Scholarly Work - Center for Biofilm Engineering
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Item Modeling biofilm growth in the presence of carbon dioxide and water flow in the subsurface(2010-07) Ebigbo, Anozie; Helmig, Rainer; Cunningham, Alfred B.; Class, Holger; Gerlach, RobinThe concentration of greenhouse gases—particularly carbon dioxide (CO2)—in the atmosphere has been on the rise in the past decades. One of the methods which have been proposed to help reduce anthropogenic CO2 emissions is the capture of CO2 from large, stationary point sources and storage in deep geological formations. The caprock is an impermeable geological layer which prevents the leakage of stored CO2, and its integrity is of utmost importance for storage security. Due to the high pressure build-up during injection, the caprock in the vicinity of the well is particularly at risk of fracturing. Biofilms could be used as biobarriers which help prevent the leakage of CO2 through the caprock in injection well vicinity by blocking leakage pathways. The biofilm could also protect well cement from corrosion by CO2-rich brine.The goal of this paper is to develop and test a numerical model which is capable of simulating the development of a biofilm in a CO2 storage reservoir. This involves the description of the growth of the biofilm, flow and transport in the geological formation, and the interaction between the biofilm and the flow processes. Important processes which are accounted for in the model include the effect of biofilm growth on the permeability of the formation, the hazardous effect of supercritical CO2 on suspended and attached bacteria, attachment and detachment of biomass, and two-phase fluid flow processes. The model is tested by comparing simulation results to experimental data.Item Imaging biologically induced mineralization in fully hydrated flow systems(2011) Schultz, Logan N.; Pitts, Betsey; Mitchell, Andrew C.; Cunningham, Alfred B.; Gerlach, RobinA number of proposed technologies involve the controlled implementation of biologically induced carbonate mineral precipitation in the geologic subsurface. Examples include the enhancement of soil stability [1], immobilization of groundwater contaminants such as strontium and uranium [2], and the enhancement of oil recovery and geologic carbon sequestration via controlled permeability reduction [3]. The most significant challenge in these technologies remains to identify and better understand an industrially, environmentally, and economically viable carbonate precipitation route.One of the most promising routes is ureolytic biomineralization, because of the ample availability of urea and the controllable reaction rate. In this process, ureolytic bacteria hydrolyze urea, leading to an increase in pH. In the presence of calcium, this process favors the formation of solid calcium carbonate, as illustrated in the following equations:CO(NH2)2 + H2O → NH2COOH + NH3→ 2 NH3 + CO2 (Urea hydrolysis) (1)2 NH3 + 2 H2O ↔ 2NH4+ + 2OH– (pH increase) (2)CO2 + 2 OH– ↔ CO32– + H2O(Carbonate ion formation) (3)CO32– + Ca2+ ↔ CaCO3 (solid)(Precipitation is favored at high pH) (4)This process relies on molecular-level chemical and biological processes that must be better understood for large-scale implementation.Researchers at the Center for Biofilm Engineering at Montana State University (USA) and Aberystwyth University (UK) have conducted several biomineralization experiments in simulated porous media reactors. Microscopy has proven to be one of the most useful analytical tools in these studies, providing the ability to non-invasively visualize, differentiate, and quantify the various components, including the cells, cell matrix, and mineral precipitates. Because of the possibility of real-time observation and the lack of dehydration artifacts, microscopy has been tremendously useful for elucidating the temporal and spatial relationships of these components.Item Influence of carbon sources and electron shuttles on ferric iron reduction by Cellulomonas sp. strain ES6(2011-09) Gerlach, Robin; Field, E. K.; Viamajala, Sridhar; Peyton, Brent M.; Apel, William A.; Cunningham, Alfred B.Microbially reduced iron minerals can reductively transform a variety of contaminants including heavy metals, radionuclides, chlorinated aliphatics, and nitroaromatics. A number of Cellulomonas spp. strains, including strain ES6, isolated from aquifer samples obtained at the U.S. Department of Energy’s Hanford site in Washington, have been shown to be capable of reducing Cr(VI), TNT, natural organic matter, and soluble ferric iron [Fe(III)]. This research investigated the ability of Cellulomonas sp. strain ES6 to reduce solid phase and dissolved Fe(III) utilizing different carbon sources and various electron shuttling compounds. Results suggest that Fe(III) reduction by and growth of strain ES6 was dependent upon the type of electron donor, the form of iron present, and the presence of synthetic or natural organic matter, such as anthraquinone-2,6-disulfonate (AQDS) or humic substances. This research suggests that Cellulomonas sp. strain ES6 could play a significant role in metal reduction in the Hanford subsurface and that the choice of carbon source and organic matter addition can allow for independent control of growth and iron reduction activity.Item NMR measurement of hydrodynamic dispersion in porous media subject to biofilm mediated precipitation reactions(2011-03) Fridjonsson, E. O.; Seymour, Joseph D.; Schultz, Logan N.; Gerlach, Robin; Cunningham, Alfred B.; Codd, Sarah L.Noninvasive measurements of hydrodynamic dispersion by nuclear magnetic resonance (NMR) are made in a model porous system before and after a biologically mediated precipitation reaction. Traditional magnetic resonance imaging (MRI) was unable to detect the small scale changes in pore structure visualized during light microscopy analysis after destructive sampling of the porous medium. However, pulse gradient spin echo nuclear magnetic resonance (PGSE NMR) measurements clearly indicated a change in hydrodynamics including increased pore scale mixing. These changes were detected through time-dependent measurement of the propagator by PGSE NMR. The dynamics indicate an increased pore scale mixing which alters the preasymptotic approach to asymptotic Gaussian dynamics governed by the advection diffusion equation. The methods described here can be used in the future to directly measure the transport of solutes in biomineral-affected porous media and contribute towards reactive transport models, which take into account the influence of pore scale changes in hydrodynamics.Item Darcy-scale modeling of microbially induced carbonate mineral precipitation in sand columns(2012-07) Ebigbo, Anozie; Phillips, Adrienne J.; Gerlach, Robin; Helmig, Rainer; Cunningham, Alfred B.; Class, Holger; Spangler, Lee H.This investigation focuses on the use of microbially induced calcium carbonate precipitation (MICP) to set up subsurface hydraulic barriers to potentially increase storage security near wellbores of CO2 storage sites. A numerical model is developed, capable of accounting for carbonate precipitation due to ureolytic bacterial activity as well as the flow of two fluid phases in the subsurface. The model is compared to experiments involving saturated flow through sand-packed columns to understand and optimize the processes involved as well as to validate the numerical model. It is then used to predict the effect of dense-phase CO2 and CO2-saturated water on carbonate precipitates in a porous medium.Item Potential CO2 leakage reduction through biofilm-induced calcium carbonate precipitation(2013-01) Phillips, Adrienne J.; Lauchnor, Ellen G.; Eldring, Joseph; Esposito, R.; Mitchell, Andrew C.; Gerlach, Robin; Cunningham, Alfred B.; Spangler, Lee H.Mitigation strategies for sealing high permeability regions in cap rocks, such as fractures or improperly abandoned wells, are important considerations in the long term security of geologically stored carbon dioxide (CO2). Sealing technologies using low-viscosity fluids are advantageous in this context since they potentially reduce the necessary injection pressures and increase the radius of influence around injection wells. Using aqueous solutions and suspensions that can effectively promote microbially induced mineral precipitation is one such technology. Here we describe a strategy to homogenously distribute biofilm-induced calcium carbonate (CaCO3) precipitates in a 61 cm long sandfilled column and to seal a hydraulically fractured, 74 cm diameter Boyles Sandstone core. Sporosarcina pasteurii biofilms were established and an injection strategy developed to optimize CaCO3 precipitation induced via microbial urea hydrolysis. Over the duration of the experiments, permeability decreased between 2 and 4 orders of magnitude in sand column and fractured core experiments, respectively. Additionally, after fracture sealing, the sandstone core withstood three times higher well bore pressure than during the initial fracturing event, which occurred prior to biofilm-induced CaCO3 mineralization. These studies suggest biofilm-induced CaCO3 precipitation technologies may potentially seal and strengthen fractures to mitigate CO2 leakage potential.Item Bacterially induced calcium carbonate precipitation and strontium coprecipitation in a porous media flow system(2013-02) Lauchnor, Ellen G.; Schultz, Logan N.; Bugni, S.; Mitchell, Andrew C.; Cunningham, Alfred B.; Gerlach, RobinStrontium-90 is a principal radionuclide contaminant in the subsurface at several Department of Energy sites in the Western U.S., causing a threat to groundwater quality in areas such as Hanford, WA. In this work, we used laboratory-scale porous media flow cells to examine a potential remediation strategy employing coprecipitation of strontium in carbonate minerals. CaCO3 precipitation and strontium coprecipitation were induced via ureolysis by Sporosarcina pasteurii in two-dimensional porous media reactors. An injection strategy using pulsed injection of calcium mineralization medium was tested against a continuous injection strategy. The pulsed injection strategy involved periods of lowered calcite saturation index combined with short high fluid velocity flow periods of calcium mineralization medium followed by stagnation (no-flow) periods to promote homogeneous CaCO3 precipitation. By alternating the addition of mineralization and growth media the pulsed strategy promoted CaCO3 precipitation while sustaining the ureolytic culture over time. Both injection strategies achieved ureolysis with subsequent CaCO3 precipitation and strontium coprecipitation. The pulsed injection strategy precipitated 71−85% of calcium and 59% of strontium, while the continuous injection was less efficient and precipitated 61% of calcium and 56% of strontium. Over the 60-day operation of the pulsed reactors, ureolysis was continually observed, suggesting that the balance between growth and precipitation phases allowed for continued cell viability. Our results support the pulsed injection strategy as a viable option for ureolysis-induced strontium coprecipitation because it may reduce the likelihood of injection well accumulation caused by localized mineral plugging while Sr coprecipitation efficiency is maintained in field-scale applications.Item Microbial CaCO3 mineral formation and stability in an experimentally simulated high pressure saline aquifer with supercritical CO2(2013-07) Mitchell, Andrew C.; Phillips, Adrienne J.; Schultz, Logan N.; Parks, Stacy L.; Spangler, Lee H.; Cunningham, Alfred B.; Gerlach, RobinThe use of microbiologically induced mineralization to plug pore spaces is a novel biotechnology to mitigate the potential leakage of geologically sequestered carbon dioxide from preferential leakage pathways. The bacterial hydrolysis of urea (ureolysis) which can induce calcium carbonate precipitation, via a pH increase and the production of carbonate ions, was investigated under conditions that approximate subsurface storage environments, using a unique high pressure (∼7.5 MPa) moderate temperature (32 °C) flow reactor housing a synthetic porous media core. The synthetic core was inoculated with the ureolytic organism Sporosarcina pasteurii and pulse-flow of a urea inclusive saline growth medium was established through the core. The system was gradually pressurized to 7.5 MPa over the first 29 days. Concentrations of NH4+, a by-product of urea hydrolysis, increased in the flow reactor effluent over the first 20 days, and then stabilized at a maximum concentration consistent with the hydrolysis of all the available urea. pH increased over the first 6 days from 7 to 9.1, consistent with buffering by NH4+ ⇔ NH3 + H+. Ureolytic colony forming units were consistently detected in the reactor effluent, indicating a biofilm developed in the high pressure system and maintained viability at pressures up to 7.5 MPa. All available calcium was precipitated as calcite. Calcite precipitates were exposed to dry supercritical CO2 (scCO2), water-saturated scCO2, scCO2-saturated brine, and atmospheric pressure brine. Calcite precipitates were resilient to dry scCO2, but suffered some mass loss in water-saturated scCO2 (mass loss 17 ± 3.6% after 48 h, 36 ± 7.5% after 2 h). Observations in the presence of scCO2 saturated brine were ambiguous due to an artifact associated with the depressurization of the scCO2 saturated brine before sampling. The degassing of pressurized brine resulted in significant abrasion of calcite crystals and resulted in a mass loss of approximately 92 ± 50% after 48 h. However dissolution of calcite crystals in brine at atmospheric pressure, but at the pH of the scCO2 saturated brine, accounted for only approximately 7.8 ± 2.2% of the mass loss over the 48 h period. These data suggest that microbially induced mineralization, with the purpose of reducing the permeability of preferential leakage pathways during the operation of GCS, can occur under high pressure scCO2 injection conditions.Item Engineered applications of ureolytic biomineralization: A review(2013-07) Phillips, Adrienne J.; Gerlach, Robin; Lauchnor, Ellen G.; Mitchell, Andrew C.; Cunningham, Alfred B.; Spangler, Lee H.Microbially induced calcium carbonate (CaCO3) precipitation (MICP) is a widely explored and promising technology for use in various engineering applications. In this review, CaCO3 precipitation induced via urea hydrolysis (ureolysis) is examined for improving construction materials, cementing porous media, hydraulic control, and remediating environmental concerns. The control of MICP is explored through the manipulation of three factors: (1) the ureolytic activity (of microorganisms), (2) the reaction and transport rates of substrates, and (3) the saturation conditions of carbonate minerals. Many combinations of these factors have been researched to spatially and temporally control precipitation. This review discusses how optimization of MICP is attempted for different engineering applications in an effort to highlight the key research and development questions necessary to move MICP technologies toward commercial scale applications.Item Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study(2016-04) Phillips, Adrienne J.; Cunningham, Alfred B.; Gerlach, Robin; Hiebert, Dwight Randall; Hwang, Chiachi; Lomans, B. P.; Westrich, Joseph; Mantilla, C.; Kirksey, J.; Esposito, R.; Spangler, Lee H.A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment.