Differences in biofilm formation between Scenedesmus obliquus and Chlorella vulgaris were examined, as well as the effects of substrate properties. Species selection and species control had significant effects. In non-sterile conditions, C. vulgaris shifted from planktonic (23.7% attachment) to sessile (79.8% attachment) growth, and formed films of higher average thickness (52 ± 19 µm) than in sterile conditions (7 ± 6 µm). By contrast, S. obliquus attained similar thicknesses (54 ± 31 µm and 53 ± 38 µm) in both sterile and non-sterile conditions. The effect of substrate properties was minimal. Both species grew films of similar thickness (~ 30 µm for S. obliquus, <10 µm for C. vulgaris) on materials ranging from hydrophilic (glass) to hydrophobic (polytetrafluoroethylene). Micropatterning the surface also had little effect on film formation. The results indicate that species selection and species control are more important that substrate properties in the development of microalgal biofilms.

From June 2006 to March 2007, the concentrations of water soluble inorganic particulates and their associated precursor gases were semi-continuously measured adjacent to a high traffic street in downtown Toronto, Canada. Measurements underwent extensive quality assurance and control protocols. Seasonal and diurnal variations in HNO3 and NH3 partitioning to NH4NO3 were observed. Long range transported air masses from southwest of Toronto were the predominant source of measured SO4 2- for all seasons. The contributing sources of PM2.5 nitrate mass fluctuated between seasons: pNO3- was predominantly locally derived in the summer and resulted from long range transport in the winter. Comparison between measurements and ISORROPIA thermodynamic model predictions identified model weaknesses and was used to explore the effect of modulating primary gas concentrations on consequent particulate levels. SO2 emissions reductions were the most influential and direct method to reduce overall PM2.5 concentrations; however, limiting ammonia emissions was also another successful strategy.

Aqueous extraction of yellow mustard seed recovers oil in the form of oil-in-water emulsion. In this study, the ternary phase diagram of IPA, oil and water was developed to design an effective oil extraction process of oil-in-water emulsion. A 4-stage extraction process recovered 92.3% of oil from the emulsion into virtually anhydrous IPA-oil miscella. The oil and water separation and IPA usage efficiency was improved by using recycled solvent, but the oil recovery was decreased to 86.0%. The obtained IPA-oil miscella can be used directly in biodiesel production. The use of IPA as a reactant and a co-solvent in transesterification was investigated in this study. Isopropanolysis at 1.2% KOH resulted in 54% ester content in the product. When IPA was used as a co-solvent in methanolysis, the transesterification was drastically improved. The product met the total glycerol limit of the ASTM biodiesel standard within 10 minutes, with over 99% ester content.

From June 2006 to March 2007, the concentrations of water soluble inorganic particulates and their associated precursor gases were semi-continuously measured adjacent to a high traffic street in downtown Toronto, Canada. Measurements underwent extensive quality assurance and control protocols. Seasonal and diurnal variations in HNO3 and NH3 partitioning to NH4NO3 were observed. Long range transported air masses from southwest of Toronto were the predominant source of measured SO4 2- for all seasons. The contributing sources of PM2.5 nitrate mass fluctuated between seasons: pNO3- was predominantly locally derived in the summer and resulted from long range transport in the winter. Comparison between measurements and ISORROPIA thermodynamic model predictions identified model weaknesses and was used to explore the effect of modulating primary gas concentrations on consequent particulate levels. SO2 emissions reductions were the most influential and direct method to reduce overall PM2.5 concentrations; however, limiting ammonia emissions was also another successful strategy.

Aqueous extraction of yellow mustard seed recovers oil in the form of oil-in-water emulsion. In this study, the ternary phase diagram of IPA, oil and water was developed to design an effective oil extraction process of oil-in-water emulsion. A 4-stage extraction process recovered 92.3% of oil from the emulsion into virtually anhydrous IPA-oil miscella. The oil and water separation and IPA usage efficiency was improved by using recycled solvent, but the oil recovery was decreased to 86.0%. The obtained IPA-oil miscella can be used directly in biodiesel production. The use of IPA as a reactant and a co-solvent in transesterification was investigated in this study. Isopropanolysis at 1.2% KOH resulted in 54% ester content in the product. When IPA was used as a co-solvent in methanolysis, the transesterification was drastically improved. The product met the total glycerol limit of the ASTM biodiesel standard within 10 minutes, with over 99% ester content.

This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.

Master of Science / Department of Chemical Engineering / Larry A. Glasgow / The military is interested in stopping suspicious vehicles at checkpoints or security positions while minimizing noncombatant fatalities. Preliminary work has shown that decreasing the oxygen concentration in proximity to the automobile air intake system and blocking the air flow through an automotive induction system provides the greatest probability of success for the broadest possible array of internal combustion engines. A non-lethal foam deployment system was developed that satisfies the military’s needs to stop suspicious vehicles. The foam is discharged from a pressurized tank and engulfs the air intake system of the target vehicle. The foam is drawn into the air intake and the protein additive contained in the foam would occlude pores in the air filter medium. Once the air filter was blocked, the vehicle would become immobilized so that security personnel can secure the vehicle. The work carried out in this project consisted of development and refinement of surfactant solution composition, improvement in the rate of absorption of carbon dioxide for increased foam volume, and characterization of discharge for optimum foam volume. In addition, a half-scale model apparatus was developed to test the foam’s ability to be ingested in an automotive intake system. These experiments demonstrated that the foam deployment system would stop an automobile within six seconds.

Ultraviolet (UV) light reactors or banks are often arranged in series in order to meet microbial inactivation credit requirements. It has been assumed that UV doses given by each reactor in series are mathematically additive, though work done to substantiate the hypothesis has been inconsistent. Based on previously developed theory of reactor additivity and the reactor additivity factor (RAF), three types of UV reactors are modelled using computational fluid dynamics and their RAFs are computed. It is noted that the assumption of perfect mixing may not be valid depending on the distance between reactors in series. It is discussed that the original formulation of the RAF is inadequate when dealing with wastewater. It is shown unexpectedly that even with perfect mixing performance, worse than additivity would be achieved. A new performance factor (PF) is introduced and the implications of this are further discussed in the context of UV reactor validation.

Ultraviolet (UV) light reactors or banks are often arranged in series in order to meet microbial inactivation credit requirements. It has been assumed that UV doses given by each reactor in series are mathematically additive, though work done to substantiate the hypothesis has been inconsistent. Based on previously developed theory of reactor additivity and the reactor additivity factor (RAF), three types of UV reactors are modelled using computational fluid dynamics and their RAFs are computed. It is noted that the assumption of perfect mixing may not be valid depending on the distance between reactors in series. It is discussed that the original formulation of the RAF is inadequate when dealing with wastewater. It is shown unexpectedly that even with perfect mixing performance, worse than additivity would be achieved. A new performance factor (PF) is introduced and the implications of this are further discussed in the context of UV reactor validation.

An electrochemical cell consisting of a flow-through yttria-stabilized zirconia (YSZ) sensor and a flow-through Ag/AgCl reference electrode has been employed to measure pH of high-temperature acidic sulphate solutions relevant to the pressure acid leaching (PAL) of nickel laterites. In a previous study, this cell was used to measure pH of H2SO4, Al2(SO4)3-H2SO4 and MgSO4-Al2(SO4)3-H2SO4 solutions at 250oC. In this work, the solutions range in complexity from the binary MgSO4-H2SO4, NiSO4-H2SO4, and Al2(SO4)3-H2SO4, through the ternary MgSO4-Al2(SO4)3-H2SO4 and NiSO4-Al2(SO4)3-H2SO4, to the PAL process solutions, whereas the temperature ranges from 200oC to 250oC. The measured and theoretical pH values typically agree within less than 0.1 pH unit and 0.2 pH units in synthetic solutions and PAL solutions, respectively. This is an improvement over the results of the previous study in synthetic solutions, which show differences between theory and experiment as high as 0.4 pH units. The conversion of measured potentials into pH values is based on the new mixed-solvent electrolyte (MSE) speciation model of the OLI Systems software calibrated independently based on solubility measurements. Both Henderson’s equation and the exact definition of the diffusion potential were employed in treating the obtained experimental data. Experimental pH values calculated using the diffusion potentials evaluated by either approach are essentially the same. This finding suggests that Henderson’s equation, which is based on readily available limiting ionic mobilities, can be effectively used. Lithium chloride is found to be a suitable alternative to sodium chloride as the reference electrode solution for the measurement of pH of aluminium-containing solutions, because it did not induce precipitation of aluminium as an alunite-type compound. The experimental results indicate that the high-temperature behaviour of Ni, Co and Mn sulphates can be satisfactorily approximated with that of MgSO4. The experimental findings also support the postulation that acid should be added to a PAL process so that the solution pH is around 1 at the leach temperature, regardless of the feed composition. The cell can be used for hydrometallurgical process research and development on a laboratory scale with very satisfactory performance, provided that a well-behaved YSZ sensor is available.