Assessing the Applicability of Cyanobacteria-Induced Carbonate Precipitation for Eco-Friendly Soil Improvement

The surface of artificial slopes, ledges or embankments is easily weathered by wind and water, which often causes geo-disasters. The deposition of soil particles in a discrete and/or loose condition is likely a major cause of surface weathering. To date, numerous technologies for preventing surface weathering, such as shotcrete, have been developed. Environmentally friendly soil improvement techniques through bio-mediation can also be used as one of these technologies. This study investigates whether artificial biomineralization by photoautotrophic microorganisms can be applied to soil improvement for loosely compacted sandy soil. Experimental results indicated that the precipitation of calcium carbonate, induced by photoautotrophic microorganisms between soil particles and on the soil surfaces, reduces the permeability coefficients of the soil. It is suggested that soil improvement based on photoautotrophic microorganisms would be useful for protecting the weathering surfaces of artificial slopes and embankments. Additionally, the experimental results suggested that the Cyanobacterial community, not just a single one, promotes carbonate precipitation. Therefore, it is desirable to add and/or activate the native communities after collecting and culturing them, instead of adding other bacteria when applying this technique to an actual field.