The Application of Biogeocementation to the Stabilization of Coal Tailings from the Victoria Junction Tailings Basin: a Bench-Scale and Pilot-Scale Study
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Authors
Rodin, Sarah
Date
Type
thesis
Language
eng
Keyword
Coal tailings , Stabilization , Microbially induced calcite precipitation , Sporosarcina pasteurii
Alternative Title
Abstract
The Victoria Junction Tailings Basin (VJTB), located in Cape Breton, Nova Scotia, currently stores sulfidic, acid-generating coal tailings sub-aqueously. Costs and ongoing maintenance requirements for the impoundment have necessitated alternative tailings stabilization methods to be explored, such that the potential for acid rock drainage and metal leaching (ARD/ML) can be minimized. Biogeocementation is a growing field of study for both the physical and chemical stabilization of earth materials, whereby microorganisms facilitate the formation of calcium carbonate deposits to cement soil particles. This treatment has the potential to improve the mechanical properties of soil and increase porewater pH. In this thesis, the feasibility of using biogeocementation as a method of stabilizing VJTB tailings was evaluated.
The treatment was first evaluated on a bench-scale using the ureolytic bacteria, Sporosarcina pasteurii. The application of S. pasteurii and treatment solutions to undrained tailings achieved a 453% increase in soil compressive strength, and a 72% increase in calcium carbonate (CaCO3) content compared to untreated tailings. The initial saturation of tailings and the distribution of treatment solutions via surface application contributed to improvements to the mechanical properties of tailings. Additionally, bacterial populations native to the tailings were stimulated by MICP treatment solutions.
A pilot-scale study was undertaken to evaluate the scalability of biogeocementation for its potential use at the VJTB. Four large-scale application methods for S. pasteurii and treatment solutions were investigated: (1) spray irrigation, (2) rotary cultivation, (3) excavation of shallow trenches, and (4) pre-mixing of tailings. After a 28-day incubation period, the spray irrigation method resulted in the most successful treatment with notable improvements in compressive strength and CaCO3 content. Pilot cells had elevated concentrations of viable bacteria and lower concentrations of sulfate relative to the control. The work outlined in this thesis supports the feasibility of using biogeocementation in the weeks following the removal of a water cover for the stabilization of VJTB tailings on both a bench and pilot scale. Additional research is necessary to determine the physical and chemical stability of the material over the months and years following MICP treatment.
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ProQuest PhD and Master's Theses International Dissemination Agreement
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.