Biosurfactant type and introduction order impact the morphology of biological CaCO₃ during the MICP process

In recent years, microbially induced carbonate precipitation (MICP) technology has attracted considerable attention; however, the morphology of biological calcium carbonate (Bio-CaCO₃) produced in MICP exhibites variability, which impacts its application. This study employed rhamnolipids and sophorolipids to investigate the impact of biosurfactant type and introduction order on the morphology of Bio-CaCO₃ in the MICP process. The findings indicated that the biosurfactant type and introduction order influenced the morphology of Bio-CaCO₃ and the composition of dissolved organic matter (DOM) in the solution. In the absence of biosurfactants, the Bio-CaCO₃ was primarily composed of rhombic calcite and spherical vaterite. The pre-introduction of rhamnolipids was observed to promote the formation of fasciculated agglomerates of calcite, while the pre-introduction of sophorolipids was observed to promote the formation of spherical agglomerates of calcite. The post-introduction rhamnolipids or sophorolipids were observed to stabilize hollow, spherical vaterite. The findings of the study indicated that the biosurfactant type and introduction order influenced the types and amount of DOM in solution, which in turn affected the MICP process and the morphology of Bio-CaCO₃. This study provides a theoretical foundation for the regulation of the morphology of Bio-CaCO₃ and the application of MICP technology.