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Biogeochemical Changes During Bio-cementation Mediated by Stimulated and Augmented Ureolytic Microorganisms
Michael G Gomez1, Charles M R Graddy2, Jason T DeJong3
1Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, 98195, USA. mggomez@uw.edu.
Scientific Reports
|August 10, 2019
Summary
Enriching native soil microbes for Microbially Induced Calcite Precipitation (MICP) shows similar soil improvements to using non-native bacteria. However, native microbes may alter the timing and spread of bio-cementation and its effects.
Area of Science:
- Geotechnical Engineering
- Environmental Microbiology
- Biogeochemistry
Background:
- Microbially Induced Calcite Precipitation (MICP) uses urease-producing microorganisms to cement soil particles with calcite.
- Current MICP methods often rely on introducing non-native bacteria, increasing costs and environmental concerns.
- Utilizing native soil microorganisms for MICP could offer a more sustainable and cost-effective approach.
Purpose of the Study:
- To investigate the biogeochemical differences between MICP mediated by native versus augmented (Sporosarcina pasteurii) ureolytic microorganisms.
- To compare the large-scale bio-cementation efficacy and temporal progression of native and augmented microbial communities in granular soils.
- To explore the role of urea hydrolysis in MICP and its impact on calcite precipitation dynamics.
Main Methods:
- Conducted large-scale bio-cementation experiments in two 1.7-meter diameter tanks.
- Performed complementary soil column experiments to assess microbial community effects.
- Analyzed biogeochemical changes, calcite distribution, engineering properties, and precipitate microstructure.
Main Results:
- Post-treatment calcite distribution and soil engineering properties were comparable between native and augmented microbial approaches.
- Significant differences were observed in ureolysis and calcite precipitation rates between native and augmented communities.
- These rate differences influenced the temporal progression and spatial distribution of bio-cementation and solution chemistry.
Conclusions:
- Enrichment of native ureolytic microorganisms is a viable alternative to non-native bacteria for soil bio-cementation.
- While overall soil improvements may be similar, native microbial communities can alter the dynamics of MICP.
- Understanding microbial community differences is crucial for optimizing MICP processes for specific applications.
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