Environmental Engineering Commons^™

Biocrude From Organic Waste And Its Conversion To Hard Carbon: Experimental And Modeling Study, Isamu Umeda

Civil & Environmental Engineering Theses & Dissertations

This study establishes a technical and theoretical foundation for the efficient conversion of organic waste into biocrude and high-value carbon materials, aiming to facilitate the industrialization of hydrothermal and solvothermal liquefaction. The dissertation research is structured as follows:

Chapter 2 developed a novel chemical kinetic model for the HTL of corn stover based on elemental balances (C, H, N, and O). By incorporating temperature, residence time, solid loading as an independent variable, the model successfully predicted product yields and properties, revealing that there was non-pseudo-first-order reaction pathways in the conversion of water soluble organics in aqueous phase (AP) to hydrochar. …

Low Dissolved Oxygen Operation Enhances Biological Phosphorus Removal In Wastewater Treatment, Haley Morgan

Civil & Environmental Engineering Theses & Dissertations

Biological phosphorus (bio-P) removal occurs when bacteria are exposed to anaerobic/aerobic conditions that stimulate polyphosphate-accumulating organisms (PAOs) to uptake phosphorus. In most treatment plants, dissolved oxygen (DO) concentrations in the aeration tanks are commonly at or above 2.0 mg O₂/L, which is often referred to as the most optimal aeration condition for bio-P. If bio-P can happen efficiently at lower DO (< 0.3 mg O₂/L), then the energy demand of aeration can be decreased appreciably. This research was conducted in a biological nutrient removal (BNR) pilot plant to assess the performance of bio-P at progressively lower DO operation. This …

Valorization Of Industrial Wastes To Low-Carbon Minerals, Nandan Nag

Civil & Environmental Engineering Theses & Dissertations

This study concentrates on developing methods for utilizing industrial waste materials such as red mud and phosphate slag. In this study, an electrochemical process was developed for recovering iron metal powder from red mud. Red mud is a waste material from aluminum refineries. Although red mud can be utilized as a construction and building material, its use is becoming controversial due to its high metal content, which contributes to its toxicity. However, the high iron oxide content in red mud makes it a good feedstock for producing iron. In this project, we employed an electrochemical technique for extracting iron powder …

Feasibility Study Of Oyster Shell Filtration Media For Stormwater Pollutants Removal, Sadiq Omer

Civil & Environmental Engineering Theses & Dissertations

The depletion of resources has raised interest in reusing or incorporating by-products into alternative materials. In the effort for net zero emissions, waste reduction, and a circular economy, it is crucial to reinvent the alternative utilization strategy for by-products as construction materials sustainably. This research examines the alternative utilization strategy for oyster shell by-products in regular stormwater pollutant removal best management practices (BMPs).

Numerous research has examined the utilization of oyster shell waste as a construction material in Asia and Europe, specifically focusing on the physical properties of crushed oyster shells as alternatives for aggregates. No studies have been identified …

Simulating The Compound Impacts Of Climate Change And Sea-Level Rise On Coastal Shallow Groundwater Using An Integrated Surface-Subsurface Hydrologic Model, Zhaoyi Cai

Civil & Environmental Engineering Theses & Dissertations

As climate change intensifies and sea levels rise, coastal aquifers become increasingly vulnerable to interacting oceanic and terrestrial processes. This dissertation examines the combined impacts of climate change and sea-level rise (SLR) on coastal shallow groundwater using an integrated surface-subsurface hydrologic model, focusing on the low-lying Little Creek watershed (LCW) in Norfolk, Virginia. The SWAT-MODFLOW model, a coupled system, unifies land surface, streamflow, and groundwater processes, providing a comprehensive framework for watershed-aquifer analysis. Model parameters were derived from U.S. Geological Survey datasets, relevant literature, station records, and technical reports, followed by meticulous calibration. The validated model first simulated baseline groundwater …

Elasto-Plastic Behavior Of Single-Story Single-Bay Orthogonal Steel Space Frame Under Angular Earthquake, Mohammad Hamayoun Stanikzai

Civil & Environmental Engineering Theses & Dissertations

A study of the elasto-plastic behavior of single-story single-bay orthogonal steel space frame under an angular earthquake ground motion is investigated. The building frame is subjected to a horizontal earthquake ground motion not aligned with the building’s principal axes. Such a frame can develop biaxial bending and torsion in its members. The governing differential equations of equilibrium for the typical biaxially loaded sway beam-column are presented and iteratively solved using a finite-difference scheme. The effects of warping and residual stresses are accounted for in the analysis. The equations are used to predict the quasi-static elasto-plastic response of the frame when …

Biochar For Heavy Metal Removal In Water: Opportunities, Challenges, And Sustainable Solutions, Pushpita Kumkum

Civil & Environmental Engineering Theses & Dissertations

The presence of heavy metals in drinking water is a significant concern due to the harmful impacts it can have on human health. Biochar has emerged as a low-cost alternative to activated carbon for lead (Pb) adsorption due to its porous structure and high surface-to-volume ratio. The last 10 years of studies have been reviewed to investigate the biochar production, activation methods, kinetic, adsorption isotherms, mechanism, regeneration, and adsorption capacities to guide future researchers and practitioners in using biochar to remove Pb from water. However, several challenges hinder the actual application of biochar as an adsorbent. These challenges include variability …

Lithium Extraction From Aqueous Solution Using Magnesium Doped Lithium Ion-Sieve Composite, Ujjwal Pokharel

Civil & Environmental Engineering Theses & Dissertations

This study focused on the development of a magnesium doped ion-sieve composite to extract lithium from an aqueous solution using adsorption process. The extraction process will provide a sustainable alternative to the currently practiced solar evaporation/concentration method which is very slow (takes 24 months) and water intensive. Currently, most of the lithium in the world comes from the mining of lithium or from the evaporative extraction process from the brine. Additionally, the Salton Sea area geothermal brines are recognized as potentially important domestic sources of lithium. Lithium concentration in geothermal brines from the Salton Sea area is reported to be …

Adaptation Of Nirtrifiers And Heterotrophs To Low Dissolved Oxygen In An Activated Sludge Biological Nutrient Removal Pilot Plant, Shashank Khatiwada

Civil & Environmental Engineering Theses & Dissertations

Low dissolved oxygen (DO) operation is one of the innovative technologies in biological nutrient removal (BNR) processes that is being investigated due to the potential to reduce aeration requirements, reduce a treatment plant’s carbon footprint, and to lower costs associated with chemical addition to promote denitrification. These benefits are achieved through development of micro-zones, within aerated basins where simultaneous nitrification and denitrification (SND) can occur. In this study, an activated sludge BNR pilot was run in an anerobic/aerobic (A/O) configuration at a controlled temperature and constant flow to observe microorganism-driven transformations of nitrogen and phosphorus at varying low DO conditions. …

Evaluating Direct Filtration As An Alternative To Conventional Carbon-Based Advanced Treatment For Indirect Potable Reuse, Savannah M. Flemmer

Civil & Environmental Engineering Theses & Dissertations

Hampton Roads Sanitation District (HRSD) is recharging purified wastewater into the Potomac Aquifer via the Sustainable Water Initiative for Tomorrow (SWIFT) project. Conventional SWIFT treatment applies coagulation, flocculation, sedimentation, ozonation, biofiltration, granular activated carbon (GAC) adsorption, and ultraviolet disinfection to secondary effluent to produce water that meets drinking water standards for managed aquifer recharge. HRSD is considering implementing direct filtration as an alternative to conventional treatment for two additional SWIFT facilities. Direct filtration presents an opportunity for significant cost savings by eliminating sedimentation, shortening flocculation detention time, and reducing coagulant usage. Without upstream removal of solids and organics, however, biofilters …

Biocrude Production From Lignin In Hydrothermal Medium: Effect Of Rapid Heating And Short Residence Time, Kyoko Hirayama

Civil & Environmental Engineering Theses & Dissertations

This study aims to address knowledge gaps in the production of valuable products from waste streams generated during lignocellulosic biofuel production. The primary objective is to develop a process that converts lignin, a byproduct of bioethanol refineries, into a sustainable biolubricant.

The first chapter examines recent advancements in synthesizing biolubricants and investigates their scalability. It explores innovative materials, catalysts, chemical modification approaches, and additives that have emerged in the field. A particular hurdle is the oxidative stability of biolubricants derived from plant oils, which are prone to autooxidation due to their C=C bonds. To overcome this, the study aims to …

Assessment Of The Hydrograv® Adapt Variable Height Secondary Clarifier Inlet At Hrsd Nansemond Treatment Plant, Matthew Poe

Civil & Environmental Engineering Theses & Dissertations

The Hampton Roads Sanitation District (HRSD) recently completed the first North American and center driven installation of the Hydrograv® Adapt Variable Height Secondary Clarifier Inlet (Adapt) at HRSD’s Nansemond Treatment Plant. This is a variable height inlet structure designed to decrease clarifier effluent turbidity and maintain low turbidity during high flow events. Low turbidity is achieved by feeding the secondary clarifier influent within the solids blanket during dry weather conditions and lifting the inlet structure during wet weather conditions to avoid disrupting the blanket. The Adapt clarifier was monitored alongside an identical fixed inlet clarifier to assess performance. Both clarifiers …

Integrated Processing Of Municipal Solid Waste For Maximizing Waste Reduction, Carbon Recovery And Fuel Production, Kameron J. King

Civil & Environmental Engineering Theses & Dissertations

Nationally and internationally, waste generation is increasing and along with it negative environmental impacts. Many people think waste ends at disposal; however, environmental impacts have already begun. Unfortunately, 50% of waste ends up in a landfill which is the third largest source of human related methane emissions and a leading cause of global climate change. This study investigated a novel waste management strategy in hopes of mitigating negative environmental effects caused by conventional waste management practices. The novelty of the study lies in the development of an integrated method of hydrothermal carbonization and an anaerobic digestion (HTC + AD) process …

Stability Of Low Crested And Submerged Breakwaters: A Reanalysis And Model Development, Christopher P. Burgess

Civil & Environmental Engineering Theses & Dissertations

Low-crested and submerged structures (LCS) play an integral part in the stabilization of shorelines for recreational purposes, yet there are a plethora of empirical models and gaps in the understanding of their stability and damage progression. The objectives were: i) to evaluate the present formulae, ii) explore variable importance, iii) formulate a stability model, iv) extend the current datasets and v) explore a new model for LCS. The literature points to an increasing understanding of the initiation of damage of LCS and recent exploration of the shear stress-induced erosion (van Rijn, 2019). Assessment of two existing models (Kramer, 2006 and …

The Impacts Of Surface Gravity Waves On Buoyant Plume Dilution, Bruce William Husselbee

Civil & Environmental Engineering Theses & Dissertations

A common practice in coastal areas is to collect, treat and discharge fluids including treated wastewater, stormwater or power plant effluent to areas of lesser impact. The discharge of these fluids, conveyed through pipelines into coastal areas, continues to be an important human health and environmental concern. The fluid discharged from these pipelines is often buoyant which allows for dilution and dispersion into these ambient waters.

Initial dilution, defined as the maximum concentration of a discharged fluid at the maximum rise in height within a buoyant plume, is critical in the consideration of the environmental impacts of a discharge into …

Catalytic Transfer Hydrogenation Reactions Of Lipids, Alexander Asiedu

Civil & Environmental Engineering Theses & Dissertations

Catalytic transfer hydrogenation (CTH) of lipids was investigated using 2-propanol as hydrogen donor for producing liquid hydrocarbons, e.g. jet fuels. The main sources of lipids selected in this study were waste cooking oil (WCO) and oil-laden algae-derived biofuel intermediate (BI). Two different catalysts were employed in this study, namely activated carbon and trimetallic-doped zeolite.

The CTH reaction was between WCO and 2-propanol in a continuous flow reactor over a packed-bed activated carbon at near atmospheric pressure. Results revealed a high level of alkenes and aromatics compounds, which are not stable and are not environmentally unfriendly. To reduce these compounds in …

Application Of A Biodegradable And Recyclable Chelating Agent For Ash Removal From Algae, Temitope George Daramola

Civil & Environmental Engineering Theses & Dissertations

Ash is inherent in algae biomass and it causes operational difficulties, equipment failure, and disposal issues during biomass conversion to biofuels and bioproducts. The objectives of this study are to (i) investigate the use of the biodegradable chelating agent for reducing ash content of algae and (ii) evaluate the potential of regeneration and recycle of the chelating agent for multiple uses. Conventionally, ethylenediamine-tetraacetic acid (EDTA) has been studied extensively to remove ash from biomass. However, EDTA is non-biodegradable and causes environmental issues at the disposal.

Nitrilotriacetic acid (NTA) is a biodegradable chelating agent and was used in this study for …

Challenges Of Designing And Operating A Pilot Scale Short Residence Time Continuous Hydrothermal Flash Hydrolysis Reactor For High Slurry Load Biomass Processing, Mason James Martin

Civil & Environmental Engineering Theses & Dissertations

Increasing demand for renewable energy, fuels, and bioproducts has resulted in a push for increasingly efficient and economically favorable biomass pretreatment methods. Flash Hydrolysis, (FH) a promising biomass pretreatment method, has been extensively studied at a laboratory scale. FH employs a continuous subcritical hydrothermal process capable of fractionating microalgae for lipid and protein recovery. FH is unique in that the residence time is very short (~ 10 s). Maintaining this residence time was key in designing a scaled pilot flash hydrolyzing unit (FHU). We have developed a one of its kind pilot FHU capable of increasing the processing output of …

Sidestream Ras Fermentation For Stable Bio-P Combined With Short Cut Nitrogen Removal In An A/B Process, Lindsey Elise Ferguson

Civil & Environmental Engineering Theses & Dissertations

It is well known that soluble organic carbon (sCOD), especially in the form of volatile fatty acids (VFA), is critical to achieving reliable enhanced biological phosphorus removal (EBPR) in biological nutrient removal (BNR) processes. Consistent and reliable EBPR in systems treating wastewaters deficient in sCOD may be accomplished by the addition of VFA and sCOD – rich fermentate produced by the fermentation of primary sludge, return / waste activated sludge (RAS / WAS), or other suitable carbon sources. The solids retention time (SRT) of fermenters being used to supplement carbon in sidestream EBPR processes must be controlled such that complex …

Measuring And Modeling Bare Desert Wind Erosion From Steppe Grassland Of Northern China As Affected By Soil Moisture And Climate, Nicholas Morgan Potter

Civil & Environmental Engineering Theses & Dissertations

Soil erosion by wind has been found to be negatively related to soil water content, as evidenced by that for a given area, such a soil erosion can be much less in a wet than a dry year. However, few studies have examined the functional relationship between wind erosion and soil moisture, primarily due to lack of field measured data. The objectives of this study were to: 1) measure wind erosion in field using a portable wind tunnel devised and made by the author; 2) use the measured data to calibrate/validate a wind erosion model previously developed by the author; …

Techno-Economic And Life Cycle Assessment Of Hydrothermal Processing Of Microalgae For Biofuels And Co-Product Generation, Andrew P. Bessette

Civil & Environmental Engineering Theses & Dissertations

Traditional processing methods of algae to biofuels require dewatering after harvesting of the algae before the lipids can be extracted. This is typically the most energy intensive and therefore the most expensive step. Old Dominion University (ODU) has successfully utilized a flash hydrolysis (a kind of hydrothermal) process where proteins are solubilized into the liquid phase of product and the remainder lipid-rich, low nitrogen product is separated into a solid phase. The solid phase (lipid-rich) is then an ideal candidate for biofuel feedstock and the liquid phase, or hydrolysate, can be used for coproducts such as a source of nutrients …

The Evaluation Of Enhancing Biological Phosphorus Removal And Improving Settleability Using Mainstream Hydrocyclones For External Selection, Amanda Carrie Ford

Civil & Environmental Engineering Theses & Dissertations

Hydrocyclones, which receive mixed liquor tangentially, separate lighter solids from more dense solids through their tapered shape. Increasing the velocity of liquid as it moves downward allows for the selection of a desired solids fraction. Limited research has been conducted utilizing 20 m³hr^-1 hydrocyclones, with the intent of improving settleability and biological phosphorus removal (Bio-P) for mainstream processes. Improved settleability would allow for increased capacity in the secondary clarifiers which prevents the loss of biomass and subsequent treatment disruption, especially during wet weather scenarios. In addition, treatment intensification can be accomplished by maintaining a higher mixed liquor …

Predicting Effects Of Climate Change And Sea Level Rise On Hydrologic Processes In A Mid-Atlantic Coastal Watershed, Rui Li

Civil & Environmental Engineering Theses & Dissertations

This dissertation assessed impacts of Climate Change (CC) and Sea Level Rise (SLR) on coastal hydrologic processes using the Lynnhaven River watershed as a test bed. The watershed is part of Chesapeake Bay Watershed and hydraulically connected with mid-Atlantic Ocean. Six CC scenarios were considered in terms of eight Regional Climate Models’ predictions for three Intergovernmental Panel on Climate Change (IPCC) emission assumptions, namely, B1, A1B, and A2, for two future periods, namely 2046 to 2065 and 2081 to 2099. The ensemble means of downscaling results from four methods were used to represent the future climates. On the other hand, …

Modeling Effects Of Rainwater Harvesting Systems On Water Yield Increase And Non-Beneficial Evaporation Reduction To Sustain Agriculture In A Water-Scarce Region Of China, Tennille Wade

Civil & Environmental Engineering Theses & Dissertations

The northwestern region of China, which has an arid/semiarid climate, relies heavily on agriculture to provide food for the growing population. Climate change is affecting water availability in the region, causing long periods of drought and water scarcity followed by shorter periods of heavy rainfall and excess water availability. The ridge and furrow rainwater harvesting systems (RFRWHS) are a means of solving the problem of water scarcity; the systems can replenish soil moisture, reduce non-beneficial evaporation from bare soils, and increase surface water yield. In such a region, the hydrologic cycle is dominated by soil evaporation, leading to minimal surface …

Value Added Products From Lignin And Biomass Derivatives, Chen Li

Civil & Environmental Engineering Theses & Dissertations

Pyrolysis is one of the traditional lignin and biomass utilization methods. The liquid products bio-oil and solid products bio-char are the main value-added products from lignin pyrolysis. Due to the narrow application and low quality, using the pyrolysis method to produce bio-oil and bio-char cannot bring sufficient economic benefits. In this dissertation, two methods were investigated to improve the quality of lignin bio-products.

Instead of direct pyrolysis, chemical activation (pyrolysis) was introduced in this dissertation. Compared to bio-char, the lignin chemical activation product lignin-activated-carbon has better economic value. With the best activation conditions, the lignin-activated-carbon produced a surface area of …

Holistic Approach In Microalgae Conversion To Bioproducts And Biofuels Through Flash Hydrolysis, Ali Teymouri

Civil & Environmental Engineering Theses & Dissertations

In recent years, the demand for renewable energy, mainly biomass has increased. The U.S. Energy Information Administration reported that more than 13.3% of the total energy production in the first seven months of 2017 was produced from a biomass source. Among all biomass resources, microalgae has brought a lot of attention due to their numerous advantages such as higher growth rate and productivity compared with the conventional energy crops, higher energy conversion efficiency by photosynthesis, and less water requirement than terrestrial crops. However, its development is far behind industrial production. Several research efforts across the globe have been concerned with …

Quantifying Pollutant Removal Rates Of Bioretention Basins As A Stormwater Best Management Practice, Evan Nathanial Waagen

Civil & Environmental Engineering Theses & Dissertations

Water pollution is an ongoing problem that can be attributed to human activities. As world population increases and countries become more developed, this problem intensifies. Fortunately, the causes and solutions of water pollution are documented and have been implemented with various levels of success. These solutions, or Best Management Practices (BMPs), vary in type and function and remove pollutants from runoff prior to it reaching rivers, lakes, and other bodies of water. This study investigates bioretention basins, a specific group of BMPs, and presents analysis and prediction of their performance, of which our knowledge is incomplete in the existing literature. …

A Comparative Study Of The Effects Of External Selection On Settleability And Formation Of Aerobic Granular Sludge, Tyler A. Brickles

Civil & Environmental Engineering Theses & Dissertations

Aerobic granular sludge (AGS) has shown much promise in the advancement of the wastewater treatment industry. AGS has been studied intensely since the early 1990’s due to highly desirable characteristics of nutrient removal efficiency, low footprint, and abnormally faster settling rates than conventional activated sludge. With the exception of a few on-going research projects, all AGS systems have been studied and implemented through the use of sequencing batch reactors (SBR). Recently, a novel approach to developing AGS and improving settling characteristics of activated sludge within conventional activated sludge (CAS) processes has being attempted through the use of external selection.

Activated …

Investigation And Analysis Of The Fluctuating Brominated To Total Trihalomethane Ratio In The Virginia Beach Distribution System, Christopher Steven Mihalkovic

Civil & Environmental Engineering Theses & Dissertations

An increasing trend in the brominated-trihalomethane to total-trihalomethane concentration ratio from 2001 to 2016 in the Virginia Beach water distribution system was established and investigated. This study aimed at identifying factors contributing to fluctuations in trihalomethane speciation in finished water. Reservoir management practices, treatment processes, and source water conditions were examined to quantitatively and qualitatively discern the impact of their variations on finished water THM speciation. Data on water quality constituents and parameters from the Moore’s Bridges Treatment Facility and within the Virginia Beach distribution system were examined to interpret spatial and temporal relationships with trihalomethane concentrations using established research …

Simulated Dynamics Of Soil Water And Pore Vapor In A Semi-Arid Sandy Ecosystem, Shohreh Pedram

Civil & Environmental Engineering Theses & Dissertations

Understanding dynamics of soil water content (SWC) and pore air relative humidity (RHpa), as influenced by wetting-drying cycles, is crucial for sustaining fragile ecosystems of desert lands across the world and needed for improving the prediction accuracy of global climate change. However, to date, such an understanding is still incomplete. The objective of this dissertation was to examine such dynamics at a typical desert site within the Horqin Sandy Land, located in Mongolian Plateau of north China. The examination was done by using a HYDRUS-1D computer simulation model and the continuous sensor-based soil water data for two calendar years. HYDRUS-1D …