Oil sand processing to extract bitumen generates large volumes of slurry comprising water, silt, sand, clay, unrecovered bitumen, and residual chemical aides and solvents added during the extraction process. The by-product stream of the bitumen extraction is pumped into constructed tailings ponds. Managing these tailings is one of the most difficult environmental challenges for the oil sand industry. This study aims to develop a novel technique to assist in the assessment of the technologies for managing mature fine tailings (MFT) in oil sands. Innovative application of a superabsorbent polymer in the oil sands industry may provide a new method for tailings management. However, thus far, no study has addressed this research gap. In fact, fundamental knowledge of the behavior of MFTs pre-dewatered with the superabsorbent polymer could provide an important way to positively affect the speed of reclamation. To this end, comprehensive instrumentation, geo-environmental, and geotechnical analyses are carried out to obtain essential knowledge on the behavior of MFTs pre-dewatered with the polymer. The results of this study reveal that the mechanical, hydraulic, and thermal properties of the MFTs are related. Evaporation and drying shrinkage can affect the hydro-mechanical properties of the tailings and have a significant influence on the developed shear strength of the MFTs. In addition, the process-affected water includes a high concentration of the dissolved ions and organic chemicals that stem from ore extraction chemicals and tailings treatments, or that may be released from oil sands ores. Through the application of a superabsorbent polymer in the dewatering of oil sand MFTs, the chemical components are entrapped in the polymer chains, thus limiting the mobility of the major ions and trace metals in water bodies beneath the oil sand tailings pond. Results show that the application of the superabsorbent polymer considerably reduces the rate of drainage from the oil sand MFTs into water bodies, which can help mitigate the risk of seepage. The author believes that the superabsorbent polymer dewatering technique can be considered as an environmentally friendly promising approach for management of oil sands MFTs. This new technique can accelerate the pace of reclamation and thus minimize the footprint of the oil industry in Canada.

The commercial rotary dryers used to dry wood wafers (of approximate dimensions 0.63 mm thick, 50 mm wide and 76+ mm long) for the production of panelboard are modified versions of agricultural dryers and have not been designed for the optimal drying of wood wafers. The lack of available information on wafer drying necessitated that the first goal of this research was the characterization of wafer drying behaviour. After the important parameters of wafer drying were identified, the applicability of fluidized bed technology to wafer drying was assessed and an industrial size dryer was designed. The proposed fluidized bed wafer dryer was then compared to a commercial rotary dryer in terms of energy efficiency. Wafer drying behaviour was investigated in two factorial experiments. Three lengths of wafers (25 mm, 44 mm and 63 mm) were individually dried in a 0.15 m draft tube at temperatures of 90°C, 120°C and 150°C. The statistical analysis of the resultant drying rate curves showed that the drying behaviour of aspen wafers was influenced by the effect of wafer length on the external heat and mass transfer rates to the wafer surface, and on the length of internal pathways for bulk flow and diffusion of water. The external drying conditions had a decreasing effect on drying rate until about 10% moisture content at which time drying became limited by internal heat and mass transport. The initial assessment of fluidized bed technology for wafer drying used a 0.15 m semi-cylindrical column for the determination of wafer drying rate curves and wafer behaviour in a fluidized bed of inert particulate solids at excess superficial velocities of 0.25 to 1.0 m/s. Wafer drying times in a bed of 0.5 mm sand at 150°C were about 40% of the drying times for wafers dried by forced convection of air at the same temperature and twice the superficial velocity (~ 1 m/s). Wafer movement in the fluidized bed followed the circulation patterns of the emulsion phase and was thus dependent on the bubbling behaviour of the bed. A minimum excess superficial velocity of 0.25 m/s (depending on distributor design) was required to prevent permanent settling of the wafers to the distributor. Preliminary experimentation on a 2-compartment bed showed that wafers could be circulated through the two compartments in near plug flow. However, the application of this technique to a 4-compartment continuous fluidized bed wafer dryer was unsuccessful because of the separation of sand and wafers caused by slugging beds in two of the compartments. A preliminary design was prepared for an industrial size, 5-compartment fluidized bed wafer dryer to approximate plug flow of wafers by a series of well-mixed fluidized beds in series. The design calculations showed that this dryer was more efficient in terms of energy and plant space than a conventional triple pass rotary dryer. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

An apparatus was constructed to measure the longitudinal gas-permeability of wood microsections about 150 microns thick. This apparatus was used to examine low surface tension drying methods of wood (freeze-drying and alcohol-benzene extraction) believed to maintain the bordered pit tori of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in the non-aspirated condition. Results were compared with drying methods believed to aspirate tori (air-drying, oven-drying and boiling-under-vacuum). Dry nitrogen gas-permeability measurements were made under "steady state" conditions. Similar drying techniques were used to prepare gross specimens which were subsequently subjected to “non-steady state" pressure treatment in end-penetration. Sapwood and heartwood specimens from impermeable interior-type and permeable coast-type Douglas fir were tested. With both gross sections and microsections, the two low surface tension drying methods provided more permeable wood than did air-drying. Boiling-under-vacuum was as effective as low surface tension methods in improving gas-permeability, but not creosote-permeability, whereas oven-drying was as effective as low surface tension methods in improving creosote-permeability, but not gas-permeability. The improvement was most striking in all sapwood samples, less in coast-type heartwood, and nil or not measurable in interior-type heartwood. Under the experimental conditions, latewood gas-permeability was about 2 darcies for all specimens and drying methods. Heartwood early-wood gas-permeability ranged from 0.02 to 2 darcies but was unaffected by drying methods. Sapwood earlywood gas-permeability was improved from 8 to 30 times by low surface tension drying. The greatest gas-permeability was found in the first-formed earlywood, which ranged from 2 to 100 darcies. The later-formed earlywood ranged from 0.02 to 100 darcies, depending on wood origin and drying method. Creosote-permeability of interior-type heartwood was uniformly low by all drying methods. Interior-type sapwood and coast-type sapwood and heartwood were much more permeable after low surface tension drying or oven-drying. By visual observations, after all drying methods, latewood was more permeable than earlywood. Low surface tension drying methods improve earlywood gas-permeability of sapwood, and latewood creosote-permeability of sapwood and coast-type heartwood. / Forestry, Faculty of / Graduate

A pilot scale machine was designed and constructed to allow study of the continuous microwave drying at 2.45 GHz of paper impregnated with water or with phenol formaldehyde resin. This equipment could deliver microwave power at levels up 2.90 KW. Resin impregnated paper dried by microwaves showed better resin distribution, abrasion resistance, and internal bond strength when compared to similar papers dried in a hot air natural convection oven. No significant differences in tensile strength, stretch, Young's modulus, or bending strength were observed. A quantitative method for the determination of resin distribution was devised. Overall efficiencies for the microwave drying based on power input to the microwave power supply were of the order of 50 to 70%. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

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A major challenge facing the global health community is the production of thermally stable vaccines that eliminate the need for unfavorable cold-chain storage protocols, which often require temperatures as low as -80°C. Spray drying is a promising technique to produce thermally stable vaccine powders that retain their efficacy when stored at ambient conditions. Spray drying is gaining popularity in the pharmaceutical community due to its scalability, low cost and high throughput. Processing by spray drying can rapidly immobilize the active vaccine ingredient, such as a viral vector, in an amorphous glassy matrix of a stabilizing excipient tailored to the biologic being stabilized. This encapsulation and reduction in mobility keeps the biologic isolated from mechanical, thermal or chemical stresses that cause damage and inactivation. However, choosing the best excipient, or excipient blend, and optimizing the formulation are costly and time-consuming processes and furthermore, the effects of spray drying on viral vector activity are not fully understood. This thesis focuses on modelling the processing environment for preparing such vaccine powders, by both experimental and numerical means, to understand the relevance of mechanical, thermal and chemical stresses on viral vector activity. Specifically, the viral vector studied here was human type 5 adenovirus (AdHu5), with intended use in tuberculosis vaccines. Mechanical stresses associated with the shear inside the nozzle of a spray dryer were experimentally studied. Viral activity losses associated with shear stresses in an atomizing nozzle were attributed to aggregation; aggregation was created by damaging the virus at very high mechanical stresses but most aggregation was attributed to dispersing the virus in the excipient solution. It was concluded that overall, mechanical stresses in the nozzle caused a minimal amount of viral activity loss compared to other processing factors during spray drying, and in fact, could have a positive influence at moderate shear rates since it actually caused the break-up of AdHu5 aggregates. To investigate thermo-chemical stresses, it was necessary to demonstrate that acoustic levitation of a single drying droplet was an effective screening method to select promising excipients for spray dried vaccines, and could be used to experimentally validate a numerical model of droplet drying. For several different sets of binary carbohydrate blends, levitated particles were found to match property and activity trends seen in spray dried powders when the surrounding temperature of the levitator matched the outlet temperature of the spray dryer. The numerical droplet drying model could predict drying time, particle size, and component distribution within a final dried particle; the component distribution was used to aid in spatially locating the viral vector which was shown to be related to vaccine thermal stability. The model predictions associated with virus location in a dried particle were confirmed experimentally using coated silica nanoparticles as virus analogues, and several different molecular weight dextrans in the mannitol/dextran blend in order to change the location of the virus. Overall, this work provides a deeper understanding of how spray drying can be used to produce thermally stable vaccine powders, and the arising guidance can be applied to improve formulation development based on the end targets and applications. Shear stress was found to be a negligible source of viral vector activity loss, and the application of heat to the acoustic levitator was found to create drying conditions that allowed the levitator to create materials that mimicked the properties of spray dried powders. Finally, a numerical model was validated experimentally, with both modelled predictions and confocal laser scanning microscopy confirming that an increase in dextran molecular weight in formulations caused a decrease in viral vector and silica nanoparticles at the air-solid interface. The knowledge gained by using screening methods and mathematical models of the spray drying process can reduce the time and cost inputs of vaccine development by identifying promising excipients with minimal experimentation. / Thesis / Doctor of Philosophy (PhD) / To retain their effectiveness, most mass-market vaccines must be stored in refrigerated or frozen conditions but the specialized equipment associated with such storage limits the success of administration programs. Creating dry powder vaccines that can be stored at room temperature is an efficient method to limit liquid vaccine wastage caused by exposure to warmer temperatures. This is achieved by combining the active ingredient with protective stabilizing materials and drying the solution into a powder using spray drying. However, identifying and developing effective dry powder products is costly and time-consuming. This research aims to reduce the costs associated with vaccine development by using other drying methods to identify potential protective sugars without the need for large-scale experiments, as well as by using mathematical models to predict the outcomes of the drying process. The effect of various stresses during the drying process on the active vaccine ingredient are evaluated to improve the effectiveness of the final dry product. Overall, the ability to produce stable dry powder vaccines will allow for more wide-spread vaccination programs and stockpiling of vaccines to better prepare for global pandemics.