Our work on the microbiological aspects of MICP has been focused on understanding changes in bacteria population, activity, degradation, and attachment/detachment for both bioaugmented and biostimulated approaches. This has occurred through field sampling and testing, small column tests, beaker tests, large tank tests, and genetic sequencing.
Current Year ’15-’16 Focus
TITLE: Microbial Ureolytic Processes and Microbial Population Change During MICP Treatment
RESEARCHER: Charles Graddy (firstname.lastname@example.org)email@example.com
ADVISOR(S): Prof. Doug Nelson (firstname.lastname@example.org), Prof. Rebecca Parales
COLLABORATOR(S): Michale Gomez, Prof. Michael Tsesarsky
THRUST: Hazard Mitigation
USE-CASE: Native bacteria are used in MICP to reduce the risk of earthquake damage to structure foundations with less environmental impact than traditional ground improvement methods.
TRANSFORMATIVE CONTRIBUTION: This research will culminate in a field scale test of a ground improvement technology that will cost-competitively prevent liquefaction while producing fewer carbon dioxide equivalents than established alternatives. The knowledge gained from monitoring microbial populations and physiology will optimize the current procedure to bring it to industry scale, indirectly help enable diverse applications of biocementation, from surface stabilization to toxic cation sequestration, improve models of subsurface bacterial transport and activity, and give insights into other soil microbe-mediated techniques.
- Incomplete knowledge of target microbe physiology
- Could dramatically improve cost and performance of treatments while increasing control over calcite deposition
- Unknown relationship between suspended and sedentary bacteria in the soil matrix
- While significant attachment bias would make representative sampling difficult, greater understanding of the process will improve all subsurface bacterial modelling
- Unclear effect of byproducts on the surroundings
- Potentially additional costs and remediation efforts
- Optimization may not be enough to bring material and environmental costs down enough to be competitive
- A plan needs to be developed to manage byproducts and wastewater
- Characterize population changes under various treatment conditions by 16S community sequencing and urease gene qPCR then relating these results to studies of isolate activity.
- Examine metabolism of stimulated isolates to drive treatment optimization towards the specific needs of the highly ureolytic subpopulations and control the geochemistry of the microsites where calcite is deposited.
- Study bacterial composition differences between aqueous and soil samples to inform modelling efforts and assess need for more involved sampling schemes.
- Run long-term experiment to observe bacterial succession, byproduct degradation, and advise possible remediation efforts.
IMPORTANCE TO STAKEHOLDERS:
- Society benefits from the availability of a technology that provides comparable protection from earthquakes while reducing greenhouse gas emissions and slowing global warming.
- Practitioners gain a novel, ecofriendly tool to add to their services which could attract potential customers.
- Regulators are given the option to incentivize environmentally conscious geotechnical engineering.
- Owners are empowered to choose soil improvement techniques that have less impact on the environment –impact that may eventually translate into cost.
- Academia advances from improved understanding of fundamental soil microbe behavior with respect to physiology, activity, and transport modelling.