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<p>Biodegradation of petroleum hydrocarbons by microorganisms is one of the most effective methods used to remediate environmental systems. However, much of what is known is based on the ability of (mostly bacterial) species to degrade hydrocarbons under enrichment conditions in a laboratory setting. In order to refine biodegradation as a remediation method, there is a critical need to understand the dynamics and mechanisms of microbial communities under <em>in situ </em>conditions. The goal of this dissertation was to provide insight and knowledge into the function of microbial communities in petroleum-contaminated environments using a combination of DNA, lipid and isotopic analyses. Microbial biomass, community structure, carbon sources were assessed at two study sites: (1) a former industrial facility contaminated by PAHs and (2) coastal salt marshes impacted by the <em>Deepwater Horizon</em> oil spill.</p> <p>Isotopic analyses of soils collected from the PAH-contaminated site revealed that microbial carbon sources were derived from vegetation and/or natural organic matter present in soils matter rather than PAHs. Similarly, microbial community structure remained consistent across samples and there were no observed shifts in phylotype diversity with increasing levels of PAHs. Bioaccessibility assays revealed that a large fraction of soil-borne PAHs at the site are not bioavailable to microorganisms; thus, highlighting the importance of environmental factors to <em>in situ</em> biodegradation.</p> <p>Biodegradation of <em>Deepwater Horizon </em>spilled oil was detected in salt marsh sediments such that petroleum-derived carbon was a primary carbon source for indigenous microbial communities in the months following the spill. Likewise, pyrosequencing of all three microbial domains showed an increase in the relative of abundance of taxonomic groups known to include hydrocarbon-degrading species, such as <em>Sphingomonadales</em>. These results suggest that Gulf of Mexico marsh sediments have considerable biodegradation potential and that natural attenuation may be feasible remediation strategy in this region.</p> / Doctor of Philosophy (PhD)

Disposal of regulated waste has become a major challenge for the generators. Disposal of such waste is regulated by local, state and federal agencies and the problem is intensified because of liability issues, public perception and increasing cost. This document describes the mechanical design, installation and testing of a system that employs bioremediation to disinfect regulated medical waste. Currently marketed treatment systems generally use either heat or extreme pH to disinfect medical waste. The most common and widely accepted of these, incineration, is rapidly losing favor because of undesirable emissions and hazardous by-product. The system described in this document is the first to use a biological process. The advantages of using this system include the absence of harmful effluents or emissions, low cost of operation, reduction of waste volume and disposal directly into landfill and sewers. The evolution of system design from conceptual stage to the design of a system for Lewis-Gale hospital is described. A general overview of the components is presented and the selection and testing criteria are explained. The components used in Lewis-Gale hospital are described with a detailed layout scheme. A detailed failure analysis was done for each component used in Lewis-Gale hospital. This is presented with contingency plans developed for prolonged system failure. Finally, the operators manual developed for the Lewis-Gale hospital is included. / Master of Science

The design and development of a system for disinfecting medical waste at the site of origin is presented. Investigation of the current commercial systems that accomplish this task shows that they all expose the waste to physical conditions that are harmful to all forms of life. Further, most are very expensive to install and to operate. A recently developed biochemical process promises to effectively inactivate harmful pathogenic organisms economically and without the danger of extreme heat or poisonous chemicals. The biochemical process is not yet fully developed. Nonetheless, the development of a marketable system to take advantage of this technology has been initiated. The motivation for developing this technology and the particular system that will employ it is presented. A general overview of the system and components is presented. Previous and suggested future testing strategies are explained. Component interactions and process control are described. / Master of Science