CAREER: Stabilization of Mining and Energy Related Byproducts using Bio-Mediated Soil Improvement

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This Faculty Early Career Development (CAREER) grant will develop sustainable methods to stabilize mining and energy related byproduct materials using natural biological processes. Mining for material and energy needs generates large volumes of byproduct material, such as ore tailings, coal ash, and oil sand tailings, and these materials must be stored for hundreds to thousands of years. Often it is the management of the generated byproducts that is one of the most difficult challenges for the industry. Safely storing these byproduct materials is a necessity to keep society and the environment safe. When these containment systems fail, they have the potential to be a catastrophic disaster. This CAREER grant will use biologically mediated methods to stabilize the byproduct materials to prevent the failure of the containment systems and the spread of the byproduct materials. The bio-mediated soil improvement methods will harness the bio-geochemistry of the materials to improve the mechanical stability of the byproduct materials as well as immobilize any trace elements within the materials. The grant will also focus on explaining to the public the treatment process and benefits of bio-mediated soil improvement in order for it to become a viable ground improvement alternative. The objective of the educational plan is to educate various audiences, including K-12 students, university students, the general public, and the state legislature, on sustainability in geo-systems, specifically the storage of mining and energy related byproduct materials. The recruitment and retention of female engineers in academia will also be a focus of the educational plan.The overall objective of this CAREER grant is to develop biologically mediated treatment methods to improve the performance of mining and energy related byproduct material. Byproduct storage systems have inherent engineering concerns, specifically: 1) failure of the stored material due to inadequate shear strength, 2) spreading of the stored material due to erosion from wind or surface water, and 3) leaching of toxic trace elements into nearby surface and ground water sources. This CAREER grant will address these concerns by using bio-mediated improvement methods. Ureolytic-driven microbial induced carbonate precipitation (MICP) methods will be used to improve the shear strength and structural stability of the stored byproducts, reduce the potential of erosion due to wind and surface water, and immobilize trace elements that may potentially leach into nearby water sources. The improvement in shear strength will be evaluated under drained and undrained simple shear loading conditions, and the reduction in erosion will be assessed using impinging jets. The ability to immobilize trace elements within the byproduct material will be evaluated using experimental and chemical equilibrium modeling techniques. In addition, alternative biological metabolic pathways, such as iron and sulfate reduction, will be explored that may result in improved bio-mineralization stabilization techniques. Since the storage life of the byproduct material is orders of magnitude longer than typical engineering projects, the permanence of the treatment techniques will also be assessed. The results of this CAREER grant will advance the understanding of bio-mediated soil improvement. In particular, the influence of microbial metabolic processes and the physical and chemical aspects of the geo-materials on the resulting material behavior will be investigated. This improved understanding will provide guidance for the storage of mining and energy related byproduct materials, using a novel bio-mediated approach. The results will also advance bio-mediated soil improvement technology to be applicable for many other geo-environments, including contaminated soils, liquefiable intermediate soils, and anoxic sediments. This CAREER grant will also provide insight into the longevity of bio-mediated improvement, which will be important for all bio-mediated soil improvement field implementation applications.