Numerical Modelling of Mineral-Microbe Interactions. Investigation on microbially induced calcium carbonate precipitation

Abstract

This thesis explores Microbially Induced Calcium Carbonate Precipitation (MICP) as a technique for soil improvement with minimal carbon footprint. In this technique, bacteria are used to drive crystallization of calcite in an aqueous solution inside a porous medium. MICP has shown promising results for soil stabilization. However, difficulties in controlling and optimizing the process have posed challenges to widespread applications. The thesis adopts a multi-scale approach to model and simulate MICP. At the micro-scale, direct numerical simulation was performed by coupling chemistry, geometry evolution, bacteria placement, and transport within the system. Understanding microscopic interactions provides a basis for macro-scale models by providing a more accurate portrayal of the spatial distribution of calcite and bacteria, and the impact of micro-scale variations. In the next step, a macro-scale model and simulation tool was developed to provide a simplified yet accurate simulation tool for MICP at the macro-scale, facilitating broader usability. Ultimately, this research strives to develop MICP simulators with optimization metrics, guiding the most effective treatment strategy based on desired outcomes. By enhancing our understanding of MICP at different scales, this thesis contributes to sustainable solutions for soil improvement, construction, and environmental remediation.