Hiibel, Sage Royal, authorReardon, Kenneth F., advisorPruden, Amy, advisor2024-03-132024-03-132008https://hdl.handle.net/10217/237779Acid mine drainage (AMD), characterized by elevated levels of sulfate, acidity, and metals, is produced by the oxidation of mining-exposed minerals and is a major environmental issue. Sulfate-reducing bioreactors (SRBRs) are an attractive AMD treatment option. SRBRs contain an organic material, usually wood chips or compost, which provides a slow-release carbon substrate to support a complex anaerobic microbial community. A relationship between the microbial inoculum and bioremediation performance was established in laboratory experiments. The use of 16S rDNA-based profiling techniques established a correlation between SRBRs that performed well and the presence of three key functional groups: cellulose degraders, fermenters, and sulfate-reducing bacteria (SRB). Subsequent analyses of pilot- and field-scale SRBRs targeted the 16S gene and apsA functional gene, which is found in all SRB. Although multivariate statistical analyses of the 16S sequences of the communities did not reveal obvious differences, the apsA sequences of each SRBR were significantly different. The apsA sequences also revealed that Thiobacillus spp., which are capable of sulfur oxidation, were prevalent at the poorly performing SRBR. A novel, high throughput, biomolecular method called active community profiling (ACP) was developed and validated using model systems. ACP identifies the active members of mixed communities through the ratio of rRNA to rDNA, which is proportional to growth rate. When coupled with physiochemical analysis, ACP offers a powerful new tool to help understand microbial community dynamics. The effects of bioaugmentation and biostimulation on the community structure of AMD treatment systems were studied. Although all columns remediated AMD to a similar level, ACP analysis revealed that the active members of their communities were distinctive. It was determined that biostimulation or bioaugmentation at the top of the microbial carbon chain increased the active community diversity. This dissertation emphasizes the role of the microbial community associated with AMD remediation. Characterization of these communities with biomolecular tools at several scales has significantly advanced the understanding of the community's structure, function, and activity. The research approaches and methodologies developed have wide application, and provide unique and valuable contributions to the scientific knowledge of AMD treatment specifically, and to microbial ecology and bioremediation in general.born digitaldoctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.acid mine drainagebioremediationmicrobial community profilingsulfate-reducing bioreactorschemical engineeringenvironmental engineeringTextPer the terms of a contractual agreement, all use of this item is limited to the non-commercial use of Colorado State University and its authorized users.