Soil improvement using biostimulated MICP: Mechanical and biochemical experiments, reactive transport modelling, and parametric analysis

Microbially induced calcium carbonate precipitation (MICP) has attracted significant attentions in recent years. In the realm of MICP advancement, bioaugmentation and biostimulation have been adopted. Biostimulation presents a potentially more cost-effective and sustainable avenue in contrast to the exogenous introduction of microbes under certain circumstances. Within the scope of the current investigation, a series of elemental-scale sand column batch tests were conducted under diverse treatment recipes (i.e., concentration of enrichment media and cementation solution), aiming to calibrate the varying apparent ureolysis kinetics parameters (i.e., the half saturation constant K_m and the maximum ureolytic activity v_max) during the biostimulated MICP treatment under the combined actions of flushing and encapsulation, and the varying apparent ureolytic kinetics parameters were incorporated into modelling for the first time. The proposed model was then validated by average cementation content of the biostimulated treated sand columns. The simulated results are consistent with the data measured in terms of average cementation content after different treatment cycles, indicating that the proposed model is feasible to simulate the kinetically controlled biostimulated MICP process. Additionally, a comprehensive parametric sensitivity analysis is undertaken to evaluate the influence of some selected key parameters on the average content of cementation and its spatial uniformity.