Theses and Dissertations at Montana State University (MSU)
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Item Investigation of microbially induced carbonate precipitation for mitigation of acid mine drainage from coal mining waste(Montana State University - Bozeman, College of Engineering, 2023) Delwiche, Jenna Anne; Chairperson, Graduate Committee: Ellen G. Lauchnor; Adrienne J. Phillips (co-chair); This is a manuscript style paper that includes co-authored chapters.Acid Mine Drainage (AMD) is a serious environmental concern associated with coal mining. Many of the existing methods for addressing AMD are costly and focus on clean-up rather than prevention. In this study, the feasibility of using microbially induced carbonate precipitation (MICP) as an alternative method for mitigating environmental impacts from coal mining waste rock was investigated using laboratory scale experiments. Flow-through column testing showed that MICP can be used to create a calcium carbonate coating on coal waste rock, acting as a barrier between the rock and water. This treatment increased leachate pH, and microscopic inspection indicated that the presence of live bacteria was important for creating a durable coating. The MICP treatment decreased concentrations of heavy metals such as aluminum, barium, beryllium, copper, nickel, zinc, and iron in the leachate, but increased concentrations of vanadium, selenium, molybdenum, uranium, and arsenic. These results indicate that MICP may be an effective technique for mitigating AMD, but additional laboratory and field testing is needed to assess the feasibility of this treatment technology.Item Feasibility study for field-scale use of Ureolysis-Induced Calcite Precipitation (UICP) for roadbed improvement(Montana State University - Bozeman, College of Engineering, 2023) Dorian, Hudson Thomas; Chairperson, Graduate Committee: Mohammad Khosravi; Adrienne J. Phillips (co-chair); This is a manuscript style paper that includes co-authored chapters.A series of tests were conducted to evaluate the feasibility of using ureolysis-induced calcium carbonate precipitation (UICP) to improve the strength of the soil layers used to in the construction of roads. This process involved three series of tests conducted on soil specimens of gradually increasing volume. The first series regarded the relative effect of treatment direction, comparing top-down treatment to bottom-upwards and alternating treatment methods on 50-by-100-millimeter soil columns. This was evaluated through unconfined compressive strength (UCS) and the calcium carbonate distribution over the length of the soil, finding that all methods generated a reliable increase in the strength of the soil specimen. This phase of research also included a batch study, evaluating the growth of the ureolytic bacteria Sporosarcina pasteurii in a solution composed of commercially available ingredients, showing that the bacteria could be cultured at a far lower cost (as low as 20 cents per liter) than with lab-grade ingredients ($2.66 per liter). The next series of tests compared the effect of applying treatment solutions to the soil surface directly and using a probe to inject solutions beneath the surface. This was done with 15-centimeter, cylindrical specimens, evaluated through the California bearing ratio (CBR) test. It was determined that the treatment process had the capacity to increase the CBR value substantially (from ~11% up to 188%), and it was suggested that each treatment mechanism resulted in a predictable distribution of calcium carbonate. There was also success in using alternative, commercially-sourced ingredients to facilitate the treatment and improve the CBR value. The last tests centered on the treatment of a 30-centimeter-by-30-centimeter mock road section, combining the treatment mechanisms used at the 15-centimeter-scale to facilitate an increase in the CBR of a soil layer under pavement. Through UICP, the CBR value of this layer was successfully increased.Item Ureolysis induced mineral precipitation material properties compared to oil and gas well cements(Montana State University - Bozeman, College of Engineering, 2018) Beser, Guneycan Dicle; Chairperson, Graduate Committee: Damon Fick; Adrienne Philips (co-chair)Novel methods are needed to prevent or mitigate subsurface fluid leakage, for example stored carbon dioxide, fuels during unconventional oil and gas resource development or nuclear waste disposal. Ureolysis-induced calcium carbonate precipitation (UICP) has been investigated as a method to plug leakage pathways in the near-wellbore environment and in fractures. The enzyme urease catalyzes the hydrolysis of urea to react with calcium to form solid calcium carbonate (similar to limestone). UICP test specimens were prepared in triplicate by filling 2.5 cm (diameter) x 5 cm (length) and 5 cm x 10 cm cylindrical molds with sand and injecting both microbial and plant-based enzymes with urea and calcium solutions to promote precipitation. Sources of urease included jack bean enzyme and S. pasteurii microbe, resulting in both enzyme and microbe induced calcite precipitation (EICP, MICP) specimens. For comparison, Class H well- and Type I-Portland specimens were made by mixing cement paste (API 10B) with sand (ASTM C305). Fine cement specimens were also included in the comparison and were made both by mixing and also injecting to match the process used to make the biocement specimens. For the 2.5 cm x 5 cm specimens, the addition of nutrient broth to the enzyme specimens (ENICP) resulted in increased compression strengths compared with specimens without nutrient (EICP). The average compression strengths of these ENICP specimens reached 77% and 66% of the compressive strength of the 28-day well cement and Type I cement mortars, respectively and were over two times larger than the 28-day strength of the fine cement specimens. For 5 cm x 10 cm specimens, compression strengths of MICP, ENICP, and EICP specimens reached 42%, 38%, and 16% of the 28-day injected fine cement specimens. The average modulus of elasticity of ENICP was 17,316 + or = 1,430 MPa with 8.3 + or = 1.8% CaCO3 content (g/g sand) and was approximately 30% larger than the average modulus measured for the fine cement specimens. The results of this study indicate that the UICP produced specimens may have adequate strength and stiffness for field applications.