For the first time, the bonding patterns of specific carbon atoms in woody plant lignin have been identified in situ. This was accomplished by administering and incorporating into the lignin fraction of Leucaena leucocephala, a tropical hardwood, ferulic acid enriched with ¹³C at either the 1-, 2-, or 3-C atom of the side chain. The plants were grown hydroponically over extended periods of time (28 days) under aseptic conditions in media containing the ferulic acid precursor, and then the tissues were examined by solid-state ¹³C NMR spectroscopy. Consequently, resonances due to the bonding patterns of the specific carbon atoms were determined. These resonances differ substantially from similarly labelled synthetic dehydrogenatively polymerized (DHP) lignin in both spectral profile and relative peak intensities. Subsequent studies using phenylalanine as precursor showed that it was better translocated into the aerial portions of the plant, and that its uptake did not result in distortion of lignification in those tissues, both in amount and monomeric composition. Consequently, the difference spectra obtained by ¹³C NMR analyses of phenylalanine-treated plants confirmed and extended the results obtained with ferulic acid. Evidence for the conversion of both precursors to the monolignols was shown by the difference spectra of [1-¹³C]-precursor-fed tissues, where the dominant resonance at 61-63 ppm is consistent with substructures containing the hydroxymethyl functionality. The spectrum obtained with roots administered [1-¹³C] ferulic acid showed the presence of a minor resonance (170-174 ppm) attributable to carboxylic acids/esters. By allowing the plant to undergo further metabolism by growing in hydroponic media without the precursor, these signals disappeared from the resulting spectrum. The first direct evidence for the dominance of the β-O-4’ linkage of lignin in situ was shown by the appearance of the resonance at 83 ppm corresponding to this substructure in both [2-¹³C] ferulic acid-treated roots and [2-¹³C] phenylalanine-treated roots and stems. Evidence for the occurrence of α-O-carbohydrate or α-O-aryl linkage in intact plant tissues was obtained in the spectra of tissues administered [3-¹³C] ferulic acid and [3-¹³C] phenylalanine. The effect of horseradish peroxidase/H₂O₂ in organic medium (dioxane/aqueous acetate buffer, pH 5, 95:5) on dehydrogenatively polymerized (DHP) lignin was reinvestigated. We found no evidence for vigorous depolymerization of DHP lignin under these conditions, contrary to claims made by Dordick, Marletta and Klibanov (1986, Proc. Natl. Acad. Sci. USA 83:6255-6257). Furthermore, we did not detect ferulic acid as a degradation product following treatment of DHP lignin with HRP/H₂O₂. Both coniferyl alcohol and DHP lignin were used in incubation experiments to determine effects of lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium and H₂O₂ on these substrates. Gel filtration chromatography showed that polymeric materials of high molecular weights were the result of these treatments. Incubation of [1-¹³C], [2-¹³C] and [3-¹³C] coniferyl alcohol with lignin peroxidase/H₂O₂ resulted in products similar to-DHP lignins prepared by horseradish peroxidase/H₂O₂ with respect to occurrence of identical resonances in corresponding solution-state ¹³C NMR spectra. Consequently, the role of polymerization of low molecular weight phenolics as a mechanism for detoxification was ascribed to these fungal peroxidases. / Ph. D.

Arsenic (As) in drinking water poses a critical threat to public health. More than 150 million people worldwide are at risk of developing diseases from unsafe concentrations of As in groundwater. Arsenic occurs naturally in rocks, soils, and sediments and generally remains associated with solid phases. However, changes in aquifer geochemistry can mobilize As into groundwater, contaminating drinking water sources. This dissertation investigates As cycling in an aquifer contaminated by petroleum hydrocarbons near Bemidji, Minnesota, where As is mobilized into groundwater due to biodegradation of hydrocarbons coupled to reduction of ferric oxides. The first project describes how aquifer sediments act as both sources and sinks for As in groundwater, depending on the prevailing redox conditions. Results show that As is released to groundwater near the hydrocarbon source but is removed near the hydrocarbon plume's leading edge. Comparison of data from 1993 to 2016 shows that As has been redistributed in aquifer sediment as the plume has expanded over time. The second project presents a mass balance for As, which shows that despite elevated As in groundwater (up to 230 μg/L), >99.7% of As mass in the aquifer is in sediments. Calculations demonstrate that As in sediment can be 22x less than the method detection limit and still cause unsafe concentrations in groundwater, suggesting that the use of standard methods limits our ability to predict where naturally occurring As poses a threat to groundwater. In the third project, a reactive transport model simulates As cycling for 400 years. Results show that sorption of As to ferrihydrite limits As transport within 300 m of the hydrocarbon source. Modeling predicts that over the plume's lifespan, more groundwater will be contaminated by As than benzene, the primary contaminant of concern in hydrocarbon plumes. Combined, these studies suggest that many aquifers are vulnerable to unsafe As concentrations due to mobilization of natural As if bioavailable organic carbon is introduced. Although aquifers can attenuate As, it may take centuries for As to be fully removed from groundwater, suggesting it is prudent to account for natural contaminants like As when developing remediation strategies at petroleum spill sites. / Ph. D. / Arsenic (As) in groundwater used for drinking water is a risk to public health. More than 150 million people worldwide are at risk of developing diseases and cancer from unsafe levels of As in groundwater. Arsenic occurs naturally in rocks, soils, and sediments. However, changes in aquifer chemistry can release As from these solid materials into groundwater, contaminating drinking water sources. This dissertation investigates As cycling in a petroleum-contaminated aquifer near Bemidji, Minnesota, where As is released into groundwater due to the breakdown of petroleum by microorganisms under zero-oxygen conditions. The first project describes how sediments release As to, and remove As from, groundwater. Results show that As in groundwater is removed by sediments under medium-to-high-oxygen conditions. Analyses of sediment collected in 1993 showed that in the past, similar processes affecting As in groundwater were occurring closer to the petroleum release site. Over time, the zero-oxygen conditions that allow As to be released into groundwater spread, causing a more widespread As release. The second project presents a mass balance for As, which shows that despite high As in groundwater (up to 230 μg/L), >99.7% of As is associated with sediments. Calculations demonstrate that the analytical methods used to detect As in sediment are not sensitive enough to predict where natural As poses a threat to groundwater. In the third project, a numerical model shows that the presence of iron oxide minerals limit As transport in groundwater. Modeling simulations suggest that in the future, more groundwater will be contaminated by As than benzene, the primary contaminant of concern in petroleum plumes. Combined, these studies suggest that many aquifers are vulnerable to the release of unsafe levels of As from naturally occurring sources if organic carbon is introduced. Although aquifers can naturally remove As from groundwater, it may take centuries for As to be fully removed, suggesting it is prudent to account for natural contaminants like As when developing clean-up plans at oil spill sites.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

Lignocellulosic biomass is a potential source of fermentable sugars such as glucose. Enzymatic hydrolysis of cellulose is a viable method of solubilizing the glucose from biomass, but the cellulose fraction of native lignocellulosic material is shielded from enzymatic attack by the lignin-hemicellulose matrix surrounding it. Pretreating lignocellulosic biomass with dilute sulfuric acid at high temperatures solubilizes hemicellulose, rendering the cellulose fraction more susceptible to enzymatic hydrolysis. Evaluation of dilute-acid, high-temperature pretreatments depends on polysaccharide analysis of the two fractions resulting from a pretreatment, prehydrolyzed solids(PHS) and prehydrolyzate liquid(PH). The polysaccharide analysis is based on a method described by the National Renewable Energy Laboratory and involves a two-stage sulfuric acid hydrolysis followed by HPLC quantification using ion-moderated partition chromatography and refractive index detection. The subject of this thesis is identifying and quantifying the sources of error associated with the polysaccharide analysis and the error associated with the evaluation of the effects of pretreatment on the polysaccharide fractions of switchgrass and poplar. This was addressed by conducting replicate polysaccharide analyses on single samples of native biomass, PHS, and PH. The variability associated with these measurements was compared to the variability associated with replicate analyses of identically pretreated biomass. It was found that the use of sugar standards to correct for sugar destroyed during the analysis adds error and most likely overestimates the amount of sugar from biomass actually destroyed. It is evident that assuming a volume after neutralization of the hydrolyzed biomass sample is more reproducible than measuring the volume. When using a batch-type reactor and the temperature and acid parameters used in this study,140°C-180°C/ 0.6-1.2 % sulfuric acid (w/w), it is evident that the major source of error in evaluating pretreatment conditions is the pretreatment itself, not the analysis. / Graduation date: 1995

ABSTRACT To compare the degree of biodegradation of petroleum hydrocarbons in sediments from Ikarama and Okwori in the Niger delta, Nigeria, concentrations of n-alkanes and polycyclic aromatic hydrocarbons in the sediments were measured. Analysis was conducted with gas chromatography using mass spectrometry detector. While the decrease in concentrations of n-alkanes and polycyclic aromatic hydrocarbons confirmed the process of biodegradation in the sediments it was not solely fit to substantiate the degree of biodegradation in the sediments. Hence the percentage proportion of n-alkanes and polycyclic aromatic hydrocarbons was used. The degree of biodegradation of n-alkanes in both Okwori and Ikarama was almost similar. However, it was observed that polycyclic aromatic hydrocarbons were biodegraded in Okwori sediments than Ikarama sediments and this indicates the degree of biodegradation of petroleum hydrocarbons impacted sediments in Okwori is greater than that of Ikarama.

by Cheung Pui Yi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 124-135). / Abstract --- p.ii / Acknowledgements --- p.iv / List of Tables --- p.viii / List of Figures --- p.ix / List of Abbreviations --- p.xiii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- General Background --- p.1 / Chapter 1.2 --- Occurrence and Structure of Cellulose --- p.1 / Chapter 1.3 --- Occurrence and Structure of Hemicelluloses --- p.4 / Chapter 1.4 --- Biodegradation of Cellulose and Hemicelluloses --- p.4 / Chapter 1.4.1 --- Cellulolytic and Hemicellulolytic Microorganisms --- p.4 / Chapter 1.4.2 --- Enzymes Involved in Cellulose Degradation --- p.10 / Chapter 1.4.2.1 --- "Endo-1,4-β-glucanases" --- p.12 / Chapter 1.4.2.2 --- "Exo-1,4-β-glucanases" --- p.14 / Chapter 1.4.2.3 --- β-Glucosidases --- p.16 / Chapter 1.4.2.4 --- Oxidative Enzymes --- p.18 / Chapter 1.4.3 --- Synergistic Action between Cellulolytic Enzymes --- p.19 / Chapter 1.4.4 --- Enzymes Involved in Hemicellulose Degradation --- p.21 / Chapter 1.4.4.1 --- "Endo-1,4-β-xylanases" --- p.22 / Chapter 1.4.4.2 --- β-Xylosidases --- p.24 / Chapter 1.4.4.3 --- Other Xylanolytic Enzymes --- p.24 / Chapter 1.4.5 --- Synergistic Action between Hemicellulolytic Enzymes --- p.25 / Chapter 1.5 --- Flammulina velutipes --- p.26 / Chapter 1.6 --- Aims of the Present Investigation --- p.27 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Organism --- p.28 / Chapter 2.2 --- Culture Medium --- p.28 / Chapter 2.3 --- Determination of the Optimal Growth pH of Flammulina velutipes --- p.29 / Chapter 2.4 --- "Preparation of Inoculum, Cultivation and Harvest of Fungal Cultures" --- p.30 / Chapter 2.5 --- Enzyme Assays --- p.30 / Chapter 2.5.1 --- "Exo-1,4-β-glucanase" --- p.30 / Chapter 2.5.2 --- "Endo-1,4-β-glucanase" --- p.31 / Chapter 2.5.3 --- "Endo-1,4-β-xylanase" --- p.34 / Chapter 2.5.4 --- Extracellular β-Glucosidase --- p.36 / Chapter 2.5.5 --- Cell-Associated β-Glucosidase --- p.38 / Chapter 2.5.6 --- Extracellular β-Xylosidase --- p.38 / Chapter 2.5.7 --- Cell-Associated β-Xylosidase --- p.38 / Chapter 2.6 --- Determination of Optimal Temperatures for Cellulolytic and Xylanolytic Enzymes --- p.39 / Chapter 2.7 --- Determination of the Optimal pH for Enzyme Reaction --- p.39 / Chapter 2.8 --- Protein Determination --- p.39 / Chapter 2.9 --- Determination of Enzyme Induction Patterns --- p.42 / Chapter 2.10 --- Elucidation of Cellulase Production Patterns in F. velutipes --- p.43 / Chapter 2.10.1 --- Native Polyacrylamide Gel Electrophoresis --- p.43 / Chapter 2.10.2 --- Activity Staining for Endoglucanases --- p.43 / Chapter 2.10.3 --- Activity Staining for β-Glucosidases --- p.44 / Chapter 2.10.4 --- Protein Staining --- p.44 / Chapter 2.10.5 --- Preparative Polyacrylamide Gel Electrophoresis --- p.44 / Chapter 2.10.6 --- Separation of Proteins and Partial Purification of Different Cellulase Species after Preparative Polyacrylamide Gel Electrophoresis --- p.45 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Determination of the Optimal pH for Fungal Growth --- p.46 / Chapter 3.2 --- Determination of the Optimal Temperature for Cellulolytic and Xylanolytic Enzyme Activity --- p.48 / Chapter 3.3 --- Determination of the Optimal pH for Enzyme Reaction --- p.64 / Chapter 3.4 --- Time Course Experiments on the Production of Cellulolytic and Hemicellulolytic Enzymes --- p.72 / Chapter 3.4.1 --- Production of Cellulolytic Enzymes --- p.72 / Chapter 3.4.2 --- Production of Hemicellulolytic Enzymes --- p.77 / Chapter 3.5 --- Determination of Enzyme Induction Patterns --- p.82 / Chapter 3.5.1 --- Induction of Exoglucanase Production --- p.82 / Chapter 3.5.2 --- Induction of Endoglucanase Production --- p.84 / Chapter 3.5.3 --- Induction of Extracellular β-Glucosidase Production --- p.86 / Chapter 3.5.4 --- Induction of β-Xylanase Production --- p.88 / Chapter 3.5.5 --- Induction of Extracellular β-Xylosidase Production --- p.90 / Chapter 3.5.6 --- Changes in Extracellular Protein Levels in DMS Media Supplemented with Different Substrates --- p.92 / Chapter 3.5.7 --- Changes in Reducing Sugar Levels in DMS Media Supplemented with Different Substrates --- p.94 / Chapter 3.6 --- Partial Purification of Different Cellulases Species Produced by Flammulina velutipes --- p.96 / Chapter 3.6.1 --- Native Polyacrylamide Gel Electrophoresis --- p.96 / Chapter 3.6.2 --- Activity Staining for Endoglucanases --- p.96 / Chapter 3.6.3 --- Activity Staining for β-Glucosidases --- p.96 / Chapter 3.6.4 --- Assay of Cellulolytic Enzymes after Preparative Polyacrylamide Gel Electrophoresis --- p.101 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- Optimal Conditions for Cellulolytic and Hemicellulolytic Enzymes of F. velutipes --- p.105 / Chapter 4.1.1 --- Optimal Temperature for Enzymic Reaction --- p.105 / Chapter 4.1.2 --- Optimal pH for Enzymic Reaction --- p.106 / Chapter 4.2 --- Production of Cellulolytic and Hemicellulolytic Enzymes --- p.109 / Chapter 4.2.1 --- Production of Cellulolytic Enzymes --- p.109 / Chapter 4.2.2 --- Production of Hemicellulolytic Enzymes --- p.110 / Chapter 4.3 --- Enzyme Induction Patterns --- p.111 / Chapter 4.4 --- Partial Purification of Different Cellulase Species Produced by Flammulina velutipes --- p.116 / Chapter 4.5 --- Conclusion --- p.121 / Chapter 4.6 --- Further Studies --- p.123 / List of References --- p.124

by Stephen, Man-yuen Cheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 124-141). / Abstract also in Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / List of Figures --- p.iv / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The development of dyes --- p.1 / Chapter 1.2 --- The chemistry of azo dyes --- p.2 / Chapter 1.3 --- "Evaluation of dyes submitted under the ""Toxic Substances Control Act"" new chemicals programme" --- p.6 / Chapter 1.4 --- Environmental concerns of dyes --- p.7 / Chapter 1.5 --- Decolorization techniques --- p.11 / Chapter 1.5.1 --- Activated sludge process --- p.11 / Chapter 1.5.2 --- Chlorination --- p.12 / Chapter 1.5.3 --- Fenton's reaction --- p.13 / Chapter 1.5.4 --- Ozonation --- p.13 / Chapter 1.5.5 --- Adsorption by activated carbon --- p.13 / Chapter 1.5.6 --- Chemical flocculation --- p.14 / Chapter 1.5.7 --- Coagulation --- p.14 / Chapter 1.5.8 --- Advance Oxidation Process --- p.15 / Chapter 1.5.8a --- Photocatalytic activation --- p.17 / Chapter 1.5.8b --- Enhancement of reaction rates of photocatalytic reaction --- p.21 / Chapter 1.5.9 --- Biosorption of azo dyes by Pseudomonas sp. K-l --- p.23 / Chapter 1.6 --- Water pollution in Hong Kong --- p.24 / Chapter 1.7 --- Purpose of study --- p.24 / Chapter 2 --- Objectives --- p.27 / Chapter 3 --- Materials and Methods --- p.28 / Chapter 3.1 --- Materials --- p.28 / Chapter 3.1.1 --- Azo dyes --- p.28 / Chapter 3.1.2 --- Biosorbent --- p.28 / Chapter 3.1.3 --- Chemicals --- p.28 / Chapter 3.2 --- Photocatalytic reactor --- p.31 / Chapter 3.3 --- Determination of the peak absorbance of five azo dyes at different pH --- p.31 / Chapter 3.4 --- Determination of dye concentration by measuring at peak absorbance --- p.37 / Chapter 3.5 --- Determination of pseudo-first-order rate constant --- p.37 / Chapter 3.6 --- Effect of initial concentration of procion red MX-5B on photocatalytic degradation --- p.39 / Chapter 3.7 --- Effect of initial concentration of hydrogen peroxide on photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.8 --- Effect of initial pH on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.9 --- Effect of initial temperature on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.10 --- Effect of titanium dioxide on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.11 --- Effect of UV intensity in the photocatalytic degradation of procion red MX-5B --- p.41 / Chapter 3.12 --- Degradation kinetics of different dyes --- p.41 / Chapter 3.13 --- Degradation of 40 mg/L of procion red MX-5B under optimized conditions --- p.41 / Chapter 3.14 --- "Degradation of 1,000 mg/L of procion red MX-5B under optimized conditions" --- p.42 / Chapter 3.15 --- Temporal change of the concentration of procion red MX-5B in calcium alginate beads --- p.42 / Chapter 3.16 --- "Temporal change of the concentration of procion red MX-5B in alginate beads of 5,000 mg/L of Ti02" --- p.43 / Chapter 3.17 --- "Temporal change of the concentration of procion red MX-5B in alginate beads of 10,000 mg/L of Ti02" --- p.43 / Chapter 3.18 --- Effect of the concentration of titanium dioxide in alginate beads in the photocatalytic degradation of procion red MX-5B --- p.45 / Chapter 3.19 --- "Effect of hydrogen peroxide in the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.47 / Chapter 3.20 --- "Temporal change of the concentration of procion red MX-5B in alginate beads with 5,000 mg/L of Ti02" --- p.47 / Chapter 3.21 --- "Effect of biomass of Pseudomonas sp. K1 on the photocatalytic degradation of procion red MX-5B in alginate beads with 5,000 mg/L of Ti02" --- p.48 / Chapter 3.22 --- Diffuse reflectance-IR spectroscopic analysis of degradation product(s) --- p.49 / Chapter 3.23 --- Nuclear magnetic resonance (NMR) spectroscopic analysis of degradation products --- p.49 / Chapter 3.24 --- Toxicological evaluation of degradation products using Microtox® test --- p.51 / Chapter 4 --- Result --- p.54 / Chapter 4.1 --- Biosorption of dyes by Pseudomonas sp. K1 --- p.54 / Chapter 4.2 --- UV intensities of the eight Cole-Parmer UV lamps at 365 nm --- p.54 / Chapter 4.3 --- Determination of the peak absorbance of five azo dyes at different pH using scanning spectrophotometer --- p.54 / Chapter 4.4 --- Determination of dye concentration by measuring at peak absorbance --- p.66 / Chapter 4.5 --- Effect of initial concentration of procion red MX-5Bin photocatalytic degradation rate --- p.66 / Chapter 4.6 --- Effect of initial concentration of hydrogen peroxide on the photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.7 --- Effect of initial pH on photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.8 --- Effect of initial temperature on photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.9 --- Effect of titanium dioxide on photocatalytic degradation of procion red MX-5B --- p.77 / Chapter 4.10 --- Effect of UV intensity on photocatalytic degradation of procion red MX-5B --- p.77 / Chapter 4.11 --- Photocatalytic degradation kinetics of different azo dyes --- p.77 / Chapter 4.12 --- Photocatalytic degradation of 40 mg/L of reactive red241 under optimized conditions --- p.77 / Chapter 4.13 --- Photocatalytic degradation of 40 mg/L procion red MX-5B under optimized conditions --- p.81 / Chapter 4.14 --- "Photocatalytic degradation of 1,000 mg/L of procion red MX-5B under optimized conditions" --- p.81 / Chapter 4.15 --- Temporal change of the concentration of procion red MX-5B in calcium alginate beads --- p.81 / Chapter 4.16 --- "Temporal changes of the concentration of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.85 / Chapter 4.17 --- "Temporal change of the concentration of procion red MX-5B in 10,000 mg/L of Ti02-alginate beads" --- p.85 / Chapter 4.18 --- Effect of the concentration of titanium dioxide in alginate beads in the photocatalytic degradation of procion red MX-5B --- p.89 / Chapter 4.19 --- "Effect of hydrogen peroxide in the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.89 / Chapter 4.20 --- "Temporal change of the concentration of procion red MX-5Bin alginate beads with 5,000 mg/L of Ti02" --- p.89 / Chapter 4.21 --- "Effect ofbiomass of Pseudomonas sp. K1 on the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.93 / Chapter 4.22 --- Degradation products analysis using diffuse reflectance-IR spectroscopy --- p.93 / Chapter 4.23 --- Degradation products analysis using nuclear magnetic resonance (NMR) --- p.101 / Chapter 4.24 --- Toxicological evaluation of degradation products using Microtox® test --- p.101 / Chapter 5 --- Discussion --- p.104 / Chapter 5.1 --- Biosorption of azo dyes in Pseudomonas sp. K-l --- p.104 / Chapter 5.2 --- Optimization of photocatalytic degradation of azo dyes --- p.105 / Chapter 5.2.1 --- Effect of initial concentration of procion red MX-5B on the photocatalytic degradation --- p.105 / Chapter 5.2.2 --- Effect of initial concentration of hydrogen peroxide on the photocatalytic degradation --- p.106 / Chapter 5.2.3 --- Effect of initial pH on the photocatalytic degradation --- p.107 / Chapter 5.2.4 --- Effect of initial temperature on the photocatalytic degradation --- p.108 / Chapter 5.2.5 --- Effect of titanium dioxide on the photocatalytic degradation --- p.109 / Chapter 5.2.6 --- Effect of UV intensity on the photocatalytic degradation --- p.110 / Chapter 5.2.7 --- Degradation kinetics of different dyes --- p.111 / Chapter 5.2.8 --- Optimized conditions for PCO of reactive red 241 and procion red --- p.112 / Chapter 5.3 --- Immobilization of titanium dioxide and Pseudomonas sp. K-l in alginate beads --- p.113 / Chapter 5.3.1 --- Temporal changes of the concentration of dye in alginate beads --- p.113 / Chapter 5.3.2 --- Effect of titanium dioxide in alginate beads in PCO --- p.114 / Chapter 5.3.3 --- Effect of hydrogen peroxide in alginate beads in PCO --- p.115 / Chapter 5.3.4 --- "Temporal change of dye concentration in alginate beads of 5,000 mg/L" --- p.115 / Chapter 5.3.5 --- Effect of biomass of Pseudomonas sp. K-l in alginate beads on the PCO of dye --- p.115 / Chapter 5.4 --- Diffuse reflectance IR spectroscopic analysis of degradation products --- p.116 / Chapter 5.5 --- 1HNMR analysis of degradation products --- p.119 / Chapter 5.6 --- Toxicological evaluation of degradation products using Microtox® test --- p.120 / Chapter 5.7 --- Application --- p.121 / Chapter 6 --- Conclusion --- p.122 / Chapter 7 --- References --- p.124 / Appendix 1 --- p.142 / Appendix 2 --- p.143

Abstract not available

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 (K[subscript s]), the maximum utilization rate (k[subscript max]X), and inhibition constants (K[subscript I]). The kinetic constants were used to model the results of inhibition studies using competitive and uncompetitive inhibition models. Acetylene was found to function as a reversible inhibitor and was used to probe the activities of reductive dechlorination. Various acetylene concentrations were used to differentiate microbial processes, including methanogenesis, acetogenesis, and halorespiration. Acetylene concentrations of 48, 192, and 12 ��M, respectively, were required to achieve 90% inhibition in the rates of methanogenesis, TCE and VC transformation. H���-dependent acetate production was not inhibited by acetylene. K[subscript s] values for TCE and VC were 12 ��M and 63 ��M, respectively. Model fitting of acetylene inhibition constants (K[subscript IC]) for TCE and VC transformations yielded the same value (0.4 ��M) for a competitive inhibition model. However, for uncompetitive inhibition the estimated K[subscript IU] for TCE to c-DCE, TCE to 1,1-DCE and VC to ethene were 13.3, 14.1 and 2.2 ��M, respectively. Competitive and uncompetitive inhibition models simulated experimental data equally well for results obtained at high TCE and VC concentrations. The models were further verified to fit transient data of acetylene inhibition at lower TCE and VC concentrations, and competitive inhibition resulted in a better fit to the experimental data. 1-chloro-1-fluoroethene (1,1-CFE) was found to track the rate of VC transformation well, since VC and 1,1-CFE had similar maximum transformation rates and K[subscript s] values. A competitive inhibition model with the measured K[subscript s] values, 63 and 87 ��M. was used to predict the rates of VC and 1,1-CFE transformation, respectively. The similar rates and results of acetylene and compound inhibition studies indicated VC and 1,1-CFE were transformed by the same enzyme. 1,1-CFE transformation by three different cultures, clearly demonstrate that 1,1-CFE was an excellent surrogate to track rates of VC transformation. / Graduation date: 2004

Récemment, de nombreuses recherches ont été dévolues à la mise au point de réacteurs biphasiques, perçus comme une nouvelle technologie pour le traitement des polluants organiques dans les effluents gazeux. Ces réacteurs impliquent lutilisation dune seconde phase non aqueuse pour améliorer la solubilité et le transfert de masse des composés hydrophobes. Dans ce travail, nous avons développé un réacteur biphasique agité utilisant lhuile de silicone comme seconde phase. Initialement, Rhodococcus erythropolis T 902.1 a été sélectionné sur base de sa capacité à dégrader lisopropylbenzène (IPB), un composé choisi comme modèle représentatif de la famille du benzène. Deuxièmement, le transfert de masse de loxygène et de lIPB a été étudié en relation avec les conditions hydrodynamiques du réacteur et le type dhuile de silicone. Lutilisation dune proportion de 10 % dhuile de faible viscosité (10cSt) naffecte pas significativement le transfert de masse de loxygène. Cependant la grande solubilité de lIPB dans lhuile de silicone conduit à une forte augmentation du potentiel de transfert, spécialement pour les proportions en huile les plus élevées. Néanmoins, il ne semble pas utile de dépasser une proportion de 10 % car le KLaIPB et le KLaO2 diminuent drastiquement pour des proportions supérieures. Lexistence dune concentration optimale en élément biotique apparaît également. En effet, les concentrations optimales en biomasse (B) et extrait surfactant (ES) peuvent être évaluées à, respectivement 0,5 g/L et 0,7 g/L, elles assurent une valeur maximale du coefficient global de transfert de masse de loxygène (KLaO2). Plus spécifiquement, lES augmente laire interfaciale « a » en diminuant le diamètre des bulles tandis que la biomasse la diminue dès quune concentration de 1 g/L est atteinte. Au contraire, lES agit négativement sur le KL tandis que la biomasse laméliore globalement. En terme de performance, il est clairement montré que la taux de biodégradation de lIPB est davantage corrélé au débit gazeux de leffluent quà la concentration en polluant. Le réacteur biphasique a été suivi sur une période de 38 jours afin de caractériser son comportement à moyen terme pour différentes conditions opératoires. Lors dune phase dalimentation transitoire (10h/j), la capacité moyenne délimination est denviron 240 g/m3 pour une charge massique de 390 g/m3. Finalement, une approche originale a été développée en utilisant un bioréacteur de type scale-down pour reproduire les conditions hydrodynamiques rencontrées dans les réacteurs industriels. Il est clairement démontré que le polluant (IPB) affecte négativement lextrapolation en augmentant la vitesse de séparation de phase. Cependant cet impact négatif est largement compensé par la présence déléments biotiques qui stabilise fortement le système biphasique, rendant totalement envisageable lextrapolation à grande échelle. En conclusion, lutilisation dun réacteur biphasique eau-huile de silicone pour lélimination de concentrations élevées (~ 6g/m3) en polluants hydrophobes est adéquate. Le réacteur proposé présente de réelles opportunités pour le traitement biologique deffluents pollués par des composés hydrophobes. Son utilisation pourrait être envisagée lorsque loxydation thermique savère trop onéreuse ou lorsque les biofiltres classiques atteignent leurs limites ( >1 g/Nm3 et une charge volumique de 90m3/m3.h.)./Recently, a lot of research has been devoted to the study of two-phase partitioning bioreactors (TPPB) as new technology for xenobiotic degradation in gaseous effluents. These reactors involve the use of a second non-aqueous phase to improve the solubility and transfer of hydrophobic compounds. In this work, we have developed a stirred two-phase partitioning bioreactor using silicone oil as second phase. Initially, Rhodococcus erythropolis T 902.1 was selected on the basis of its capacity to metabolize isopropyl-benzene (IPB), used as representative of the benzene-containing compounds. Secondly, the mass transfer of both IPB and oxygen has been considered with relation to their influence on the hydrodynamics of the reactor and the type of silicone oil used. The addition of 10% low viscosity silicone oil (10 cSt) in the reactor does not significantly affect the oxygen transfer rate. The very high solubility of IPB in the silicone oil leads to an enhancement of the driving force term, especially when high proportion of silicone oil are used. However, it is not necessary to use a volume fraction higher than 10% since KLaIPB and KLaO2 decrease sharply at above such proportion. In addition, an optimal concentration appeared to exist for both biotic components, respectively 0,5 g/L and 0,7 g/L for biomass (B) and surfactant extract (SE) when the global mass transfer coefficient (KLa) of oxygen was measured in the TPPB. More specifically, SE improved the interfacial area a by decreasing the bubble diameter, while B reduced it at concentrations up to 1 g/L. In contrast, the SE concentration acted negatively on KL, while it was favoured by the B concentration. In term of performances, it was clearly shown that the biodegradation rate is more directly related to the inlet flow of IPB than to the concentration of IPB in the inlet gas. The TPPB was monitored for 38 days to characterise its behaviour under several operational conditions. During an intermittent loading phase (10 h/day), the average elimination capacity remained above 240 g/m3.h for an average IPB inlet load of 390 g/m3. h. Finaly, an original approach was developed using a scale-down bioreactor allowing to reproduce the hydrodynamics encountered under full scale TPPB. It was clearly shown that the IPB affects negatively the scaling-up of the process by increasing the speed of phase partitioning. However, this negative impact was strongly compensated by the presence of biotic compounds stabilizing the two phase system and rendering the scaling-up process feasible. In conclusion, the use of a water-silicone oil TPPB to remove a high inlet load of IPB was successful. The proposed reactor retains a high potential for the biological treatment of gas effluents polluted by hydrophobic aromatic compounds. The suggested process might be applied in the range of concentration and flow where thermal oxidation is too expensive (between 1 and 7 g/Nm3) or when the biofilters are usually limited, i.e. to treat a polluted effluent concentrated with > 1 g/Nm3 at a flow of 90m3/m3.h.