Halogenated organic compounds have had widespread and massive applications in industry, agriculture, and private households, for example, as degreasing solvents, flame retardants and in polymer production. They are released to the environment through both anthropogenic and natural sources. The most common chlorinated solvents present as contaminants include tetrachloroethene (PCE, perchloroethene)...
Ammonia oxidizing bacteria, including Nitrosomonas europaea, are inhibited by aromatic hydrocarbons which can be found in wastewater treatment plants. In recent studies, changes have been observed in N. europaea cell size upon exposure to benzene, but not toluene. Additionally, NE 1545, a gene proposed to be involved in fatty acid...
Carbon tetrachloride (CT) and chloroform (CF) were transformed in batch reactor experiments conducted with anaerobic dechlorinating cultures and supernatant (ADC+S) harvested from continuous flow reactors. The Evanite (EV-5L) and Victoria/Stanford (VS-5L) cultures capable of respiring trichloroethene (TCE), 1,2-cis-dichloroethene (cDCE), and vinyl chloride (VC) to ethene (ETH) were grown in continuous...
This research focused on anaerobic transformation of trichloroethene (TCE), a
groundwater contaminant. The mixed anaerobic Evanite culture (EV) was studied to determine community behavior and composition responses to different electron donors and chloroethene electron acceptors. The potential toxicity from high concentrations of TCE and its daughter product cis-1,2-dichloroethene (cDCE) was...
1,4-dioxane, a probable human carcinogen at low (< 1ppb) concentrations, has emerged as a groundwater contaminant due to its historical use as a stabilizer for the chlorinated solvent 1,1,1-trichloroethane. Aerobic cometabolism, the use of a primary substrate to induce the production of microbial enzymes that fortuitously degrade other compounds, is...
Due to the effective antimicrobial properties of silver nanoparticles they represent a significant proportion of all consumer-‐related nanomaterials. The introduction of silver nanoparticles from these products into domestic and industrial wastewater streams poses potential complications for biological treatment systems. A critical component of biological treatment that is extremely sensitive to...
This dissertation explores the physiology and gene expression of the ammonia-oxidizing bacterium Nitrosomonas europaea in surface-associated bacterial communities, or biofilms. Biofilms of N. europaea were cultivated in drip flow reactors for several weeks and gene expression microarrays were used to detect 240 genes differentially expressed between the mature biofilms and...
This research focuses on the anaerobic transformation of trichloroethylene (TCE) that is occurring in the subsurface of the Evanite site in Corvallis, OR. Two anaerobic studies were conducted to investigate the effects of microbial communities in the presence of different electron donors during the anaerobic degradation of trichlorofluoroethylene (TCFE), and...
Methanotrophic bacteria are promising means of producing value-added products as they have the ability to transform methane under atmospheric temperature and pressure. Efforts to develop methanotrophs to produce value-added products are hoped to incentivize a decrease in methane flaring operations. The data collected during this study was used to inform...
Despite decades of cleanup efforts, chlorinated solvents are some of the most common groundwater and subsurface contaminants of the industrialized world. These compounds include chlorinated ethenes (CEs) such as trichloroethene (TCE) and chlorinated methanes (CMs) such as carbon tetrachloride (CT). Dehalococcoides mccartyi belongs to a class of microorganisms called organohalide-respiring...
Identifying the inhibition of ammonia oxidizing bacteria (AOB) by emerging organic contaminants is crucial due to the importance of AOB in wastewater treatment, the widespread use of antibacterial agents such as triclosan (TCS) in consumer products, and the sensitivity of N. europaea to inhibitors. Triclosan inhibition of nitrification by AOB...
Chlorinated ethenes are common groundwater contaminants that may be treated through in-situ bioremediation. Relationships between the reducing environment, available electron donors and acceptors, reaction kinetics, and microbial community composition must be further understood to successfully engineer remediation schemes in the complex subsurface environment. This thesis work investigated the effect of...
1,4-dioxane and chlorinated aliphatic hydrocarbons (CAHs) such as trichloroethylene (TCE) and 1,1-dichloroethene (1,1-DCE) are hazardous compounds commonly found in soil and groundwater. Bioremediation through aerobic cometabolism is a potential option for the remediation of these contaminated sites. The purpose of this study was to examine the use of different primary...
Two methanotrophs, M. trichosporium OB3b and M. buryatense 5GB1, were encapsulated using two methods to investigate the potential of methane conversion for biofuel production. Ca-alginate and low melt agarose were used to immobilize the methanotrophs for batch and continuous flow column testing. Varying protein concentrations, residence times, and immobilization methods...
At Site-300, Lawrence Livermore National Laboratory (LLNL), CA,
trichloroethene (TCE) is present along with tetraalkoxysilanes such as tetrabutoxysilane
(TBOS) and tetrakis(2-ethylbutoxy) silane (TKEBS), as subsurface contaminants.
Intrinsic transformation of TCE to cis-dichloroethene (c-DCE) was observed in the
groundwater at locations co-contaminated with TBOS or TKEBS. Attenuation of TBOS
and TKEBS...
This study investigated complete reductive dechlorination of chlorinated aliphatic hydrocarbons (CAHs) over a broad range of concentrations. Tetrabutoxysilane (TBOS), as a slow-release anaerobic substrate, was studied for enhanced reductive dechlorination of tetrachioroethylene (PCE) present as a dense non-aqueous liquid (DNAPL). Four different site-mixed cultures were used in the study: Site-300...
This thesis explores the factors limiting the alkene substrate range of the vinyl chloride (VC)-utilizing bacteria, and describes a method for measuring VC transformation in situ. Vinyl fluoride (VF) was evaluated as a surrogate for monitoring aerobic VC-transformation utilizing three isolates, Mycobacterium EE13a, Mycobacterium JS60 and Nocardioides JS614. JS614 grew...
Silver nanoparticles are increasingly being incorporated into consumer products due to their broad-spectrum antimicrobial properties. The resulting influx of silver nanoparticles into wastewater may pose a threat to bacteria involved in biological wastewater treatment. Ammonia-oxidizing bacteria, which convert ammonia to nitrite in the first step of nitrification, are highly sensitive...
Bioremediation of chlorinated ethenes by the augmentation of contaminated soils with microorganisms is a proposed method of reducing contaminant concentrations in groundwater. To determine the viability of using ELW-1 or R. rhodochrous for groundwater remediation, kinetic analyses of transformation rates must be performed. The focus of this research was to...
The goal of this research was to mathematically simulate the ability of bioaugmented microorganisms to aerobically cometabolize a mixture of chlorinated aliphatic hydrocarbon (CAH) compounds during in-situ treatment. Parameter values measured from laboratory experiments were applied to the transport model with biotransformation processes included. In laboratory microcosm studies, a butane-grown,...
The aerobic transformation of TCE and cis-DCE by a tetrabutoxysilane-grown microorganism (Vancheeswaran et al., 1999) led to the investigation of novel substrates, including benzyl alcohol, for promoting cometabolism. The culture grew on carboxylic compounds and alcohols, but did not grow on formate, methanol, methane, propane, butane, ethylene, benzene, toluene, or...
Laboratory and modeling studies were performed with a mixed-anaerobic-culture obtained from the Evanite site in Corvallis, Oregon. The culture completely transforms trichloroethene (TCE) to cis-dichloroethene (c-DCE), vinyl chloride (VC), and finally to ethene. Acetylene inhibition studies were used to examine the culture's microbial activities. Kinetic studies determined the half-saturated constant...
The ability of Mycobacterium sp. ELW1, a novel microbe capable of alkene oxidation, to co-metabolize phenanthrene (PHE) was studied. ELW1 was able to completely co-metabolize PHE, at different concentrations below its water solubility limit, in an aqueous environment. The alkene monooxygenases in ELW1, used to initiate oxidation of PHE, were...
This study investigated the use of radon-222 as an in situ partitioning tracer for quantifying nonaqueous phase liquid (NAPL) saturations in the subsurface. Laboratory physical aquifer models (PAMs), field experiments, and numerical simulations were used to investigate radon partitioning in static (no-flow) experiments and in single-well, 'push-pull' tests conducted in...
Persistence of Non aqueous phase liquids (NAPLs) in the subsurface at residual
saturations eventually contributes to undesirable groundwater contamination. Proper
characterization of subsurface NAPL, its location, composition and distribution, is
essential for the chosen remediation technology to be effective. It is also desirable to
assess the performance of remedial actions...
Laboratory scale microcosm studies were conducted using site specific groundwater and aquifer solids to assess the feasibility of stimulating indigenous microorganisms in-situ to biologically transform Trichloroethylene (TCE) and its lesser chlorinated daughter products dichloroethylene (DCE) and vinyl chloride (VC). Three different treatments were conducted to determine the best approach for...
The 1,1-dichloroethene (1,1-DCE) cometabolic transformation abilities of indigenous and bioaugmented microorganisms were compared in microcosms constructed with groundwater and aquifer solids from the Moffett Field site, CA. Microbial community structure in the microcosms and possible community shifts due to 1,1-DCE transformation stress was evaluated by terminal restriction fragment length polymorphism...
This thesis focused on using microcosms to better understand the aerobic cometabolic processes of TCE and cis-DCE transformation that occurred during a Cometabolic Air Sparging (CAS) demonstration at McClellan Air Force Base. The microcosms were created with groundwater and aquifer materials from the demonstration site. Concentrations of compounds in the...