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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.
311

Avaliação da gestão e tecnologia Ambiental Aplicada ao pó de aciaria elétrica

Acosta, Clóvis Dutra January 2013 (has links)
Esta tese apresenta os métodos de gerenciamento associados ao Pó de Aciaria Elétrica (PAE) gerado no forno elétrico a arco (FEA) e no forno-panela (FP), envolvendo dois grandes tópicos: sistema de gestão ambiental e fatores relacionados à tecnologia. O processo do PAE percorre as seguintes etapas: entrada e beneficiamento da matériaprima, preparação, carregamento e fusão de carga no FEA, formação e retirada de escória, vazamento do aço para a panela, refino no forno-panela, assim como o sistema de captação das emissões atmosféricas e destinação do PAE captado no FEA e FP. Os métodos de gerenciamento foram estruturados em cima do aprendizado técnico, qualitativo e quantitativo adquirido no desenvolvimento das atividades profissionais, dos levantamentos sobre as tecnologias disponíveis para destinação e reciclagem do PAE, dos mapeamentos das características das instalações de captação do PAE de empresas siderúrgicas, bem como das bibliografias e visitas técnicas realizadas. As informações reunidas foram empregadas para desenvolver duas matrizes de avaliação, consolidando assim, um critério para verificar as práticas de gestão ambiental e de tecnologias que estão associadas ao PAE. O principal resultado das matrizes foi a identificação e priorização das necessidades de melhorias, tanto do sistema de gestão ambiental como da área de tecnologia. A avaliação das empresas siderúrgicas, segundo estas matrizes, mostrou quais práticas possuem menores valores e que, por conseqüência, devem requerer maior esforço para melhorar seus desempenhos, bem como aquelas de maior valor que requerem uma consolidação da sua rotina para manterem o elevado nível de desempenho atingido. Como conclusão, foi obtida uma ferramenta robusta que respondeu de forma consistente a avaliação do processo do PAE e a pergunta sobre “O que se encontra mais desenvolvido, os processos de gestão ou os de tecnologia?”. As matrizes de avaliação foram preenchidas por especialistas ambientais de três Empresas siderúrgicas. O resultado obtido com essa ferramenta mostrou que os desempenhos sobre as práticas de gestão são superiores aos desempenhos das práticas de tecnologia e que esta metodologia de avaliação está apta para ser aplicada em qualquer outro processo ou empresa. Ficou evidenciado que o conhecimento e a inteligência ambiental são requisitos para assegurar que as estratégias de médio e longo prazo estejam corretamente alinhadas às boas práticas de gestão e melhores tecnologias disponíveis. / The thesis presents the methods associated with the management of the electric arc furnace (EAF) baghouse dust and ladle furnace (LF) dust. The management methods cover two broad topics: environmental management system practices and technology related factors. The EAF baghouse dust and ladle furnace (LF) dust process has the following steps: input and processing raw materials, EAF charging and melting, slag generation and removal, furnace tapping of the steel to the LF, refining in the LF, as well as the EAF dedusting system, dust recycling and final destination. The management methods were determined based on professional experience of the author, assessment of typical installations of steel plant dedusting system, bibliographies review, available technologies to EAF/LF dust destination and recycling and subject technical literature, as well technical visits undertaken. Collectively the information was used to develop two standard evaluation standard matrices which provide criteria to assess environmental management system practices and technology associated with EAF dust management. The primary goal of the assessments was to identify and prioritize areas for potential improvement - either in environmental management systems area or the technology area. The assessment results showed that steel plants which have practices with lower values, according to these matrices, should require greater effort to improve their performance, while those with good score, will require a consolidation of their routine to maintain the high level of performance already achieved. The matrices were filled by environmental experts from three steelmaking companies. Finally, as a result of this project a rigorous and reliable assessment tool was designed to evaluate the meltshop dust generation and management process and provide a quantitative answer to the following question: `Which area has achieved a higher level of development as it relates to meltshop dust management: environmental management system practices or control technology?’ The results from using this tool have shown that the performance of management practices is superior to the control technology. Furthermore, experiences captured during the assessment indicate this evaluation methodology is fully adaptable and can be applied to other processes and/or other businesses. It was clearly highlighted how knowledge and environmental intelligence are requirements to assure that the medium and long term strategies are properly aligned with the available best practices to environmental management system and control technology.
312

Polybrominated diphenyl ethers (PBDEs) in indoor and outdoor environments

Muenhor, Dudsadee January 2011 (has links)
PBDEs were detected in all air and dust samples. The PBDE congener profile in both outdoor and indoor air samples from Thai e-waste storage facilities and homes was dominated by BDE-47 and 99, whilst the predominant BFRs in all dust samples from Thai e-waste storage facilities were BDE-209, BDE-208, BDE-207, BDE-206, BDE-197, BDE-183, BDE-99, BDE-47 and DBDPE. Furthermore, BDEs 99 and 47 were the most abundant congeners in all dust samples from Thai houses and cars and UK homes. Under realistic high-end scenarios of occupational exposure to BDE-99 via dust ingestion, workers in Thai e-waste storage facilities were exposed above a recently-published Health Based Limit Value for this congener. For non-occupational exposure, under a high-end exposure scenario, the exposure to BDE-99 of such Thai children via dust ingestion is either very close to or in exceedance of the HBLV. PBDE levels in most of the areas monitored within the same rooms were not statistically significantly different. Similarly, concentrations of PBDEs in the majority of rooms within the same houses were not statistically significantly different between rooms. Possible dilution of PBDE levels in dust with increasing dust loadings has been identified in a small number of rooms.
313

Accelerator Mass Spectrometry of 36Cl and 129I : Analytical Aspects and Applications

Alfimov, Vasily January 2004 (has links)
Two long-lived halogen radionuclides (36Cl, T1/2 = 301 kyr, and 129I, T1/2 = 15.7 Myr) have been studied by means of Accelerator Mass Spectrometry (AMS) at the Uppsala Tandem Laboratory. The 36Cl measurements in natural samples using a medium-sized tandem accelerator (~1 MeV/amu) have been considered. A gas-filled magnetic spectrometer (GFM) was proposed for the separation of 36Cl from its isobar, 36S. Semi-empirical Monte-Carlo ion optical calculations were conducted to define optimal conditions for separating 36Cl and 36S. A 180° GFM was constructed and installed at the dedicated AMS beam line. 129I has been measured in waters from the Arctic and North Atlantic Oceans. Most of the 129I currently present in the Earth's surface environment can be traced back to liquid and gaseous releases from the nuclear reprocessing facilities at Sellafield (UK) and La Hague (France). The anthropogenic 129I inventory in the central Arctic Ocean was found to increase proportionally to the integrated 129I releases from these reprocessing facilities. The interaction and origin of water masses in the region have been clearly distinguished with the help of 129I labeling. Predictions based on a compartment model calculation showed that the Atlantic Ocean and deep Arctic Ocean are the major sinks for the reprocessed 129I. The variability in 129I concentration measured in seawater along a transect from the Baltic Sea to the North Atlantic suggests strong enrichment in the Skagerrak–Kattegat basin. The 129I inventory in the Baltic and Bothnian Seas is equal to ~0.3% of the total liquid releases from the reprocessing facilities. A lake sediment core sampled in northeastern Ireland was analyzed for 129I to study the history of the Sellafield releases, in particular the nuclear accident of 1957. High 129I concentration was observed corresponding to 1990 and later, while no indication of the accident was found. The results of this thesis research clearly demonstrate the uniqueness and future potential of 129I as a tracer of processes in both marine and continental archives.
314

Biological And Chemical Sludge Filtration

Yukseler, Hande 01 July 2007 (has links) (PDF)
Up to date, sludge filterability has been characterized by the Ruth&rsquo / s classical filtration theory and quantified by the well-known parameter specific cake resistance (SCR). However, the complexity of the actual phenomenon is clearly underestimated by the classical filtration theory and SCR is often not satisfactory in describing filterability. Although many scientific studies were conducted for a better analysis and understanding of the filtration theory, still a practically applicable solution to replace the classical theory for a better description of filterability has not been proposed yet. In the present study, blocking filtration laws proposed by Hermans and Bred&eacute / e, dating back to 1936, which have been extensively used in the membrane literature for the analysis of fouling phenomenon and the multiphase filtration theory developed by Willis and Tosun (1980) highlighting the importance of the cake-septum interface in determining the overall filtration rate have been adopted for the analysis of filterability of sludge systems. Firstly, the inadequacy of the classical filtration theory in characterizing the filterability of real sludge systems and also the lack of the currently used methodology in simulating filtration operation was highlighted. Secondly, to better understand the effect of slurry characteristics and operational conditions on filtration, model slurries of spherical and incompressible Meliodent particles were formed. Finally, a methodology was developed with the gathered filtration data to assess the filterability of the sludge systems by both theories. The results clearly show that both approaches were superior to the classical approach in terms of characterizing the filterability of sludge systems. While blocking laws yielded a slurry specific characterization parameter to replace the commonly used SCR, the multiphase theory provided a better understanding of the physical reality of the overall process.
315

Anaerobic Treatment Of Dilute Wastewaters

Ener Alptekin, Emel 01 April 2008 (has links) (PDF)
In this study, domestic wastewater was used to determine the anaerobic treatment performances of a dilute wastewater in one-phase upflow anaerobic sludge blanket (UASB) system and two-phase upflow anaerobic filter (UAF) and UASB system. The acidification performances of domestic wastewater were compared in UAF and UASB reactors. The degree of acidification is higher in UAF reactor (31%) compared to UASB reactor (18%) at 2 h hydraulic retention time (HRT) in the anaerobic treatment of domestic wastewaters. The effluent total volatile fatty acid (tVFA) concentration was higher in UAF reactor than that the UASB reactor at 2 h HRT. The total chemical oxygen demand (tCOD) removal is 40% in winter and 53% in summer in UAF reactor at 2 h HRT. The tCOD removals in two-phase UAF and UASB system and one-phase UASB system were 83% and 63%, respectively, in 4 h HRT. The conversion rate of COD removed to methane were between 0.005 and 0.067 Nm3 methane/kg COD removed and between 0.158 and 0.233 Nm3 methane/kg COD removed in the UAF and the UASB reactor of the two-phase system, respectively. The conversion rate of COD removed to methane varied between 0.029 and 0.199 Nm3 methane/kg COD removed in one-phase UASB reactor. The results of this study showed that the two-phase reactor system consisting from UAF and UASB reactors provide a good removal of soluble organics variations in acidification reactor and better methane productions in UASB reactor at temperatures 20&deg / C and 35&deg / C through the treatment of domestic wastewater at a HRT of 4 hours.
316

Drinking Water Quality In Ankara: A Monitoring Study

Tezce, Gozde 01 December 2010 (has links) (PDF)
ABSTRACT DRINKING WATER QUALITY IN ANKARA: A MONITORING STUDY Tezce, G&ouml / zde MS, Department of Environmental Engineering Supervisor: Prof. Dr. &Uuml / lk&uuml / Yetis Co-Supervisor: Prof. Dr. Filiz B. Dilek December 2010, 124 pages Following the event of severe drought experienced in 2007, it was decided to use Kesikk&ouml / pr&uuml / Reservoir as an additional source of water supply for the city of Ankara. Thereupon, there have been debates on the quality of Kesikk&ouml / pr&uuml / Reservoir water with the claims that some parameters, primarily sulfate and arsenic, were not complying with the quality standards and therefore there was a threat to public health. This study aims to determine whether the water quality in the distribution network in Ankara exceeds water quality standards, and to assess the status of water quality of Ankara. To this end, monthly samples were collected from 24 districts as distribution network water and also from the Kesikk&ouml / pr&uuml / Reservoir as source water, and were monitored in terms of certain water quality parameters during the period of July 2008 through June 2009. Sulfate concentration in Kesikk&ouml / pr&uuml / Reservoir water was measured as 300-500 mg/l and this high sulfate concentration in the source water led to high sulfate values in distribution system. On the other hand, the arsenic concentration in Kesikk&ouml / pr&uuml / water was analyzed between 9-11 &micro / g/l which is lower than the expected high arsenic concentration in Kizilirmak water. Moreover, monitoring of THM and HAA in distribution network was carried out to follow DBPs formation. The highest THM concentration was observed as 109 &micro / g/l for Bilkent in July 2008. Although for some districts and some months throughout the year THM concentration was higher than the EPA Stage-I (80 &micro / g/l) and Stage-II (40 &micro / g/l) limits, mean annual THM concentrations for districts in distribution system satisfies the standards. Furthermore, the highest HAA5 concentrations were determined as 75 &micro / g/l for Dikmen in February 2009. However, annual average HAA5 in any of the districts did not exceed USEPA limit of 60 &micro / g/l. Nonetheless, total/fecal coliform bacteria, which are the indicators of microbiological contamination, were detected in distribution system between the months of July 2008 and January 2009. However, the coliform bacteria did not appear with the increasing residual chlorine in the distribution system since January 2009. Results from this study demonstrate a temporal variability in water quality / indicating water quality deterioration in the distribution system during some months, while almost full compliance with the water quality standards during other months. Overall / due to Kesikk&ouml / pr&uuml / raw water, sulfate content appears to be the major concern in the water quality when considered the one-year monitoring period.
317

Biodiversity in environmental assessment : tools for impact prediction

Gontier, Mikael January 2005 (has links)
<p>Urbanisation and infrastructure developments impact on the surrounding natural environment and threaten biodiversity. The fragmentation of natural habitats in particular is a major obstacle for the preservation of biodiversity in a long-term perspective. In the planning process, both the environmental impact assessment and strategic environmental assessment processes play a central role in the identification and prediction of impacts on biodiversity. At the same time, the devel-opment of GIS technologies and GIS-based ecological models offer new perspectives in the elaboration of predictions. In order to analyse current practices and identify the need for im-provements in the environmental impact process, a review of environmental impact assessment reports was carried out. Further, a review of existing GIS methods and GIS-based ecological models is presented. The results of the review of environmental impact assessment reports show a lack of predictions in current biodiversity assessments. These asssessments often concentrate on impacts at the local scale, failing to consider large-scale and widespread impacts at the ecosys-tem and landscape levels. The review of GIS methods and GIS-based ecological models demon-strate the possibility to generate quantitative predictions for a specific area as well as for it’s sur-rounding environment. At the same time, the flexibility and reproducibility of such methods would allow predictions to be made for different alternatives or scenarios, therefore providing decision makers with relevant information of potential impacts on biodiversity. This would, in turn, result in an improved integration of biodiversity issues in physical planning and contribute to a sustainable development.</p>
318

Modelling the impacts of deicing salt on soil water in a roadside environment

Lundmark, Annika January 2005 (has links)
<p>This study tested a dynamic modelling approach based on salt application, meteorological data and generic descriptions of hydrogeological environments for describing the spread of deicing salt to the surroundings and the corresponding increase in chloride storage in soil. Both the amount of chloride storage and the annual variation pattern were significantly altered due to deicing salt application and spread to the roadside environment. Data from field investigations comprising different hydrogeological environments and different methods of measurement were used to examine the variability of the salt deposition pattern in the vicinity of the road, and to test the performance of the model with respect to different soils and vegetation types. The use of typical hydrogeological environments to represent inputs to the model was shown to be useful to demonstrate the importance of soils, vegetation type and groundwater conditions for modelling the impact of deicing salt on soil water and the response to environmental changes in the vadose zone. However, the use of hydrogeological environment could also be misleading in view of the high degree of variability at the field scale. The different methods of measurements and simulations represented different spatial and temporal scales that were shown to be complementary useful to quantify the different pathways of deicing salt in the roadside environment. Continuous simulations complemented with selected field monitoring should therefore be promoted.</p> / QC 20100526
319

Domestic Wastewater Treatment In Pilot-scale Constructed Wetlands Implemented In The Middle East Technical University

Korkusuz, Asuman Elif 01 September 2004 (has links) (PDF)
To foster the practical development of constructed wetlands used for wastewater treatment in Turkey, a pilot-scale subsurface constructed wetland system (90 m2) was designed to treat the domestic wastewater produced by 60 PE living in the residential area of METU. In summer 2001, two parallel sets of hybrid wetland systems (vertical flow connected with horizontal flow) with identical design configuration, but with different fill media (blast furnace granulated iron slag and gravel) were built on the old sludge-drying bed of the abandoned wastewater treatment plant of METU, which has not been operating since the 1990s. Wetland cells were planted with common reed (Phragmites australis). The main objective of this research was to quantify the effect of different filter media on the removal performance of subsurface flow constructed wetlands in the prevailing climate of Ankara. Thus, slag-filled and gravel-filled vertical flow wetlands were operated identically with pre-settled domestic wastewater (3 m3.d-1) at a hydraulic loading rate of 110 mm.d-1 for 12 months, intermittently. According to the first year results, annual average removal efficiencies for the slag and gravel wetland cells were as follows: TSS (63% &amp / 59%), COD (47% &amp / 44%), NH4+-N (88% &amp / 53%), TN (44% &amp / 39%), PO43--P (44% &amp / 1%) and TP (45% &amp / 4%). The slag-filled vertical flow system removed phosphorus and ammonium efficiently than the gravel-filled system due to the differences in physical structures and chemical compositions of the fill media, and the different aerobic and anaerobic environments within the wetland cells. These results indicated that the well-designed constructed wetlands could also be used for secondary and tertiary treatment in Turkey, successfully.
320

Modelling the impacts of deicing salt on soil water in a roadside environment

Lundmark, Annika January 2005 (has links)
This study tested a dynamic modelling approach based on salt application, meteorological data and generic descriptions of hydrogeological environments for describing the spread of deicing salt to the surroundings and the corresponding increase in chloride storage in soil. Both the amount of chloride storage and the annual variation pattern were significantly altered due to deicing salt application and spread to the roadside environment. Data from field investigations comprising different hydrogeological environments and different methods of measurement were used to examine the variability of the salt deposition pattern in the vicinity of the road, and to test the performance of the model with respect to different soils and vegetation types. The use of typical hydrogeological environments to represent inputs to the model was shown to be useful to demonstrate the importance of soils, vegetation type and groundwater conditions for modelling the impact of deicing salt on soil water and the response to environmental changes in the vadose zone. However, the use of hydrogeological environment could also be misleading in view of the high degree of variability at the field scale. The different methods of measurements and simulations represented different spatial and temporal scales that were shown to be complementary useful to quantify the different pathways of deicing salt in the roadside environment. Continuous simulations complemented with selected field monitoring should therefore be promoted. / QC 20100526

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