published_or_final_version / Architecture / Master / Master of Landscape Architecture

Over the last decade, luminescence measurements have been used primarily to detect and quantify specific organic pollutants and heavy metals, and in a few cases for monitoring microbial activity. In this study, a fiber-optic luminescence detection system was developed to examine the relationship between microbial activity and the resultant impact on biodegradation and transport of substrate in porous media. This system allows rapid, real-time, and non-destructive measurements of in-situ luminescence from a specific lux reporter microbial population in porous media. An understanding of the formation and dynamics of bioactive zones is very important for in-situ bioremediation applications because it is in these zones that the remediation process is optimal. This study also examined the location and size of a biologically active zone in response to changes in local substrate and electron acceptor availability. Results show that when DO was not a limiting factor, the bioactive zone encompassed the entire system. However, as the availability of DO became limiting for the higher-00 experiments, the size of the bioactive zone shrank and was ultimately limited to the proximity of the substrate source. Furthermore, a decrease in the size of the bioactive zone enhanced the rate of substrate biodegradation per unit area. This study also investigated the impact of several coupled factors including substrate concentration, pore-water velocity, and initial cell density on solute biodegradation and transport behavior for a system influenced by three stressors, microbial lag, microbial growth, and cell transport. Results showed that temporal changes in biodegradation potential, and therefore attendant substrate transport behavior, were influenced by microbial lag, growth, dissolved oxygen limitations, and cell elution. As a result, substrate transport behavior was non-steady except for relatively short residencetime conditions wherein substrate degradation exhibited quasi first-order behavior. Cell transport and elution was important, especially under significant growth conditions. Under such conditions, the majority of the cells in the system (60 to 90%) was distributed in the solution phase where most of the biodegradation took place. This study illustrates the complex behavior that can be associated with microbially mediated processes, and which should be included in solute transport models to accurately predict the fate of contaminants in the subsurface environment.

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Rhamnolipid biosurfactants are investigated to determine their role in biological processes, and for discovery of novel, more biocompatible applications in areas related to medicine, agriculture, and environment. Fundamental understanding of the physical and chemical properties of rhamnolipids is needed. Thus, systematic studies on solution and interfacial properties on rhamnolipids from P.aeruginosa ATCC 9027 were undertaken. A purification protocol was developed and a thorough qualitative and quantitative speciation analysis was performed with high performance liquid chromatography-mass spectrometry (HPLC-MS), nuclear magnetic resonance (NMR) spectroscopy and HPLC with evaporative light scattering detection (ELSD). Acid-base properties of the mixture of 30 monorhamnolipid congeners, including both saturated and unsaturated species, were characterized at concentrations below and above the CMC at fixed ionic strength using potentiometry and attenuated total reflectance-Fourier transform infrared (ATRFTIR) spectroscopy. A pKₐ of 4.3 was found for concentrations below 50 μM and a pKₐ of 5.6 above 100 μM. The pKₐ is dictated by aggregation in solution. Molecular areas of monorhamnolid monolayers at the air-water interface are strongly influenced by protonation state, and increase from 31 to 109 Ų/molecule as pH increases from 4 to 8.5 and as ionic strength decreases. Adsorption isotherms of monorhamnolipids on γ-Al₂O₃ were investigated as a function of pH using ATR-FTIR spectroscopy and Frumkin model fits, from which K(ads) values of 1.20 (± 0.10) x 10⁵ M⁻¹ at pH 4.0, 2.14 (± 0.51) x 10⁴ M⁻¹ at pH 6.3 and 1.31 (± 0.09) x 10³ M⁻¹ at pH 8.6 were obtained. Interaction parameters were positive at all pH values. Cooperative adsorption is driven by hydrophobic interactions (physisorption) at any pH including hydrogen bonding and electrostatic interactions. Chemisorption was also observed at high pH values. Formation constants for monorhamnolipid-Pb²⁺ and monorhamnolipid-Cd²⁺ complexes were determined using differential pulse polarography in the low μM concentration range. A modified Lingane equation was developed to account for monorhamnolipid adsorption on the Hg surface. β values for adsorbed metal complexes are ~10^3.2 and ~10^0.8 for Pb²⁺ and Cd²⁺, respectively, compared to previously published β values of 10^8.58 and 10^6.89, respectively. Evidence for 1:1 and 2:1 monorhamnolipid-metal complexes was provided by electrospray ionization-mass spectrometry.

Thermal remediation is an efficient and cost effective method for the removal of organic compounds from the subsurface. However, complete removal of these compounds cannot be achieved by this technology alone. It is generally assumed that bioremediation will provide the polishing steps at thermally treated sites. In this study, soil was collected from a hydrocarbon contaminated site that previously underwent thermal remediation. A microcosm batch study was conducted to determine the impacts of thermal remediation on indigenous microorganisms and their ability to degrade naphthalene. Soils that reached varying peak temperatures were set up in microcosms at temperatures experienced along their respective cooling profiles. Naphthalene degradation was not detected within any of the unamended microcosms within a 6 month time frame, although, archaea growth was detected in the microcosms after 2 months of acclimation, accompanied by iron reduction and significant methane production assumed to have arisen from degradation of methanol.

Thermal remediation is an efficient and cost effective method for the removal of organic compounds from the subsurface. However, complete removal of these compounds cannot be achieved by this technology alone. It is generally assumed that bioremediation will provide the polishing steps at thermally treated sites. In this study, soil was collected from a hydrocarbon contaminated site that previously underwent thermal remediation. A microcosm batch study was conducted to determine the impacts of thermal remediation on indigenous microorganisms and their ability to degrade naphthalene. Soils that reached varying peak temperatures were set up in microcosms at temperatures experienced along their respective cooling profiles. Naphthalene degradation was not detected within any of the unamended microcosms within a 6 month time frame, although, archaea growth was detected in the microcosms after 2 months of acclimation, accompanied by iron reduction and significant methane production assumed to have arisen from degradation of methanol.

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The objective of this study was to examine the effect of heat on the growth of a biofilm in a parallel glass plate fracture table. Groundwater was collected from a limestone aquifer and amended with a nutrient mixture to stimulate the indigenous microbial population. The amended water was heated to approximately 30oC in an upgradient reservoir attached to the fracture table and recirculated through the 2-m long, 0.6-m wide, parallel glass plate fracture having an approximate fracture aperture of 2000 μm. The fracture was maintained at approximately 10oC to simulate natural in situ groundwater temperature and the upgradient reservoir maintained at 30oC. Geochemical parameters and bacterial counts were measured regularly throughout the biostimulation to monitor biofilm growth in the fracture. Hydraulic tests and tracer experiments completed before and after the biostimulation were used as the primary indicators of the successful bioclogging of the fracture. Geochemical parameters measured throughout the trial revealed an increasingly reducing environment capable of supporting the development of a diverse biofilm. Direct and indirect bacterial counts revealed the dominant bacteria within the system included common groundwater bacteria pseudonomads, enteric, and slime-forming bacteria. Heterotrophic bacteria were also present in significant concentrations. Visible clusters of biofilm were observed on Day 2 of the trial with a fully-connected biofilm observed by Day 7. The biofilm impacted the groundwater flow through the fracture resulting in an approximately 2.75-hour delay in the tracer’s breakthrough during the tracer experiment completed on Day 13 of the trial compared to an experiment conducted during the initial stages of biofilm development. Based on the results of the tracer experiment, the biofilm growth reduced the velocity of the groundwater by 9.8%, the fracture aperture by 37.8%, and increased the bulk dispersivity to 50mm. Recommendations for future work include the application of heated biostimulation at the field scale in a well-characterized, isolated fracture. / Thesis (Master, Civil Engineering) -- Queen's University, 2011-08-01 12:33:25.286

No description available.

No description available.