UC Davis

There is a growing interest in microbially induced calcite precipitation (MICP) treatment in carbonate rich soils. Research has found MICP bio-augmentation and bio-stimulation to be effective in carbonate rich soils with potential differences dependent on chemical formulation, treatment time, soil composition and soil fabric. This study focused on lab-scale MICP stimulation applications on carbonate rich soils in preparation for large scale tests and field trials. This test program investigated the robustness of bio-stimulation in carbonate particles with respect to the effectiveness of treatment solution concentrations, the effectiveness of commercial grade chemicals, and the effectiveness of byproduct removal in carbonate rich soils. Despite significant differences in urea degradation between treatment solution concentrations, all soil columns resulted in improvement in shear wave velocity (Vs ) and increase in calcite contents. Results showed commercial grade chemicals can be as effective as laboratory grade chemicals in bio-stimulation applications and ammonia byproduct removal methods decreased aqueous ammonia concentrations by four to five orders of magnitude. The results of this study suggest MICP bio-stimulation is successful for laboratory scale and may be successful in field scale applications.