Abstract
Microbial induced calcium carbonate precipitation (MICP) is a widespread phenomenon in nature. In this paper, various factors affecting microbial growth and urease activity were studied, including temperature, initial pH, urea concentration, Ca2+ concentration and gelling solution concentration, and the optimal process conditions for calcium carbonate preparation were determined. Subsequently, the changes of Ca2+ concentration, NH4+ concentration and pH value in alkaline medium with and without bacteria were studied carefully, and the dynamic process of calcium carbonate deposition was also revealed. Finally, the mineralization mechanism model of MICP was established by characterization and analysis of the precipitates. The results indicated that urease produced by bacteria in the metabolism process of bacteria could accelerate the hydrolysis rate of urea and the formation rate of carbonate. In addition, the bacterial cells themselves were negatively charged, which could adsorb Ca2+ with positive charge. Meanwhile, they could also be used as the nucleation sites to accelerate the generation of calcium carbonate.
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