Kinetic theory and numerical simulation of biomineralization

The biomineralization technology that becomes an emerging research topic has attracted wide attentions in recent years. However, it is hard to quantify the reaction process of biomineralization on temporal and spatial scales due to its complicated reactive mechanisms. Based on the principle of microbially induced carbonate precipitation, considering the adsorption and straining of bacteria, adopting the kinetic model for urea hydrolysis and precipitation, a reactive kinetic theory of biomineralization is investigated. Finally, based on the biomineralization experiments on a pore scale, a finite element software is adopted for multi-physics coupling. The results show that the adsorption and straining effects lead to the differences in distribution of bacteria, and then further influence the spatial distribution of calcium carbonate. The transverse distribution of CaCO₃ content during the initial mixing stage is not uniform, while the longitudinal distribution shows an increasing trend. The permeability shows an 80% reduction after 40 hours of reaction. The rate of CaCO₃ precipitation is limited by the rate of urea hydrolysis when calcium ions are abundant. The decay rate of bacteria due to CaCO₃ encapsulation is the combined effect of amounts of adsorbed bacteria and precipitation rate. The model can reflect the evolution of biomineralization-induced precipitation during reaction process, further enrich the theory of biomineralization reaction. This study is expected to provide reference in predicting the effect for the field-scale geotechnical engineering.