Use of Ureolytic Bacteria S. pasteurii for Soil Improvement and the Development of Predictive Computational Models

Weak and unstable soils can limit the building of new infrastructure. Current soil strengthening techniques such as chemical grouting have detrimental effects on the environment from greenhouse gas production, soil pH modification and groundwater contamination. Microbial-induced calcium carbonate precipitation (MICCP) is a technique that utilises the ability of bacteria to precipitate calcium carbonate (CaCO₃), which can be used for a variety of applications including binding adjacent soil particles and filling the pore spaces of soils to increase their mechanical properties. A commonly used bacterium is Sporosarcina pasteurii. A range of factors influences MICCP which presents challenges with process optimisation. Past studies have investigated these factors on an isolated basis, but not systematically considered the influence of a range of factors. These factors need to be systematically investigated in the laboratory before they can be applied for engineering purposes. Furthermore, input of a systematic data set into computational models could be useful for predicting biocementation under different environmental conditions at a larger scale.

An aim of my research is to optimise urease activity in S. pasteurii by comparing different growth media, growth stages, pH and temperatures. I am also investigating the biocementation of S. pasteurii in sand syringe setups to compare the effects of changing influencing factors such as growth stage and cell concentration of S. pasteurii, sand particle size, cementation media concentration, duration between cementation media applications and overall number of cementation treatments. Ultimately, raw data generated from the project will be used to build a computational model for predicting biocementation at a larger scale.