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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Ammonium and Potassium Removal from Real Hydrolyzed Urine Using Natural Zeolites

January 2019 (has links)
abstract: The goal of this research was to study the effect of dilution on ammonium and potassium removal from real hydrolyzed urine. The performance of two natural zeolites, clinoptilolite and chabazite, was studied and compared with the help of batch equilibrium experiments at four dilution levels: 100%, 10%, 1% and 0.1% (urine volume/total solution volume). Further, the sorption behavior of other exchangeable ions (sodium, calcium and magnesium) in clinoptilolite and chabazite was studied to improve the understanding of ion exchange stoichiometry. Ammonium and potassium removal were highest at undiluted level in samples treated with clinoptilolite. This is a key finding as it illustrates the benefit of urine source separation. Chabazite treated samples showed highest ammonium and potassium removal at undiluted level at lower doses. At higher doses, potassium removal was similar in undiluted and 10% urine solutions whereas ammonium removal was the highest in 10% urine solutions. In general, chabazite showed higher ammonium and potassium removal than clinoptilolite. The result showed that ion exchange was stoichiometric in solutions with higher urine volumes. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019
202

Concurrent reduction of trichloroethylene and perchlorate in continuous flow-through soil columns

January 2019 (has links)
abstract: The objective of this study was to evaluate possible bioremediation strategy for aerobic aquifers by combining ZVI chemical reduction and microbial reductive dechlorination for TCE and ClO4-. To achieve this objective, continuous flow-through soil columns were used to test the hypothesis that bioaugmentation with dechlorinating enrichment cultures downstream of the ZVI injection can lead to complete reduction of TCE and ClO4- in aerobic aquifers. We obtained soil and groundwater from a Superfund site in Arizona. The experiments consisted of 205 cm3 columns packed with soil and ZVI, which fed 1025 cm3 columns packed with soil, biostimulated with fermentable substrates and bioaugmented. Aerobic groundwater was pumped through the ZVI columns. The ZVI reduced the oxidation-reduction potential (ORP) of groundwater from +150 mV to -190 mV. The reduced groundwater and biostimulation with fermentable substrates created anaerobic conditions in the bioaugmentation columns favorable for anaerobic microbial activity. Perchlorate (ClO4-) reduction to non-detectable levels occurred after biostimulation. Reduction of TCE to cis-dichloroethene, vinyl chloride and ethene was observed only after bioaugmentation. Within ~120 days of continuous columns operation, ethene was produced in the bioaugmentation columns this dechlorination activity was sustained until the end of experiments. The groundwater from the Superfund site had high concentration of sulfate (~1000 mg/L). Substantial sulfate reduction occurred in the bioaugmentation columns. Complete microbial reduction of TCE and perchlorate is usually challenging in the presence of high sulfate concentration; however, the strategy tested in this study suggests that a bioremediation scheme for simultaneous reduction of TCE and perchlorate in aerobic aquifers containing high sulfate concentration is feasible. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019
203

Organic toxic substances monitoring in Virginia

Croonenberghs, Robert Emile. 01 January 1983 (has links)
This project attempts to identify toxic organic substances used in Virginia, which cannot be detected by conventional analytical procedures. A list from the Virginia Bureau of Toxic Substances Information which contained substances reported as used in manufacture or produced in Virginia was cross-referenced with the Master File of toxic substances compiled pursuant to the Toxic Substances Control Act. Organic chemicals appearing on both lists were thus identified as toxic substances used in Virginia, and were the subjects of this research. Due to the reporting requirements of the Virginia Toxic Substances Information Act, the 113 "compounds" do not include substances used solely in repair work in Virginia. In addition, since chemicals used only as pesticides or drugs were not included in the Master File, these types of substances do not appear in the list of 113 "compounds". Conventional organic analytical procedures were studied, and five basic critical parameters which could impair analysis were determined: volatility, stability, solubility, adsorption in liquid chromatography, and problems in GC and GC/MS. The literature was then researched for these critical parameters to indicate the ability of conventional techniques to detect the 113 "compounds". "Compounds" which were either not detectable or possibly detectable by conventional techniques were assessed for potential long term environmental accumulation. An analytical technique, involving a minimum of steps, was then developed to analyze specifically for those "compounds" requiring special monitoring.
204

Resin acid compounds in a kraft pulp and paper mill effluent and their distribution in bottom sediments near the outfall

Unkulvasapaul, Manida 01 January 1984 (has links)
Kraft pulp and paper mill effluents (KPPME) collected on three occasions were analyzed for resin acids, aliphatic hydrocarbons, and aromatic hydrocarbons. The maximum total concentrations of these compounds found in secondary effluents were 8 mg/L resin acids, 4.0 mg/L resolved aliphatic hydrocarbons, and 0.2 mg/L resolved aromatic hydrocarbons. Abietic acid and dehydroabietic acid were the two major components in resin acid fractions and were responsible for > 70% of the total concentration. Analyses of estuarine water and sediments collected from the outfall and nearby areas showed that dehydroabietic acid was the major resin acid in either water or sediment. Concentrations of dehydroabietic acid ranging from 0.4 (mu)g/L to 3.6 (mu)g/L were found in water samples collected during high water slack and up to 5.8 (mu)g/g dry sediment were found in sediments. This indicates that dehydroabietic acid is persistent in the estuarine environment. Most of the resin acids identified in the KPPME were present in sediments taken near the outfall. Concentration-station profiles of the major resin acids showed maximum concentrations near the outfall which indicates that the KPPME is a major source for these acids. The concentration-depth profiles of the resin acids in core samples appear to reflect the major events occurring in the mill. If this is true, average sedimentation rates after 1973 are estimated to be 2-3 cm/year near the outfall and 1 cm/year in the nearby areas. Sediment hydrocarbon concentrations also peaked near the outfall area. Discharge of the KPPME and the use of fuel oil in the mill are among the contributors of petroleum hydrocarbons in the sediments. Cordgrass (Spartina cynosuroides) in the adjacent marsh areas is likely to be the major source for high MW n-alkanes to the sediments. Retene was identified in the sediments. The concentration-station and concentration-depth profiles of retene in river sediments, however, suggests that it is unlikely to be derived primarily from resin acids near the discharged area. Retene was found to be predominant in one sample taken from the marsh area in March 1981, but it was a minor component in the sample taken in November 1982. Further study is needed to understand production process of this compound.
205

The Recent History of Wachapreague Inlet, Virginia

DeAlteris, J. T. 01 January 1973 (has links)
No description available.
206

Stormwater Treatment Effectiveness of Established Bioretention Facilities in Portland, Oregon

Kohlsmith, Emma Rose 03 October 2019 (has links)
Bioretention systems are commonly used to treat and detain stormwater runoff and help mitigate for many negative effects of urbanization. Despite the widespread use of bioretention systems, few field-based studies have assessed how these facilities affect water quality many years after installation. The goal of this project is to assess the pollution reduction effectiveness of lined bioretention facilities that have been in use and functioning for 4-8 years. To meet this objective, this project measured water quality characteristics of stormwater flowing into and out of seven facilities installed throughout Portland, Oregon during real storm events. Stormwater grab samples were taken over a 2-year period during the fall, winter, and spring. Results showed decreased concentrations of total suspended solids (TSS; 94%), ammonia (85%), total copper (59%), total zinc (80%), and dissolved zinc (41%). Results for dissolved copper indicated an overall increase in outflow concentrations of 23%, however variability between facilities was high. These results support other similar findings showing that TSS is effectively reduced by bioretention facilities, even after 4-8 years of use. However, based on this study, effective TSS removal by bioretention facilities does not necessarily equate to equally effective treatment of other pollutants, especially orthophosphate and nitrate, which increased in outflow from the bioretention facilities by 141% and 2070%, respectively. Results of this study indicate that additional research is necessary to determine the significance of the observed increase in nutrients, understand the underlying mechanisms, and test possible design modifications to improve nitrate and orthophosphate removal.
207

The Influence of Neighborhood Landscape Characteristics on Native Bird Communities: Implications for Increasing Biodiversity in Our Yards

Vermeulen, Michael E. 20 August 2019 (has links)
Avian communities, because of their potential high diversity, are ideal for studying the response to potential quantity of resources provided by local and regional habitat. Urban neighborhoods vary in types and magnitudes of anthropogenic stressors they experience, resulting in a continuum of anthropogenic disturbance, often referred to as a gradient of urbanization. The aim of this study was to investigate anthropogenic drivers of urban bird communities in three Portland, OR neighborhoods (Hillsdale, Lents, and Pearl). The three major questions of this study were: 1) What are the significant landscape traits that characterize the neighborhoods? 2) Is there evidence that the urban matrix may host similar avian community assemblages as neighborhood green space? And 3) Are landscape characteristics able to predict native bird communities, and if so, what scale is most explanatory? Neighborhoods were sampled for three months (May - July, 2018) during the breeding season of local birds. Utilizing a community-based approach, parks (n = 17) and neighborhood residential areas (n = 34) were sampled using 50-meter point counts. Community attributes (richness, abundance, and diversity) were compared to landcover (percent canopy, herbaceous and grass, and impervious surface cover), anthropogenic factors (population density and building density), and front-yard vegetative characteristics. Neighborhoods differed in degree of urbanization, with Hilldale being the least urbanized, Lents intermediate, and Pearl the most urbanized. My study found that Portland's urban and suburban avian communities are dominated by relatively few species (13 account for ~98% of observations). Differences between native avian community attributes were detected by neighborhood but avian communities did not respond strongly to gradient analysis or regression modeling with landcover characteristics. Within neighborhoods, habitat patches had differing levels of native bird diversity. Recreational parks, on average, tended to have lowest bird diversity when compared to residential sites and nature parks. Though few species were represented, avian guilds responded to urban gradients within neighborhoods. Foliage gleaners and insectivores were seen to decrease with increasing urbanization, whereas omnivorous birds increased. This shift in avian guild abundance indicates that species with more specialized traits did less well in more urban areas when compared to generalist species such as omnivores.
208

Rank-Date Distribution Method (R-D Method) For Daily Time-Series Bayesian Networks And Total Maximum Daily Load Estimation

Lee, Joon-Hee 01 December 2008 (has links)
Daily time series-based models are required to estimate the higher frequency fluctuations of nutrient loads and concentrations. Some mechanistic mathematical models can provide daily time series outputs of nutrient concentrations but it is difficult to incorporate non-numerical data, such as management scenarios, to mechanistic mathematical models. Bayesian networks (BNs) were designed to accept and process inputs of varied types of both numerical and non-numerical inputs. A Rank-Data distribution method (R-D method) was developed to provide large time series of daily predicted flows and Total Phosphorus (TP) loads to BNs driving daily time series estimates of T-P concentrations into Hyrum and Cutler Reservoirs, Cache County, Utah. Time series of water resources data may consist of data distributions and time series of the ranks of the data at the measurement times. The R-D method estimates the data distribution by interpolating cumulative failure probability (CFPs) plots of observations. This method also estimates cumulative failure probability of predictions on dates with no data by interpolating CFP time series of observations. The R-D method estimates time series of mean daily flows with less residual between predicted flows and observed flows than interpolation of observed flows using data sets sampled randomly at varying frequencies. Two Bayesian Networks, BN 1 (Bayesian Network above Hyrum Reservoir) and BN 2 (Bayesian Network below Hyrum Reservoir) were used to simulate the effect of the Little Bear River Conservation Project (LBRCP) and exogenous variables on water quality to explore the causes of an observed reduction in Total Phosphorus (TP) concentration since 1990 at the mouth of the Little Bear River. A BN provided the fine data distribution of flows and T-P loads under scenarios of conservation practices or exogenous variables using daily flows and TP loads estimated by R-D method. When these BN outputs were connected with the rank time series estimated by interpolation of the ranks of existing observations at measurement dates, time series estimation of TP concentrations into Cutler Reservoir under two different conservation practice options was obtained. This time series showed duration and starting time of water quality criterion violation. The TMDL processes were executed based on daily TP loads from R-D instead of mean or median values.
209

The Sacred and the Mundane: The Resilient Social-Ecological Landscape of a Maya Community

January 2019 (has links)
archives@tulane.edu / Over the course of research from 2008-2010 in the Kaqchikel Maya community of Ch’aqa’ Ya’, Guatemala, in which I documented the sacred sites utilized by residents who practice costumbre, or indigenous Maya spirituality, I began to find links between concepts fundamental to this belief system and local strategies of ecological management. The report below details subsequent research (2011-2016) into local human interaction with the environment as mediated through a sacred relationship with the landscape. In the pages that follow I show how local sacred sites are vital to human-ecological interaction in Ch’aqa’ Ya’ as well as highlight how beliefs essential to costumbre engender a conservation ethic that assures the continuance of a healthy ecosystem over the long-term. Moreover, I describe how local sacred sites also illustrate the adaptive nature of Maya belief and ritual, indicating the means in which ecological knowledge has remained viable through the many changes of the last centuries (even millennia). I found that long-term traditional ecological knowledge (TEK) – the body of institutions, beliefs, and practices developed through interaction with the biophysical environment over a long period – is embedded in the local spiritual system. However, institutional or social frameworks nested across scales are necessary for the acquisition, transmission, and effective use of TEK. In this report I detail how Maya spirituality is such a framework, remaining highly adaptive and transcending scalar issues to mediate between short-term wants and long-term sustainability as well as transfer on-the-ground ecological knowledge into long-term social memory. In fact, even in the face of the abandonment of ‘traditional’ belief, prior conceptions of the sacred still impact ecological management practices in ways that safeguard the health and resilience of both the local landscape as well as the human population integral to it. Scholars have noted that the best means to learn how to manage resources is to inquire of those who have been doing it the longest (Berkes et al. 2000:1251-1253; Peters 2000:219), and it is through such enquiry that I gained an understanding of the system of environmental management practice and belief extant in Ch’aqa’ Ya’ that I offer in the dissertation below. / 1 / Michael P Saunders
210

Degradation of Perfluorooctanoic Acid by a Non-Thermal Plasma Reactor and Bio-Reactors

Unknown Date (has links)
Perfluorooctanoic acid (PFOA) is persistent in environment due to its stable structure. It is also toxic to animals and human. The objective of this research is to remove PFOA with a non-thermal plasma reactor, anaerobic and aerobic bio-reactors, and their combination. Mineralization and defluorination (i.e., fluoride production) occurred in the plasma reactor. Neither PFOA removal nor fluoride production was observed in the bioreactors. In the plasma reactor with Argon as the carrier gas, 20 µM of PFOA in deionized (DI) water was removed to 4.22 and 4.04 µM, respectively, when the hydraulic retention time (HRT) was 0.21 s and 0.15 s, respectively. When the carrier gas was changed to Helium, PFOA was removed to 3.85 µM and 3.77 µM, respectively. Therefore, the carrier gas and HRT did not have significant effect on PFOA degradation. However, the carrier gas and HRT strongly affected the defluorination rate: 11% (for HRT = 0.21 s) and 6.5% (for HRT = 0.15) when Argon was the carrier gas, and 22% (for HRT = 0.21 s) and 8.6% (for HRT = 0.15 s) when Helium was the carrier gas. Consequently, a higher energy yield was achieved with Helium as the carrier gas (maximum of 11.3×10-11 mole F- production/J) than with Argon as the carrier gas (maximum of 6.43×10-11 mole F- production/J). Perfluoroheptanoic acid (PFHpA) and perfluorohexanoic acid (PFHxA) were observed in the effluent of the non-thermal plasma reactor by using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The intermediates production rate was higher when argon was the carrier gas compared with Helium, probably because the degradation mechanisms are different for PFOA and their intermediates. / A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2019. / March 25, 2019. / Includes bibliographical references. / Youneng Tang, Professor Directing Thesis; Bruce R. Locke, Committee Member; Clayton J. Clark Ⅱ, Committee Member.

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