Heavy metal immobilisation using ureolytic bacteria via microbial induced carbonates precipitation

Abstract The application of Microbial Induced Carbonates Precipitation (MICP) has gained recognition as a sustainable solution for various engineering problems, including soil improvement, crack repair, and bio-concrete production. Researchers have discovered the potential of MICP in immobilising heavy metals, further expanding its scope of applications. Although extensive studies have been conducted to explore the potential of MICP in addressing engineering challenges, limited effort has been dedicated to the exploration of new species of ureolytic bacteria, particularly those originating from agricultural areas. This study focused on characterising bacterial isolates obtained from paddy soil and goat manure, assessing their ability to induce carbonate precipitation for soil treatment and heavy metal immobilisation. Specific urease activity analysis revealed values of 5.78 and 10.28 mM urea hydrolysed.min −1 .OD −1 for the isolates from goat manure and paddy soil, respectively. The optical density of the isolated bacteria was observed under different concentrations of cadmium (Cd) to evaluate their tolerance to the heavy metal. Interestingly, the goat manure sample exhibited the highest bacterial density in the presence of 2 g/L Cd, surpassing the paddy soil isolates. This study demonstrates the potential of the isolates as viable ureolytic bacteria for enhancing soil quality and immobilising heavy metals via the MICP process. However, further research is required to ascertain the optimal conditions and methods for soil treatment to attain optimal outcomes for large-scale field applications.