Effects of Various Factors on Carbonate Particle Growth Using Ureolytic Bacteria

Abstract

In Microbially Induced Carbonate Precipitation (MICP), bacteria can perform metabolic activities that promote the deposition of carbonate particles in the form of calcite. Previously, purified urease and CaCl₂ have been used for hydrolysis of urea to deposit carbonate particles. In our present study, Mg²⁺ ions were added to investigate the effect on the deposition of carbonate particles, because Mg²⁺ ions can delay the reaction rate and enhance the crystal deposition rate. Additionally, other parameters (temperature, solvent, bacterial population, and CaCl₂ concentration) were taken into consideration to enhance the amount of carbonate deposition by ureolytic bacteria. The aim of this study was to investigate the mechanism of carbonate particle generation using urease producing bacteria (Pararhodobacter sp.) in laboratory test conditions using a translucent cell. In this study, marine ureolytic (Pararhodobacter sp.) bacteria were used and their urease activity was estimated considering bacterial concentration, temperature, and the effect of Ca²⁺ and Mg²⁺ ions. Digital microscopy analysis revealed the direct involvement of these parameters on the deposition of carbonate particles. The results of this study also showed that the type of deposited crystals, their shapes, and bacterial growth rate change depending on the medium used, the type of carbonate (metal ion used), CaCl₂ concentration, and temperature. In addition, when Mg²⁺ and Ca²⁺ ions were used, the amount of particle deposition increased, which enhanced the possibility of becoming a superior binder for sand particles. This study is useful for the various sand solidification experiments and to regulate the most suitable conditions for engineering applications in future studies.