Environmental Sciences Commons^™

Organic Fouling Mitigation In Forward Osmosis Technology Through The Use Of Oscilatting Alternating Current Electric Fields, Logan Werner

Graduate College Dissertations and Theses

Forward osmosis (FO) is the term given to osmosis in water filtration applications. FO has many advantages to conventional membrane filtration processes. The lack of external pressure needed to force solvent through the membrane is dramatically decreased in FO, resulting in a lower cost of operation compared to reverse osmosis. Lower external pressures also result in decreased fouling on the membrane surface and improved permeate flux. Fouling is one of the foremost challenges within the membrane filtration industry and is one of the biggest contributors to operating costs. While FO results in less fouling than RO, fouling remains a major …

Constraint-Aware And Efficiency-Aware Control Of Air-Path In Fuel Cell Vehicles, Eli Bacher-Chong

Graduate College Dissertations and Theses

Fuel cell technology offers the potential for clean, efficient, robust energy productionfor both stationary and mobile applications. But without fast and robust control systems, fuel cells cannot hope to maintain real-life efficiencies near enough to their theoretical potential. This work studies control and constraint management techniques to regulate a nonlinear multivariable air-path system for a proton exchange membrane fuel cell (PEMFC). The control objectives are to avoid oxygen starvation, run at the maximum net efficiency, achieve fast tracking of air flow and pressure set-points, and be easy to calibrate. To operate at maximum efficiency, a set-point map is generated for …

A Holistic Approach To River Restoration Design And Conservation Planning On The Reach And Basin Scales Using Hydraulic Modeling And Multi-Objective Optimization Tools, Lindsay Courtney Worley

Graduate College Dissertations and Theses

Flooding events around the world cost billions (USD) in damages each year. For decades, engineers have combated flood related damages by implementing flood mitigation controls such as channelization, levees or berms, and armoring. Recent advances in the study of river dynamics, however, have challenged the efficacy of these traditional flood mitigation techniques and pose that these structures are disconnecting channels from their floodplains, increasing flow rates, and contributing to more erosion. The effects of climate change combined with future predictions of increased storm frequency and intensity make it necessary to revise flood hazard mitigation strategies. A more nature-based alternative to …

Upcycling Dairy Manure Fine Solids Captured By Dissolved Air Flotation As Part Of A Phosphorus Recovery And Reuse Strategy, Katherine Keith Porterfield

Graduate College Dissertations and Theses

Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure, enabling new management options. However, at < 25% total solids, further dewatering and other upcycling is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. I generated plant foods using DAF-captured dairy manure fine solids thermally dried to 45% total solids blended with other organic residuals. Dry biomass of tomato and marigold seedlings amended with 6% v/v plant food was six-times greater than the unamended control and not significantly different from a market alternative treatment. Because thermal dewatering can be prohibitively costly, I generated a second batch of plant foods using DAF-captured dairy manure fine solids conditioned with 3, 4.5 and 6% (w/w) quicklime or lime kiln dust (LKD) and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato seedling biomass was similar for thermally dried and LKD plant foods, but quicklime plant foods had no effect compared to the unamended control. Quicklime and LKD conditioned fine solids contained approximately 30 and 10 times less plant-available P than thermally dried fine solids, respectively—likely due to precipitation of Ca-P minerals. These studies indicate that DAF-captured dairy manure fine solids could be upcycled to bagged horticultural products with substantial agronomic value, however sustainable materials drying remains a key challenge to realizing this potential.

The Food-Energy-Water Nexus, Embodied Injustices, And Transboundary Sustainability, Sonya Ahamed

Graduate College Dissertations and Theses

Intersections of food, energy, and water systems (the FEW nexus) pose many sustainability and governance challenges, including risks to ecosystems, inequitable distribution of benefits and harms across populations, and reliance on distant sources for food, energy, and water. Nexus-based approaches can offer more holistic pathways for societal transitions to FEW systems that are just and sustainable, but tend to focus narrowly on inputs (e.g. water ‘for’ energy) in ways that do little to address the historical roots and structural underpinnings of current system inadequacies, thus risking their perpetuation.

This dissertation widens the FEW nexus in two contexts in which the …

An Analysis Of Energy Transitions At Different Scales: Fossil Fuel Divestment In Higher Education And Individual Behavior, Elizabeth Palchak

Graduate College Dissertations and Theses

A sociotechnical energy transition requires both a shift to new technologies and attention to social issues like political movements, policy and human behavior. This dissertation investigates social elements of the renewable energy transition occurring at different scales. The core research questions are: How are universities creating and responding to the shifting language of fossil fuel investments? How and for whom do behavioral interventions work? And finally, do in-home displays (IHDs) change behaviors and attitudes of millennial energy users?

The three studies covered here occurred within higher education and reflect the importance of colleges and universities as dynamic players in energy …

Quantifying The Seismic Vulnerability Of Bridges In Low To Moderate Seismicity Regions, John Edward Lens

Graduate College Dissertations and Theses

The U.S. Congressional Research Service issued a report for Congress in May 2016, entitled” Earthquake Risk and U.S. Highway Infrastructure: Frequently Asked Questions” which highlighted the absence of a national database on the status of seismic vulnerability of bridges or other infrastructure, and thus no estimate of costs to retrofit vulnerable bridges. Low to moderate seismicity regions exist in each of the continental United States, with over 30 states having mostly or entirely low-to-moderate seismicity. Resources at state transportation agencies and municipalities are focused on higher seismicity regions, creating a gap in quantifying the system-wide seismic vulnerability despite an overall …

Edge-Of-Field Hydrology And Nutrient Fluxes Within Northeastern Agroecosystems: Evaluation Of Alternative Management Practices And Water Quality Models, Cameron Robert Twombly

Graduate College Dissertations and Theses

Agricultural runoff is one of largest contributors of phosphorus (P), nitrogen (N), and sediment affecting freshwater systems in watersheds across the Northeastern U.S., including the Lake Champlain Basin in Vermont. Agricultural cropping systems, such as corn silage and haylands, used for dairy feed production have been shown to impact watershed hydrology and water quality. Agricultural best management practices (BMPs) have the potential to decrease runoff volumes and flow rates and the associated export of nutrients and sediment from agricultural fields. Many states in the Northeastern U.S., including Vermont, are beginning to require farmers to implement water quality BMPs and further …

An Autothermal, Representative Scale Test Of Compost Heat Potential Using Geostatistical Analysis, William J. Mccune-Sanders

Graduate College Dissertations and Theses

Composting has been practiced for thousands of years as a way of stabilizing and recycling organic matter into useful soil amendments. Thermophilic compost releases significant amounts of heat at temperatures (~140 °F) that are useful for environmental heating or process water. This heat has been taken advantage of in various ways throughout history, but development of a widely adopted technology remains elusive.

The biggest barrier to adoption of compost heat recovery (CHR) systems is projecting accurate, attractive economic returns. The cost of transfer equipment is significant, and with variability in composting substrates and methods, it is difficult to predict the …

Consumer Engagement With Efficient And Renewable Energy Technology: Case Studies On Smart Meter Utilization And Support For A Community Anaerobic Biodigester System In Vermont, Samantha Whitney Lewandowski

Graduate College Dissertations and Theses

Residential electricity consumption in the United States has many adverse impacts, such as greenhouse gas emissions, dependence on fossil fuels, and costs. Efficient and renewable energy technologies have the potential to help mitigate some of these impacts, but appear to be under-utilized in the United States. One major barrier to expanding the deployment of these kinds of technologies and maximizing the benefits they can provide is a lack of consumer engagement. The overall purpose of this thesis is to better understand the extent to which efficient and renewable energy technologies are being engaged with and what factors may influence such …

Renewable Energy Transition: Dynamic Systems Analysis, Policy Scenarios, And Trade-Offs For The State Of Vermont, Christopher Ernest Clement

Graduate College Dissertations and Theses

There is broad consensus that a transition to renewable energy and a low-carbon economy is crucial for future development and prosperity, yet there are differing perspectives on how such a transition should be achieved. The overarching goal of this dissertation, which is comprised of three interrelated studies, is to analyze and compare energy futures scenarios to achieve a renewable energy transition and low-carbon economy in the State of Vermont. In the first study, an analysis is presented of the role of energy pricing regimes and economic policy in the context of pursuing a renewable energy transition in the State of …

A Framework For Estimating Nutrient And Sediment Loads That Leverages The Temporal Variability Embedded In Water Monitoring Data, Baxter G. Miatke

Graduate College Dissertations and Theses

Rivers deliver significant macronutrients and sediments to lakes that can vary substantially throughout the year. These nutrient and sediment loadings, exacerbated by winter and spring runoff, impact aquatic ecosystem productivity and drive the formation of harmful algae blooms. The source, extent and magnitude of nutrient and sediment loading can vary drastically due to extreme weather events and hydrologic processes, such as snowmelt or high flow storm events, that dominate during a particular time period, making the temporal component (i.e., time over which the loading is estimated) critical for accurate forecasts. In this work, we developed a data-driven framework that leverages …

Monitor: Automation Tools For Landscape-Scale Acoustic Monitoring, Jonathan Edward Katz

Graduate College Dissertations and Theses

Climate change coupled with land-use change will likely alter habitats and affect state parameters of the animal populations that dwell in them. Affected parameters are anticipated to include site occupancy and abundance, population range, and phenophase cycles (e.g., arrival dates on breeding grounds for migrant bird species). Detecting these changes will require monitoring many sites for many years, a process that is well suited for an automated system. We developed and tested monitoR, an R package that is designed for long-term, multi-taxa automated passive acoustic monitoring programs. monitoR correctly identified presence for black-throated green warbler and ovenbird in 64% and …

Phosphate Removal And Recovery From Wastewater By Natural Materials For Ecologically Engineered Wastewater Treatment Systems, Daniel Thomas Curran

Graduate College Dissertations and Theses

Eutrophication due to excess loading of phosphorus (P) is a leading cause of water quality degradation within the United States. The aim of this study was to investigate P removal and recovery with 12 materials (four calcite varieties, wollastonite, dolomite, hydroxylapatite, eggshells, coral sands, biochar, and activated carbon. This was accomplished through a series of batch experiments with synthetic wastewater solutions ranging from 10-100 mg PO₄-P/ L. The results of this study were used to establish large-scale, calcite-based column filter experiments located in the Rubenstein School of Environment and Natural Resources' Eco-Machine. Influent and effluent wastewater samples were routinely collected …

Local Energy Governance In Vermont: An Analysis Of Energy System Transition Strategies And Actor Capacity, Tarah Rowse

Graduate College Dissertations and Theses

While global, national, and regional efforts to address climate and energy challenges remain essential, local governments and community groups are playing an increasingly stronger and vital role. As an active state in energy system policy, planning and innovation, Vermont offers a testing ground for research into energy governance at the local level. A baseline understanding of the energy planning and energy organizing activities initiated at the local level can support efforts to foster a transition to a sustainable energy system in Vermont. Following an inductive, applied and participatory approach, and grounded in the fields of sustainability transitions, energy planning, and …