well to predict methane concentrations throughout the reactor over time. Model input parameters were then analyzed for their influence on model predictions. I found that the Michaelis-Menten maximum rate of methane utilization and Monod maximum specific growth rate had the largest effect on model predictions. I also found that mass transfer from the bulk liquid to bacteria attached to particles could have a large impact on model predictions. The mass transfer effect was greatest when the substrate concentration was less than or equal to the Michaelis-Menten affinity coefficient and Monod half-maximum growth rate constant.