Electrochemical arsenic remediation for rural Bangladesh (open access)

Electrochemical arsenic remediation for rural Bangladesh

Arsenic in drinking water is a major public health problem threatening the lives of over 140 million people worldwide. In Bangladesh alone, up to 57 million people drink arsenic-laden water from shallow wells. ElectroChemical Arsenic Remediation(ECAR) overcomes many of the obstacles that plague current technologies and can be used affordably and on a small-scale, allowing for rapid dissemination into Bangladesh to address this arsenic crisis. In this work, ECAR was shown to effectively reduce 550 - 580 mu g=L arsenic (including both As[III]and As[V]in a 1:1 ratio) to below the WHO recommended maximum limit of 10 mu g=L in synthetic Bangladesh groundwater containing relevant concentrations of competitive ions such as phosphate, silicate, and bicarbonate. Arsenic removal capacity was found to be approximately constant within certain ranges of current density, but was found to change substantially between ranges. In order of decreasing arsenic removal capacity, the pattern was: 0.02 mA=cm2> 0.07 mA=cm2> 0.30 - 1.1 mA=cm2> 5.0 - 100 mA=cm2. Current processing time was found to effect arsenic removal capacity independent of either charge density or current density. Electrode polarization studies showed no passivation of the electrode in the tested range (up to current density 10 mA=cm2) and ruled out oxygen …
Date: January 1, 2009
Creator: Addy, Susan Amrose
System: The UNT Digital Library
Interweaving History: The Texas Textile Mill and McKinney, Texas, 1903-1968. (open access)

Interweaving History: The Texas Textile Mill and McKinney, Texas, 1903-1968.

Texas textile mills comprise an untold part of the modern South. The bulk of Texas mills were built between 1890 and 1925, a compressed period of expansion in contrast to the longer developmental pattern of mills in the rest of the United States. This compression meant that Texas mill owners benefited from knowledge gained from mill expansion elsewhere, and owners ran their mills along the same lines as the dominant southeastern model. Owners veered from the established pattern when conditions warranted. This case study focuses on three mills in Texas that operated both independently and as a corporation for a total of sixty years. One mill in McKinney dominated the economy of a small town and serves as the primary focus of this paper. A second mill in Waco served a diversified economy in the center of the state; and the third mill, built in Dallas was concentrated in a major city in a highly competitive job market. All three of these mills will illuminate the single greatest difference between Texas mills and mills elsewhere, the composition of the labor force. Women did not dominate the mill labor force in Texas nor did children, except in limited cases, make-up a …
Date: August 2009
Creator: Kilgore, Deborah Katheryn
System: The UNT Digital Library
Development of a Progeny Marker for Steelhead; A Thesis submitted to Oregon State University. (open access)

Development of a Progeny Marker for Steelhead; A Thesis submitted to Oregon State University.

This study was undertaken to determine if strontium chloride could be used to create a trans-generational otolith mark in steelhead (Oncorhynchus mykiss). I completed two strontium injection trials and a survey of juvenile steelhead from various steelhead hatcheries. The two trials measured Sr:Ca ratios in otoliths in response to injections and the survey measured the natural variation in Sr:Ca ratios in otoliths of juvenile hatchery steelhead in response to the natural variation. In 2003, adult female Wallowa River, Oregon O. mykiss, were captured at the hatchery and evenly divided between a control group and two treatment groups. These females received an intraperitoneal injection of 1cc/500 g of body weight of a physiologically isotonic solution (0.9% saline) containing concentrations of 0 (control), 1000, or 5000 parts per million (ppm) of strontium chloride hexahydrate (SrCl{sub 2}* 6H{sub 2}O). Females were housed in a single outdoor tank until spawned artificially, and a distinct external tag identified each female within each treatment group. In 2004, female steelhead were captured throughout the duration of the adult returns to the Umatilla River basin and injected with 0, 1000, 5000, or 20,000-ppm strontium. In both trials, progeny of fish treated with strontium had significantly higher Sr:Ca ratios …
Date: April 15, 2009
Creator: Shippentower, Gene E.
System: The UNT Digital Library
Deliberative Democracy, Divided Societies, and the Case of Appalachia (open access)

Deliberative Democracy, Divided Societies, and the Case of Appalachia

Theories of deliberative democracy, which emphasize open-mindedness and cooperative dialogue, confront serious challenges in deeply divided political populations constituted by polarized citizens unwilling to work together on issues they collectively face. The case of mountaintop removal coal mining in Appalachia makes this clear. In my thesis, I argue that such empirical challenges are serious, yet do not compromise the normative desirability of deliberative democracy because communicative mechanisms can help transform adversarial perspectives into workable, deliberative ones. To realize this potential in divided societies, mechanisms must focus on healing and reconciliation, a point under-theorized by deliberativists who do not take seriously enough the feminist critique of public-private dualisms that illuminates political dimensions of such embodied processes. Ultimately, only a distinctly two-stage process of public deliberation in divided populations, beginning with mechanisms for healing and trust building, will give rise to the self-transformation necessary for second-stage deliberation aimed at collectively binding decisions.
Date: August 2009
Creator: Tidrick, Charlee
System: The UNT Digital Library
Quasi-Three Dimensional Experiments on Liquid-Solid Fluidized Bed of Three Different Particles in Two Different Distributors (open access)

Quasi-Three Dimensional Experiments on Liquid-Solid Fluidized Bed of Three Different Particles in Two Different Distributors

This thesis is an experimental study of the fluidization of binary mixture in particulate flows. A fluidized bed with two distributors was built with water being used as carrying fluid. Three types of solid particles of nylon, glass and aluminum of the same size and different densities are used in the experiments. The wall effect on a single particle fluidization, the fluidization of binary mixture of large density difference (nylon and aluminum of density ratio of 0.42), and the fluidization of binary mixture of close density (glass and aluminum with density ratio of 0.91) were investigated. Also, the effect of distributors on mono-disperse and bi-disperse particle fluidization was investigated. Results show that the presence of narrow walls reduces the minimum fluidization velocity for a single particle by as much as nearly 40%. Also, in the case of binary mixture of close density particles, uniform mixing was easily achieved and no segregation was observed, but in the case of large density difference particles, there exists significant segregation and separation. At high velocity, the uniform distributor behaves like a transport bed. To achieve a full bed in the single jet, it requires 1.5 times velocity of the uniform distributor. This behavior determines …
Date: December 2009
Creator: Obuseh, Chukwuyem Charles
System: The UNT Digital Library
Design of a rural water provision system to decrease arsenic exposure in Bangladesh (open access)

Design of a rural water provision system to decrease arsenic exposure in Bangladesh

Researchers at the Lawrence Berkeley National Laboratory have invented ARUBA (Arsenic Removal Using Bottom Ash) a material that effectively and affordably removes high concentrations of arsenic from contaminated groundwater. The technology is cost-effective because the substrate?bottom ash from coal fired power plants?is a waste material readily available in South Asia. During fieldwork in four sub-districts ofBangladesh, ARUBA reduced groundwater arsenic concentrations as high as 680 ppb to below the Bangladesh standard of 50 ppb. Key results from three trips in Bangladesh and one trip to Cambodia include (1) ARUBA removes more than half of the arsenic from contaminated water within the first five minutes of contact, andcontinues removing arsenic for 2-3 days; (2) ARUBA?s arsenic removal efficiency can be improved through fractionated dosing (adding a given amount of ARUBA in fractions versus all at once); (3) allowing water to first stand for two to three days followed by treatment with ARUBA produced final arsenic concentrations ten times lower than treating water directly out of the well; and (4) the amount of arsenic removed per gram of ARUBA is linearly related to the initial arsenic concentrationof the water. Through analysis of existing studies, observations, and informal interviews in Bangladesh, eight design …
Date: January 7, 2009
Creator: Mathieu, Johanna
System: The UNT Digital Library
The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas. (open access)

The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas.

Tree cores of Fraxinus pennsylvanica were used in a dendrochronological analysis investigating the species' responses to climate and flooding. The objective was to develop a model that incorporates the effects of precipitation, temperature, and flooding on radial growth in this species in north-central Texas. The trees exhibited strong climatic signals. The study clearly shows that all three factors have significant impacts on tree ring growth both prior to and during growth; however, the nature and extent of these impacts are highly dependent on what time of year they occur. The large temporal variations in growth responses emphasize the importance of considering the timing of environmental events when studying tree growth responses.
Date: December 2009
Creator: Komperod, Mari
System: The UNT Digital Library
God's Perfect Timing (open access)

God's Perfect Timing

When I was thirty-three years old, I discovered I was an adoptee. In this memoir of secrecy and love, betrayal and redemption, I reflect on my early experiences as a doted-on only child firmly rooted in the abundant love of my adoptive family, my later struggles with depression and obsessive-compulsive disorder, my marriage to a fellow-adoptee, my discovery of my own adoption and the subsequent reunion with my birth family, my navigation through the thrills and tensions of newly complicated family dynamics, and my witness to God's perfect timing through it all.
Date: August 2009
Creator: Rizzo, Steven
System: The UNT Digital Library