MICP for Environmental Protection and Circular Bioeconomy: A Critical Review

Microbiologically induced calcium carbonate precipitation (MICP) links microbial metabolism with carbonate biomineralization and offers a platform for environmental protection and a circular bioeconomy. This critical review synthesizes ureolytic and non-ureolytic pathways, including denitrification, sulfate reduction, photosynthesis, ammonification and carbonic-anhydrase-mediated routes, and evaluates their efficiency, scalability, environmental impacts and field applicability. MICP can immobilize heavy metals and metalloids, stabilize soils and mine wastes, reduce permeability, control erosion and dust, seal cracks in cementitious materials, and support brine or wastewater treatment. Representative studies report >90% Cd2+ removal in selected wastewater systems, 50–90% hydraulic-conductivity reduction at about 10–15% CaCO3, 2.7 MPa compressive strength in urine-based bio-bricks, 31.87% calcium-source cost reduction using waste-limestone-derived calcium acetate, and geothermal-brine treatment removing 96% Ca, 88% Mn, and 91% Sr while retaining >96% Li. The review emphasizes that circular MICP requires more than waste input substitution; it must include nitrogen management, feedstock quality control, long-term contaminant stability, LCA/TEA, regulatory readiness, biosafety, field monitoring, and technology-readiness assessment. Future research should develop low-ammonia, waste-fed and data-guided MICP systems with standardized quantitative performance metrics.