• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 189
  • 184
  • 29
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 471
  • 471
  • 170
  • 85
  • 77
  • 66
  • 65
  • 62
  • 60
  • 48
  • 46
  • 45
  • 42
  • 42
  • 38
  • 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.
291

Legal and institutional barriers to municipal wastewater reuse in Virginia Beach, Virginia

Powleson, Kimberly A. January 1982 (has links)
The availability of water is one of the key elements of urban and rural development. The Western United States has dealt with the problem of inadequate water supply for many years; in recent years the concern over ways to meet the water needs of growing populations and industries has been nationwide. This thesis is built upon the concept that municipal wastewater reuse is an increasingly important option in the development of new water supplies and that there are four identifiable factors which affect the evolution of reuse applications. In opening chapters the nature of wastewater reuse and its applications are reviewed; technological, economic, social acceptance, and legal-institutional issues are discussed as the major factors affecting the use of reclaimed wastewater. The preliminary hypothesis of this thesis is that legal and institutional factors are critical obstacles to the reuse of wastewater in satisfying municipal water demand in the State of Virginia. The objective of this thesis is to explore this preliminary statement and generate some information on the nature of legal and institutional factors in Virginia. The City of Virginia Beach is used as a case study because of the City's active interest in water supply and reuse issues, and because of the availability of information. The State level decision making context within which Virginia localities operate in the areas of water supply and sewage treatment is covered and the institutional and legal issues involved in Virginia Beach's recent reuse proposal are discussed. It is concluded that the hypothesis appears to be supported by the evidence available in Virginia Beach; however, the institutional and legal factors are strongly influenced by State agency perceptions of public health and technological uncertainties in the reuse field. Recommendations for further study are presented in the final pages. / Master of Urban and Regional Planning
292

A Water Quality Assessment of the Occoquan Reservoir and its Tributary Watershed: 1973-2002

Van Den Bos, Amelie Cara 29 July 2003 (has links)
The Occoquan Reservoir is a public water supply in northern Virginia. The Occoquan Watershed has developed over the years from rural land uses to metropolitan suburbs within easy commuting distance from Washington, DC. Due to this urbanization, the Occoquan Reservoir is especially vulnerable to hypereutrophication, which results in problems such as algal blooms (including cyanobacteria), periodic fish kills, and taste and odor problems. In the 1970's, a new management plan for the Occoquan Reservoir called for the construction of the Upper Occoquan Sewage Authority (UOSA), an advanced wastewater treatment plant that would take extraordinary measures for highly reliable and highly efficient removal of particulates, organics, nutrients, and pathogens. Eliminating most of the water quality problems associated with point source discharges in the watershed, this state-of-the-art treatment is the foundation for the successful indirect surface water reuse system in the Occoquan Reservoir today. A limnological analysis of thirty years of water quality monitoring data from the reservoir and its two primary tributaries shows that the majority of the nutrient and sediment load to the reservoir comes from nonpoint sources, which are closely tied to hydrometeorologic conditions. Reservoir water quality trends are very similar to trends in stream water quality, and the tributary in the most urbanized part of the watershed, Bull Run, has been identified as the main contributor of sediment and nutrients to the reservoir. Despite significant achievements in maintaining the reservoir as a source of high quality drinking water, the reservoir remains a phosphorus-limited eutrophic waterbody. / Master of Science
293

Treatment of secondary municipal wastewater by submerged hollow fiber microfiltration membrane for water reuse : pilot-scale evaluation

Kim, Eung D. 01 January 2004 (has links)
No description available.
294

Performance investigation of a newly developed ultrafiltration capillary membrane: effect of operating conditions on fouling behavior and filtrate water quality

Decarolis, James Frank 01 October 2000 (has links)
No description available.
295

Reuso de águas: aspectos jurídicos e socioambientais no Estado da Paraíba. / Reuse of waters: juridical and socioenvironmental aspects in the State of Paraíba.

SOUSA NETO, João Batista. 25 September 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-25T20:18:35Z No. of bitstreams: 1 JOÃO BATISTA DE SOUSA NETO - DISSERTAÇÃO PPGRN 2009..pdf: 8487748 bytes, checksum: 47b0d8b970cc25abf8565ce1cc6cc3a0 (MD5) / Made available in DSpace on 2018-09-25T20:18:35Z (GMT). No. of bitstreams: 1 JOÃO BATISTA DE SOUSA NETO - DISSERTAÇÃO PPGRN 2009..pdf: 8487748 bytes, checksum: 47b0d8b970cc25abf8565ce1cc6cc3a0 (MD5) Previous issue date: 2009-06-09 / O crescimento dos problemas de escassez da água vem solicitar a inclusão de novos instrumentos capazes de mitigar seus efeitos. O reuso de água surge como um instrumento adicional para a gestão das águas, visando reduzir as demandas sobre os mananciais de abastecimento e, favorecendo o uso de águas qualidade mais nobre para os fins devidos, ao mesmo tempo em que produz benefícios ambientais, sociais e econômicos. Contudo, a disseminação dessa prática no Estado da Paraíba pode trazer consequências diversas, sobretudo à saúde humana. A ausência de uma legislação específica favorece a prática clandestina e aumentando os riscos à saúde pública e ao meio ambiente. A proposta básica do trabalho é a análise a partir do método hermenêutico, através da técnica interpretativa-comparativa, das normas componentes do ordenamento jurídico e administrativo brasileiro que prevejam o reuso de águas como um instrumento de redução de consumo e, ao mesmo tempo como um recurso hídrico complementar. Para tanto foram utilizadas pesquisas bibliográficas e a aplicação de questionários as classes representativas da sociedade. Descreve-se de forma determinante obter uma maior integração entre os segmentos sociais, visto a ausência de conhecimentos adequados para uma discussão de maior amplitude para a afirmação do reuso em suas amplas dimensões e diferentes fins, não bastando somente a proliferação desregrada da técnica de reuso, e sim uma divulgação abrangente, que venha desde a academia até os mais distantes lugares. Infere-se que mesmo diante de normas de foco geral, sejam de caráter jurídico ou administrativo, federal ou estadual, é necessário buscar elementos para a efetiva institucionalização, regulamentação e promoção da prática sustentável do reuso de águas no contexto da Política Nacional de Recursos Hídricos, necessitando da instituição de dispositivos legais específicos e de acordo com a competência constitucional. / The growth of the problems of shortage of the water comes to request the inclusion of new instruments capable to mitigate their effects. The water reuse appears as an additional instrument for the administration of the waters, seeking to reduce the demands on the springs of provisioning and, favoring the use of waters nobler quality for the due ends, at the same time in that it produces benefits environmental, social and economical. However, the spread of that practice in the state of Paraíba can bring several consequences, above all to the human health. The absence of a specific legislation favors the clandestine practice and increasing the risks the public health and to the environment. The basic proposal of the work is the analysis starting from the hermeneutical method, through the interpretative-comparative technique, of the component norms of the juridical and administrative Brazilian rules that foresee the water reuse as an instrument of consumption reduction and, at the same time as a water recourse complementai. For so much bibliographical researches and the application of questionnaires will be used the representative classes of the society. It is described in a decisive way to obtain a larger integration among the social segments, seen the absence of appropriate knowledge for a discussion of larger width for the statement of the reuse in their wide dimensions and different ends, not being enough only the messy proliferation of the reuso technique, but an including popularization, that it comes from the academy to the most distant places. It is inferred that even before norms of general focus, be of character juridical or administrative, federal or state, it is necessary to look for elements for the effective institucionalization, regulation and promotion of the maintainable practice of the waters reuse in the context of Recursos Hidricos's National Politics, needing the institution of specific legal devices and in agreement with the constitutional competence.
296

Development and testing of a multipurpose hydrologic yield model

Hayden, Judith Marie. January 1979 (has links)
Call number: LD2668 .T4 1979 H38 / Master of Science
297

Apparent fate of recharged nonpurgeable chlorinated organics

Weissenborn, Richard Carl, 1952- January 1988 (has links)
Secondary effluent from the Roger Road Wastewater Treatment Plant undergoes tertiary treatment of dual media filtration and chlorination. The tertiary effluent is recharged and subsequently extracted for irrigation in Tucson, Arizona. The fate of chlorinated organics in this recharge system was investigated in this research. Nonpurgeable organic carbon was found to reach a constant level in the groundwater after being recharged. Not all of the organic carbon was removed from the water. Nonpurgeable organic halogens increased as they flowed away from the recharge basins. Reasons for this increase were not determined. Attempts were made to define the apparent molecular weight distribution of the NPOC and the NPOX. Measured values of the two parameters were consistently greater after the analytical processing than before, making the determination impossible.
298

The use of treated effluent for agricultural irrigation in the Bottelary River area: Effluent quality, farmers perception and potential extent.

Rui, Li January 2005 (has links)
The Bottelary River area is located in a Mediterranean climate region, where the agricultural sector plays an important role. During the dry summer season, there is not enough precipitation to meet the agricultural irrigation requirements. Some farmers extract river water which is practically the final treated effluent from the Scottsdene Wastewater Treatment Works to irrigate crops. This research investigated the use of treated effluent for agricultural irrigation in this area, particularly focused on the effluent quality, farmers perception, and the potential extent.
299

Identifying the Structure and Fate of Wastewater Derived Organic Micropollutants by High-resolution Mass Spectrometry

Getzinger, Gordon James January 2016 (has links)
<p>Human activities represent a significant burden on the global water cycle, with large and increasing demands placed on limited water resources by manufacturing, energy production and domestic water use. In addition to changing the quantity of available water resources, human activities lead to changes in water quality by introducing a large and often poorly-characterized array of chemical pollutants, which may negatively impact biodiversity in aquatic ecosystems, leading to impairment of valuable ecosystem functions and services. Domestic and industrial wastewaters represent a significant source of pollution to the aquatic environment due to inadequate or incomplete removal of chemicals introduced into waters by human activities. Currently, incomplete chemical characterization of treated wastewaters limits comprehensive risk assessment of this ubiquitous impact to water. In particular, a significant fraction of the organic chemical composition of treated industrial and domestic wastewaters remains uncharacterized at the molecular level. Efforts aimed at reducing the impacts of water pollution on aquatic ecosystems critically require knowledge of the composition of wastewaters to develop interventions capable of protecting our precious natural water resources.</p><p>The goal of this dissertation was to develop a robust, extensible and high-throughput framework for the comprehensive characterization of organic micropollutants in wastewaters by high-resolution accurate-mass mass spectrometry. High-resolution mass spectrometry provides the most powerful analytical technique available for assessing the occurrence and fate of organic pollutants in the water cycle. However, significant limitations in data processing, analysis and interpretation have limited this technique in achieving comprehensive characterization of organic pollutants occurring in natural and built environments. My work aimed to address these challenges by development of automated workflows for the structural characterization of organic pollutants in wastewater and wastewater impacted environments by high-resolution mass spectrometry, and to apply these methods in combination with novel data handling routines to conduct detailed fate studies of wastewater-derived organic micropollutants in the aquatic environment. </p><p>In Chapter 2, chemoinformatic tools were implemented along with novel non-targeted mass spectrometric analytical methods to characterize, map, and explore an environmentally-relevant “chemical space” in municipal wastewater. This was accomplished by characterizing the molecular composition of known wastewater-derived organic pollutants and substances that are prioritized as potential wastewater contaminants, using these databases to evaluate the pollutant-likeness of structures postulated for unknown organic compounds that I detected in wastewater extracts using high-resolution mass spectrometry approaches. Results showed that application of multiple computational mass spectrometric tools to structural elucidation of unknown organic pollutants arising in wastewaters improved the efficiency and veracity of screening approaches based on high-resolution mass spectrometry. Furthermore, structural similarity searching was essential for prioritizing substances sharing structural features with known organic pollutants or industrial and consumer chemicals that could enter the environment through use or disposal.</p><p>I then applied this comprehensive methodological and computational non-targeted analysis workflow to micropollutant fate analysis in domestic wastewaters (Chapter 3), surface waters impacted by water reuse activities (Chapter 4) and effluents of wastewater treatment facilities receiving wastewater from oil and gas extraction activities (Chapter 5). In Chapter 3, I showed that application of chemometric tools aided in the prioritization of non-targeted compounds arising at various stages of conventional wastewater treatment by partitioning high dimensional data into rational chemical categories based on knowledge of organic chemical fate processes, resulting in the classification of organic micropollutants based on their occurrence and/or removal during treatment. Similarly, in Chapter 4, high-resolution sampling and broad-spectrum targeted and non-targeted chemical analysis were applied to assess the occurrence and fate of organic micropollutants in a water reuse application, wherein reclaimed wastewater was applied for irrigation of turf grass. Results showed that organic micropollutant composition of surface waters receiving runoff from wastewater irrigated areas appeared to be minimally impacted by wastewater-derived organic micropollutants. Finally, Chapter 5 presents results of the comprehensive organic chemical composition of oil and gas wastewaters treated for surface water discharge. Concurrent analysis of effluent samples by complementary, broad-spectrum analytical techniques, revealed that low-levels of hydrophobic organic contaminants, but elevated concentrations of polymeric surfactants, which may effect the fate and analysis of contaminants of concern in oil and gas wastewaters. </p><p>Taken together, my work represents significant progress in the characterization of polar organic chemical pollutants associated with wastewater-impacted environments by high-resolution mass spectrometry. Application of these comprehensive methods to examine micropollutant fate processes in wastewater treatment systems, water reuse environments, and water applications in oil/gas exploration yielded new insights into the factors that influence transport, transformation, and persistence of organic micropollutants in these systems across an unprecedented breadth of chemical space.</p> / Dissertation
300

Optimisation multivariée d’un traitement des eaux usées par DEL-UV en vue d’une réutilisation pour l’irrigation

Chevremont, Anne-celine 18 December 2012 (has links)
Le développement de nouvelles technologies pour le recyclage des eaux usées est une priorité pour les régions arides et semi-arides tels que les pays du bassin méditerranéen. L'objectif de ce travail a été, dans un premier temps, de développer un système de traitement tertiaire des eaux usées en testant l'efficacité de diodes électroluminescentes émettant des UV-A et/ou des UV-C (DEL-UV) sur l'inactivation de souches bactériennes indicatrices de pollution fécale (Escherichia coli et Enterococcus faecalis) puis sur des effluents urbains, en étudiant la diminution des pollutions microbiennes et chimiques. Cette première étape a mis en évidence l'efficacité accrue du couplage UV-A et UV-C, permettant d'obtenir une eau de qualité répondant aux exigences législatives relatives à la réutilisation des eaux usées pour l'irrigation. La deuxième partie de ce travail était l'étude de l'impact de l'arrosage avec des eaux usées traitées par DEL-UV sur les paramètres du sol et sur le devenir de certain polluant aromatiques dans les sols (anthracène et carbamazépine). L'arrosage avec des eaux usées traitées par DEL-UV ne modifie pas la composition chimique de la matière organique de sol, l'activité catabolique globale des microorganismes, et le nombre et la diversité de bactéries indicatrices de pollution fécale par rapport au sol arrosé avec de l'eau d'irrigation. Certaines activités enzymatiques liées à la dégradation de la matière organique augmentent dans les sols arrosés avec des eaux usées traitées par DEL-UV, montrant que la matière organique apportée par l'effluent est activement dégradée par les microorganismes. / The development of new technologies for wastewater reuse is a priority for arid and semi-arid areas such as Mediterranean countries. The objective of this work was, firstly, to develop a system for tertiary treatment of wastewaters testing LEDs emitting UV-A and / or UV-C (UV LEDs) on fecal indicator inactivation (Escherichia coli and Enterococcus faecalis) and then on urban effluents, by studying the decrease in both microbial and chemical pollution. This first step has highlighted a higher efficiency of this system when UV UV-A and UV-C are coupled. Wasterwaters with quality meeting the statutory requirements for the reuse of wastewater for irrigation were obtained and used in the second part of this work was to study the impact of watering with UV-LED- treated wastewaters on soil parameters and on the fate of pollutants (anthracene and carbamazepine) in soils. Watering with UV-LED treated wastewater does not change the chemical composition of soil organic matter, the global catabolic activity of soil microorganisms, and the number and diversity of fecal indicators compared to control (irrigation water). Certain enzymatic activities related to the degradation of organic matter increased in soil watered with UV-LED treated wastewater, showing that the organic matter added by the effluent is actively degraded by microorganisms. In addition, aromatic pollutants are oxidized two to three times faster in soils watered with UV-LED treated wastewater.

Page generated in 0.0867 seconds