Immobilization of cadmium in soil by microbially induced carbonate precipitation with Exiguobacterium undae at low temperature

• Microbially induced carbonate precipitation (MICP) is tested for Cd immobilization.
• MICP using ureolytic Exiguobacterium undae for immobilizing Cd at 10 °C.
• Urease and dehydrogenase are enhanced in activities by MICP.
• More than 90% of Cd is converted to carbonate-bound fraction in 14 days.
• MICP with E. undae is effectively to immobilize Cd in soils of cold regimes.

Microbially induced carbonate precipitation (MICP) is an advanced biological treatment technology to immobilize heavy metals in form of carbonate salts. In this MICP study, ureolytic Exiguobacterium undae was employed for immobilization of cadmium in contaminated soil at low temperature (10 °C). The sequential extraction test revealed conversion of more than 90% of cadmium in the tested soil from the soluble-exchangeable fraction to carbonate-bound fraction in 14 days of treatment. The cadmium may be precipitated in a separate CdCO3 phase or be co-precipitated in calcite crystals. Activities of urease and dehydrogenase were enhanced during MICP, which were not affected by the testing temperatures. MICP with E. undae is a biological approach that may be worth investigating further to immobilize cadmium in soils of cold regimes.