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Enhanced MICP for Soil Improvement and Heavy Metal Remediation: Insights from Landfill Leachate-Derived Ureolytic Bacterial Consortium

Summary

Researchers used naturally-occurring bacteria from landfill waste liquid to create a sustainable method for cleaning contaminated soil and removing heavy metals like cadmium and nickel. The bacteria produce calcium carbonate (a mineral similar to limestone) which strengthens soil and traps pollutants. This biological approach is cheaper, more environmentally friendly, and more effective than traditional chemical cleaning methods, making it promising for treating contaminated sites worldwide.

Background

Landfill leachate is a hazardous liquid containing organic and inorganic contaminants including heavy metals and organic pollutants. Traditional treatment methods such as physical filtration and chemical processes are energy-intensive and do not completely remove dissolved contaminants. Microbial-induced calcium carbonate precipitation (MICP) using ureolytic bacteria offers a sustainable alternative for environmental remediation and soil stabilization.

Objective

This study aimed to optimize growth conditions for ureolytic bacteria from landfill leachate, evaluate MICP efficiency for heavy metal removal and soil stabilization, analyze structural and thermal properties of biocemented soil, and compare the method with traditional remediation techniques.

Results

Yeast extract medium supported the highest bacterial biomass and urease activity, producing 3.02 g/mL of CaCO₃. Optimal MICP conditions were pH 8-9 and 30°C. Heavy metal removal achieved 99.10% for Cd²⁺ and 78.33% for Ni²⁺. MICP treatment increased soil strength to 440 psi with 18.83% CaCO₃ content, and crystals exhibited well-defined rhombohedral and polyhedral morphologies.

Conclusion

MICP using landfill leachate-derived ureolytic bacteria effectively stabilizes soil and immobilizes heavy metals, particularly cadmium and nickel. Thermal analyses confirmed successful CaCO₃ formation with enhanced soil geotechnical properties. This sustainable biostimulation approach provides an economical and environmentally friendly alternative to traditional soil remediation and heavy metal treatment methods.
  • Published in:Microorganisms,
  • Study Type:Experimental Study,
  • Source: PMID: 39858942
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