Removal Behavior of Heavy Metals from Aqueous Solutions via Microbially Induced Carbonate Precipitation Driven by Acclimatized Sporosarcina pasteurii

Microbially induced carbonate precipitation (MICP) driven by Sporosarcina pasteurii was highly efficient for heavy metal (i.e., Cd2+, Cu2+ and Pb2+) removal in the range of 50 to 800 mg/L. Sporosarcina pasteurii bacteria were sequentially inoculated in nutrient broths amended with increased concentrations of heavy metals separately to improve the resistance to heavy metal environments. In the absence of Ca2+, the increasing urea concentration was conducive to Cd2+ removal with the best removal ratio 89.9–99.7% at a urea concentration of 2.0 mol/L, but had little positive effect on Cu2+ and Pb2+ removal, with a removal ratio of 62.6–64.4% and 71.4–97.6%, respectively, at a urea concentration of 0.5 mol/L. The heavy metal coprecipitated with Ca2+, leading to much more effective heavy metal removal, and the removal efficiency of Cd2+, Cu2+ and Pb2+ could reach 98.0–99.0, 78.1–82.1 and 98.0–100.0%, respectively. The Cu2+ deposit aggregated and cemented to form clusters, different from Cd2+ and Pb2+ deposits with comparatively dispersed microstructure. For all the three heavy metal precipitates, the predominant mineral was identified as calcite, the most thermodynamically stable polymorph of CaCO3.