Influence of soil mineralogy on calcium carbonate precipitation induced by calcifying bacteria

This study investigates the influence of soil mineralogy on microbially induced carbonate precipitation (MICP) using the ureolytic bacterium Sporosarcina pasteurii. Silica sand (SS), kaolinite clay (KC), and montmorillonite-rich bentonite clay (BC) were evaluated in soil supensions, minimising structural effects of porosity and density to assess mineralogical influence. During treatment, pH, dissolved oxygen, and calcium concentration were monitored, and calcium carbonate (CaCO3) precipitation was quantified by acid dissolution and characterised by FTIR. Mineralogy strongly affected MICP efficiency: BC yielded the highest CaCO3 content (0.261 g/g soil), followed by KC (0.178 g/g) and SS (0.1254 g/g). The superior performance of BC was associated with montmorillonite‘s capacity to enhance Ca2+ adsorption and calcite nucleation, while the substrates showed distinct pH, oxygen consumption, and calcium depletion patterns. xponential decay models captured calcium depletion behaviour across the substrates. By directly linking soil mineralogy with MICP efficiency and carbonate polymorphism, this study provides new insights into the role of mineralogy in biocementation.