Microbial calcification in subsurface environments
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MICROBIAL CALCIFICATION IN SUBSURFACE ENVIRONMENTS. Sookie S. Bang Department of Chemistry and Chemical Engineering South Dakota School of Mines and Technology. Microbial Calcification. Microorganisms Soil bacteria (Urease-positive) Phototrophs Occurs in

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MICROBIAL CALCIFICATION IN SUBSURFACE ENVIRONMENTS

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MICROBIAL CALCIFICATION IN SUBSURFACE ENVIRONMENTS

Sookie S. Bang

Department of Chemistry and Chemical Engineering

South Dakota School of Mines and Technology


Microbial Calcification

  • Microorganisms

    • Soil bacteria (Urease-positive)

    • Phototrophs

  • Occurs in

    • Terrestrial environments: alkaline soil

      e.g., plugging of porous media

    • Aquatic environments: marine and freshwaters

      e.g., whitings, calcareous mats


Calcification

Ca2+ + HCO3- CaCO3 + H+


Microbial Urease

  • Intracellular Enzyme

  • Urea hydrolysis

    UREASE

    NH2-CO-NH2 + H2O —— 2NH3 + CO2

    NH3 + H+ NH4+ (pH )

  • Microorganisms: Eubacteria-Bacillus pasteurii, Proteus vulgaris,

    Pseudomonas spp., etc.


CaCO3 Precipitation Experiments

  • Microorganism: Bacillus pasteurii ATCC11859

  • Medium:

    3 g Nutrient broth, 20 g Urea, 2.8 g CaCl2, and 2.12 g NaHCO3, pH 7.8 – 8.0


Microbiologically InducedCalcite Precipitation (MICP)

At higher pH : in medium containing Urea, CaCl2 and NaHCO3

Ca2+ + Cell  Cell–Ca2+

Cl- + HCO3- + NH3 NH4Cl + CO32-

Cell–Ca2+ + CO32- Cell-CaCO3


Calcification in Aquatic Environments

  • Photosynthetic microorganisms:

    Ca2+ + HCO3- CaCO3 + H+

    H+ + HCO3-  CH2O + O2

  • Ureolytic microorganisms:

    Ca2+ + HCO3- CaCO3 + H+

    NH3 + H+ NH4+


Potential Applications of MICP

  • Microbial plugging in porous media:

    (NSF/CMS-9412942)

  • Remediation of cracks and fissures in granite and concrete

  • Subsurface stabilization in highways with urease enzyme

  • Dust control for surface soils

  • Carbon sink in ecosystems


Potential Applications of MICP

  • Microbial plugging in porous media

  • Remediation of cracks and fissures in granite and concrete:

    (NSF/CMS-9412942; CMS-9802127 )

  • Subsurface stabilization in highways with urease enzyme

  • Dust control for surface soils

  • Carbon sink in ecosystems


Potential Applications of MICP

  • Microbial plugging in porous media

  • Remediation of cracks and fissures in granite and concrete

  • Subsurface stabilization in highways with urease enzyme: (NSF/INT-0002608)

  • Dust control for surface soils

  • Carbon sink in ecosystems


Potential Applications of MICP

  • Microbial plugging in porous media

  • Remediation of cracks and fissures in granite and concrete

  • Subsurface stabilization in highways with urease enzyme

  • Dust control for surface soils

  • Carbon sink in ecosystems


Potential Applications of MICP

  • Microbial plugging in porous media

  • Remediation of cracks and fissures in granite and concrete

  • Subsurface stabilization in highways with urease enzyme

  • Dust control for surface soils

  • Carbon sink in ecosystems


Proposed Research Experiments at NeSS

  • Identification of diversity in microorganisms that participate in CaCO3 precipitation:

    • DNA extraction / PCR amplification / phylogenetic analysis

  • MICP in subsurface environments:

    • Effects of pressure, temperature, and CO2 concentration on CaCO3 precipitation kinetics

  • Measurement of CO2 sequestration rates:

    • CO2 flux using the eddy covariance methods


Hypotheses/Possibilities

  • CaCO3 at Homestake has percolated from the surface.

  • Surface soil microbial populations may have been introduced to the subsurface.

  • Ecological interactions among microbes in the subsurface result in phyogenetic diversity.

  • Subsurface environmental factors will influence kinetics of CaCO3precipitation and CO2 flux.


Significance of Proposed Research

  • Phylogenetic diversity of microbial communities involved in subsurface calcification

  • Effects of MICP on subsurface hydrology

  • Application of MICP in subsurface bioremediation

  • Evaluation of the range of carbon sequestration in deep subsurface


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