Characteristics of bio-CaCO3 from microbial bio-mineralization with different bacteria species

Abstract

Nowadays, MICP (Microbially Induced Calcite Precipitation) technology has broad application prospects in civil engineering, such as sand consolidation, crack healing in cement-based materials, solid waste treatment, etc. Nevertheless, there were no systematic studies on the difference of bio-CaCO3 produced by different microbial strains. In this study, XRD, TEM, SEM, STA and AFM were used to investigate the differences in crystalline form, morphology, size, decomposition temperature, and adhesion force of mineralized products. Those products were produced by Photosynthetic bacteria, Bacillus mucilaginosus, Bacillus alcalophilus, Bacillus pasteurii and chemical pathway. The results showed that all four microbial pathways were more productive than the chemical pathway. The calcite crystals formed by the chemical pathway presented an oblique hexagonal lattice structure, while calcite crystals formed by four microbes presented a spherical or irregular polyhedral structure under the action of organic substrate. The calcite crystals formed by Bacillus pasteurii were smallest in size and those formed by Photosynthetic bacteria were the largest, and their crystalline sizes were smaller than that of calcite produced by chemical pathway. The decomposition temperature and adhesion force of chemical CaCO3 were lower than that of bio-CaCO3, with the highest decomposition temperature (765.80 ℃) and the largest adhesion force (68.91 nN) of calcite induced by Bacillus pasteurii.