This thesis describes the characterization of benzene-degrading denitrifying cultures. Four objectives were pursued. The first objective was to identify conditions that promote or inhibit benzene decomposition and thus, to improve the biodegradation capacity of the cultures. FeS, resazurin, and nitrite had a detrimental impact on benzene degradation, whereas addition of supernatant from an active culture improved the benzene degradation activity by reducing the lag times. The second objective was to determine the microbial community composition in enrichment cultures and to identify the bacterial species that mediate benzene mineralization. Five dominant bacterial Operational Taxonomic Units (OTUs) were identified. The most abundant phylotype was related to the gram-positive Peptococcaceae family. Other bacteria present were closely affiliated with Dechloromonas, Azoarcus, Chlorobi and Anammox species. To correlate the growth of these specific microbes with benzene degradation, the abundance of specific 16S rRNA genes was monitored during mineralization process using quantitative polymerase chain reaction (qPCR). Based on the result of qPCR experiments and information about the metabolisms of the above bacteria, a syntrophic mode of benzene degradation was hypothesized to occur under denitrifying conditions. In this process, Peptococcaceae initiate attack on benzene, and ferment benzene to hydrogen and low molecular weight products such as acetate. These products are then consumed by nitrate-respiring Azoarcus and Dechloromonas or phototrophic Chlorobi. Anammox bacteria recycle and detoxify nitrite, and stabilize the culture. The third objective was to isolate and characterize pure cultures with the ability to mineralize benzene anaerobically. Dechloromonas- and Dechlorosoma-like microorganisms were isolated from several benzene-degrading microcosms. Theses bacteria, however, were not able to metabolize benzene anaerobically. The fourth objective was to investigate the key metabolic steps in the anaerobic benzene degradation pathway and to identify enzymes that are involved in this process. Differential transcription during growth of the culture on benzene versus growth on a metabolite of benzene degradation, i.e. benzoate was examined. Carboxylase-related genes were specifically transcribed in the presence of benzene. Furthermore, mRNA sequences corresponding to the genes that encode different enzymes of the benzoyl-CoA degradation pathway were present in the culture. These findings suggest that mineralization of benzene starts by its activation to benzoate through a carboxylation reaction catalyzed by benzene carboxylase. Benzoate is further metabolized through benzoyl-CoA pathway.

The thesis objective was to investigate methods for improving the solubility of yellow mustard precipitated protein isolate (RTech Laboratories, USA) to allow for its use in protein enhanced acidic beverages along with soluble protein isolate in the pH range of 2 to 4.5. Four treatments were tested: hydrolysis with Alcalase®; cross-linking with transglutaminase; salting in with sodium chloride, sodium tripolyphosphate, and sodium hexametaphosphate; and protective colloid formation with pectin. The effectiveness of each was determined by its ability to improve nitrogen solubility (Nx6.25, AOCS-Ba11-65). The most effective treatments were hydrolysis and pectin stabilization. Pectin (1.5 w/v%) improved solubility from 6% to 29% at pH 4. Alcalase increased solubility from 20% to 70% at pH 3 after 2 h of hydrolysis (0.5AU/5g PPI, pH 8.5, 50-55degC) and eliminated the protein’s isoelectric point in the acidic pH range. Investigating the combined use of both treatments to further increase PPI solubility is recommended.

The development of genome scale metabolic models have been aided by the increasing availability of genome sequences of microorganisms such as Geobacter sulfurreducens, involved in environmentally relevant processes such as the in-situ bioremediation of U(VI). Since microbial activities are the major driving forces for geochemical changes in the sub-surface, understanding of microbial behavior under a given set of conditions can help predict the likely outcome of potential subsurface bioremediation strategies. Hence, a model based lookup table was created to capture the variation in physiology of G. sulfurreducens in response to environmental perturbations. Thermodynamically feasible flux distributions were generated by incorporating thermodynamic constraints in the model. These constraints together with the mass balance constraints formed the thermodynamics based metabolic flux analysis model (TMFA). Metabolomics experiments were performed to determine the concentration of intracellular metabolites. These concentrations were posed as constraints in the TMFA model to improve the model accuracy.

Multiple Effect Evaporators (MEE) are used in kraft pulp mills to concentrate black liquor. In order to verify if the MEE is operating at an optimum condition, thermal performance of evaporators is calculated. Due to the interconnection of many variables involved, this can be a challenging task. Thus, this work involved the study of operating data from two Canadian pulp mills using Multivariate Data Analysis (MVDA) techniques: Principal Component Analysis (PCA) and Partial Least Squares Analysis (PLS). Moreover, the evaporation system was modelled using a dynamic simulation software called CADSIM. MVDA determined that the thermal performance of the evaporators was positively correlated with the weak black liquor flow rate and negatively correlated with the steam pressure (to the first effect). The CADSIM model confirmed these findings. Therefore, these two techniques show to be useful tools in identifying operating variables that may be adjusted to improve thermal performance of evaporators.

Factors that may govern diesel particulate matter (DPM) oxidation at low temperatures (~200°C) were studied using reactivity and TP-ToFSIMS analysis. Best-case scenarios that give maximum gasification rates were determined for DPM impregnated with KOH and non-catalyzed DPM using temperature programmed oxidation and isothermal experiments. Conditions of intimate catalyst-carbon contact (K/C molar ratio=1/50) and high NO2 concentrations (1%) to improve the reactivity of the carbon reactive sites were unable to meet the steady state gasification rate needed for particulate filter regeneration for a modern diesel engine at 200°C. Oxygen-free thermal annealing (>500°C) caused reactivity losses of a maximum of 40% that correspond to changes to surface morphology and/or concentration of oxygen-containing functional groups. TP-ToFSIMS identified surface functional group changes with temperature on non-dosed and NOX pre-dosed (1.5%NO, 1%NO2, 4.5%O2, balance helium) diesel soot and sucrose char. Detailed analysis of the NOX dosed sucrose char spectra using both inspection and principal component analysis techniques revealed that the 1200 ion fragments created could be reduced to five sets of ions that are chemically and kinetically distinct. These sets presumably represent surface functional groups on the carbon. For example, Set IV may represent carboxylic acid, lactone, or carboxylic anhydride functional groups. Based on these results a mechanism for the surface reaction of NO2 with carbon under vacuum conditions was postulated. At temperatures less than 200°C the ion fragments contain primarily carbon-NO2 type ions. As temperature increases between 200 and 400°C the ion fragments are primarily carbon-NO and carbon-N type fragments. At higher temperatures (>500°C) the surface is enriched with nitrogen containing functional groups. A surface reaction mechanism is proposed where NO2 is bonded to an armchair site and with increasing temperatures and molecular rearrangements the N is incorporated into the carbon ring. The initial surface composition of NOx containing functional groups changes within the area of relevance of low temperature soot regeneration (i.e. between 25° and 200°C). Further studies are needed to understand the effect of N-incorporation on carbon reactivity. No rate processes either in reactor studies or based on surface functional groups met the rate criteria for low temperature DPM oxidation.

A microencapsulation-based technology platform for effective delivery of multiple micronutrients for food fortification has been developed. The technology, consisting of extrusion agglomeration followed by encapsulation through surface coating, has been successfully tested on three size scales in typical staple foods: as a surface treatment on salt and sugar, on 20-100µm scale; in salt on a 300-1200 μm scale; and on reconstituted rice on the 5-10 mm scale. The process results in effective delivery systems for one or more active ingredients with organoleptic properties that are unnoticeable to the average consumer. Particularly, salt double fortified with iodine and iron using the microencapsulated ferrous fumarate premix made by the extrusion-based agglomeration process had acceptable sensory properties and stability when stored at 40oC and 60% relative humidity (RH) for up to a year. In these tests >85% of iodine and >90% of ferrous iron were retained. Reconstituted Ultra Rice® grains made by extrusion stabilized by internal gelation has resulted in improved grain integrity and a much simplified process, compared to the original, patented surface crosslinking technique. The most effective internal gelation system is composed of alginate, calcium sulphate (CaSO4), and sodium tripolyphosphate (STPP) at a best ratio of 3%:3%:0.6% (w/w). It is feasible to incorporate folic acid into the existing fortification programs using the technology platform developed in this study. The results indicate that the potential interactions of folic acid with other added micronutrients or with the food vehicles could be prevented by incorporating folic acid as a premix made by the extrusion-based technology. Virtually no folic acid was lost after 9 months storage at 40oC and 60% RH when the folic acid premix was added into salt or sugar samples. The technical feasibility of the microencapsulation-based technology platform has been successfully demonstrated for micronutrient delivery in food vehicles of different size ranges, resulting in fortified staple foods with desired physical, chemical, nutritional, and organoleptic properties. The technology should be adaptable to formulating customized delivery systems of active ingredients for broader applications, and promises to bring immediate benefits in combatting micronutrient deficiencies, that will have far reaching effects in health and social development.

Pretreatment of waste activated sludge (WAS) and the subsequent near-critical water gasification (NCWG) is a potential avenue to convert WAS into value added products. Part one of the research investigated thermal and thermochemical pretreatments. No difference was observed in the percentage of sludge liquefied beyond 10min between 200°C to 300°C. It was found that pretreated activated sludge supernatant (PASS) doubled the gas yield compared to untreated sludge when gasified. The order of effectiveness for sludge treatment was thermo-alkali > thermal > thermo-acid for hydrogen production in NCWG. Part two investigated NCWG parameters to identify optimal conditions. High gasification yields were obtained using a commercial catalyst (Raney nickel), with hydrogen content of 65-75% of the gas phase products. Thermo-alkali treated PASS was found to perform well at subcritical temperatures with 25% higher yields than thermally treated PASS. Increased catalyst loading had little additional effect on gas yields above 0.075g.

Wastewater microbial flocs can protect microorganisms from inactivation by UV light. This effect is detected as tailing at high UV doses in the UV dose response curve. A double-layer structure composed of an inner compact core surrounded by a loose outer layer was proposed by earlier studies to describe UV resistance of microbial flocs. Due to limited oxygen diffusion into the compact cores, the UV inactivation of compact cores and microbial flocs under anaerobic conditions needed to be addressed. The UV disinfection kinetics under anaerobic culturing condition was nearly identical to that of the aerobic study. Moreover, the role of iron concentration on the differences in the UV inactivation kinetics of flocs and cores was assessed. The increase in UV absorbance of floc material due to iron addition could dominate the UV disinfection kinetics of flocs and cores such that they exhibited similar UV disinfection kinetics.

A half-zone experimental set-up was used to study the effects of various liquid bridge and helium flow parameters on the onset of thermocapillary convection in silicone oil liquid bridges. Experiments confirmed that helium flow has a stabilizing effect, with the effect increasing with helium velocity. Furthermore, helium flow in the same direction as surface flow due to Marangoni convection had a more stabilizing effect than countercurrent flow. It was established that increasing helium temperature has a mixed effect, producing a less stable bridge at low helium flow rates, but a more stable flow pattern at higher helium flow rates. Finally, it was confirmed that decreasing the cold disk temperature results in a decrease in critical temperature difference.

A computer-controlled microfluidic extensional flow device is developed for trapping and manipulating micron-sized hard and soft particles. The extensional flow is generated in a diamond-shaped cross-slot that has each corner connected to a pressure-controlled liquid reservoir. By employing an imaging-based control algorithm, a particle can be made to move to an arbitrary position within the slot by adjusting the reservoir pressures and hence the fluid flow rates into/out of the slot. Thus, a soft particle can be trapped indefinitely at a point within the slot, and a known hydrodynamic force can be applied to study the dynamics of stretching and breakup of the particle. Alternatively, adhesion or coalescence dynamics of soft particles may be investigated by effecting a controlled collision between two particles. The device is validated by measuring the low interfacial tension of a compatibilized oil-water interface.