The Microbial-Induced Calcium Carbonate Precipitation by the Flow-Through Method: Effect of Bacterial Suspension Volume and Relative Density

Abstract

Microbially-induced calcium carbonate precipitation (MICP) is the technique of employing microorganisms to produce biocements. MICP is applied to resolve engineering problems like ground improvement, slope stabilization, soil and rock seepage control, erosion control, and heavy metal immobilization. The literature reports four primary MICP methods: injection, flow-through method (FTM) or surface infiltration method, immersion, and mixing. Among these methods, injection stands out as the most commonly used method. However, the present study opts for the FTM, where the liquid permeates the soil through gravity. We systematically investigate the impact of relative density and the volume of bacterial suspension on various parameters, including bacterial retention efficiency, calcium carbonate precipitation, permeability, and strength parameters. The strength and calcium carbonate content in the lower parts of the columns. Notably, calcium carbonate precipitation is more uniform at lower densities. Overall, FTM improves the properties of sand more effectively at greater depths compared to shallower depths, and at higher densities compared to lower ones. Also, applying FTM under the conditions outlined in this study proves to be more straightforward than other methods. Considering its gravity-driven penetration and no need for specialized equipment, the FTM aligns more closely with natural ground conditions, rendering it a cost-effective alternative.