• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 51
  • 17
  • 13
  • 9
  • 4
  • 4
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 182
  • 182
  • 29
  • 18
  • 17
  • 16
  • 16
  • 15
  • 14
  • 14
  • 14
  • 12
  • 12
  • 12
  • 12
  • 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.
131

Optimalizace provozních parametrů na úpravně vody Bzenec-Přívoz / Optimization of operating parameters in drinking water treatment plant in Bzenec-Přívoz

Sukopová, Martina January 2010 (has links)
Water treatment plant Bzenec Přívoz represents important supply of potable water for Hodonín district. After a longtime operation it was in 2008-2010 reconstructed in order to make water treatment technology more effective. The basic step was dividing technology into one stage and two stage water treatment for particular spring areas of ground water. The character of raw water requires effective removal of iron and manganese, therefore intensification and optimization of operating parameters were the purposes of the project. Installation of new aerators and hyperboloid stirrers in flocculation tank required an operating tests for proving of high technological efficiency while the operating costs were decreased. The water treatment process was completly automatized, which made the operation easy and minimized human element impact. Results of the reconstruction are more effective water treatment and a distinct decrease of operating costs.
132

Optimalizace zdrojů tepla pro bytový dům / Optimization of heat generators for residential house

Smola, Vojtěch January 2016 (has links)
This diploma thesis solves design of heating in a residental building. This work is focused on the selection of appropriate one of the two options a heat source, which are cascade heat pumps ground-water and gas condensing boilers. The theoretical part of the diploma thesis deals with introducing to the issue of heat pump systems. The functional principle of the widely most used types and particularized type ground-water. In the practical part calculation and design of heating system with selected heating source that is cascade of gas condensing boilers.
133

Hebungen der Tagesoberfläche als Folge des Grundwasserwiederanstiegs stillgelegter Braunkohlentagebaue

Lieske, Katharina, Schade, Marco January 2016 (has links)
Die Grundwasserstände unterliegen in den Gebieten des Braunkohlenbergbaus permanenter, bergbaulich bedingter Veränderung. Im Einflussbereich der aktiven Braunkohlentagebaue überwiegen sinkende - im Bereich der ehemaligen Tagebaubereiche nach Einstellung der Wasserhaltungsmaßnahmen dagegen steigende Grundwasserstände. Der Grundwasserwiederanstieg im Verantwortungsbereich der LMBV mbH ist schon weit vorangeschritten aber noch nicht überall abgeschlossen. Im Zuge der Auswertung von regelmäßig durchgeführten Präzisionsnivellements wurden in den gewachsenen Randbereichen der in Flutung befindlichen Tagebauseen Hebungen festgestellt, die in ihrer räumlichen Ausdehnung und dem Betrag mit den Ergebnissen der Beobachtungen der Grundwasserstände korrelieren. Rückblickend werden die Zusammenhänge zwischen Grundwasserwiederanstieg und Hebungen des gewachsenen Bodens anhand von Beispielen von bereits gefluteten Tagebauseen aus dem Mitteldeutschen Braunkohlenrevier betrachtet. Die festgestellten Hebungen vollziehen sich längerfristig über mehrere Jahre. Die Hebungsbeträge erreichen maximale Werte von einigen Zentimetern - erreichen aber nicht die Beträge der früheren sümpfungsbedingten Senkungen. Schädliche Auswirkungen auf Bauwerke durch grundwasserwiederanstiegsbedingte Hebungen waren nicht zu erwarten und sind auch nicht eingetreten. / Water tables in lignite mining areas are characterized by a permanent mining-related variation. In the sphere of influence of the active lignite mines preponderates decreasing – in reach of the abandoned lignite mining areas in contrast increasing water tables. The groundwater resurgence within the areas of responsibility of LMBV mbH is widely pro-ceeded but yet not completed in all areas. In the course of the evaluation of regularly conducted precision levellings uplifts were detected in the natural boundary areas of post-mining lakes still in flooding progress. These uplifts correlate in their regional/areal dimension and magnitude with the results of the water tables. The coherence between groundwater resurgence and the uplifts will be examined retrospectively based on examples of flooded post-mining lakes from the mining area around the cities of Leipzig and Halle. The observed elevation take place over some years. The elevation amount reaches maximum values of a few centimeters, but doesn’t reach the amount of the former drainage caused subsidence. Adverse effects on buildings by groundwater resurgence caused elevation were not expected and didn’t occur so far.
134

Sensitivity studies with a surface and channel runoff module coupled to a mesoscale atmospheric model

Mölders, Nicole, Rühaak, Wolfram 06 December 2016 (has links)
A module to investigate ground water recharge was developed, and implemented into the mesoscale meteorological model GESIMA (Geesthacht’s simulation model of the atmosphere) as well as coupled to a soil-vegetation scheme. Important features of the ground water module are the determination of surface and channel runoff. A comparison of the results provided by GESIMA with and without consideration of surface and channel runoff shows a remarkable impact of surface runoff on the soil moisture fluxes. Substituting water meadows by willow-forests demonstrates their importance for soil moisture fluxes. / Ein Modul zur Untersuchung von Grundwasserneubildung wurde entwickelt, in das mesoskalige meteorologische Modell GESIMA (Geesthachter Simulationsmodell der Atmosphäre) integriert und an ein Boden-Vegetationsmodell gekoppelt. Wesentliche Bestandteile des Grundwassermoduls sind die Berechnung des Oberflächen- und Gerinneabflusses. Ein Vergleich der Ergebnisse von GESIMA, die mit und ohne Oberflächen- und Gerinneabfluss erstellt wurden, belegt einen deutlichen Einfluss des Oberflächenabflusses auf die berechneten Feuchteflüsse im Boden. Untersuchungen zum Einfluss von Auenwäldern auf die Grundwasserneubildung belegen deren Bedeutung für die Wasserflüsse im Boden.
135

Nitrate in Private Wells:Knowledge, oppinions,and Perceptions of Stakeholders

JaJa, Augustus D 01 January 2015 (has links)
The purpose of this quantitative study was to examine data describing nitrate concentration and cases of congenital cardiac defects. Residents with private wells and other stakeholders need data to make informed environmental decisions about the adverse health implications of nitrate contamination of private well water. Researchers have examined the exposure of nitrate in contaminated groundwater, but they have not examined nitrate levels in unregulated water systems. This gap in the literature highlighted the need to provide nitrate data for future research and private well users. Guided by the social ecological model, a quantitative, cross-sectional, nonexperimental design was used to survey 231 adult participants about community perceptions of stakeholders' collaboration about groundwater and the sustainability of private water wells. Multiple linear regression was used to test the hypotheses. Survey results showed that gender, age group, and distance from animal waste sites or farmland were associated with barriers to community collaboration to achieve groundwater sustainability. Use of private wells for irrigation and distance from animal waste sites or farmland were associated with community members' perceptions of community collaboration to achieve groundwater sustainability. Community perceptions and barriers to stakeholders' collaboration were not affected by any demographic factors. The data will facilitate the design and implementation of effective public health outreach services for private well users. The implications for positive social change include increased understanding of stakeholders' perceptions of private well nitrate contamination and reduction of the risk factors for birth defects.
136

<i>In Situ</i> Chemical Oxidation Schemes for the Remediation of Ground Water and Soils Contaminated by Chlorinated Solvents

Li, Xuan 02 July 2002 (has links)
No description available.
137

A comprehensive modeling approach for BMP impact assessment considering surface and ground water interaction

Cho, Jae-Pil 12 June 2007 (has links)
The overall goal of this study was to develop a comprehensive tool for assessing the effectiveness of selected BMPs on both hydrology and water quality and to demonstrate the applicability of the system by considering 1) temporally and spatially changing land use management practice in an agricultural watershed and 2) interaction between surface and ground water over the entire system. A user interface and Dynamic Agricultural Non-point Source Assessment Tool (DANSAT) were developed to achieve this goal. DANSAT is the only distributed-parameter, physically-base, continuous-simulation, and multi-soil layer model for simulating impacts of agricultural BMPs on hydrology and water qulality in small agricultural watersheds. DANSAT was applied to QNB plot (18m à 27m) and two agricultural watersheds in Virginia, including Owl Run watershed (1140 ha) and QN2 in the Nomini Creek watershed (216 ha), to evaluate the model components and its performance in predicting runoff, sediment yield, and pesticide load. DANSAT performed well in predicting total runoff and temporal variations in surface runoff for both field-scale and watershed-scale applications. Total percent errors between the measured and predicted results were less than 10% except for one case (39.8% within a subwatershed of Owl Run watershed), while the daily Nash-Sutcliffe model efficiencies were greater than 0.5 in all applications. Predicted total sediment yields were within ±35% of observed values in all applications. However, the performance of DANSAT in predicting temporal trend and spatial distribution of sediment loads was acceptable only within Owl Run watershed, where high correlations between flow rates and sediment loads exist. The predicted total pesticide loads were within ±100% of observed values. DANSAT failed to simulate the temporal occurrence of pesticide loads with a 0.42 daily Nash-Sutcliffe efficiency value. The Dual-Simulation (DS) was developed within the linked ground water approach to resolve problems encountered due to the existence of different temporal scales between DANSAT and the existing ground water models such as MODFLOW and MT3D. The linked approach performed better in predicting the seasonal trend of total runoff compared to the integrated approach by showing an increase in monthly Nash-Sutcliffe efficiency value from 0.53 to 0.60. Surface and subsurface output variables were sensitive to the changes in spatially distributed soil parameters such as total porosity and field capacity. A maximum grid size of 100 m was recommended to be appropriate for representing spatial distribution of topographic, land use, and soil characteristics based on accuracy analysis during the GIS manipulation processes. Larger time-step based on predefined acceptable maximum grid size, decreased the computational time dramatically. Overall sensitivity to different grid sizes and time-steps was smallest for hydrology components followed by sediment and pesticide components. Dynamic crop rotation was considered by DANSAT, and the model successfully simulated the impacts of temporal and spatial changes in crop rotations on hydrology and water quality for both surface and subsurface areas. DANSAT could prove to be a useful tool for non-point source pollution managers to assess the relative effectiveness of temporally and spatially changing BMPs on both surface and ground water quantity and quality. / Ph. D.
138

Indoor atmospheric radon in Hamadan, Iran : atmospheric radon indoors and around Hamadan city in Iran

Jabarivasal, Naghi January 2010 (has links)
Radon gas may be a major air quality hazard issue inside the home. Radon (222Rn) comes from the natural breakdown of radioactive uranium (238U) via radium (226Ra) in soil, rocks, and water. Radon and its progeny contribute more than 50% of the total radiation dose to the human population due to inhalation; it can result in severe and fatal lung disease. This investigation has determined the radon concentrations in seventy-seven domestic houses in a mountainous area of Hamadan in Iran which were monitored using track-etch detectors of type CR-39 exposed for three month periods. The arithmetic mean radon concentration in Hamadan buildings was determined to be 80 Bqm-3 and also an average indoor annual effective dose equivalent for the Hamadan city population was calculated as 1.5 mSv. Maximum radon concentrations were noted during the winter and spring season. In addition to this, 28 water wells were monitored by utilizing a Sarad Doseman detector at hourly intervals over extended periods. Radon measurements were also carried out in the nearby Alisadr show cave, using Solid State Nuclear Track etch Detectors (SSNTDs) during the winter and the spring periods. In the cave, the average annual effective geometric and arithmetic mean dose for guides was 28.1 and 34.2 mSv respectively. The dose received by visitors was very low. Hamadan city is built on alluvial fan deposits which are the source of the local water supply. The data from the wells shows that the groundwater in these alluvial deposits influences the flux of radon. The atmospheric radon concentration measurement in wells above the water surface ranged from 1,000 Bqm-3 to 36,600 Bqm-3. There is evidence that radon-rich ground waters play a significant role in the transport of radon through the alluvial fan system. There is evidence that the radon concentrations in homes in Hamadan are greatly influenced by the porous nature of the underlying geology and the movement of groundwater within the alluvial fan.
139

Contaminação do solo e das águas subterrâneas por sepultamento de carcaças de animais no solo / Soil and groundwater contamination by burial of animal carcasses on the ground

Figueiredo Filho, Yadyr Augusto 11 May 2011 (has links)
Em área classificada como área contaminada sob investigação, de acordo com os processos de investigação de áreas contaminadas da Companhia de Tecnologia de Saneamento Ambiental (CETESB, 2001), no Município de Pirassununga (SP), foi instalado um processo de pesquisa objetivando avaliar possível contaminação do solo e das águas subterrâneas por sepultamento de carcaças de animais no solo. Foram instalados poços de monitoramento que permitiram a coleta de água para análise física, química e microbacteriológica, localizados a partir de sondagens geofísicas e estudos geológicos, geomorfológicos e pedológicos. Os resultados preliminares indicaram forte presença de microorganismos que, de acordo com os índices de potabilidade de águas estipulados pela Agência Nacional de Vigilância Sanitária (ANVISA, 2005) e Ministério da Saúde (2004), implicam impactos ambientais e riscos à saúde pública. A partir de questões surgidas em campo e problemas técnicos encontrados, novas metodologias foram desenvolvidas e aplicadas, tendo, em uma primeira análise, se mostrado bastante eficazes. Essas novas metodologias incluem novos procedimentos de coleta e de acondicionamento e transporte das amostras de água e de solo. Os resultados obtidos nas análises das águas subterrâneas e do solo revelam que há uma expressiva contaminação por uma importante diversidade de microorganismos, alguns muito importantes para a saúde pública, como Salmonella sp e Clostridium perfringens, além de diversidade de outros patógenos de origem fecal. Também foram detectados esporos de bactérias mesófilas anaeróbias e de bactérias mesófilas aeróbias, que podem representar, no caso de contaminação causada por cadáveres de origem animal, patógenos importantes como o Clostridium botulinum e o Bacillus anthracis, que representam risco epidemiológico e morte. Estes dados, interpretados em conjunto com as interpretações pedológicas e climáticas, revelam que há uma notável possibilidade de que esses contaminantes estejam sendo transportados a distâncias consideráveis, para além da área de sepultamento de cadáveres e partes de animais. / In the area classified as contaminated area under investigation, according to the procedures for investigation of contaminated areas of the Technology and Environmental Sanitation Company (CETESB, 2001), in the city of Pirassununga (SP), was installed a research process to evaluate possible soil and groundwater contamination by animal carcasses burial on the ground. Monitoring wells were installed that allowed the collection of water for physics, chemistry and microbacteriological analysis, located from geophysical surveys and geological, geomorphological and soil studies. Preliminary results show a strong presence of microorganisms that, according to the indices of drinking water stipulated by the National Sanitary Surveillance Agency (ANVISA, 2005) and Ministry of Health (2004), indicate environmental impacts and risks to public health. The questions raised in the field and encountered technical problems, new methodologies were developed and implemented, and on a first analysis, proved quite effective. New methodologies include new procedures for collecting and packaging and transportation of water and soil samples. The analysis results of groundwater and soil analysis show that there is significant contamination by a large diversity of microorganisms, some very important public health such as Salmonella and Clostridium perfringens, and diversity of other pathogens of faecal origin. Were also detected spores of mesophilic anaerobic and aerobic mesophilic bacteria, which may represent, in the case of contamination from animal corpses, important pathogens such as Clostridium botulinum and Bacillus anthracis, which represent epidemiological risk and death. These data, interpreted in conjunction with soil and climatic interpretations show that there is a remarkable possibility that these contaminants are being transported considerable distances beyond the area of burial of corpses and animal parts.
140

Contaminação de solos por metais tóxicos provenientes do descarte inadequado de pilhas Zinco-Carbono de uso doméstico / Soil contamination of toxic metals from zinc carbon batteries inadequate disposal

Gazano, Vanessa Santos Oliveira 29 March 2006 (has links)
O presente trabalho determinou a concentração dos metais zinco, manganês, cádmio, chumbo, níquel, cobre e cromo no efluente e solo de quatro colunas de latossolo indeformadas. Duas colunas foram contaminadas por pilhas do tipo zinco-carbono e duas colunas foram utilizadas como referência, além de pilhas isoladas, foram todas lixiviadas por uma solução \"água de chuva\" (HNO3 + H2SO4, pH 4,0). Os metais no efluente e no solo foram determinados pela técnica de ICP-OES. A avaliação do efluente e do solo das colunas contaminadas pelas pilhas mostrou um incremento das concentrações dos metais, principalmente de zinco, manganês e chumbo. A sequência das massas acumuladas dos metais no efluente e no solo da coluna contaminada apresentaram uma sequência semelhante a da lixiviação isolada da pilha (Zn > Mn > Pb > Cr > Cu > Ni > Cd), confirmando a influência da pilha nas concentrações dos metais no efluente e solo das colunas. Observou-se também que a contaminação de Zn e Mn tende a migrar da camada superior da coluna de solo para as camadas inferiores. O estudo mostrou que as pilhas podem causar uma contaminação significativa do solo para os metais Zn, Mn e Pb e possivelmente também para Cd. Esta contaminação do solo poderia vir a causar uma contaminação da água subterrânea para os metais Zn, Mn e Pb, dependo das características do perfil do solo. / The aim of the present study was to determine the concentration of Zn, Mn, Pb, Cd, Cu, Cr, and Ni in an oxisol column contaminated with zinc-carbon batteries. Two control and two contaminated columns, and batteries alone were leached for a periods of six months and one year with aqueous solution of HNO3 and H2SO4 (1:1, pH 4,0) to simulate rainwater. The metal concentrations in effluent and soil were measured by means of ICP-OES technique. Results from the contaminated column showed enhanced concentrations in both effluent and soil (mainly zinc, manganese and lead). In addition, the total amount of metals in effluent and soil showed similar sequence order as observed for batteries alone (Zn > Mn > Pb > Cr > Cu > Ni > Cd) indicating that batteries can be considered the main source of contamination. We also observed migration of Zn and Mn from the top to the lower layers of the soil columns. The study gives further evidence that batteries can significantly contaminate the soil with metals like Zn, Mn and Pb, and maybe Cd too. This soil contamination combined with the enhanced concentrations found in the effluent can point out a probable groundwater contamination.

Page generated in 0.0954 seconds