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Analyses For Assessing The Centreline Translation, Asymmetrical Wind-Field, And Velocity Fluctuations Of Tornado Vortices, Niall C. Bannigan

Electronic Thesis and Dissertation Repository

Tornadoes present an ever-increasing threat to communities worldwide, especially those with geographic conditions that place them in the path of several tornadoes annually. These conditions are likely to be exacerbated by ongoing trends in the climate. As such, it is necessary to move towards experimental and numerical tornado-like vortex studies that allow for more advanced simulation methods. Novel techniques for tracking and analysing tornado vortices simulated at high spatial and temporal resolution are presented herein. Significant wandering of the tornado's position and large peaks in the velocity field can be captured, demonstrating tangential gusting at more than 1.5 times the …

Temperature-Controlled Partial Nitrification For Mainstream Wastewater Deammonification Using Batch, Semi-Batch And Continuous Systems, Niema Afroze

Electronic Thesis and Dissertation Repository

Aeration is a critical component of the two-step nitrification, the biological conversion of ammonia (NH₃) to nitrite (NO₂-) and then to nitrate (NO₃-), in municipal wastewater treatment plants. Aeration provides the necessary dissolved oxygen for the growth and activity of nitrifying bacteria to Partial nitrification-Anammox (PN-Anammox) is a two-step biological wastewater treatment process, used to remove nitrogen compounds from wastewater efficiently without the need for external carbon. It combines partial nitrification, where ammonia is partially oxidized to nitrite, with anaerobic ammonium oxidation (Anammox) to remove both ammonia and nitrite. About a 60% to 80% …

Effect Of Land Use Type And Stormwater Control Measures On Non-Point Source Phosphorus Concentrations And Loads In A Cold Climate Urban Subwatershed, Dillon H. Vyn

Electronic Thesis and Dissertation Repository

Non-point source phosphorus (P) exports from urban areas including contributions from different urban land use types and seasonal variations are not well understood, especially for cold climates. Additionally, the effectiveness of different stormwater control measures (SCMs) in reducing P concentrations and loads are poorly quantified with assessments rarely considering total watershed P loads. To address these gaps, detailed field monitoring of total P (TP), soluble reactive P (SRP), total suspended solids (TSS), and water quantity was conducted over a 19-month period in a mixed urban watershed in London, ON. Monitoring sites were located at watershed outlets, at the outlets of …

Monitoring Remediation Of Organic Contaminants Using Electrical Resistivity And Induced Polarization Techniques, Angelos Almpanis

Electronic Thesis and Dissertation Repository

Effective characterization and monitoring of subsurface processes associated with the remediation of sites contaminated by dense non-aqueous phase liquids (DNAPLs) remains a substantial environmental challenge. Geophysical techniques such as direct current (DC) resistivity and induced polarization (IP) offer the potential to considerably enhance our understanding of such complex phenomena occurring in the subsurface. However, despite extensive research highlighting the benefits of employing IP – in the time domain (DCIP) and/or frequency domain (spectral IP, SIP) – for contaminant investigations, more research is needed to understand the role of IP for monitoring DNAPL remediation. The goal of this thesis was to …

Effect Of Morphology And An Upstream Tall Building On A Street Canyon Flow, Haoran Du

Electronic Thesis and Dissertation Repository

The effects of the morphological model and the existence of an upstream tall building on the turbulent street canyon flow and the overlying boundary layer are investigated in a wind tunnel, using Stereoscopic Particle Image Velocimetry (S-PIV) measurements. The velocity variances, Reynolds shear stress, and turbulent kinetic energy are found to be larger than in a similar idealized street canyon model. Increasing building height results in a decrease in vertical mass fluxes across the opening of the canyon, at least in the canyon portion directly downstream of the building. The interaction between the large-scale structures in the overlying boundary layer …

Geoelectrical Signatures Of Acid-Generating Mine Waste Rock, Difan Su

Electronic Thesis and Dissertation Repository

Acid mine drainage (AMD) contamination associated with waste rock piles (WRPs) at mining sites is a global concern, and understanding the generation and release of AMD from these piles is highly desirable. Traditional WRP monitoring techniques involve the installation of monitoring wells and periodic core sampling; however, these approaches are invasive, expensive and can only provide data with limited spatial and temporal resolution. An attractive alternative is non-invasive geophysical techniques that can provide non-invasive and continuous information on subsurface features and processes. This thesis aims to investigate the feasibility of the spectral induced polarization (SIP) method for monitoring changes in …

Effects Of Climate Change On The Probability Of Urban Tree Failures From Wind Gusts, Samuel J. Woolsey

Electronic Thesis and Dissertation Repository

Trees grown in urban environments provide environmental, economic and psychological benefits to their surrounding communities. However, urban trees also pose significant risks since damaged trees can cause serious harm to people, housing, and infrastructure by falling on sidewalks, roads, houses or power lines. To better understand the risk posed to trees by wind, models have been developed that estimates the required wind speed needed to damage a tree or group of trees, and the likelihood that such a wind speed is met or exceeded annually. The importance of such models is rising each year as the associated risk grows as …

The Novel Application Of Electrical Resistivity Tomography For Spatiotemporal Monitoring Of Urban Stormwater Bioretention Systems, Darren Alvarenga

Electronic Thesis and Dissertation Repository

Bioretention systems are an increasingly popular low-impact development (LID) stormwater management approach that are used to reduce the water quantity and quality impacts of urban stormwater. The study investigated the feasibility and benefits of using non-invasive time-lapse electrical resistivity tomography (ERT) to understand the infiltration and soil moisture dynamics within bioretention systems. This was achieved through monitoring two field-scale operational bioretention systems in London, Ontario, Canada. High-resolution two-dimensional time-lapse ERT surveys were first completed during synthetic and natural rain events to assess the viability of time-lapse ERT to monitor soil moisture changes during events. Following this, three-dimensional ERT surveys were …

Compound Flooding Analysis Over The Canadian Coastal Regions, Farshad Jalili Pirani

Electronic Thesis and Dissertation Repository

The communities settling in the Canadian coastal regions are threatened by multiple flood-generating mechanisms including riverine, pluvial, and sea level forces. Reliable design flood estimation and risk assessment in these regions demand characterization of the interrelationships between different drivers as well as the corresponding compounding effects. In this study, as our first step, we assess the compound flood risks across Canada’s coasts considering eight bivariate flooding scenarios acquired from four flooding drivers including total water level, streamflow, precipitation and the skew surge at 41 sites located at three main regions of the Pacific, the Great Lakes (GL) and the Atlantic. …

Evaluation Of Fresh Groundwater Resources And Nitrogen Discharge To The Coastal Lagoon Of An Atoll Island, James D. Gale

Electronic Thesis and Dissertation Repository

Atoll island communities face socio-economic challenges together with environmental pressures imposed by climate change that are causing increased water quality degradation. Wastewater from domestic septic systems is released into the subsurface on Fongafale Islet, Tuvalu. It is unclear if this is contributing to high nitrogen (N) concentrations and eutrophication of the adjacent coastal lagoon. In this study, a variable-density groundwater flow and conservative contaminant transport model was developed in SEAWAT-2005 to simulate the salinity distribution and N transport through the Fongafale Islet aquifer. Model simulations evaluated the influence of tides, variable (interannual) recharge patterns, wastewater loading rates and wastewater source …

Exploring Valuable And Potentially Harmful By-Products Formed And/Or Released From Smouldering Treatment Of Sewage Sludge, Taryn Ashley Fournie

Electronic Thesis and Dissertation Repository

The presence of potentially toxic elements (PTEs) and emerging contaminants (e.g., per- and polyfluoroalkyl substances (PFAS)) makes sewage sludge management challenging. Due to their hazards, there is significant interest in thermal treatment technologies that can destroy these compounds, like incineration. However, incineration still poses several risks due to forming and/or releasing hazardous emissions (e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PTEs). More recently, the use of smouldering has been introduced as a potential treatment technique for managing sewage sludge. Smouldering presents several advantages over traditional incineration due to its lower energy and pre-treatment requirements and potential for beneficial …

Carbon Injection To Support In-Situ Smouldering Remediation, Gillian Wilton

Electronic Thesis and Dissertation Repository

Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic contaminants that are growing increasing concern due to their associated negative health affects. The properties of PFAS result in their persistence and stability which present challenges for remediation. Activated carbon is currently the most widely used method for PFAS treatment since carbon microparticle injection can be used for in-situ treatment; however, this method does not result in PFAS destruction. Thermal treatment is a promising post-treatment method that can be used with activated carbon as long as sufficient PFAS-destroying temperatures are achieved (> 900°C). A promising in-situ thermal treatment technology is …

Hydrogen-Rich Syngas Derived From Smouldering Biomass And Hydrocarbon Wastes, Joshua K. Brown

Electronic Thesis and Dissertation Repository

In the face of climate change, the world is looking to new fuel sources to meet the surging global energy demand. Hydrogen has been proposed as a promising energy vector being both a net-zero carbon emitter and having one of the highest gravimetric energy densities of known fuels. Production of hydrogen, however, is difficult with many of the technologies which exist today failing to be economically feasible or environmentally sustainable. Smouldering has recently been developed as a cost effective and energy efficient technology for destruction of organic wastes. The unique reaction zones created within a smouldering system have the potential …

Wastewater Aeration Process Dynamic Modelling: Combined Mechanistic And Machine Learning Approach, Yuehe Pan

Electronic Thesis and Dissertation Repository

The aeration process is the largest energy consumer in wastewater treatment plants (WWTPs), and the optimization of the process based on computational models can offer significant savings for the plant. Recent theoretical developments have revealed that many of the parameters commonly assumed as constants in aeration modelling, in fact, have a dynamic nature; however, there still lacks a universal way to model these factors in an easy, accurate and timely manner. This work proposed a machine learning-based modelling approach to offer real-time estimations of the oxygen transfer rate, airflow demand, and energy consumption.

Utilizing the field data collected from Adelaide …

Evaluation Of The Impacts Of De-Icing Salts On The Performance Of Bioretention Media In Retaining Phosphorus From Urban Stormwater, Brennan S. Donado Visbal

Electronic Thesis and Dissertation Repository

Bioretention systems are a low impact development system that can remove pollutants such as phosphorus (P) from urban stormwater. P retention in bioretention systems is complicated in cold climate regions due to factors such as inputs of road de-icing salts. This study evaluates the impact of prolonged and periodic salt inputs on P retention by conducting column experiments using three different bioretention media with and without an amendment added. Non-amended columns showed net P release, whereas amended columns showed net P retention. While some non-amended columns showed prolonged salt exposure increases P release, the largest P release for all columns …

Physical Investigation Of Downburst Winds And Applicability To Full Scale Events, Federico Canepa

Electronic Thesis and Dissertation Repository

Thunderstorm winds, i.e. downbursts, are cold descending currents originating from cumulonimbus clouds which, upon the impingement on the ground, spread radially with high intensities. The downdraft phase of the storm and the subsequent radial outflow that is formed can cause major issues for aviation and immense damages to ground-mounted structures. Thunderstorm winds present characteristics completely different from the stationary Gaussian synoptic winds, which largely affect the mid-latitude areas of the globe in the form of extra-tropical cyclones. Downbursts are very localized winds in both space and time. It follows that their statistical investigation, by means of classical full scale anemometric …

Engineering Cooling Time And Waste Heat Recovery For Thermal Treatment Beds, Ryan B. Morales

Electronic Thesis and Dissertation Repository

Applied smouldering systems harness fixed bed smouldering combustion to remediate contaminated soils and organic wastes. In this technology, contaminants/wastes are embedded or purposefully mixed into a fixed, porous medium, waste treatment bed. Then, a smouldering front is ignited and propagated through the bed, burning away the embedded contaminants/wastes as it travels. At the conclusion of smouldering treatment, only a clean, hot porous bed remains. Ahead of a following treatment cycle, the bed is cooled via air injection and off-loaded from the system to allow for the on-loading of more contaminated material. Due to large system sizes and high temperatures, cleaned …

Spatio-Temporal Variability Of Phosphorus Near The Groundwater-Stream Interface, Meghan Vissers

Electronic Thesis and Dissertation Repository

Agricultural practices can cause excess inputs of soluble reactive phosphorus (SRP) to freshwater catchments leading to eutrophication. This study evaluates spatio-temporal variability of SRP in an agricultural streambed including the influence of groundwater-stream interactions, and examines the associated geochemical and hydrological controls. High porewater SRP (>1000 µg/L) and high SRP sediment fractions were observed in low groundwater discharge zones, specifically in the shallow (≤ 0.1 m) streambed sediments. Porewater SRP concentrations were linked to iron redox cycling with SRP concentrations concordant with more reducing conditions. Porewater SRP varied temporally but distinct seasonal changes were not observed. The conditions in …

Effect Of Pretreatment Of Resin Acids On Anaerobic Digestibility Of Pulp And Paper Mill's Primary Sludge, Sreejon Das

Electronic Thesis and Dissertation Repository

Pulp and paper (P&P) mills’ wastewater contain high concentrations of resin acids (10–10,000 mg/L) which are toxic to aquatic organisms. In mill’s primary and waste activated sludge treatments reduced concentrations of resin acids in effluent; however, most of the resin acids are ultimately ended up in sludge after primary and secondary clarification due to their extreme hydrophobic nature (log K_ow 6.0). Nevertheless, adsorbed resin acids on the surfaces of anaerobes and substrates affect anaerobic digestion (AD) process negatively. The objective of the present work was to determine the effect of pretreatment of thermomechanical pulping mill’s primary sludge (TMP-PS) on …

Treatability Of Micropollutants And Microplastics Using Selected Wastewater Treatment Processes, Juan Li

Electronic Thesis and Dissertation Repository

Micropollutants and microplastics are ubiquitously detected in environment, which are directly linked to human health and ecosystems safety. Conventional wastewater treatment plants (WWTPs) are regarded as a major source for discharging these contaminants into environment. Therefore, it is of great significance to study the behavior of these pollutants and their removal potential in WWTPs. This work investigated specific treatment processes to determine their efficiency in removing target micropollutants and microplastics.

Primary treatments in WWTPs are first step to removal solid particle and other floated materials from the water stream. Therefore, the process is important for microplastics particles. The behavior of …

Experimental Simulation Of Tornado-Like Vortices And Their Impact On High-Rise Buildings, Arash Ashrafi

Electronic Thesis and Dissertation Repository

One of the most crucial research areas in wind engineering is tornadoes due to the widespread damages to infrastructure and the environment in North America and other parts of the world. The proper scaling of tornadoes in experimental facilities, generating tornado-like vortices (TLVs) is, therefore, an essential part of evaluating tornado-indued damages on engineered buildings. The capability of producing TLVs of length scales in the range between 1:300 and 1:150 inside the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University has already been demonstrated using only one mode of the full potential of this simulator. A new mode …

Active Fluids: Rheological Properties And Response To Light Of Suspensions Of Synechocystis Sp. Cpcc 534, Zahra Habibi

Electronic Thesis and Dissertation Repository

Despite our current understanding of active fluid mechanics, more knowledge is required to fully understand their rheological properties, response to light, and details of the interactions between cells in diluted suspensions.

The focus of this thesis is on investigating the rheological properties of suspensions of cyanobacterium Synechocystis sp. CPCC 534 under shear, induced by stirring. Experiments were conducted at different stirring rates and results are compared with the stationary condition. A notable increase in growth and biomass of Synechocystis sp. under various shear conditions was observed and the yield was nearly doubled. Besides, the data showed Newtonian behavior for suspensions …

Inter-Disciplinary Characterization Of Streambed Heterogeneity And Its Influence On Groundwater-Stream Water Interactions, Kyle Robinson

Electronic Thesis and Dissertation Repository

It is well recognized that groundwater-surface water interactions influence the quantity and quality of various hydrogeological systems (rivers, lakes, streams). Groundwater-stream systems are an important investigative area for understanding fate and transport of nutrients and chemicals within the stream. While traditional methodologies are established to provide measurement and mapping of the spatial distribution of groundwater-stream interactions and exchange fluxes across a streambed, many can be invasive, labour intensive and suffer from low sampling density. The complexity in such systems is due largely to the heterogeneous nature both spatially and temporally. Given the strong control by streambed lithology on groundwater-surface water …

Long-Term Field Performance Of Geomembrane-Lined Cover Systems At Mine Waste Rock Piles, Deanna Hersey

Electronic Thesis and Dissertation Repository

Mine waste rock piles (WRPs) are anthropogenically created landforms at active and former mining sites that can generate and release highly toxic acid mine drainage (AMD) to the environment. A common solution to control AMD generation is the use of cover systems at the WRPs to isolate the reactive waste from water and oxygen in the atmosphere. Geomembranes exhibit the characteristics needed to be highly effective barriers to atmospheric influx; however, knowledge on their performance at in-service WRPs is limited. The objective of this thesis is to comprehensively assess the field performance of geomembrane-lined cover systems for limiting meteoric water …

Modelling And Investigating The Impact Of Thermal Hydrolysis Pretreatment On The Anaerobic Co-Digestion Of Sewage Sludges And Food Waste, Amr Ismail

Electronic Thesis and Dissertation Repository

In this study, the impact of thermal hydrolysis pretreatment (THP) on the mono- and co-digestion of thickened waste activated sludge (TWAS) and food waste (FW) was carried out at temperatures of 150, 170, 190, and 210 ˚C for a contact time of 30 min and mixing ratios of 90:10, 70:30, and 50:50 on a volumetric basis in batch anaerobic tests. Thermal hydrolysis influenced the solubilization of the particulate organic constituents of TWAS, reduction in volatile suspended solids (VSS) and particle size with the increase in temperature to 210 ˚C, achieving a reduction in VSS up to 62% and a reduction …

Urban Heat Mitigation For Current And Future Conditions: A Case Study For Downtown London On, Maryam Shams

Electronic Thesis and Dissertation Repository

The urban heat island is a phenomenon wherein urban areas experience warmer temperatures than their surrounding rural areas. Techniques to reduce excess heat in urban environments are known as heat mitigation or heat island mitigation solutions, with the intent that they reduce urban temperatures. This research presents an investigation on the impacts and effectiveness of urban heat mitigation techniques on improving the outdoor thermal conditions of downtown London, Ontario. The impact of increasing vegetated areas and applying higher albedo materials for road pavements is assessed with ENVI-Met software for current and future summer weather. Furthermore, investigations were conducted for current …

Assessing The Evolution Of Mine Water Quality With Empirical 'First-Flush' Models, Patrick J. Merritt

Electronic Thesis and Dissertation Repository

Coal mining activities can leave an extensive network of abandoned underground workings that gradually flood after operations cease. This rising mine water, with low pH and high sulfate, acidity, and metals can lead to uncontrolled releases of harmful acid mine drainage to the environment. Treatment plants are used to extract and treat the mine water to maintain its elevations below suspected discharge zones. Accurate predictions of long-term water quality is highly challenging due to the complexity and volume of the underground workings. As numerical models have difficulty recreating complex mine pool geometry and hydrogeochemical processes, empirical models that are based …

Anammox Process For Nitrogen Removal: Development Of Sustainable Gel Beads And Its Application In Fluidized Bed Reactors (Fbrs), Mohammad M I Chowdhury

Electronic Thesis and Dissertation Repository

Biological nitrogen removal (BNR) processes have been widely used for removing wastewater nitrogen because of effectiveness, economics, and environmental friendliness. Considering the energy requirements for nitrification and need for external carbon for denitrification in conventional BNR processes, anaerobic ammonia-oxidizing bacterial (anammox) processes facilitate energy-neutral or net energy positive biological treatment as well as reduce operational costs because of reduction in aeration energy, which constitutes 50%-60% of the overall energy consumption at municipal wastewater treatment plants, elimination of external organic carbon requirements, and lower sludge production. However, one of the major challenges in the practical application of the anammox process is …

Cellulose Biodegradability And Its Impact On Enhanced Biological Phosphorus Removal, Moustafa Ibrahim Elbahrawi

Electronic Thesis and Dissertation Repository

Cellulose from toilet paper contributes approximately one third of the influent organic suspended solids (TSS) to wastewater treatment plants and is a key target for resources recovery. Cellulose recovery is beneficial as it reduces the required energy for treatment and biosolids treatment cost. Hence, understanding the hydrolysis of cellulose in wastewater which is mainly affected by temperature and the solids retention time (SRT), is a major key to determine the optimum location for its recovery. In order to assess the impact of temperature and SRT on cellulose degradation, this study investigated the biological aerobic degradation of cellulose in four laboratory-scale …

Assessment Of The Impacts Of Climate Change, Land Cover Transition, And Internal Climate Variability On The Hydrology Of A Forested Watershed, Vahid Mehdipour

Electronic Thesis and Dissertation Repository

In this study, the impacts of climate and land cover (LC) changes on the hydrologic processes of the Batchawana watershed in Central Ontario are assessed. Batchawana is a snow-dominated forested watershed with coniferous, deciduous and mixed trees and numerous small lakes. A semi-distributed hydrological model, based on the Raven hydrological framework, is calibrated and validated using ground-based observations for 1981-2001 and 2002-2011, respectively. Eight downscaled General Circulation Models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and three large ensembles (50 members) of Regional Climate Model (RCM) simulations, under the Representative Concentration Pathway (RCP) 8.5, are …