Biofilm Characterization and Establishing Microbial-Induced Calcite Precipitation Treatment Process for Ganga River Sand by Using the Sand Column Method
Abhishek Tarun, Arvind Kumar Jha
Abstract
Biocementation using the microbial-induced calcite precipitation (MICP) technique is an environmentally friendly method that imitates the natural cementation phenomenon to improve the behavior of soils. Urea hydrolysis performed by ureolytic microorganisms results in the immobilization of the calcium ions by electrostatic attraction, leading to the formation of calcite crystals. The Ganga River sand (GRS) used in the present study is a fine-grained sand possessing serious engineering problems and in need of such improvements, for which a detailed study is necessary beforehand. Hence, the present study has explored the competence of different soil bacterium of the Bacillus family i.e., Bacillus sphaericus, Bacillus sp., and Bacillus subtilis in hydrolyzing urea, and also for forming the desirable biofilm over GRS in India. The colloidal behavior of the prepared bacterial solution along with the hydrodynamic diameter for different bacteria and its importance in the biofilm formation over GRS particles have been examined. The study is extended to determine biofilm formation’s competence for urea hydrolysis and calcite precipitation at different intervals. It is revealed that the biofilm formed by B. subtilis was stronger but the precipitation by B. sphaericus was maximum with 23% precipitation. Further, the rate of precipitation over time and its effect on the morphology of calcite crystals for all the selected bacteria have been discussed.