The feasibility of primary microscreening and algae photobioreactors for small-scale passive wastewater treatment and reuse in urban areas
This research seeks a resolution between two opposing trends in cities around the world: the greening of the urban realm and the exhausting of municipal water supplies. Green space in urban areas has been widely shown to increase economic productivity, physical and mental health, social cohesion, and lower urban energy consumption. However, a lush urban realm comes with an expense: water and nutrients. Even in rainy Vancouver, we struggle to keep our lawns alive in summer months, let alone places not located amidst a temperate rainforest. Wastewater is an abundant and nutrient rich water source capable of reconciling this rift. This research project is a feasibility study on a wastewater treatment process designed for distributed small scale reuse within the urban realm–primary microscreening followed by an algae photobioreactor and UV disinfection. To assess feasibility, wastewater is collected from two points in UBC’s sewer network and first gravity filtered through a 54um microscreen to remove suspended particulate. The filtered water is then fed to a flow cell resembling a solar panel where a symbiotic community of algae and bacteria consume the remaining dissolved carbon and nutrients powered by sunlight. The efficiency of the treatment processes is being analysed according to energy use and effluent quality, and the microbial community is being DNA sequenced for characterization. The primary research objective is to determine whether the treatment train is capable of meeting unrestricted urban reuse guidelines in British Columbia and elsewhere.
Effect of initial fabric in behavior of granular materials influenced by multidirectional cyclic shear loading
The arrangement of granular materials before undergoing cyclic back and forth loading can have significant effects on cyclic strength degradation and eventual liquefaction in undrained condition. Historically, soil fabric has been studied using limited anisotropic parameters with spherical particles, mostly limited to mechanical anisotropy suggested otherwise. However, strong contradicting evidence exists in literature which depicts stress-strain response of granular materials for constant void ratio and confining stress as a function of initial soil fabric. This can hold true for both drained and undrained behavior of cohesion-less materials. Also, if the limited effects of specific anisotropic parameters are removed and a wide range of parameters already available in literature are used, this can provide substantial evidence of the initial anisotropic effects. In our research, the influence of geometric anisotropy in terms of particle shape and multidirectional cyclic loading are also investigated in lieu of closely resembling the ideal conditions using Discrete Element Method.
User mobility management in wireless networks
Supporting user mobility is considered to be an intrinsic feature of wireless networks. With the massive deployment of wireless nodes to support increasing traffic demands, there exists a number of challenges in offering streamless services to users with mobility. Such user mobility issues need to be incorporated in the capacity planning phase and there arises a need to have mobility management techniques that could minimize the effect of user mobility on the desired data rate. As a part of my PhD, I am working on such novel mobility management techniques using tools from stochastic geometry to quantify and reduce the effect of user mobility in various wireless networks.
Towards an adaptive, robust and efficient resource allocation system for highly dynamic resource constrained IoT environment.
Because of the Internet of Things or IoT in short, every day, more and more objects are getting online and there isn’t a single area of our life that won’t be touched by IoT devices in the next decade. Day by day, the advancement of microtechnology is enabling embedded IoT devices to perform more complex jobs written with high-level languages to get more productivity. But despite the increase of job complexity and advancement of emended devices, in terms of the “elasticity of available resources”, the IoT devices are still far more behind compared to the available resources in the cloud. Because of this, when we send programs to run on any IoT devices, we must be extra careful in terms of allocating resources, as the result of a small fraction of misallocation might be devastating, especially for the safety-critical jobs. Hence, we are in a great need for a new, efficient and fault tolerable resource management system for resource-constrained IoT devices in the forthcoming days where the classical and existing techniques won't work. My research focuses on finding a solution for this scenario.
Sulfur deportment in ferronickel production via Rotary Kiln-Electric Furnace process
Nickel is an essential component of stainless steel with a wide range of application in architecture, construction, automotive and transportation. The rotary kiln-electric furnace (RKEF) process is a pyrometallurgical route that has long been used for the production of ferronickel. Since the presence of impurities would have negative effects on the properties of ferronickel, it is necessary to control the form and concentration of impurities. Sulfur is a deleterious impurity that reacts with alloy components and forms non-metallic inclusions that lead to decrement in mechanical properties of nickel alloys. This project aims to investigate sulfur deportment in the RKEF process by employing various fuels and reducing agents as well as regulating the conditions in the rotary kiln. The long-term goal of this study is to produce high purity ferronickel while diminishing the load of the refinery.
Wastewater to drinking water: Alternative low cost water reuse technologies
Drinking water supplies are derived from a variety of natural surface and ground water sources across the globe. As population grows, urbanization, droughts and climate change continue to impact natural water resources. Public water supplies are becoming stressed and necessitate the development of new strategies to meet future demands. One such strategy is the reuse of municipal wastewater, which is an increasingly important water supply option worldwide. Planned potable reuse has recently gained interest in the arid areas of Western Australia and North America, where the community’s wastewater is used as a source of drinking water. However, wastewater reuse requires advanced treatment technologies since these waters contain a range of chemical and microbial contaminants that can result in a range of human health implications when ingested, inhaled or absorbed through the skin. These technologies are often quite expensive since they employ processes like Reverse Osmosis (RO) and chemical oxidation to ensure maximum removal of the known contaminants. This research aims to investigate the potential application of ion exchange (IX) resins, a low-cost treatment process for the removal of organic contaminants, and Vacuum-UV, a chemical free advanced oxidation technology, as a low-cost and robust alternative for wastewater reuse purposes. Extensive studies will be performed on municipal wastewaters to optimize the resin dosage and the effect of source water characteristics on treatment processes will be evaluated to fabricate efficient low-cost reactor set-up configurations.
Momentum and Heat Transfer in Suspension Flows
Particle-laden flows are ubiquitous in environmental flows, geophysical flows and man-made processes. The overall dynamics in these flows are mostly governed by the momentum, heat and mass transfer between the solid dispersed particles and the surrounding fluid. Particle-laden flows are generally quite challenging to model as they are multi-scale by nature. In fact, large structures in the flow - e.g., clustering, bubbles or shear-banding - are controlled by the local exchange at the particle level. The strong interphase coupling leads to remarkable phenomena - e.g. particle-induced turbulence or shear-induced migration. Different models corresponding to different scales of description (essentially micro, mess and macro) have been suggested in the literature, and in turn these models are associated with specific numerical methods (particle-resolved, two-way Euler-Lagrange and Euler-Euler methods respectively). The principle of multi-scale analysis is to conduct high-fidelity simulations at the micro-scale level, to extract valuable information from these data to enhance the comprehension of the flow dynamics and to use this novel comprehension to improve models at the meso-scale. A similar transfer of knowledge can be carried out from the meso-scale to the macro-scale. In the framework of a micro/meso multi-scale approach, we use our in-house simulation tools to investigate momentum and heat transfer in particle-laden flows. We perform both micro-scale and meso-scale simulations in flow regimes relevant to fluid/solid and gas/solid flows. The question of how to filter the micro-scale high-fidelity results and to develop enhanced and coherent meso-scale heat transfer models is central in this PhD project.
Molecular Dynamics simulation of piezo-ionic sensors
With increasing interest in motion capture, soft robotics, and wearable medical technologies, human (bio) compatible sensors are required. When creating these bio-friendly sensors, they need to be flexible, conductive and compatible with human tissue. Unfortunately, the materials currently available are either solid, as in electric wire, or liquid, as in car batteries. Smart hydrogels are a promising class of materials that can potentially bridge the gap between current sensor technologies and tomorrow’s soft-sensor requirements. On a nanoscopic level, hydrogel resembles three-dimensional hollow honeycomb cells that trap the conducting particles (ions). By choosing the correct chemical process for creating the gel, one can virtually program it to respond to external stimuli like temperature, pH or mechanical impact (as in touch sensors) - hence the name “smart.” To optimize the performance of hydrogels in touch sensors, one needs to understand in detail the behavior of ion movement in the honeycomb cells when pressure is applied. Through a computer simulation tool called Molecular Dynamics, we perform an extensive analysis of the flow of ions in the gel cells. Through extensive virtual trials, we select the most optimal chemical structure. The computational screening will allow the experimentalist to synthesize the most favorable gel possible and gain insights into it on a nano level. The optimized hydrogel structures could revolutionize the field of soft tissue human-friendly sensors or artificial muscles.
Electrocatalytic hydrogenation-hydrodeoxygenation of lignin-derived aromatics for the production of valuable chemicals and fuels
In the scheme of a sustainable biorefinery, the valorization of lignin is a key factor to improve the economic feasibility of the overall process. Lignin, being a valuable by-product in the cellulosic ethanol industry, is a highly complex natural polymer that constitutes the cell walls of plant biomass, especially lignocelluloses. As the earth’s most plentiful source of organic carbon after cellulose and the only large-scale biomass source of aromatic compounds, lignin has been regarded as a promising renewable feedstock for the production of higher value chemicals, fuels, and materials. Phenol and guaiacol are the most representative monomers of lignin-derived aromatics in biomass-derived pyrolysis oils. The former is the hydrogenolysis product of the latter, and both can be converted further into cyclohexanol and cyclohexane, which have versatile applications in the industry. This upgrading process is carried out via a catalytic hydrogenation-hydrodeoxygenation reaction, either thermochemically or electrochemically. The electrochemical process, known as electrocatalytic hydrogenation-hydrodeoxygenation (ECH), can be performed without the external supply of molecular hydrogen at the milder conditions. In ECH, hydrogen must be adsorbed on the electrocatalyst surface in order to hydrogenate the organic compounds. The reduction of protons to hydrogen gas would be the undesirable reaction that decreases the current efficiency. In this work, we develop strategies to design a process with the active and stable electrocatalysts that is capable of producing high product yields at the optimum current efficiency. This research will contribute to the development of electrochemical process for sustainable energy production from renewable resources.
CO2 Sequestration by Mineral Carbonation with Valuable Metals Recovery Enhancement
This project aims to develop a novel economically-feasible mineral carbonation process to sequestrate CO2 for mitigating global warming, which can be used in practical industrial application. The international community has become increasingly concerned that greenhouse gas emissions due to our human’s excessive activities have a potentially adverse effect on global climate conditions. Especially, CO2 has been attributed as the primary causal greenhouse gas (approximately 77%) towards climate change. Except for improving the efficiency of fossil-fuel-fired power plants, the methods to sequester the CO2 emitted from these plants are also necessary. Mineral carbonation, one of the methods of CO2 sequestration, is the only permanent method which can form environmentally benign carbonate minerals stable over geologic time periods. However, mineral carbonation technology remains in relative infancy mainly because of high costs and slow reaction rate as well as low sequestration efficiency. Thus, this project will develop a new and economically feasible process for mineral carbonation to sequestrate waste industrial CO2 and apply it into practical industry.