AN INVESTIGATION OF BACTERIAL CALCIUM CARBONATE PRECIPITATION IN ORGANIC SOIL FOR GEOTECHNICAL APPLICATIONS

This study focused on the process of bacterial calcium carbonate (CaCO3) precipitation
(BCCP) in organic soil. Two samples, organic soil and sand, in glass boxes having dimensions
6×6×2 cm were immersed in bacterial medium (Bacillus pasteurii, urea, and CaCl2) for 4 days.
During the treatment period, the samples were treated with urea medium and CaCl2 every 6 h.
Changes in pH values were monitored at different time intervals. At the end of the treatment
period, the amount of CaCO3 was determined with a calcimeter test. The test results showed that
the pH values fluctuated between 9 and 9.4 during the treatment period. This range of pH values
indicates that the treatment medium is appropriate for BCCP. The amount of precipitated CaCO3
in the organic soil sample increased about 8% compared with the untreated sample. Calcium
carbonate precipitation in sand is found to be higher than the organic soil. The results were
supported by Scanning Electron Microscopy (SEM) analysis and Energy-Dispersive X-ray (EDX)
analysis.