Total number of abstracts: 33
Number of institutions represented: 21
List of Posters
ICBBGPoster-1
Title: Designs of optimal and efficient bio-inspired drilling into lunar regolith for space exploration
Authors: Lei Wang; Liang Zhang
Institute: University of Cincinnati
Abstract: In recent years, many nations have launched lunar exploration missions. Designing an optimal lunar drill and determining its controlling strategies become crucial to the research on the lunar regolith. This paper presents a discrete element modeling and multi-objective optimization design framework for the bio-inspired drill design into the lunar regolith. An adaptively updating two-stage multi-objective optimization design framework based on Multivariate Adaptive Regression Splines (MARS) is proposed for the design of the bio-inspired drill into the lunar regolith. In this framework, the geometry parameters (i.e., anchor height, anchor shape, and cone apex angle) and the controlling strategies (i.e., downward velocity, rotation velocity, expansion velocity, and anchor-cone distance) are optimized in Stage 1 and Stage 2, respectively, aided by discrete element modeling of the bio-inspired drilling process. The proposed discrete element modeling and design optimization framework provide an efficient solution for the design of a bio-inspired drill into the lunar regolith, which can also serve as a guide for the design of bio-inspired tools and technologies for other extraterrestrial bodies.
ICBBGPoster-2
Title: Exploring the Potential of Microbially Induced Struvite Precipitation (MISP) for Clay Stabilization
Authors: Hua Yang; Chung Yee Kwok; Wei Li
Institute: The University of Hong Kong
Abstract: Microbially induced struvite precipitation (MISP) has been demonstrated as a promising technique for sand stabilization, offering reduced ammonia emissions compared to Microbially induced calcite precipitation (MICP), while achieving comparable strength. However, its applicability to clay stabilization remains unknown. This study evaluates the feasibility of MISP for stabilizing clay, incorporating specific adaptations and optimizations to enhance soil strength and minimizing ammonia emissions. The effects of urea concentration, magnesium salt concentration, and curing time on stabilization were systematically examined. The results demonstrate that the modified MISP method can achieve a strength up to 2.77 times greater than MICP. While the modified MISP significantly reduces ammonia emissions, the by-product of carbon dioxide becomes a new problem. This issue, however, can be mitigated through the addition of alkaline salts. The findings highlight the potential of MISP as a sustainable and efficient alternative for clay stabilization.
ICBBGPoster-4
Title: Trenches for Peace through Bio-Inspired Soil Improvement
Authors: Yvo Veenis; Nico Heijligers (Franki Grondtechnieken); Leon van Paassen (CBBG); Caroline van de Steenoven (GTBV); Ronny van der Heijden (GTBV)
Institute: Groundwater Technology BV
Abstract: Studio Marco Vermeulen, Landscape Architects, designed a ‘landscape monument’ that allows visitors to view military operations at the Eindhoven training facility (army as well as air force) from a ‘trench’ perspective. Creating life-size trenches in the shape of the international peace symbol (diameter: 70 m), clearly visible on Google Earth, makes a powerful statement. Franki Grondtechnieken was commissioned by the Municipality of Oirschot, The Netherlands, to physically create this work of art. Franki collaborated with Groundwater Technology and CBBG to design and implement the project. The installation was completed in 2020 and has been open to the general public ever since. Extreme precipitation in winter 2023-2024 and a very wet autumn/early winter 2024-2025 flooded the trenches, exposing the MICP-stabilized soils to open water. This poster contribution presents the results of: The application of MICP at this site; Laboratory tests on soil samples using the BISI to optimize recipes and application modes, including in situ recording of the efficacy of the biological process; Lessons learned from the implementation; Longevity of the MICP results when exposed to the elements; Long-term monitoring of the fate and transport of MICP by-products in the natural soil and groundwater beneath this work of art. Poster Presentation: Sections on the Poster: Full-scale MICP application; Lessons learned; Longevity of the MICP when exposed to the elements, including recent photos; Long-term monitoring of the fate of by-products (up to January 2025); Conclusions, citations/acknowledgments, references; Background image: Aerial photo of the trench.
ICBBGPoster-5
Title: Comparative Study on the Impact of EICP Biocementation on the Hydraulic Properties of Sandstone
Authors: Mary Ngoma; Dr. Oladoyin Kolawole
Institute: New Jersey Institute of Technology
Abstract: Biological-induced rock alteration is a process that harnesses biogeochemical activities to change the hydraulic properties and behavior of rocks. It often relies on enzyme-induced carbonate precipitation (EICP) which utilizes biomineralization by promoting the formation of calcium carbonate (CaCO3) in the rock discontinuities. However, there is still a lack of knowledge on the impact of biocementation on the hydraulic properties of rocks at varying scales. This study uses non-destructive methods to investigate the micro- and core-scale effect of EICP biocementation in sandstones. We first conducted a biological treatment of sandstone rock samples using an enzyme over 3 days at a temperature of 30°C. Subsequently, the pore-structural and resultant permeability change of the treated samples were measured using Microcomputed tomography (micro-CT). Further, we assessed the bulk-scale hydraulic properties (permeability) using the gas permeability test technique. We then evaluated and compared the influence of biocementation on the assessment of hydraulic properties at the micro (micro-CT) bulk scale (gas permeability test). The results suggest that in sandstone rocks, enzyme-induced biocementation can impact rock pores and fractures at micro- and core-scales resulting in an enhancement of the hydraulic properties of bio-cemented rocks.
ICBBGPoster-6
Title: Unconfined Compressive Strength Variability in EICP-Treated Ottawa 20-30 Sands
Authors: Logan Tsosie; Edward Kavazanjian
Institute: Arizona State University
Abstract: Enzyme-induced carbonate precipitation (EICP) was used to biocement five distinct batches of “standard” Ottawa 20-30 sand sourced from different vendors but recovered from the same geological formation. Despite being subjected to identical biocementation processes, the sands show significant variance in unconfined compressive strength (UCS). The results of x-ray diffraction and sieve analysis confirmed that all samples shared similar mineral compositions, and grain sizes distributions. The results from the scanning electron microscopy (SEM) and optical microscopy analysis suggest that the surface characteristics of these standard sands play a significant role in determining their UCS. These results highlight the importance of understanding the influence of the physical surface properties on the effectiveness of biocementation techniques, which has implications for their application in geotechnical engineering for ground improvement and sustainable construction practices.
ICBBGPoster-7
Title: Surficial Crust Formation and Fugitive Dust Suppression Using Fungi-Induced Biocementation
Authors: Anna Kwablah; Taylor Tuckett; Emmanuel Salifu
Institute: Arizona State University
Abstract: This study investigates the potential application of urease-positive fungi for biocementation through calcium carbonate precipitation as a sustainable approach to mitigate wind-induced soil erosion in arid environments. The urease enzyme facilitates urea hydrolysis, triggering a series of biochemical reactions that culminate in calcium carbonate precipitation, resulting in biocementation and crust formation. A notable advantage of ureolytic fungi is the spatial mobility and growth of fungal mycelium, which promotes a more homogeneous distribution of calcium carbonate, thereby improving material efficiency and performance. Laboratory experiments were conducted to evaluate the mechanisms of surficial crust formation under varying fungal culture conditions and soil treatment methods using Fungal-Induced Calcium Carbonate Precipitation (FICP). The study also assessed the effectiveness of FICP in reducing dust emissions from wind erosion-prone desert soils. Key evaluation parameters included calcium carbonate content, crystal polymorphs, crust strength, mycelial biomass and morphology, and dust emission. These were analyzed using loss-on-ignition tests, calcimeter tests, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), penetration resistance tests, and the Portable In Situ Wind Erosion Laboratory (PI-SWERL™). Results confirmed successful calcium carbonate precipitation and significant dust suppression, even at minimal treatment concentrations. This demonstrates the potential of FICP as an efficient and environmentally friendly solution for mitigating wind erosion in desert soils. Future research should focus on optimizing treatment protocols for a wider range of soil types and exploring the use of native fungal strains to enhance applicability and scalability. This work highlights FICP’s promise as a novel biogeotechnical solution for addressing soil erosion challenges in arid and semi-arid regions.
ICBBGPoster-9
Title: Predicting the mechanical behavior of MICP-treated sands based on untreated soil properties
Authors: Gloria M. Castro; Mary Anderson; James Minto; Qi Zhang; Grainne El Mountassir; Rebecca Lunn
Institute: University of Birmingham
Abstract: Microbially Induced Carbonate Precipitation (MICP) is a promising bio-mediated method for enhancing the mechanical properties of porous media. Studies have explored various MICP treatments and their effects on coarse-grained soils, demonstrating improvements in transmission properties (e.g., ultrasound wave and permeability) and strength, as measured by direct shear, Uniaxial Compressive Strength (UCS), tensile, and triaxial tests. Despite these advancements, predicting the achievable soil strength post-MICP treatment remains challenging. Our study draws from a vast array of triaxial test results from both literature and new experimental analyses to introduce a framework that predicts compressive strength evolution in MICP-treated sands based on calcite content and index soil properties. Initial analysis highlighted a specific data gap regarding angular sand treatments. To address this, we performed consolidated-drained triaxial tests in MICP-treated highly angular sand, with variable MICP treatments cycles to achieve different cementation levels. Post-treatment, specimens were analyzed with X-CT scans before and after undergoing consolidated-drained triaxial tests, providing insights on deformation behaviors at failure. This comprehensive data set enabled the calibration of a beta factor within a pre-existing model, allowing for the prediction of UCS values based on initial porosity, calcite content, and untreated soil properties. When applied to UCS data from additional literature, the model demonstrated remarkable consistency with existing findings. This research establishes a solid foundation for accurately predicting the mechanical improvement of MICP-treated sands, marking a significant advancement towards the reliable application of bio-mediated soil enhancement techniques.
ICBBGPoster-11
Title: Enhancing Seismic Resistance of Liquefiable Sands Using Polysaccharide-Based Biopolymer Treatment
Authors: Dong-Yeup Park; Hyun-Joong Hwang; Dong-Hyeong Choi; Gye-Chun Cho
Institute: Korea Advanced Institute of Science and Technology
Abstract: Geotechnical engineering has proposed numerous techniques to mitigate seismic liquefaction and minimize earthquake-induced damage. Among these, cement-based soil stabilization is widely recognized as a conventional method for improving ground stability through injection techniques. However, the use of cement in injection applications poses several challenges, including adverse effects on human health due to the interaction of cement with groundwater and limited effectiveness in attenuating seismic waves. In recent years, biopolymer-based soil treatment (BPST) has gained attention as a sustainable alternative in geotechnical soil improvement. This study focuses on evaluating the enhancement of seismic resistance in liquefiable loose sands treated with polysaccharide-based biopolymers. Cyclic resistance was assessed using a cyclic direct simple shear (CDSS) apparatus, while a centrifuge model test was conducted to validate the liquefaction resistance of BPST further. The results demonstrate that BPST significantly improves the resistance of soils vulnerable to liquefaction. However, further research is necessary to optimize the treatment methodology for practical implementation.
ICBBGPoster-12
Title: Effects of plant-derived ureases on calcium carbonate characteristics through enzyme-induced carbonate precipitation: a microfluidic chip experiment
Authors: Yi Bian; Yanbo Chen; Liangtong Zhan; Yufeng Gao
Institute: Zhejiang University
Abstract: Enzyme-induced carbonate precipitation (EICP) has been extensively studied as an alternative to Microbial-induced carbonate precipitation (MICP) in recent years. This study aims to investigate the effects of different plant-derived ureases on the morphology, growth, size, and distribution of calcium carbonate at particle-scale within microfluidic chips. The commercial urease (CU), as well as crude sword bean urease (SWU), jack bean meal (JBM), and soybean urease (SOU) were used. The results revealed that crystal morphology and growth are noticeably influenced by organic molecules in different ureases. Relatively low concentrations of organic molecules in SWU and JBM may provide heterogeneous nucleation sites and promote crystal growth, thus achieving the largest individual crystal and total crystal area. For CU, smaller crystal size and total crystal area were observed due to tiny amounts of organic molecules. A high concentration of organic molecules in SOU would limit crystal nucleation and growth, thereby achieving smaller crystal size and total crystal area. In addition, crystals in Test-SWU and Test-JBM present preferential deposition at interparticle contacts with better cementation type than Test-CU and -SOU. Acid digestion experiments were also conducted to provide evidence for the hypothesis that organic matter precipitates induced by crude ureases act as heterogeneous nucleation sites. SWU and JBM are recommended as raw materials for EICP to enhance the engineering properties of soil.
ICBBGPoster-13
Title: Shear Behavior of calcareous sand treated with Fungal-Induced Calcite Precipitation
Authors: Akanksha Bhurtel; Akanksha Bhurtel; Emmanuel Salifu; Sumi Siddiqua
Institute: University of British Columbia, Okanagan Campus.
Abstract: The general approach for soil stabilization includes the addition of chemical additives such as cement or other coal combustion bioproducts into the soil. However, these materials are responsible for increasing the carbon footprint in the environment. Microbial-induced calcite Precipitation (MICP), one of the biomediated techniques, could be considered an alternative treatment method for reducing cement production. Usually, this method utilizes bacterial strain; the urease enzymes in the microorganism are activated by reacting with urea and cementing solutions. Apart from bacteria, many non-hazardous urease active fungal strains have the potential for biomineralization. Also, the fungal strains can extend filamentous hyphal extensions into the voids of the soil, entangling them. The following research focuses on the shear behavior of sand treated by the ureolytic fungus Penicillium chrysogenum, adopting the bioaugmentation technique. The samples were prepared by injecting fungal suspension into a sand column setup, and the cementing solutions were introduced to the system after the complete growth of fungus in the soil. The shear behavior of the sand was analyzed with the help of the uniaxial compression test (UCS). The uniformity of calcium carbonate (CaCO3) precipitation was inspected in 3 layers by measuring CaCO3 concentration with the help of a calcimeter, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electronic Microscopy (SEM). UCS test reveals an improvement in the shear property of the sand with uniform crystallization in the hyphal extensions.
ICBBGPoster-15
Title: Biotechnical Erosion Control for Lake Michigan Shoreline Protection
Authors: Rebecca Jones; Minchae Seok; Dr. Kyle Kershaw
Institute: Rose-Hulman Institute of Technology
Abstract: Recent water level fluctuations, intense storms, and changes in freeze-thaw patterns on and around Lake Michigan have exacerbated the existing problem of shoreline erosion. Adaptable and resilient stabilization methods are needed to protect natural ecosystems and human infrastructure because of uncertainties in weather patterns related to climate change. Along the vast shoreline of Lake Michigan, many different methods of stabilization have been employed. Hardscape solutions are relatively common in highly developed areas, but are expensive and may result in unintended consequences to adjacent properties and natural ecosystems. Other, more sustainable methods have been used, but some are unproven and lack engineering design standards. Biotechnical erosion control is one such sustainable option. This poster presentation explains the methodology behind an ongoing scale model experimental program to assess the effectiveness of biotechnical erosion control options. A modified Emriver wave table is being used to assess soil movement with different erosion control options. Non-color-coded modeling media ranging in particle sizes of 0.4mm to 2.0mm was used to model sediment transportation. The baseline data assed the sediment transport of the modeling material at different slopes. Once the baseline was established, different erosion control options were added to the experiment to determine their effectiveness and collect quantitative data. The biotechnical option was modeled using thread to create a pseudo-vegetated mat and placed in the wave table to mimic the root structures of Ammophila breviligulata (American beachgrass).
ICBBGPoster-16
Title: Characterizing Granular Materials for Development of a Deployable Granular Anchor
Authors: Navleen Kaur; Aly Ghanem; Alejandro Martinez
Institute: University of California, Davis
Abstract: Geotechnical site characterization is crucial for construction activities to estimate soil conditions. However, access to sites in remote locations, steep slopes, or congested areas can be challenging. This is a particular problem for in-situ testing and drilling to obtain samples owing to the large size of the rigs. A bio-inspired probe is being developed to enable the performance of in-situ tests with smaller equipment. This bio-inspired probe will include a deployable anchor filled with a granular material that can generate the reaction force needed to advance the probe. The phase-changing properties of granular materials are beneficial for the desired performance. Specifically, the granular material is first fluidized during anchor deployment, allowing it to change shape as the anchor is expanded. Suction is then applied to solidify to increase the material’s strength so that it can resist the loads applied during anchorage. This study aims to identify candidate granular materials that can be used for the successful design of a deployable granular anchor. Six materials were tested, including two natural sands, three abrasives (walnut shell, garnet, and aluminum oxide), and a lunar regolith simulant. Angle of repose (AoR) and direct shear (DS) tests were performed on the six materials to characterize their peak and critical state friction angles and their dilative behavior. The results are analyzed as a function of the materials’ particle shape, revealing that the materials with smaller roundness and sphericity exhibit greater internal friction angles. Among the materials tested, the lunar regolith simulant, aluminum oxide abrasive, and garnet grit showed the greatest friction angles, making them promising materials for the granular anchor. These materials have the ability to increase the internal capacity of the granular anchor, allowing the probe to advance to greater depths in the soil.
ICBBGPoster-17
Title: Ground Improvement by Large Amplitude Penetration
Authors: Miguel Eduardo Olivas Mendez; Douglas D. Cortes
Institute: New Mexico State University
Abstract: In large construction projects such as bridges, one of the main methods of distributing the loads from the structure to the ground are pile foundations. Pile foundations are steel or concrete cylinders which rely on the friction on their sides and the normal force on their tip to bear the design load imposed on them. The design of these piles involves the determination of a required depth of embedment in which either the side friction is enough to bear the design load, or the tip of the pile has reached a bedrock layer. Pile foundations are normally built in one of two ways, drilled or driven. In drilled piles, a hole is drilled into the ground and then reinforcing steel and concrete is placed within the hole. Driven piles are precasted and pushed into the ground. This project looks to improve the ground during construction of driven piles to reduce the required depth of embedment and therefore reduce the concrete and steel used for a project.
ICBBGPoster-18
Title: Cost Comparison for CVOCs and 1,4-Dioxane Treatment: In Situ Aerobic Cometabolic Biodegradation versus Active Pump-and-Treat Through an Advanced Oxidation Process
Authors: Aide Robles; Dr. Min-Ying Jacob Chu; Darrin Costantini
Institute: Haley Aldrich
Abstract: Despite years of research and technology development, chlorinated volatile organic compounds (CVOCs) and 1,4-dioxane (1,4-D) remain a primary suite of contaminants of concern for many sites. One of the greatest remaining challenges for remediating these recalcitrant compounds at sites is the treatment of deep, large, dilute plumes that contain CVOCs and 1,4-D. Active remediation is often cost-inefficient and establishing and maintaining reducing conditions for anaerobic biological treatment for CVOCs can be difficult as well as ineffective in treating 1,4-D. The current energy-intensive approach, pump-and-treat through advanced oxidation process (AOP) needed to degrade 1,4-D, comes with high cost for installation, and operation and maintenance. In situ aerobic cometabolic biodegradation (ACB) has been shown in field and laboratory demonstrations to effectively treat 1,4-D and several CVOCs. This study presents a cost comparison between the combined granular activated carbon (GAC) and in situ ACB approach and the active pump-and-treat approach that utilizes an AOP for a hypothetical scenario associated with treatment of a deep, large, dilute plume that contains 1,4-D, PCE, TCE, and 1,1-DCE. The cost comparison study was completed based on data from a field demonstration test that utilized bioaugmentation and groundwater recirculation to treat 1,4-D in situ and used an aboveground GAC unit primarily for CVOC treatment; in addition, cost data from other project experiences related to a pump-and-treat system that required an AOP were also used. The combined GAC and in situ ACB approach was 43% more cost-effective than the pump-and-treat method. Key cost drivers included chemical cost, pump-and-treat equipment costs, and electrical consumption, rather than concentrations of contaminants. This cost comparison highlights the importance of considering operational factors when evaluating treatment options for large, deep, dilute plumes.
ICBBGPoster-19
Title: Benefit of Bioaugmentation for Aerobic Cometabolism - Field Case Studies
Authors: Min-Ying Jacob Chu; Dr. Aide Robles
Institute: Haley & Aldrich, Inc.
Abstract: Success of using an anaerobic culture containing Dehalococcoides spp., which can metabolically degrade chlorinated ethenes to environmentally friendly products, has encouraged practitioners to apply bioaugmentation for treating groundwater impacted by emerging contaminants. Aerobic cometabolic biodegradation (ACB) is recognized as a promising technology to treat dilute plumes containing emerging contaminants, such as 1,4-dioxane (1,4-D), ethylene dibromide (EDB), 1,2,3-trichloropropane (1,2,3-TCP), and N-nitrosodimethylamine (NDMA). The main difference between metabolic biodegradation and cometabolic biodegradation is that bacteria that carry out metabolic biodegradation of contaminants can obtain sufficient energy for growth, but bacteria that carry out aerobic cometabolic biodegradation cannot obtain sufficient energy for growth, thereby needing external supply of growth substrate to support contaminant degradation. It is believed that, without the advantages of using a contaminant as a growth substrate, bioaugmentation of an ACB-capable culture has not received comparable success like the use of a Dehalococcoides spp. containing culture. In this presentation, we will present three case studies to discuss considerations needed to increase the probability of success when using ACB bioaugmentation cultures. The first case study is associated with the use of the engineered bacterial strain Burkholderia cepacia PR1301. The PR1301 strain can use lactate as the primary substrate and constitutively expresses toluene ortho-monooxygenase (toluene 2-monooxygenase) whereas the native strain cannot express this enzyme when grown on lactate. It was found that this bacterial strain likely could not effectively compete with indigenous bacterial population for the added lactate. The second case is associated with the use of Rhodococcus ruber ENV425 for NDMA biodegradation; the strain ENV425 appeared to be completely replaced by native propane consuming bacteria over time without an obvious impact on treatment efficiency. The third case study shows that the competition of four bioaugmentation cultures for 1,4-D biodegradation led to the enrichment of Mycobacterium spp. and demise of Rhodococcus spp.
ICBBGPoster-20
Title: Effect of Enzyme-Induced Carbonate Precipitation (EICP) on Hydraulic Conductivity of Sands
Authors: Noah Madrigal; Emilia Marmolejo, Sergio Ruiz Trujillo, Paola Bandini
Institute: New Mexico State University
Abstract: Enzyme Induced Carbonate Precipitation (EICP) is a biogeotechnical ground improvement technique. The EICP chemical reaction consists of hydrolysis of urea, catalyzed by free urease enzyme, to precipitate calcium carbonate creating a weakly cemented soil. An application of the EICP technique under development is the creation of a cemented crust to mitigate soil erosion from rainfall runoff. For this application, potentially reducing the permeability of the sand with EICP treatment could unintentionally increase runoff. Thus, the permeability of EICP-treated sand should be preserved while reducing the susceptibility to erosion. The literature about the impact of EICP treatments on hydraulic conductivity of sand is inconclusive. The present study discusses the findings of a series of laboratory tests conducted to assess the hydraulic conductivity of EICP-treated and untreated sand. Test specimens were prepared using three soils: Ottawa 20-30 sand, Chaparral #2 sand, and Blended soil. Chaparral #2 is a quarry sand, and Blended soil is a laboratory prepared sand mixture. Soil specimens were prepared with targeted relative densities of 55% and 80% and received 0 through 9 treatment cycles applied by percolation. The results were evaluated based on hydraulic conductivity, calcium carbonate content throughout the specimen’s length, and scanning electron microscopy (SEM). The results of the treated specimens indicated relatively small changes in hydraulic conductivity when compared with the corresponding untreated specimens, regardless of number of treatment cycles and relative density states. A comparative analysis in hydraulic conductivity showed similarities between Chaparral #2 and Blended soil samples, and a marginally higher hydraulic conductivity for Ottawa 20-30 specimens. The calcium carbonate content was in the range of 0-8.3%, depending on the number of treatment cycles, density, and sand type. SEM of selected treated specimens confirmed calcite precipitation. Overall, the reduction in hydraulic conductivity as the number of treatment cycles increased was not significant.
ICBBGPoster-21
Title: Cometabolic Degradation of Chlorinated Solvents in Cultures Fed with Propane and Methanol
Authors: Riley Berg; Anca G. Delgado
Institute: Arizona State University
Abstract: Large, dilute plumes of chlorinated solvents in groundwater are challenging to remediate, driving the need to continue the advancement of innovative and sustainable treatments like aerobic cometabolism. The use of primary substrates (carbon sources) necessary for microbial growth is often hindered by impurities in the substrates as well as logistical difficulties in their delivery and distribution at field sites. Challenges with propane, such as low solubility, volatility, and uneven distribution, can be mitigated by using methanol instead. Long term experiments (40-100 days) were conducted using microbial mixed/enriched cultures to evaluate the degradation of trichloroethylene (TCE) and 1,1-dichloroethylene (1,1-DCE) while comparing the efficiency of propane and methanol as primary substrates. Aerobic conditions, a neutral pH (6.8-7.1), and carbon source levels were carefully monitored and controlled as desired. Complete degradation of low concentrations of 1,1-DCE (3 µM) and TCE (10 µM) was achieved with propane as the carbon source. However, higher concentrations of 1,1-DCE (50 µM) showed initial degradation followed by stagnation, likely due to toxicity. Comparable degradation rates were observed with methanol as the carbon source, suggesting its potential as a safer and more practical alternative to propane. Once a carbon source was fully depleted, the degradation of the contaminant was slowed until ceasing entirely, emphasizing the importance of the primary substrate in cometabolic processes. These findings demonstrate the potential of methanol as a viable primary substrate for aerobic cometabolism, offering a safer and more practical alternative to propane for field-scale remediation of chlorinated solvent plumes. This will help advance the development of aerobic cometabolism technologies for remediating dilute chlorinated solvent plumes.
ICBBGPoster-23
Title: Microbial Chain Elongation Supports Reductive Dechlorination of Chlorinated Ethenes: Outlook from a Study at a Superfund Site
Authors: Caleb McLaughlin; Anca Delgado; Aide Robles; Peter Bennett; Min-Ying Jacob Chu; Michael Calhoun
Institute: Biodesign Swette Center for Environmental Biotechnology & Center for Bio-mediated and Bio-inspired Geotechnics
Abstract: Chlorinated solvents like trichloroethene (TCE) are toxic groundwater contaminants commonly treated via in situ reductive dechlorination, a process reliant on dechlorinating bacteria fed by H2-producing bacteria. However, substrate delivery challenges, particularly due to site-specific hydrogeology and microbial communities, limit the effectiveness of this process. In situ reductive dechlorination has been a major treatment approach at a Superfund Site in the San Francisco Bay Area, but due to the aforementioned challenges, treatment abilities reached a bottleneck. Specifically, traditional H2-generating substrates molasses, lactate, and emulsified vegetable oil are rapidly consumed and diverted towards non-dechlorinating microbial communities (e.g., methanogens). At the same time, these highly viscous substrates led to (bio)clogging in Site injection wells, limiting further substrate injection. These issues prompt a need for low viscosity substrates that do not clog wells and alternative H2-producing bacteria that effectively deliver H2 to dechlorinating bacteria. Chain-elongation is a H2-producing bacterial metabolism where short-chain carboxylates (e.g., acetate) are elongated to medium-chain carboxylates using reduced organic compounds (e.g., ethanol). Chain-elongation has been demonstrated as an effective approach to support complete reductive dechlorination of TCE in microcosm studies by using low viscosity substrates ethanol and acetate while demonstrating potential to inhibit competing microorganisms (i.e., methanogens). The current study is the first field examination of microbial-chain elongation-driven reductive dechlorination. Two field tests, a groundwater push-pull test and a groundwater recirculation test, were performed at the Site using ethanol and acetate as substrates. The 8-week push-pull test revealed that microbial-chain elongation-driven reductive dechlorination could be achieved in situ and identified the need for bioaugmentation with a chain-elongating culture (MAT-1 from Arizona State University) and greater substrate concentrations at the Site. Lessons learned were utilized in the subsequent 10-week groundwater recirculation test, in which greater extents of chain elongation and reductive dechlorination were achieved.
ICBBGPoster-25
Title: Angelwing shells (cyrtopleura costata) inspired rock drilling
Authors: Jackson Stewart; Yumeng Zhao; Jackson C. Stewart; Sheng Dai
Institute: Georgia Institute of Technology
Abstract: Drilling has played a significant role in the history of human civilization and remains crucial to modern infrastructure construction. To drill to greater depths, through extreme environments and hazardous areas, novel drilling technologies must be developed to reduce costs and improve safety. Nature presents biological drilling examples to inform modifications and innovations to current drilling technologies. This poster presents a combined experimental and numerical investigation into the drilling mechanisms of the angelwing clam (cyrtopleura costata). Discrete element method (DEM) was used to examine the influence of denticle curvature, rake angle, and spacing on boring efficiency. Bio-inspired drill bits incorporating optimized cutter face curvature and rake angle were designed, 3D-printed, and tested with a bench-scale prototype with wax drilling substrate. Drilling parameters rate of penetration (ROP) and weight on bit (WOB) were measured and demonstrate increased efficiency of the bio-inspired design compared to a conventional design.
ICBBGPoster-26
Title: Biogenic and Geogenic Origins of Glauconite Sands and the Glauconitization Processes
Authors: Guoping Zhang; Wei Sun; Md Ashikuzzaman; Zachary Westgate; Don DeGroot
Institute: University of Massachusetts Amherst
Abstract: Recent offshore wind energy development in the US Atlantic Coast has encountered an intricate, challenging marine sediment, glauconite sand, which is classified as an “Offshore Geohazard” by the wind energy industry. Glauconite is an Fe‐rich mica that forms in shallow marine environments as a result of weathering of silicates with fecal pellets or foraminifera under reducing or suboxic conditions. Visually the deposit appears to be a coarse‐grained, bluish green sand featuring cross-through white and yellowish cracks. Such deposits can be authigenic or allogenic depending on local/regional geological processes and alterations. Under remolding (e.g., induced by compression and shearing from pile installation) at stresses as small as finger pressures, the initially sandy deposit readily degrades into a very soft, highly plastic, cohesive clayey material. An intricate puzzle is that such a remolding process leads to a change in color, from a brownish sand to a pure/dark green clay. Such alterations also inevitably lead to a significant reduction in the mechanical strength and stiffness, which undermines the stability and safety of the wind turbine systems built in it. The poster presents a compressive chemical, compositional, and microstructural characterization of the intriguing glauconite sand recovered from the Mid-Atlantic Coast, and the wealth of new data and findings enables the integration and interpretation of both biogenic and geogenic origins along with the glauconitization processes. Compositional analyses reveal the presence of glauconite mineral, swelling clays, pyrite, gypsum, and siderite within a single glauconite sand particle, while microstructural imaging uncovers the inclusion of biogenic silica and carbonates (including siderite and dolomite), most likely inherited from the initial organic fecal pellets and foraminifera. The microbial decompositions may have led to the transformation of organic matter, silicate dissolution, and mineral transformation to Fe-rich smectites. Subsequent geogenic processes are featured by the chemical exchanges between the maturing glauconite grains and the local marine environments rich in Fe and K, resulting in the formation of pyrite and glauconite. In essence, both biogenic and geogenic processes are intertwined with the chemical exchanges between the glauconitic grain and localized submarine environment, with the intake of Fe3+/Fe2+, Mg2+, and K+, but the leaching of Al3+ and Si4+. This new knowledge has engineering implications on the anomaloys mechanical behavior of this special sediment.
ICBBGPoster-27
Title: Bio-Mediated Soil Improvement Using Xanthan Gum and Sticky Rice
Authors: Shafi Ullah; Xiong (Bill) Yu
Institute: Case Western Reserve University
Abstract: Soil stabilization constitutes a fundamental process in geotechnical engineering, underpinning the construction of resilient infrastructure. Soil stabilization is traditionally achieved through the application of cement and lime, both of which improve soil strength and durability. However, these materials contribute significantly to atmospheric carbon dioxide (CO₂) emissions, posing environmental challenges. Consequently, researchers and geotechnical experts have increasingly explored bio-based materials as sustainable and eco-friendly alternatives. This study examines the efficacy of xanthan gum (XG) and sticky rice (SR) as biopolymer stabilizers, comparing their geotechnical performance against untreated and lime-treated soils. A series of laboratory experiments was conducted to evaluate key properties, including unconfined compressive strength (UCS) tests to quantify mechanical strength, soil water characteristic curve (SWCC) analysis to assess water retention behavior, soil erosion tests to determine resistance to degradation, and scanning electron microscopy (SEM) to examine microstructural and strength improvement. These tests aim to evaluate the capacity of XG and SR to improve soil cohesion, stability, and environmental compatibility relative to traditional stabilizers. The experimental results demonstrated that both SR and XG exhibit potential as viable replacements for lime and cement in soil stabilization, attributable to their elevated mechanical strength, enhanced water retention, and effective control of soil erosion. Comparative analysis of performance under varying moisture conditions revealed distinct behaviors: SR demonstrated superior efficacy in wet conditions, whereas XG outperformed SR in dry conditions. These findings suggest complementary strengths between the two biopolymers, dependent on environmental moisture levels. To optimize geotechnical properties across a broader range of conditions, this study recommends the development of a composite stabilizer through the cross-linking of SR and XG. Such an approach could synergistically combine their respective advantages, yielding a material with exceptional mechanical and hydrological performance for soil stabilization applications.
ICBBGPoster-28
Title: Discrete Element Modeling of Biocemented Sand: Impact of Microscopic Calcite Characteristics on Macroscopic Properties
Authors: Chengshun Shang; Alejandro Martinez; Jason T. DeJong; Guillermo Casas; Miguel A. Celigueta
Institute: Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE), Universidad Politècnica de Catalunya (UPC)
Abstract: Microbially induced carbonate precipitation (MICP) is an innovative ground improvement technique that strengthens soil by facilitating the precipitation of calcium carbonate at particle contacts. The Discrete Element Method (DEM) provides a powerful tool to model the microstructure of biocemented sand at the particle-contact scale, enabling the prediction and explanation of its macroscopic mechanical properties, thus complementing experimental studies. In this study, biocemented sand is simplified as a combination of clean sand and cementation. First, with an RVE-scale particle packing, the parameters of Fontainebleau sand are calibrated and kept constant to isolate the influence of cement content and distribution on macroscopic mechanical properties. Based on the simplified morphology and distribution of cementation, the bond volume and spatial distribution for a given calcite content are determined. These cementation contact characteristics in DEM simulations are compared with CT scan data of biocemented Fontainebleau sand. Drained triaxial shear tests are conducted with the calibrated model to quantitatively assess the effects of cementation distribution, strength, and modeling approach on macroscopic mechanical properties. The modeling methodology is then applied to simulate biocemented Ottawa sand to evaluate its general applicability. Additionally, the shear wave velocity of the DEM sample is measured and compared with experimental results. By linking the microscopic cementation state to macroscopic shear wave velocity, this study aims to provide deeper insights into the mechanical behavior of biocemented sand from a microscale view.
ICBBGPoster-29
Title: “Solidifying” Bio-Mediated Soil Improvement Methods in GeoTech Tools
Authors: Santosh Pokharel; Dr. Leon Van Paassen, Dr. Edward Kavazanjian
Institute: Arizona State University
Abstract: Bio-mediated soil improvement methods are emerging techniques that utilize various biological processes, such as bio-cementation, bio-gas generation, and bio-film production, to enhance geotechnical performance. Increases in shear strength, reductions in hydraulic conductivity, and de-saturation in poor soil are just a few examples. Over the past few decades, extensive research has explored these methods across multiple scales, from controlled laboratory tests to full-scale field trials. These studies have demonstrated promising results, positioning bio-mediated methods as viable alternatives to conventional soil improvement strategies. Reliable control of reaction rates with well-understood biological catalysts, minimal site disruption with reduced environmental impact, and the capacity to utilize non-invasive monitoring techniques make bio-mediated approaches preferable over traditional methods, which are often site disruptive, costly, or involve complex field implementation procedures. Numerous research findings within this domain need thorough documentation and synthesis for dissemination to field practitioners, fellow researchers, and students. This study aims to gather pertinent information on bio-mediated techniques (bio-cementation and bio-gas generation) and synthesize this information to guide field implementation. It also suggests approaches for monitoring, quality control, and assessment in geotechnical engineering, as well as general information for individuals unfamiliar with bio-mediated techniques. This effort will substantially contribute to the field application of these emerging methods, benefiting both geotechnical practitioners and researchers alike.
ICBBGPoster-30
Title: Bio-Inspired Modulation of Granular Media Using Non-Newtonian Fluids
Authors: Mobina Taghaddosi; Nariman Mahabadi
Institute: Arizona State University
Abstract: Non-Newtonian fluids exhibit remarkable rheological properties, offering potential benefits for geotechnical engineering applications. Unlike water, which has a constant viscosity regardless of the applied shear rate, non-Newtonian fluids display shear-dependent behavior, meaning their viscosity changes with the rate of deformation. Shear-thickening fluids—whose viscosity increases with increasing shear rate—show promise for improving the mechanical response of granular soils under cyclic or dynamic loading conditions, such as those encountered during earthquakes. In contrast, shear-thinning fluids—whose viscosity decreases with increasing shear rate—can enhance particle mobility, reducing interparticle resistance and enabling more efficient soil displacement. This behavior suggests a potential mechanism for controlling soil response, with possible applications in excavation, ground improvement, and liquefaction mitigation. This study adopts a bio-inspired approach by drawing insights from natural systems that exhibit similar stress-responsive behaviors. A particularly compelling example is hagfish slime, which demonstrates a dual-mode rheological response. It shear-thins to reduce viscosity and facilitate escape from predators, yet thickens under extensional stress to form a protective, viscous barrier. Similarly, plant mucilage—a gel-like secretion—enables roots to penetrate compacted soils by reducing mechanical resistance through shear-thinning behavior. These biological systems reflect analogous principles to those employed in engineered shear-thinning and shear-thickening fluids, which are used to modulate flow and resistance in granular media for geotechnical applications. Using numerical simulations, we investigated the interactions between non-Newtonian fluids and granular soils. Shear-thinning fluids promoted particle mobility and facilitated excavation, while shear-thickening fluids formed high-resistance meta-structures that enhanced soil stability and redistributed internal stresses, mitigating liquefaction potential. Our findings suggest a nature-inspired strategy for modulating soil behavior, offering promising avenues for excavation, ground reinforcement, and liquefaction mitigation in geotechnical engineering.
ICBBGPoster-31
Title: Field-Scale Enzyme-Induced Carbonate Precipitation (EICP) Treatment for Erosion Mitigation in Sloping Ground
Authors: Sergio Ruiz Trujillo; Emilia Marmolejo; Paola Bandini
Institute: New Mexico State University
Abstract: Soil erosion poses a major threat in arid areas like New Mexico, particularly on sloped terrain. This study explores Enzyme-Induced Carbonate Precipitation (EICP) as a sustainable method for erosion control, focusing on refining its application for sloping sandy soils ahead of field-scale deployment. EICP uses urease to hydrolyze urea, precipitating calcium carbonate that weakly cements soil particles. EICP effectiveness was tested on six sandy soil specimens inclined at a 27 degrees slope using a calibrated rainfall simulator. Two spray methods (A and B) and three application sequences were assessed for their impact on erosion and calcium carbonate distribution. Sequence 2—applying 30% of the void volume in each of five treatment cycles—produced the most uniform crusts and highest overall performance, despite some inconsistencies in measured soil loss.Results showed soil loss varied across treatments, with the best result observed in a specimen treated using Method A and Sequence 1. Calcium carbonate content ranged from 1.2% to 4.4%, generally increasing from the top to the toe of the slope. Method A and Sequence 2 produced the most consistent carbonate distribution. The study now progresses to testing EICP in three different soil types. In partnership with the City of Las Cruces, field testing will begin with 4’ × 4’ plots and later expand to 8’ × 8’. Rainfall simulations and laser scanning will compare treated and untreated plot performance.
ICBBGPoster-32
Title: Enhancing Thermal Properties of Arid Soils Through Bio-Mediated Calcite Precipitation for Geothermal Applications
Authors: Mani Rambothu; Hamed Khodadaditirkolaei; Edward Kavazanjian; Nariman Mahabadi
Institute: Arizona State University
Abstract: Hot-arid regions face growing challenges in sustainable cooling due to increasing ambient temperatures, water scarcity, and the limitations of conventional cooling systems. Ground-Coupled Heat Pump (GCHP) systems present a water-conserving alternative that harness the thermal stability of the subsurface for efficient cooling. However, the poor thermal properties of dry soils in hot-arid environments often lead to oversized ground heat exchanger (GHE) systems and increased installation costs. This study investigates the impact of subsurface thermal properties and GHE configurations on GCHP performance in hot-arid climates using a coupled simulation framework based on EnergyPlus and Ground Loop Design (GLD) software. Simulation scenarios were conducted across various thermal conductivity and diffusivity values for small and large office prototype buildings in Phoenix, Arizona. The results demonstrate that enhancing the thermal conductivity of backfill materials can significantly reduce GHE length or depth, improving system feasibility. While saturating soils improves thermal exchange efficiency, maintaining saturation in arid conditions is often impractical. Vertical systems can benefit from naturally saturated soils below the groundwater table, but such conditions are site-dependent. To address these challenges, the study explores the use of thermally enhanced geomaterials—both natural and engineered—with high conductivity (e.g., k > 2 W/m·K) to reduce system size and cost. Furthermore, this work highlights the potential of bio-mediated soil improvement techniques, such as Microbially Induced Calcite Precipitation (MICP) and Enzyme-Induced Carbonate Precipitation (EICP), to enhance the thermal conductivity of in-situ soils in an environmentally sustainable manner. These findings offer valuable insights into optimizing GCHP design in water-stressed regions and support the adoption of integrated soil-thermal improvement strategies to enable scalable, efficient, and climate-resilient cooling systems.
ICBBGPoster-33
Title: The Effect of Different MICP Treatment Methods on Bio-Brick Properties
Authors: Xinyu Lu; Changming Bu; Lin Li; Shihui Liu; Beatrice Magombana
Institute: Tennessee State University
Abstract: This study aimed to enhance clay bio-bricks by comparing four different MICP treatments. The methods evaluated include the surface alternate infiltration bacterial suspension method, the surface first infiltration bacterial suspension method, the surface infiltration combined mixing method, and the pre-mixing method. The pre-mixing method (Method D) resulted in the highest compressive strength, reaching 1080.3 kPa, with the most uniform distribution of calcium carbonate. In contrast, the surface alternate infiltration method (Method A) had the poorest reinforcement effect, as the rapid formation of surface calcium carbonate hindered deeper penetration into the bio-brick, resulting in a compressive strength of only 410.8 kPa.
ICBBGPoster-34
Title: A PLANT-EXTRACTED BIO-POLYMER FOR FUGITIVE DUST CONTROL
Authors: Hamed Khodadadi Tirkolaei; Rashid Alwashahi
Institute: Arizona State University
Abstract: Fugitive dust emissions from unpaved roads, mine tailings, and fallow lands pose significant environmental and health risks in arid regions like Arizona. Traditional dust suppression methods, such as water spraying and chemical suppressants, are either unsustainable or environmentally concerning. This study explores the use of a novel plant-extracted biopolymer as a sustainable alternative for surface stabilization and dust control. The biopolymer, characterized by its hydrophobicity and strong adhesion, was tested on fine-grained soils for its effectiveness in crust formation, resistance to erosion, and mechanical strength.
A series of laboratory experiments were conducted, including hydrometer analysis to quantify PM₁₀ content, rainfall-induced water erosion tests, penetration resistance measurements, and wind erosion simulations using a Portable In-Situ Wind Erosion Lab (PISWERL). The biopolymer-treated surfaces showed a 30-fold increase in crust strength compared to untreated samples, withstanding stress levels greater than those exerted by heavy truck traffic. Treated soils also demonstrated significant resistance to erosion, with up to 90% reduction in mass loss during simulated rainfall and an 8-fold decrease in airborne PM₁₀ under high wind conditions.
Microscopic observations confirmed effective crust formation at varying depths, depending on soil type and treatment volume. Results indicate that the plant-based biopolymer forms a durable, erosion-resistant surface crust with no toxic byproducts, making it a promising candidate for environmentally friendly dust control.
Future work will focus on scaling up treatment applications and performing a life cycle analysis to evaluate cost-effectiveness and environmental impact.
ICBBGPoster-35
Title: Stabilization of dredged marine sediment using biopolymer
Authors: Hamed Khodadadi Tirkolaei; Yaser Ghafoori, Parisa Samadi, Pooria Ghadir, Stanislav Lenart, Sabina Dolenec, Hamed Khodadadi Tirkolaei
Institute: Arizona State University
Abstract: The frequent dredging of sediments from port areas often leads to the rapid accumulation of excess material, potentially resulting in landfill challenges. Dredged marine sediments typically exhibit high water content, a significant proportion of fine-grained soil, limited bearing capacity, substantial settlement tendencies, and low shear strength. Addressing these issues is imperative for construction projects on such soil types. Recent trends in soil stabilization have witnessed the rising popularity of sustainable bio-binders, particularly biopolymers, owing to their environmentally friendly attributes and extensive use in various geoenvironmental applications. This study investigates the utilization of four different types of biopolymers for the stabilization of marine dredged sediment sourced from the Port of Koper, Slovenia. The research investigates the influence of biopolymer incorporation on the geotechnical properties of biopolymer-treated sediment through Atterberg limits and cone falling tests. In addition, samples were analyzed by scanning electron microscopy (SEM) to elucidate the interaction between biopolymer and the sediment. The findings demonstrate a significant enhancement of undrained shear strength with the addition of biopolymers to the sediment. The formation of hydrogel within the soil pores not only increases the sediment consistency but also positively affects the soils shear strength.
ICBBGPoster-36
Title: Enhancing Adhesion of EICP to Soil Particle Surfaces with Proteins
Authors: Hamed Khodadadi Tirkolaei; Abishek Aryal; Hamed Khodadadi Tirkolaei
Institute: Arizona State University
Abstract: Enzyme-Induced Carbonate Precipitation (EICP) is a promising biocementation technique for ground improvement, but its performance can be limited by the weak adhesion of calcium carbonate (CaCO₃) precipitates to soil particle surfaces. This study investigates the use of milk-derived proteins, particularly casein, to enhance the strength of EICP-treated materials. The research evaluates whether incorporating milk proteins into the EICP treatment solution can improve carbonate-soil binding at the interface.
Glass slide samples were treated with both baseline and modified (milk protein–enhanced) EICP solutions at different curing times (3–72 hours). A centrifuge-based detachment test was developed to simulate shear forces and quantify the mass and area of detached precipitates. In parallel, protein-specific staining and Raman spectroscopy were used to visualize protein presence and confirm their role in binding mechanisms. Scanning Electron Microscopy (SEM) provided microstructural insight into precipitate morphology and surface interactions.
The results demonstrate significantly lower detachment of calcium carbonate precipitates in the protein-modified samples compared to the baseline, both in terms of mass loss and detachment area. Raman spectra confirmed the presence of amide I protein bands only in the modified samples, suggesting successful incorporation of milk proteins at the particle-precipitate interface. These findings indicate that milk proteins, such as casein, improve adhesion by modifying interfacial properties, potentially enabling stronger and more durable biocementation with lower carbonate content.
Future work will focus on identifying the spatial distribution of proteins in treated samples and expanding the method to soil-based systems. This approach presents a low-cost, bio-based enhancement to EICP, with potential applications in sustainable geotechnical engineering.
ICBBGPoster-37
Title: Shear Mechanisms in Granular Media Interacting with Bio-inspired Surfaces
Authors: Prabhat Paudyal; Prabhat Paudyal; Hamed Khodadadi Tirkolaei
Institute: Arizona State University
Abstract: Understanding the interaction between soft bio-inspired materials and granular soils is critical for the design of systems that mimic biological penetration mechanisms, such as plant roots, burrowing animals, or soft robots. This study investigates how material softness and surface texture affect shear response at the soil–continuum interface using Discrete Element Method (DEM) simulations. The goal is to identify critical thresholds in material softness that govern the transition between elastic–plastic and strain-softening behaviors, and to explore how texture influences these interactions.
A series of DEM-based direct shear tests were simulated for smooth and textured continuum materials of varying stiffness. Shear stress–strain and volumetric strain behavior were analyzed, along with displacement vector fields to capture strain localization. Results show that for smooth materials, a critical “softness” threshold exists—below this threshold, soil exhibits elastic–plastic behavior, while above it, strain-softening and shear banding dominate. In contrast, the presence of surface texture alters the interaction mechanism, leading to shear localization regardless of material softness. This indicates that texture can override the influence of stiffness in dictating shear response.
These findings suggest that both softness and surface texture must be considered when designing bio-inspired systems that interact with granular media, especially in geotechnical or robotic applications where energy dissipation and shear resistance are key performance factors. Ongoing efforts aim to experimentally validate the simulation results and develop predictive models for energy dissipation based on interface properties.
ICBBGPoster-38
Title: Surficial Stabilization of Mine Tailings Using Enzyme Induced Carbonate Precipitation (EICP): A Case Study
Authors: Hamed Khodadadi Tirkolaei; Abishek Aryal; Edward Kavazanjian; Emmanuel Salifu; Hamed Khodadadi Tirkolaei
Institute: Arizona State University
Abstract: This study presents a comprehensive field-scale demonstration of using Enzyme-Induced Carbonate Precipitation (EICP) for surficial stabilization of mine tailings at the Cash Mine site in Yavapai County, Arizona. The site, historically mined and currently undergoing remediation by the Arizona Department of Environmental Quality (ADEQ), has been identified as a significant contributor of metal-laden sediments to the Hassayampa watershed. The objective was to apply EICP as a minimally disruptive treatment to strengthen the surface of tailings and reduce erosion-induced contaminant transport into nearby tributaries.
Preliminary laboratory experiments confirmed the potential of EICP to create a biocemented crust on tailing materials using a treatment solution composed of urea, calcium chloride, crude urease, and milk powder. Treated surfaces demonstrated significantly improved strength and erosion resistance, as measured by penetration, PI-SWERL, and rainfall simulation tests. These findings led to a full-scale deployment of 1,230 gallons of EICP solution across the tailing slope, crown, and drainage areas.
Post-deployment monitoring over one year confirmed successful carbonate precipitation and improved surface stability, particularly in the slope and crown zones. However, reduced effectiveness in the drainage area was attributed to metal-induced urease inhibition, as higher concentrations of lead and zinc were detected in leachates from that zone. Laboratory tests supported this observation, showing suppressed enzyme activity and lower carbonate formation. While the treatment effectively mitigated sediment erosion, runoff water from treated areas exhibited increased metal concentrations—likely due to the chloride and organic compounds in the EICP solution enhancing metal solubility.
Overall, the project demonstrated that EICP can serve as a promising technique for erosion control and surface stabilization of mine tailings, although future work is needed to mitigate potential trade-offs such as increased metal leaching.
ICBBGPoster-39
Title: Biochemical Species Plume Migration under Diverse Injection Strategies during Microbially Induced Calcite Precipitation Treatment in Soils
Authors: Pavan Kumar Bhukya; Xuerui Wang; Dali Naidu Arnepalli
Institute: Indian Institute of Technology Madras
Abstract: Microbially driven soil stabilization process known as microbially induced calcite precipitation (MICP) improves the strength and hydraulic characteristics sustainably. However, the biocementation employing MICP treatment depends on numerous factors affecting the biochemical species migration dynamics (i.e., bacterial and chemical injection source location, number of chemical injection cycles, biochemical injection, and retention durations). The sequence, duration, and location of injections of biochemical species decide the biocement spatial distribution in the soil domain. Therefore, the present study attempts to understand the impact of these influencing factors on the biocement distribution in a heterogeneous soil domain. Accordingly, the study developed a coupled bio-chemo-hydraulic (BCH) model in an open-source code (OpenGeoSys) to investigate the influence of diverse injection strategies on biochemical species plume migration and subsequent alterations in the hydraulic characteristics. The results indicated that distinct injection sources for bacteria and chemicals promote closer precipitation to the injection source. However, a single point source for biochemicals migrates the biochemicals front to farther locations, thereby biocement. Besides, multiple chemical injection cycles effectively enhanced precipitation rates compared to single injection cycles. Further, the chemical retention time was crucial in improving the biocement content for both injection scenarios. The chemical injections with retention were comparatively efficient in precipitating higher biocement content than those without retention. Based on the findings from the numerical modeling, the present work also indicated a few guidelines for choosing injection strategies to achieve near-field and far-field precipitation. Besides, the study specified the prominent mechanisms of biochemical species migration under variable injection strategies.