Microbial-induced carbonate precipitation (MICP) is a promising bioremediation technology for heavy metal immobilisation. This review explores the applications and efficacy of MICP in environmental challenges. It provides a comprehensive overview of the mechanism, primarily through ureolysis, detailing the process from urea hydrolysis to heavy metal precipitation as carbonate minerals. Alternative pathways such as photosynthesis and nitrate reduction are also discussed, highlighting the broad applicability of MICP. The review covers the historical evolution and advancements of MICP as a sustainable solution for heavy metal contamination. Recent studies demonstrate the efficiency of MICP in achieving high removal rates in diverse environments. The sustainable operation, precise targeting of heavy metal species, and versatility of MICP are examined. Challenges such as high copper concentrations, acidic conditions, and cost considerations are addressed. The article provides future directions and solutions to these challenges, including leveraging machine learning for optimal performance and enhancing cost considerations through detailed analyses. This review improves understanding of MICP’s potential, provides a valuable resource for researchers in environmental engineering and the built environment, and encourages innovative approaches within these fields.

Enzyme-induced carbonate precipitation (EICP) is an acellular biomineralisation process in which free plant-derived urease catalyses the hydrolysis of urea to precipitate calcium carbonate (CaCO₃), thereby sealing cracks and densifying porous construction materials. EICP has attracted growing interest as a cell-free, shelf-stable, and field-deployable alternative. This critical review synthesises evidence on EICP for the repair of cracks and the enhancement of durability in cementitious and related construction materials. Genuine concrete/mortar crack-repair EICP constitutes the largest experimental category in the field. Across this core, narrow cracks below about 0.3 mm respond to EICP-only treatment with compressive-strength recovery of up to 98.4% and permeability reductions of two to three orders of magnitude, while additive- and fibre-assisted strategies extend the effective repair envelope to approximately 2.0 mm at 45–69% strength restoration. Soybean-derived crude urease is the overwhelmingly preferred source. CaCO₃ polymorph outcome is study- and condition-dependent: calcite dominates the literature, vaterite is characteristic of rapid or narrow-crack precipitation, and additive control can shift the calcite fraction from 38% to 81%. Durability evidence is the field’s weakest dimension, with only one study reporting a coupled freeze–thaw and carbonation dataset and none exceeding roughly six months of monitoring. We discuss why EICP has not attracted the same research intensity as MICP, identify the principal barriers to translation, and outline the standardisation, durability-validation, and regulatory steps required for EICP to mature into a mainstream low-carbon repair technology. These figures are aggregated performance ranges drawn from studies with differing specimen geometries, curing regimes, and loading ages, and are therefore reported as an envelope rather than as directly normalised single values. Because the corpus was assembled principally from Scopus and Web of Science, supplemented by manual searching, relevant studies indexed elsewhere cannot be fully excluded.

Introduction: Soil degradation and landslide susceptibility represent major environmental challenges in steep terrains affected by inadequate soil management. Microbial-induced carbonate precipitation (MICP) has emerged as a promising bio-based technique to improve soil stability; however, comparative evaluations across different soil textures remain limited. Methods: This study investigates the application of MICP using Sporosarcina pasteurii to improve sandy, silty, and clayey soils collected from active slopes in Loja, Ecuador. Physicochemical, microstructural, and geomechanical properties were evaluated before and after treatment using carbonate quantification, ion exchange analysis, Atterberg limits, direct shear tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Results: Calcium carbonate precipitation was detected in all soil types, with higher accumulation in finer-textured soils. Exchangeable calcium increased markedly, while sodium decreased in sandy and clayey soils, indicating ion exchange associated with carbonate cementation. The plasticity index decreased in all soils, with reductions of up to ∼65% in clayey samples. Geomechanical testing showed consistent improvements, with cohesion increasing by approximately 25–35% in sandy and clayey soils and exhibiting a pronounced relative increase in silty soils. The internal friction angle increased by approximately 30–100%, depending on soil texture. Microstructural analyses confirmed the formation of calcite and vaterite bridging soil particles. Discussion: Unlike most previous MICP studies focused on a single soil type, this work demonstrates that soil texture strongly governs both the magnitude and mechanisms of MICP-induced improvement. The results support the potential of MICP as a sustainable and environmentally friendly strategy for near-surface slope stabilization in heterogeneous natural soils.