Investigation of the Microstructure of Brahmaputra Sand Treated with Bacillus megaterium-Mediated Single-Dosed Bio-Cementation

The bio-mediated soil improvement has promising capabilities to provide sustainable aid to the geotechnical challenges. The geotechnical behavior of the soil can be modified utilizing bio-mediated processes. Most of the studies on the bio-mediated soil improvement focuses on a particular bacteria Sporosarcina pasteurii. This study utilizes urease positive bacteria Bacillus megaterium (NCIM 5472) as an alternative to S. pasteurii and Brahmaputra riverbank sand for the investigation of bio-cementation in the soil. In this study, the primary characterization of B. megaterium has been reported. The qualitative urease activity of the bacteria has been assessed with Urea Agar Base (Christensen), and quantitative analysis of urease activity assay has been evaluated by the phenol-hypochlorite method. Quantitative calcite precipitation has been evaluated at equimolar cementation solution. After the characterization, single dosing of bacterial broth solution mixed along with cementation solution (one pore volume) is introduced to Brahmaputra riverbank sand, and the microstructure of the sand has been investigated with the help of field emission scanning electron microscope (FESEM) images. The influence of bio-cementation was observed significantly on the microstructure of Brahmaputra riverbank sand in the form of bridging of the calcite precipitated. This study is a preliminary study to investigate the applicability and potential of the bacteria B. megaterium for bio-mediated soil improvement. The study concludes that the bacteria B. megaterium is moderately urease active, and it has the potential for bio-cementation.