Approaches for Effective Microbial-Induced Carbonate Precipitation (MICP) for Heavy Metal-Contaminated Soil Bio-Remediation: A Review

Heavy metals (HMs) threaten ecosystems via food chain accumulation. Conventional passivation with cement or chemicals is constrained by environmental harm and high CO₂ emissions. Microbially induced calcium carbonate precipitation (MICP) provides a sustainable, low-carbon solution for HM immobilization. This review offers a comprehensive overview of recent MICP advancements in soil remediation. It systematically examines the precipitation mechanisms, key influencing factors including pH, temperature, calcium ion concentration, and bacterial species, as well as practical strategies for field application. The paper also addresses current limitations, such as uneven bacterial distribution and ammonium byproduct generation. Notably, integrating MICP with adsorbent materials like biochar and zeolite can synergistically reduce NH4+ production, as these materials selectively adsorb contaminants while facilitating MICP induced solidification and storage. Future research should explore innovative injection techniques, e.g., electrodialysis and pneumatic drive, to enhance bacterial penetration and reaction solution uniformity in heterogeneous soils. Additionally, long term ecological monitoring is crucial to evaluate the durability of calcium carbonate precipitates under various environmental stresses and to assess the potential for heavy metal remobilization over time. This review aims to provide valuable insights for engineers and interdisciplinary researchers, supporting the transition of MICP from laboratory to large scale practical applications.