Bio-mediated soil improvement

DeJong, Jason T.; Mortensen, Brina M.; Martinez, Brian; Nelson, Douglas C.

doi:10.1016/j.ecoleng.2008.12.029

Cited by 1,388 publications

(675 citation statements)

References 23 publications

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“…Calcite precipitation modifies the rock porosity, and can have either benefits or side effects for the mechanical and transport properties of porous media. Calcite precipitation in porous media has broad applications in geotechnical engineering for soil strengthening (DeJong et al 2006(DeJong et al , 2010Whiffin et al 2007) and in environmental studies for the sequestration of heavy metals (Sturchio et al 1997;Cheng et al 1999), radionuclides (Fujita et al 2004;Mitchell & Ferris 2005), and CO 2 in geological formations Xu et al 2003). However, calcite precipitation can also have undesirable effects such as the decrease of the permeability of reactive barriers for the remediation of aquifers (Wilkin et al 2003;Scheibe et al 2006;Jeen et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

Leroy

Li²,

Jougnot

et al. 2017

Geophys. J. Int.

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S U M M A R YWhen pH and alkalinity increase, calcite frequently precipitates and hence modifies the petrophysical properties of porous media. The complex conductivity method can be used to directly monitor calcite precipitation in porous media because it is sensitive to the evolution of the mineralogy, pore structure and its connectivity. We have developed a mechanistic grain polarization model considering the electrochemical polarization of the Stern and diffuse layers surrounding calcite particles. Our complex conductivity model depends on the surface charge density of the Stern layer and on the electrical potential at the onset of the diffuse layer, which are computed using a basic Stern model of the calcite/water interface. The complex conductivity measurements of Wu et al. on a column packed with glass beads where calcite precipitation occurs are reproduced by our surface complexation and complex conductivity models. The evolution of the size and shape of calcite particles during the calcite precipitation experiment is estimated by our complex conductivity model. At the early stage of the calcite precipitation experiment, modelled particles sizes increase and calcite particles flatten with time because calcite crystals nucleate at the surface of glass beads and grow into larger calcite grains. At the later stage of the calcite precipitation experiment, modelled sizes and cementation exponents of calcite particles decrease with time because large calcite grains aggregate over multiple glass beads and only small calcite crystals polarize.

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Section: Introductionmentioning

confidence: 99%

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

Leroy

Li²,

Jougnot

et al. 2017

Geophys. J. Int.

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“…In order to control the process, a reliable predictive model is needed. The Biogrout process is based on microbially induced carbonate precipitation (MICP) (Bang et al 2001;Cheng et al 2014;DeJong et al 2006) and is a bio-mediated soil improvement method (DeJong et al 2010(DeJong et al , 2013Ivanov and Chu 2008). The proposed variant of Biogrout is urea-based.…”

Section: Introductionmentioning

confidence: 99%

A Reactive Transport Model for Biogrout Compared to Experimental Data

et al. 2015

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Biogrout is a method for reinforcement of granular soil. In the Biogrout process, calcium carbonate is produced. This solid connects the grains, and therefore the strength of the soil is increased. The calcium carbonate is formed with the use of micro-organisms. Experiments and numerical simulations have been performed to demonstrate the process under various conditions. In this paper, it has been examined whether a reactive transport model can be used to describe a Biogrout experiment that was performed in a column with a length of 5 m. Four different models for the course of the reaction rate are considered. The concentration of micro-organisms and the reaction rate are fine-tuned in order to find a description of the experiment that is a best fit for the particular model. This is done by minimizing the error between the experimental and numerical results for the concentration of calcium carbonate and the by-product of the reaction. List of symbolsInjected concentration of micro-organisms (normalized) (1) S bac Ratio of micro-organisms that is fixated (with respect to the injected concentration) (1)

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“…The application of MICP in industry as a biotechnology is proposed to help reduce the need for current structure repair practices such as chemical grouting, which have been found to be environmentally detrimental in its permanence (DeJong et al, 2010) and, in some cases, posing serious human health risks (Karol 2003). That said, ureolytic MICP does produce excess ammonia which can be harmful (van Paassen et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Improving the Strength of Sandy Soils via Ureolytic CaCO<sub>3</sub> Solidification by <i>Sporosarcina ureae</i>

Whitaker¹,

Vanapalli²,

Fortin³

2018

Preprint

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15'Microbial induced carbonate precipitation' (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP.In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ~9.0) conditions which favoured 20 MICP and could degrade urea (30.28 U/mL) at levels similar to S. pasteurii (32.76 U/mL), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD 600 ~15-20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl 2 ) and urea into a model sand, repeated treatments (3 x 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.8 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and 25 energy dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO 3 ), organized as calcite, across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No significant (p < 0.05) change in strength was observed for samples that underwent freeze-thaw cycling or flood-like simulations.However, samples fell to 29.2 % of untreated controls following acid-rain simulations. Overall, the species S. ureae 30 was found to be an excellent organism for MICP by ureolysis to achieve ground strengthening. However, the feasibility of MICP as a durable reinforcement technique is limited by specific climate conditions (i.e. acid rain).

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Bio-mediated soil improvement

Cited by 1,388 publications

References 23 publications

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

A Reactive Transport Model for Biogrout Compared to Experimental Data

Improving the Strength of Sandy Soils via Ureolytic CaCO<sub>3</sub> Solidification by <i>Sporosarcina ureae</i>

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Bio-mediated soil improvement

Cited by 1,388 publications

References 23 publications

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

A Reactive Transport Model for Biogrout Compared to Experimental Data

Improving the Strength of Sandy Soils via Ureolytic CaCO&lt;sub&gt;3&lt;/sub&gt; Solidification by &lt;i&gt;Sporosarcina ureae&lt;/i&gt;

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Improving the Strength of Sandy Soils via Ureolytic CaCO<sub>3</sub> Solidification by <i>Sporosarcina ureae</i>