Evaluation of Multiple Soil Improvement Techniques Based on Microbial Functions

In this paper, we propose several soil improvement techniques based on microbial functions. These techniques can control soil strength and permeability. The ureolytic bacterium, Bacillus pasteurii, was used to accelerate the precipitation of calcium carbonate(CaCO₃). Soil permeability can be controlled by 2 types of microbial functions; type 1 metabolizes a carbon source aerobically and anaerobically to generate the carbon dioxide and enhance the precipitation of CaCO₃, and type 2 produces organic acids, depending on the type of microorganism, by degrading a carbon source. The organic acid dissolve the carbonate precipitates, i.e. cause decalcification, and thus, restore soil permeability. We attempt to explain the scheme of these methods, and illustrate the results of each experiment. Each technique controls the physical property of soil and can be beneficial in reducing construction costs and lowering environmental impact.