Civil Engineering

Permanent URI for this collection

https://hdl.handle.net/10315/34418

Browse

Now showing 1 - 20 of 81

Open Access
Biological Conversion Process of Methane into Methanol Using Mixed Culture Methanotrophic Bacteria Enriched from Activated Sludge System
(2018-03-01) Mahmoud, Ahmed Mohamed AlSayed; Eldyasti, Ahmed
Wastewater treatment plants contribute to the global warming phenomena not only by GHG emissions, but also, by consuming enormous amount of fossil fuel based energy. Therefore, methane bio-hydroxylation has attracted the attention as methanol is an efficient substitute for methane (GHG) due to its transportability and higher energy yield. This work is destined to investigate and optimize the factors affecting the microbial activity within methane bio-hydroxylation system using type I methanotrophs enriched from activated sludge system. The optimization resulted in a notable enhancement of the growth kinetics. The attained maximum specific growth rate (max) (0.358 hr-1) and maximum specific methane biodegradation rate (qmax) (0.605 g-CH4,Total/g-DCW/hr-1) were the highest reported in mixed cultures. Furthermore, the maximum methanol productivity achieved is comparable with pure cultures and equal to 211581 mg/L/day. Whereas, methanol concentration of 48521 mg/L was attained which is two times higher than the reported using mixed culture.
Open Access
Geothermal Systems Performance and Environmental Impacts
(2018-03-01) Daemi, Negar; Krol, Magdalena
The use of fossil fuels for heating and cooling purposes is plagued by problems including environmental impacts, unsustainable production, and increased greenhouse gas production. This had led to a worldwide interest in developing sustainable sources of energy. One such energy is ground source heat which is the ubiquitous low-enthalpy heat found in the shallow subsurface. Vertical ground source heat pumps (GSHPs) can be used to extract or inject subsurface heat by installing borehole that circulate an antifreeze-based carrier fluid which is cooled or heated through the subsurface. Although GSHPs have many advantages, they might develop thermal subsurface plumes, which can affect the efficiency of the system and other subsurface infrastructures. In the present research, the effect of a multi-borehole vertical GSHP system located in various locations in Canada was examined. To do so, a three-dimensional model was developed in FEFLOW that simulated a hypothetical GSHP system in different Canadian climates. Consequently, the resulting thermal plumes were studied and a sensitivity analysis was conducted to determine the effect of different groundwater and soil parameters on the development and movement of thermal plumes.
Open Access
Enhancement of Anaerobic Digestion and Dark Fermentation Process Using Attached Growth System and Chemical Additives
(2018-03-01) Izadi, Parnian; Eldyasti, Ahmed
High-energy demand, global warming and shortage of fossil fuels have motivated researchers to investigate on new energy alternatives with higher efficiencies. Anaerobic digestion as a biochemical process for degrading complex organics without oxygen, has been used as a promising technology for waste management systems and the production of energy and mitigation of the greenhouse gas by utilizing the waste for environmental causes. In this research, a particulate BioCord bioprocess technique is used to enhance of the AD process and increase the process performance. Usage of surface as a support media for bacterial growth and creation of biofilm has resulted in many benefits for the AD system such as shortening the operation and hydraulic retention time and increased efficiency. Moreover, additives of vitamins and micronutrients have been used to enhance the metabolic rate of AD process. The lab scale anaerobic biofilm bioreactors were utilized for evaluating the performance of 4 different BioCords (LS1, LS2, HS1 and HS2). Also, the impact of BioStreme, which as a mixture of metals in specific concentrations, and vitamins using a mixture of different groups of vitamins has been experimented as an additive to the system and showed a positive effect on both the biomethane end biohydrogen production.
Open Access
Effects of Climate Change on Soil Embankments
(2018-03-01) Pk, Shubhra; Bashir, Rashid; Beddoe, Ryley
The Intergovernmental Panel on Climate Change has reported that the climate change process will continue over the next century. The changes in climate variables can make the currently stable embankments unstable. It is therefore imperative that we understand how climate change will affect embankments. This research focuses on understanding and quantifying the effects of climate change on the stability of soil embankments in Ontario, Canada. The stability of embankments was analyzed for the current and future climates using numerical modeling technique. The effects of future climate were then quantified by comparing the future stability of embankments with its historical stability. The results of this research show that the effects of climate change also depend on the hydraulic properties of the fill materials. Embankments with sand fill withstand the adverse effects of climate change, and showed better performance over the embankments with silt fill.
Open Access
Effects of Climate Type and Temporal Variability in Meteorological Input Data in Modeling of Salt Transport in Unsaturated Soils
(2018-03-01) Chevez, Eric Mauricio Pastora; Bashir, Rashid
Oilfield produced brine is a major source of salt contamination in soil and groundwater. Salt transport in the upper soil layers is controlled by the atmospheric interactions via infiltration of meteoritic water. In lower layers, it is controlled by fluctuations in groundwater table, which are also linked to atmospheric interactions via groundwater recharge. Therefore, climate is an important factor in the movement of contaminants in the unsaturated zone. A one-dimensional variably saturated flow and transport model with soil atmospheric boundary condition was used to estimate the effect of climate type and soil texture on soil water and salt dynamics in variably saturated soils. Numerical simulations were run with Hydrus-1D, using daily and sub-daily climate. Simulations were run for nine-year climate datasets for ten different ecoclimatic locations in Alberta, Canada. Results show that flow and transport are function of climate type. Results also indicated that higher temporal resolutions of precipitation data resulted in higher net infiltration values. Higher net infiltration values resulted in faster solute displacement, especially, if the precipitation events were assumed to occur outside the evaporation hours. Minimal to no interaction was observed between groundwater table and atmosphere in coarse-grained soil material, especially in wetter climatic conditions. Keywords: Variably saturated soils, climate, soil-atmosphere boundary, water and salt dynamics, groundwater table
Open Access
Biodegradability Enhancement in Municipal Wastewater Using New Environmentally Friendly Biostreme
(2018-03-01) Izadi, Parin; Eldyasti, Ahmed
Microorganisms metabolic rate is the ultimate operational basis of diverse biological treatment processes. A variety of assorted factors can affect the biological wastewater treatments metabolic rate. One of the prominent means, is the use of supplements such as trace metals and vitamins. Both batch and continuous experiments have been used to study the effect of a variety of trace metals solution (named biostreme solution) and vitamins solution on biological organic removal process. The results show that, in average addition of 500 ppm of the biostreme had the highest rate of organic removal. The colloidal removal was enhanced by a rate of between 65 to 75% in specific batch tests. When the wastewater was supplemented with concentrations of biostreme individually and in a mixture with the vitamins solution, chemical oxygen demand fractionation showed a significant decrease in the colloids, however there is a different effect observed when returned activated sludge was used as the seed.
Open Access
Development of High Efficiency Partial Nitrification as a First Step of Nitrite Shunt Process using Ammonium-Oxidizing Bacteria (AOB)
(2018-03-23) Soliman, Moomen Mahmoud Moharram Abdallah; Eldyasti, Ahmed
Shortcut biological nitrogen removal is a non-conventional way of removing nitrogen from wastewater using two processes either nitrite shunt or deammonification. In this research, a complete partial nitrification as a first step of the Nitrite Shunt process has been developed under a high nitrogen loading rate (NLR) using a novel strategy to control the DO depending on using a constant air flow rate with a variable mixing speed using a Sequential Batch Reactor (SBR). The SBR has been successfully running at NLR of 1.2 kg/ (m3.d) maintaining an ammonia removal efficiency (ARE) of 98.6 ± 2.8% with a nitrite accumulation rate (NAR) of 93.0 ± 0.7%, which is 2 times higher than the previous NLR reported in the literature. Moreover, a dynamic and pseudo-state model of partial nitrification has been developed and calibrated using BioWin software for long-term dynamic behavior of the lab-scale SBR at different nitrogen loading rates (NLR).
Open Access
Comsol Modelling of Uniform Corrosion of Used Nuclear Fuel Canisters
(2018-08-27) Moinuddin, Mohd; Krol, Magdalena
Uniform corrosion of copper can occur in spent nuclear fuel canisters placed in deep geological repositories (DGR). To estimate the minimum thickness for safe design of canisters, it is necessary to analyze the corrosion rate. Copper Corrosion Model (CCM) has been used to model the corrosion process taking into account processes including adsorption/desorption, precipitation/dissolution, oxidation, and parameters including oxygen concentration, chloride, moisture and associated rate constants. In this work, CCM has been incorporated in COMSOL and validated with CCM. Once validated, the COMSOL model was used to examine the sensitivity of various parameters with respect to copper corrosion. It was found that initial chloride concentration, adsorption/desorption of cupric ions are parameters that most effect copper corrosion. The developed model can be used to simulate the uniform corrosion process under DGR conditions with more complexity including variation in temperature, saturation and pressure, and aid in the design of copper canisters.
Open Access
Development of Low Energy Aeration System For Enhanced Biological Phosphorus Removal (EBPR)
(2018-08-27) Mansour, Mahmoud Amr; Eldyasti, Ahmed
In a world that is witnessing an everlasting growth and accelerating increase in its population, an increase in the amount of wastewater produced is inevitable. In order to recycle this wastewater back to the environment, all nutrients should be removed. Unfortunately, removing the nutrients from wastewater is expensive due to the oxygen and chemicals requirement. Phosphorus removal is an important part of wastewater treatment process; Enhanced Biological Phosphorus Removal (EBPR) is one of the main processes responsible for phosphorus removal in wastewater treatment plants. EBPR consist of two major phases: anaerobic phase and aerobic phase. Aeration costs in the aerobic phase are relatively high in EBPR system. Finding a new approach for decreasing the amount of aeration needed for EBPR systems recently has grown in importance. Most of the research done on EBPR process was focusing on continued aeration, the effect of intermittent aeration is not widely researched. Thus, this research aims to overcome the previously mentioned challenges towards achieving stable EBPR process through different optimization techniques. To achieve this goal, a new aeration strategy has been developed to stepwise decrease the dissolved oxygen (DO) to reach very low DO conditions for EBPR. The new strategy depends on using intermittent aeration as a method of providing DO to the system. The SBR was operated over the span of 140 days under very low DO concentrations ranged from 0.5-1.0 mg/L, and achieved stable nutrients removal with removal efficiencies of: phosphorus removal efficiency (99%), ammonia removal efficiency (99%), COD removal Efficiency (100%). In addition, the effect of acetate to propionate ratio as a carbon source for EBPR systems under low DO concentrations have been studied, to investigate the effect of carbon source on the competition between Glycogen Accumulating Organism (GAO) and Polyphosphate Accumulating Organism (PAO) in EBPR systems. Propionate was found to be the best carbon source for EBPR process, after different compositions of COD were used as a carbon source for the EBPR process. The combination of low DO concentrations and propionate as a carbon source has been found to be a successful approach in controlling the competition between GAO and PAO in EBPR systems.
Open Access
Simulation of Climate Data for Geotechnical and Geoenvironmental Design Problems
(2018-11-21) Sahi, Muhammad Abid Nawaz; Bashir, Rashid; Sharma, Jit
Multi-year daily climate datasets are required in the design of several different geotechnical and geoenvironmental projects. The compilation of multi-year daily measured climate data requires a considerable amount of time and effort. The amount of time and effort depends on the availability, completeness, and quality of the measured climate dataset. In this research, a general-purpose climate generator SIMETAW is used to generate daily climate variables of interest from readily available monthly climate normals for nine different sites across Canada. The climates at these sites range from semi-arid to pre-humid. The historical measured data for these locations were also compiled. Measured data were compared with simulated climate data based on visual presentations and numerical measures. The comparison revealed that SIMETAW is capable of simulating various climates types across Canada. Simulated climate data was used in simulations of infiltration in unsaturated soils, soil cover assessment and estimation of swelling potential of expansive soils. Adequacy of simulated climate data for use in geotechnical and geoenvironmental design problems was assessed by comparing simulations run with measured and simulated climate data. The comparison indicated that for all practical purposes, the daily climate datasets generated from monthly climate normals are quite adequate for use in geotechnical and geoenvironmental problems. It is anticipated that the work presented in this research will facilitate the future researchers and practitioners by making the climate data more accessible.
Open Access
Behaviour and Analysis of Strain Hardening Fiber Reinforced Cementitious Composites Under Shear and Flexure
(2019-03-05) Eshghi, Najmeh; Pantazopoulou, Stavroula
Significant effort has been vested over the years in quantifying the contribution of concrete to the shear strength of concrete members. By introduction of novel cementitious material, a much greater need to develop a standard to treat the concrete in a systematic manner is felt. In this thesis, an alternative framework of analysis to interpret the shear failure and the corresponding strength of the failure mechanism is suggested which gives an insight into a new interpretation of shear failure and relates to the state of bond of reinforcement over the entire span of a member. This approach is adaptable to be used for new concrete materials such as Strain Hardening Fiber Reinforced Cementitious Composites. An experimental program is also designed to provide a basis for the development of design rules which are prerequisite for the introduction of these novel materials in new construction. All experiments are conducted at York University.
Open Access
Effect Of Climate Change on a Monolithic Desulphurized Tailings Cover
(2019-03-05) Fiaz Ahmad; Bashir, Rashid; Beddoe, Ryley
Climate change is expected to impact the stability and functionality of several geotechnical infrastructures. Soil covers are one of the main classes of geotechnical infrastructure which would exhibit pronounced changes in its functional performance due to climate change. It is therefore imperative to study the effects of climate change on soil covers. The current study focuses on the effects of climate change on soil covers over tailings (tailings cover) at a site in Northern Ontario, Canada. Covers were analyzed using historical and future climate datasets using numerical modelling techniques. In addition to climate change, effects of changing hydraulic properties were also quantified. The results of this research show that fine grained covers performed better under adverse climate change conditions as compared to coarse grained covers. However, the performance of fine covers will deteriorate with time due to evolutionary changes in their hydraulic properties.
Open Access
Transport of Nanoscale Zero Valent Iron in Heterogeneous Soils: Model Development and Sensitivity Study
(2019-03-05) Asad, Md. Abdullah; Krol, Magdalena
Subsurface remediation using nanoscale zero valent iron (nZVI) is a promising in-situ technology that can convert groundwater contaminants into non-toxic compounds. Despite its promising characteristics, field scale implementation of nZVI technology has faced major challenges due to poor subsurface mobility and limited longevity, all leading to smaller nZVI travel distance. How far nZVI travels in the subsurface is an important parameter as it influences the amount of contaminants that could be reached and thereby remediated. This thesis examined various factors (viscosity, groundwater velocity, injection flux, soil heterogeneity, lag period) on nZVI travel distance through a numerical model and by performing a statistical analysis which revealed that viscosity has a statistically significant impact on nZVI travel distance while the impact of groundwater velocity and injection flux are statistically insignificant. The model also revealed that soil heterogeneity plays an important factor and that longer nZVI injection periods are better for nZVI deployment in the field.
Open Access
Development of Hotzone Identification Models for Simultaneous Crime and Collision Reduction
(2019-07-02) Oluwajana, Seun Daniel; Park, Peter
This research contributes to developing macro-level crime and collision prediction models using a new method designed to handle the problem of spatial dependency and over-dispersion in zonal data. A geographically weighted Poisson regression (GWPR) model and geographically weighted negative binomial regression (GWNBR) model were used for crime and collision prediction. Five years (2009-2013) of crime, collision, traffic, socio-demographic, road inventory, and land use data for Regina, Saskatchewan, Canada were used. The need for geographically weighted models became clear when Moran's I local indicator test showed statistically significant levels of spatial dependency. A bandwidth is a required input for geographically weighted regression models. This research tested two bandwidths: 1) fixed Gaussian and 2) adaptive bi-square bandwidth and investigated which was better suited to the study's database. Three crime models were developed: violent, non-violent and total crimes. Three collision models were developed: fatal-injury, property damage only and total collisions. The models were evaluated using seven goodness of fit (GOF) tests: 1) Akaike Information Criterion, 2) Bayesian Information Criteria, 3) Mean Square Error, 4) Mean Square Prediction Error, 5) Mean Prediction Bias, and 6) Mean Absolute Deviation. As the seven GOF tests did not produce consistent results, the cumulative residual (CURE) plot was explored. The CURE plots showed that the GWPR and GWNBR model using fixed Gaussian bandwidth was the better approach for predicting zonal level crimes and collisions in Regina. The GWNBR model has the important advantage that can be used with the empirical Bayes technique to further enhance prediction accuracy. The GWNBR crime and collision prediction models were used to identify crime and collision hotzones for simultaneous crime and collision reduction in Regina. The research used total collision and total crimes to demonstrate the determination of priority zones for focused law enforcement in Regina. Four enforcement priority zones were identified. These zones cover only 1.4% of the Citys area but account for 10.9% of total crimes and 5.8% of total collisions. The research advances knowledge by examining hotzones at a macro-level and suggesting zones where enforcement and planning for enforcement are likely to be most effective and efficient.
Open Access
The Use of Human Behaviour in Fire to Inform Canadian Wildland Urban Interface Evacuations
(2019-07-02) Folk, Lauren Hanna; Gales, John A.
Wildland urban interface (WUI) communities are generally the most at risk of being impacted by wildfires. In order to assess the vulnerability of these communities, it is important to understand the impact that human behaviour in fire (HBiF) can have on wildfire evacuations, specifically in Canada where such data is lacking. To lay the groundwork for a comprehensive vulnerability assessment of a Canadian case study community, a conceptual model of protective action decision-making during WUI fires was created. This was used to develop a survey to understand the WUI fire awareness and experience as well as the anticipated protective actions of the case study community residents. The microsimulation software PTV VISSIM was used to model 10 evacuation scenarios to identify key evacuation modelling considerations and potential evacuation challenges faced by the community. In doing so, a framework for using HBiF to inform WUI vulnerability assessments and evacuations was developed.
Open Access
Bond Behaviour of Steel Reinforcing Bars Embedded in Ultra-High-Performance Steel Fiber Reinforced Concrete
(2019-07-02) Saikali, Elisabeth Rita; Pantazopoulou, Stavroula; Palermo, Dan
Ultra-High-Performance Steel Fiber Reinforced Concrete (UHP-SFRC) is an emerging concrete considered as an optimal, durable material that can substitute conventional concrete owing to its distinct fresh and hardened properties. Thus, it is essential to understand the mechanism of stress transfer between this concrete and conventional reinforcement that permits the composite action of both materials. A four-point bending test program (FPBT) was arranged and conducted on 19 beams designed for the bond development to occur in the constant moment region along a short embedment length in order to achieve a uniform distribution of bond stresses, enabling measurement of bond strength through reverse engineering of beam strength and deformation. Additional material testing was conducted on prisms under 4-point loading in order to extract the mechanical properties for all material mixes considered. The bond-specimens failed either by pullout or by cone formation with minimal deterioration of the concrete cover, illustrating the high confinement provided by the novel concrete surrounding the bar in tension. The bond strength was determined to be directly proportional to the tensile strength capacity of the design mix, where for the strongest material the bond strength was approximately 30 MPa. Moreover, the test results indicated a very ductile flexural beam response accompanied by significant mid-span deflection reaching 27 mm and substantial bar-slip values attaining 19 mm. Different UHP-SFRC mixes, concrete covers, and embedment lengths were considered. A numerical model was developed to simulate the FPBT using a nonlinear finite element analysis platform, VecTor2, with the ability to model this novel concrete. This high bond strength provided by the concrete cover enables a significant reduction in the design development length as compared to what is used today for conventional concrete.
Open Access
The Use of Human Behaviour to Inform Egress Modeling in Stadiums
(2019-07-02) Aucoin, Danielle Robyn; Gales, John A.
With growing concerns of public safety in infrastructure where large crowds gather, designing for egress under normal and emergency conditions is pertinent to ensuring efficient and safe conditions in stadia. There is a need for a large database of publicly available pedestrian movement profiles through experiments and the evaluation of relevant case studies. This thesis outlines novel human behaviour data collection at two stadia. Subsequent egress model validation using the MassMotion Advanced Crowd Simulation Software (MassMotion) was performed and measured total egress times. Although demographics and anthropometry in the stands slightly influenced the egress times, the stadium architecture was the governing factor which impeded pedestrian flow under non-emergency conditions. Analysis of a stadium fire case study allowed for evaluation of this conclusion during an evacuation which revealed that behavioural aspects of both occupant and staff may begin to dominate the egress simulation in an emergency context.
Open Access
Numerical Study of the Lateral Response of Precast Composite Wall Systems
(2019-07-02) Mirarab, Amir Hossein Haji; Palermo, Dan
A novel, light gauge steel stud-thin shell precast concrete panel system was developed to serve as a vertical wall panel element to resist vertical and out-of-plane horizontal loads. The behavior and capacity of this system to sustain in-plane lateral loads arising from wind and earthquake actions are currently not understood. The focus of this research is to assess the performance of such a system when subjected to lateral loading. Two-dimensional monotonic and reverse cyclic nonlinear finite element analyses of the Thin Shell Precast (TSP) panel was conducted using Program VecTor2. The analyses evaluated the effect of various components of the system including the type and size of the internal reinforcing bars and the influence of the exterior light-gauge steel framing. The modelling also shed light on the effect of reinforcement bonding and the difference in response between squat and slender wall systems. Through the nonlinear modelling, lateral load-displacement (drift) responses were generated for monotonic and reverse cyclic motions, in addition to quantifying the yield and ultimate loads and corresponding displacements (drifts). Preliminary analyses were used to modify the design of the Thin Shell Panel to achieve an improved lateral response.
Open Access
Bond Strength of Ultra-High-Performance Concrete Under Direct Tension Pullout
(2019-07-02) Tsiotsias, Konstantinos; Pantazopoulou, Stavroula
Bond occurs at the interface between the reinforcing bars and the cover concrete and enables force transfer between the two media. Thirteen specimens comprising four distinct UHPC or ECC (Engineered Cementitious Composite) material compositions and two different values cover thicknesses to the embedded bar were tested. Experimental results were compared with bond strength values obtained from beam tests where anchorage length in the constant moment region and material properties were the same. Bond strength measurements obtained from the DTP setup were half the corresponding values obtained from beam specimens, whereas the DTP setup showed more sensitivity to the increase of the cover thickness. Detailed nonlinear finite element analysis was conducted using two alternative levels of approximation in modeling the bar matrix interface. The occurrence of unaccounted for confining pressures and restraint effects were shown in conventional pullout methods, while the DTP setup provided the most conservative estimate of bond strength.
Open Access
Artificial Neural Network-Based Flood Forecasting: Input Variable Selection and Peak Flow Prediction Accuracy
(2019-11-22) Snieder, Everett Joshua; Khan, Usman
Floods are the most frequent and costly natural disaster in Canada. Flow forecasting models can be used to provide an advance warning of flood risk and mitigate flood damage. Data-driven models have proven to be suitable for flow forecasting applications, yet there are several outstanding challenges associated with model development. Firstly, this research compares four methods for input variable selection for data-driven models, which are used to minimize model complexity and improve performance. Next, methods for reducing the temporal error for data-driven flood forecasting models are investigated. Two procedures are proposed to minimize timing error: error weighting and least-squares boosting. A class of performance measures called visual measures is used to discriminate between timing and amplitude errors, and hence quantifying the impacts of each correction procedure. These studies showcase methods for improving the performance of flow forecasting models, more reliable flood risk predictions, and better preparedness for flood events.