Engineering Commons^™

Antibiotic Resistance In Urban Stormwater Runoff And Green Stormwater Infrastructure, Kassidy N. O'Malley

Dissertations (1934 -)

Antibiotic resistance in the environment poses significant risks to human health, especially through the transmission of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) via pathways like food and water. Urban stormwater runoff has been identified as a significant contributor to the release and transport of ARGs in the environment but has remained under-researched. This dissertation aimed to address this gap by investigating the fate of ARGs in urban stormwater runoff to guide future stormwater management decisions. Two phases were completed; the first sought to investigate extracellular antibiotic resistance genes (eARGs) in stormwater runoff, and the second focused on quantifying …

The Role Of Membrane Porosity In Ion Removal By Ro/Nf Membranes And Development Of A Regenerable Pac-Loaded Membrane, Yizhi Hou

Dissertations (1934 -)

Reverse osmosis (RO) and nanofiltration (NF) membranes are widely used for water treatment applications. They are charged porous materials, in which size exclusion and charge exclusion work together to dictate solute transport. In this study, membrane porosity was primarily determined by pore size. Thicker, more porous membranes with smaller pores had higher NaCl removal and less permeate water flux. Higher porosity membranes have greater inner pore surface area available to support a greater number of functional groups, thereby rejecting ion flux and increasing ion removal. The Donnan steric pore model (DSPM) was used to determine that the contribution of diffusion …

Micropollutant-Free Nutrient Recovery: Adsorption Of Micropollutants On Ion Exchangers And Biosolids-Derived Biochar, Yiran Tong

Dissertations (1934 -)

The presence of excessive nutrients in treated wastewater effluent is a growing concern in terms of water quality and ecological balance. Thus, removal of nutrients is of great interest. Moreover, the removed nutrients can be recovered in forms amenable for agricultural reuse, which yields a sustainable supply of nonrenewable phosphorus that can be used to support global food production. As nutrient recovery gains interest, it is essential that the products be free of harmful contaminants. One class of contaminants of great concern is organic micropollutants. To help address these issues, this study evaluated the fate and impact of micropollutants during …

Bioaugmentation And Correlating Anaerobic Digester Microbial Community To Process Function, Kaushik Venkiteshwaran

Dissertations (1934 -)

This dissertation describes two research projects on anaerobic digestion (AD) that investigated the relationship between microbial community structure and digester function. Both archaeal and bacterial communities were characterized using high-throughput (Illumina) sequencing technology with universal 16S rRNA gene primers. In the first project, bioaugmentation using a methanogenic, aerotolerant propionate enrichment culture was investigated as a possible method to increase digester methane production. Nine anaerobic digesters, seeded with different biomass, were operated identically and their quasi steady state function was compared. Before bioaugmentation, different seed biomass resulted in different quasi steady state function, with digesters clustering into high, medium or low …

The Role Of Household Antimicrobials In The Proliferation Of Antibiotic Resistance During Anaerobic Digestion, Daniel Elliott Carey

Dissertations (1934 -)

Antimicrobial chemicals in consumer personal care products have been found to increase antibiotic resistance in pure culture studies. Although many studies focus on antibiotic resistance development pertinent to medical scenarios, resistance developed in natural and engineered environments might be significant and has become an emerging concern for human health. This dissertation focuses on the antimicrobial chemicals triclosan and triclocarban. These compounds are distinctly different from antibiotics and are used in products like soaps that are labelled as “antibacterial”. Municipal wastewater treatment plants receive triclocarban and triclosan loads higher than most contaminants of emerging concern because they are frequently used in …

Anaerobic Membrane Bioreactors To Treat Municipal Wastewater At Ambient Temperatures, Matthew D. Seib

Dissertations (1934 -)

Anaerobic biotechnology is viewed as a sustainable alternative to aerobic biotechnology for municipal wastewater recovery. However, anaerobic processes have not been successful in cold climates. Past examples have not been able to meet low organic effluent concentrations, or have failed due to biomass washout resulting from low temperature operation and short hydraulic residence time. Recently, the anaerobic membrane bioreactor (AnMBR) has been shown to achieve low effluent organic concentrations and maintain stable anaerobic biomass. However, shortcomings have included high energy demands for membrane operation and poor understanding of microbial community structures within AnMBRs. This dissertation describes efforts to improve AnMBRs …

A Semantics-Based Approach To Construction Cost Estimating, Mehrdad Niknam

Dissertations (1934 -)

A construction project requires collaboration of different organizations such as owner, designer, contractor, and resource suppliers. These organizations need to exchange information to improve their teamwork. Understanding the information created in other organizations requires specialized human resources. Construction cost estimating is one of the processes that requires information collected from several sources including a building information model (BIM) created by designers, estimating assembly and work item information maintained by contractors, and construction resource cost information provided by resource suppliers. Currently, it is not easy for computers to integrate the information for construction cost estimating over the Internet. This study discusses …

The Contribution Of Syntrophic Fatty-Acid Degrading Microbial Communities To Anaerobic Digester Function And Stability, Prince Peter Mathai

Dissertations (1934 -)

Anaerobic digestion (AD), the conversion of complex organic matter to methane, occurs through a series of reactions mediated by different guilds of microorganisms. AD process imbalances, such as organic overload or high organic loading rates (OLR), can result in the accumulation of volatile fatty acids (VFA) e.g., propionate, which must be degraded to maintain stable reactor function. VFAs are metabolized by syntrophic fatty-acid degrading bacteria (SFAB) in association with methanogenic archaea (collectively, syntrophic microbial communities, SMC). Despite their indispensable role in AD, little is known about the ecology of SFAB, especially under stressed conditions. To facilitate ecological studies, four quantitative …

Failure Mechanisms And Key Parameters Of Frp Debonding From Cracked Concrete Beams, Tayyebeh Mohammadi

Dissertations (1934 -)

Intermediate crack (IC) induced debonding failure of Fiber Reinforced Polymer (FRP)-strengthened reinforced concrete beams starts at the tip of flexural/shear cracks within the shear span and propagates towards the FRP plate termination. In this study, experimental and numerical programs are performed to characterize and predict the failure mechanisms of IC debonding failure, and identify the key parameters affecting such failure. It is found that the bond-slip relation obtained from the pullout test does not represent the bond-slip relation of the FRP/concrete interface in the FRP-strengthened concrete beams, and it cannot be directly used for predicting the load capacity of the …

Reliability-Based Fatigue Assessment Of Mast-Arm Sign Support Structures, Joseph A. Diekfuss

Dissertations (1934 -)

Over the past few decades, there have been issues of poor fatigue performance (the main failure mechanism) of the welded, tube-to-transverse plate connections within sign support structures. Review of the literature has indicated that a considerable amount of research has been devoted to identifying the structural response characteristics of these signs. Others have tried to identify how these connections may be repaired, retrofitted or simply better designed to sustain longer fatigue lives. However, little attention has been given to using a systematic reliability-based approach to assess the risk of fatigue-induced fracture in these structures.

Using a reliability-based approach to solve …

Effect Of Support Compliance On The Resonant Behavior Of Microcantilever-Based Sensors In Viscous Fluids, Rabin Maharjan

Dissertations (1934 -)

Resonant microcantilevers are often considered for use in chemical sensing and biosensing applications. However, when excited in the conventional transverse flexural mode, their performance in liquids is severely compromised. Theoretical and experimental studies have shown that the detrimental effects of the liquid may be mitigated by operating the microcantilever in lateral flexure, especially for microbeams having smaller length-to-width (L/b) ratios. However, for these most promising geometries the predictions of existing models tend to diverge from experimental data for resonant frequency (f_res) and quality factor (Q). A likely reason for these discrepancies is support compliance, which has been neglected …

Lateral-Mode Vibration Of Microcantilever-Based Sensors In Viscous Fluids Using Timoshenko Beam Theory, Joshua Schultz

Dissertations (1934 -)

Dynamic-mode microcantilever-based devices are well suited to biological and chemical sensing applications. However, these applications often necessitate liquid-phase sensing, introducing significant fluid-induced dissipative forces and reducing device quality factors (Q). Recent experimental and analytical research has shown that higher in- fluidQis achieved by exciting microcantilevers in the lateral flexural mode. However, the experimental results show that, for microcantilevers having larger width-to-length (b/L) ratios, the behaviors predicted by current analytical models differ from measurements.

To more accurately model microcantilever resonant behavior in viscous fluids and to improve understanding of lateral-mode sensor performance, a new analytical model is developed, incorporating both viscous …

Relating Methanogen Community Structure And Function In Anaerobic Digesters, Benjamin T.W. Bocher

Dissertations (1934 -)

A deeper understanding of how microbial community structure relates to process function would help improve anaerobic digester design. This dissertation describes both qualitative and quantitative relationships between anaerobic digester function and microbial community structure. Community structure was characterized using banding pattern intensities from denaturing gradient gel electrophoresis (DGGE) for the mcrA gene of methanogenic Archaea. The first project compared a single-stage continuously mixed stirred tank reactor (CSTR) and staging with an acidogenic CSTR followed by a methanogenic CSTR. After seeding with the same biomass, these unique process configurations exhibited different function and qualitatively different methanogen communities. Compared to a single-stage …

Preservation Of Methanogenic Cultures To Enhance Anaerobic Digestion, Ujwal H. Bhattad

Dissertations (1934 -)

The use of anaerobic biotechnology is increasing as a sustainable process to treat various organic wastes. Methanogens convert organic COD into CH4 and play the key role to drive thermodynamically unfavorable biochemical fermentation reactions and keep the digestion process steady and efficient. Progressive understanding of anaerobic microbiology with digester functionality may help to develop efficient, customized methanogenic cultures to enhance anaerobic bioprocesses. Preservation of methanogenic cultures via drying would be a cost-effective option for research and practical applications. However, preservation of methanogenic cultures is challenging due to methanogen sensitivity to O2 toxicity and drying, and very limited work is reported …

Anaerobic Co-Digestion For Enhanced Renewable Energy And Green House Gas Emission Reduction, Navaneethan Navaratnam

Dissertations (1934 -)

The need to develop renewable energy is important for replacing fossil fuel, which is limited in quantity and also tends to increase in price over time. The addition of high strength organic wastes in municipal anaerobic digesters is growing and tends to increase renewable energy production. In addition, conversion of wastes to energy significantly reduces uncontrolled greenhouse gas emissions. Co-digestion of municipal sludge with any combination of wastes can result in synergistic, antagonistic or neutral outcomes. The objectives of this study were to identify potential co-digestates, determine synergistic, antagonistic and neutral effects, determine economic benefits, quantify performance of bench scale …

A Quantitative Study Of Robustness Characteristics In Steel Framed Structures, Christopher Herman Raebel

Dissertations (1934 -)

Robustness is a desirable property in any structural design. Robustness may be thought of as the building's inherent structural ability to resist loads other than those anticipated during design. Examples of unanticipated loads are damage to a column or beam due to impact; damage due to the concussion of a blast; strength reduction due to extreme heat during a fire; and localized accidental overload of a beam or column. Each of these events, although very different in their nature, has one major point in common; in each case the path of load resistance changes in a way that was not …

Evaluation Of Runoff Response To Moving Rainstorms, Jin Liang

Dissertations (1934 -)

The primary hypothesis from the hydrological literature is that downstream moving storms with storm length (Ls) less than watershed length (Lc) magnify the peak discharges. This hypothesis was developed from the kinematic-wave modeling, and was evaluated in a plot between the dimensionless peak discharge and dimensionless storm velocity. Previously unpublished experimental data collected from the Watershed Experimentation System (WES), obtained from the late Professor Ben C. Yen at the University of Illinois at Urbana-Champaign, were used in comparison with the simulation results of the kinematic-wave model. It is found that downstream moving storms with Ls/Lc <1 increase the peak discharges to a limited extent compared to stationary storms, but the kinematic-wave model overstates the increase in the peak flows resulting from downstream moving storms with Ls/Lc <1. This difference between model projections and laboratory data was attributed to backwater effects in the experimental runoff.

To evaluate the importance of …

Bioaugmentation For Recovery Of Anaerobic Digesters Subjected To Organic Overload, Vaibhav Panjabrao Tale

Dissertations (1934 -)

Anaerobic digester upset due to organic overload is common and methods to reduce recovery time would be beneficial. One potential method is bioaugmentation, the addition of an external culture for performance improvement. Methanogenic community structure differs from digester to digester and there may exist a relation between specific methanogenic activity (SMA) and microbial community composition. The research presented herein tested whether there is a relationship between SMA and community structure. Also, the effectiveness of bioaugmentation was tested by hypothesizing that bioaugmenting with a methanogenic, propionate-degrading culture acclimated to small oxygen doses will help rapid recovery of organically overloaded digesters.

Fourteen …

Risk-Based Seismic Design Optimization Of Steel Building Systems With Passive Damping Devices, Junshan Liu

Dissertations (1934 -)

Nonlinear time history analysis software and an optimization algorithm for automating design of steel frame buildings with and without supplemental passive damping systems using the risk- or performance-based seismic design philosophy are developed in this dissertation. The software package developed is suitable for conducting dynamic analysis of 2D steel framed structures modeled as shear buildings with linear/nonlinear viscous and viscoelastic dampers. Both single degree of freedom (SDOF) and multiple degree of freedom (multistory or MDOF) shear-building systems are considered to validate the nonlinear analysis engine developed. The response of both un-damped and damped structures using the 1940 EI Centro (Imperial …

Perpetual Pavement Analysis For The Marquette Interchange Instrumentation Project, Nicholas James Hornyak

Dissertations (1934 -)

With the emergence of the mechanistic-empirical pavement design process, development of pavements rely on the structural response and fatigue characteristics of pavement materials due to traffic loads. In the past, pavement design has been almost entirely based on empirical data. One area of interest in designing hot-mix asphalt (HMA) pavements is the fatigue life of the pavement, which has been shown to be dependent on the horizontal strain in the pavement.

This research is focused on measuring the structural response of a pavement located within the Marquette Interchange Project in order to analyze fatigue behavior with great detail. Virtually all …