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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.
461

Considerações sobre os métodos de dimensionamento estrutural de pavimentos com camadas recicladas a frio com espuma de asfalto. / Considerations on the methods of structural design of cold recycled pavements with foamed asphalt.

Marcelo Oliveira da Costa 29 February 2016 (has links)
A reciclagem profunda com espuma de asfalto tem sido uma alternativa de sucesso para a restauração de pavimentos degradados. Em relação às soluções tradicionais de reabilitação, como os recapeamentos, tem a vantagem de proporcionar a correção de defeitos em camadas inferiores, com a manutenção ou pequena elevação do greide da pista, além de ganhos ambientais, como um menor consumo de materiais virgens da natureza e redução do volume de material descartado. Entretanto, no Brasil não há método para dimensionamento estrutural para esta tecnologia, o que dificulta seu emprego. Para o desenvolvimento de um procedimento de dimensionamento que contemple este tipo de solução, foram estudados métodos presentes na bibliografia internacional: guia da AASHTO de 1993 e Caltrans, dos EUA, TRL386 e TRL611, da Inglaterra, as duas versões do guia sul-africano TG2 e os métodos oriundos do Austroads, tanto o procedimento interino de 2011 como adaptações de órgãos da Austrália e Nova Zelândia. Observou-se divergência de opiniões quanto ao comportamento do material reciclado com espuma de asfalto. Alguns órgãos e autores consideram o comportamento do mesmo mais próximo às misturas asfálticas, sendo o mecanismo de falha o trincamento, e outros o definem como semelhante a um material granular modificado com alta coesão e ruptura devido às deformações permanentes. Correlaciona-se tal associação ao teor de espuma usualmente utilizado nas obras rodoviárias. Outros aspectos que se destacam para este tipo de base são o ganho de resistência ao longo do tempo devido à cura, mesmo com início da operação da rodovia e a importância da infraestrutura remanescente no dimensionamento. Tais fatos foram corroborados pelos estudos de caso e resultados do trecho experimental construído na Rodovia Ayrton Senna - SP 070, monitorado por meio de ensaios deflectométricos com FWD durante um ano. Como resultado do trabalho, foi proposto um procedimento para o dimensionamento estrutural de pavimentos com camadas recicladas a frio com espuma de asfalto utilizando dados deflectométricos que atende o método do Manual de Pavimentação do Departamento Nacional de Infraestrutura de Transportes (DNIT) e incorpora diferentes aspectos na análise mecanicista. Outras conclusões são a viabilidade técnica a longo prazo da solução mencionada e a importância do controle tecnológico, com ênfase para o monitoramento deflectométrico nos primeiros meses de operação do pavimento para averiguar a evolução da cura do material. / Full-depth pavement reclamation with foamed asphalt has been a successful alternative for the rehabilitation of degraded pavements. In relation to the traditional rehabilitation methods, such as overlays, it has the advantage of provide the correction of the lower layer\'s defects considering the maintenance of the road grade or slight increase of it. Besides that, there are environmental gains, with less consumption for virgin materials and reduction of discarded material volume. However, in Brazil there is no structural design method for this technology, which hinders its use. To develop a design procedure which includes this kind of solution, several international methods were studied, like AASHTO (1993) and CALTRANS, from the USA; TRL386 and TRL611, from England; TG2 guide, from South Africa; and methods derived from the Austroads were studied, both, the interim procedure 2011 and local departments adaptations from Australia and New Zealand. There are divergent opinions of the behavior of the recycled material with foamed bitumen. Some agencies and authors consider the behavior of it similar to the asphalt mixtures, and the failure mechanism cracking due to fatigue. Others define it as similar to modified granular material with high cohesion and disruption due to permanent deformation. Such association is related to the foamed asphalt content usually used in road works. Other aspects that stand for such basecourse material are the gain of strength over time due to cure, even with the beginning of the highway operation and the importance of the remaining pavement\'s layers in design process. These facts were corroborated by case studies and results of the test section built in Ayrton Senna Highway - SP 070, which was monitored through falling weight deflectometer (FWD) measurements for a year. As result of this work, it is proposed a procedure for the structural design of cold recycled pavements with foamed asphalt using deflectometer data that meets the method of paving manual of the Brazilian National Department of Transport Infrastructure (DNIT). Other findings are the technical long-term viability of that solution and the importance of technological control, with emphasis on the deflection monitoring in early pavement operation to ascertain the evolution of the curing process.
462

Formation of Trihalomethanes (THMs) as Disinfection by-Products (DBPs) when Treated Municipal Wastewater is Disinfected with Sodium Hypochlorite

Kassouf, Helene 03 November 2016 (has links)
Disinfection is an essential process in the treatment of municipal wastewater before the treated wastewater can be discharged to the environment. Hillsborough County's Northwest Regional Water Reclamation Facility (NWRWRF) in Tampa, Florida, currently uses ultraviolet (UV) light for disinfection. However, this method has proven expensive to implement and maintain, and may not be effective if the light transmission is poor. For these reasons, Hillsborough County is considering switching from UV light to sodium hypochlorite for disinfection. However, hypochlorite (chlorine) disinfection has disadvantages as well, such as the production of disinfection by-products (DBPs) such as trihalomethanes (THM) and haloacetic acids (HAAs), which may have adverse impacts on the quality of surface waters that receive the treated wastewater. Therefore, the objectives of this research are (1) to compare NWRWRF typical operating conditions and water quality to those of two nearby facilities (River Oaks and Dale Mabry Advanced Wastewater Treatment Plants) that currently employ chlorine disinfection, (2) to determine the chlorine demand of treated effluent from NWRWRF, (3) to quantify the DBP formation potential of treated effluent from NWRWRF, and (4) to determine the effects of temperature, reaction time, and chlorine dose on chlorine demand and THM formation. To inform laboratory experiments, the quality of final effluent was monitored at NWRWRF and at two nearby wastewater treatment plants that currently use hypochlorite for disinfection. At these two facilities, pH of 7.0-8.0, chemical oxygen demand (COD) of 12-26 mg/L, alkalinity of 200-250 mg/L as CaCO3, chlorine residual of 1.5-6.0 mg/L, and total trihalomethanes of 100-190 ix μg/L (mostly chloroform) were observed. Conditions at NWRWRF were similar to those at Dale Mabry and River Oaks AWWTP, suggesting that chlorine demand and THM formation at NWRWRF would be similar to those at the two AWWTP, if chlorination is to be used. THM experimental results agreed with this suggestion. Chlorine dose and temperature effects on the free chlorine residual and THMs production in NWRWRF filtered wastewater effluent were determined. Filtered effluent was collected and transported to USF laboratory where it was tested for 3 different chlorine doses (6 mg/L, 9 mg/L and 12 mg/L as Cl2) and 3 different temperatures (16°C, 23°C, and 30°C) at 7 different contact times (15, 30, 45, 60, 75, 90, and 120 min) in duplicate. The total number of batches prepared was: 3 different chlorine doses × 3 different temperatures × 7 different reaction times = 126 reactors. According to Florida Administrative code 62-600.440, total chlorine residual should be at least 1 mg/L after a contact time of at least 15 min at peak hourly flow. Also, according to Florida Administrative code 62-600.440, if effluent wastewater has a concentration of fecal coliforms greater than 10,000 per 100 mL before disinfection, FDEP requires that the product of the chlorine concentration C (in mg/L as Cl2) and the contact time t (in minutes) be at least 120. Results showed that free chlorine residual was always above 1 mg/L in 15 min contact time for all chlorine doses and temperatures tested in this thesis. However, to be conservative, thesis conclusions and recommendations were based on the more stringent regulation: C*t ≥ 120 mg.min/L, assuming that the number of fecal coliform in NWRWRF wastewater effluent exceeds 10,000 per 100 mL prior to disinfection. The analysis showed that free chlorine residual for 6 mg/L was below the FDEP standard at all temperatures. At 16 °C and 23 °C, chlorine doses of 9 and 12 mg/L resulted in an appropriate free chlorine residual above the FDEP standard. However, a chlorine dose of 12 mg/L was resulting in high residual, which means high THM would be expected. Therefore, at 16 x and 23°C, 9 mg/L would be preferable. At 30 °C, only the chlorine dose of 12 mg/L met the standard at all contact times. As expected, free chlorine residual decreased with an increase in temperature from 23°C to 30°C. Surprisingly, the residual at 16°C was lower than residual at 23°C. The production of THMs increased with higher contact time in all the experiments completed. Chlorine dose didn't have an effect on THM formation at 23°C, but it did at 30°C and 16°C, where THM concentrations were generally higher with the increase of chlorine dose. Temperature effect was noticed in most of the experiments, where THM production was usually higher at higher temperatures, except some cases where formation was similar for different temperatures. Chloroform, dichlorobromomethane, dibromochloromethane production ranges were respectively: 20-127 μg/L, 18-59 μg/L, and 3-7 μg/L. Bromoform concentrations were not observed in this experiment at any temperature or chlorine dose. According to Florida Administrative code 62-302.530, Criteria for Surface Water Quality Classifications, the Florida Department for Environmental Protection (FDEP) set the following limits for THM concentrations in wastewater effluent to be as the following; 470 μg/L for chloroform, 22 μg/L for dichlorobromomethane, 34 μg/L for dibromochloromethane, and 360 μg/L for bromoform. Experimental results on NWRWRF filtered effluent showed that only dichlorobromomethane exceeded the limits set by FDEP at about 30 min contact time for all temperatures and chlorine doses tested. However, according to Florida Administrative code 62- 302-400, proposed changes to the code have set higher DCBM limit of 57 μg/L. Chlorination would be recommended at NWRWRF if the DCBM regulated limit increases to 57 μg/L. The recommended chlorine dose would be 9 mg/L for water temperatures around 16-23 °C and 12 mg/L for water temperatures around 30 °C
463

Cost-effective, post-mining environmental restoration of an open-cast phosphate mine at Langebaanweg, South Africa / Cost-effective post closure environmental restoration of an open-cast mine in a semi-arid environment on the West coast of South Africa

Van Eeden, Joseph Deon January 2010 (has links)
Approaching the ecological rehabilitation of an open-cast phosphate mine in the West Coast of South Africa during the post-operational phase presented some challenges. The area was extensively modified during the mining operations. Soils from different layers were mixed with topsoil being covered by subsoil, overburden dumps and tailing dams being constructed resulting in extensive cross-zoned soils. Large areas of subsoil areas were exposed on the mine floor with localized and small scale salinity being evident. The modified topography as well as the complex new surface material posed a challenge in terms of identifying suitable local species that could be used to rehabilitate the post-mining environment. The mine area was heavily infested with woody alien invasive plants, such as Acacia cyclops, established in an attempt to reduce the dust and little natural vegetation cover was present. In the arid west coast environment, the four-month-long winter growing season is followed by hot and windy dry summers (Chapter 2) presenting a challenge reestablishing local vegetation in modified soils. Moreover, little was known about the local vegetation in terms of their propagation and use in stabilization techniques as an alternative to exotic vegetation such as the A. cyclops, which had been more often used in revegetation projects. A study was conducted to determine the most efficient and cost-effective methods of vegetative rehabilitation of the Chemfos site (Chapter 1). A review of the literature available at the time as well as approaches that were successfully implemented in other Western Cape rehabilitation projects such as the Du Toitskloof Pass and the Sishen–Saldanha railway line (Chapter 3), were considered. Previous studies on the west coast dunes at Blaauwberg had shown using Marram grass as a dune stabilizer was most successful. Marram grass was tested in trials alongside local grasses, such as Chaetobromus dregeanus and Ehrharta villosa, that showed potential but had not been formally evaluated. The environmental context of Chemfos (Chapter 2) as well as the Conceptual Rehabilitation Plan that considered the modified environment, soils and closure objectives of the mine, were reviewed to determine the most pressing rehabilitationrelated questions that required answers. This led to the final experimental design that was implemented mid-winter in 1996 (Chapter 5). The trials were implemented in the areas perceived to be the most difficult to rehabilitate, namely the mobile sands in the tailings dam and the exposed subsoil or mine floor areas. The use of brushwood together with specific plants and seeds appropriate for the use in either sandy soil or subsoil were evaluated in a variety of combinations and application densities to determine the most effective treatment combination at the minimum effective density. The best initial cover of the tailings dam were recorded in the Ammophila arenaria trials but the use of the local grass species Ehrharta villosa, performed better from year two onwards and was much cheaper to establish. On the subsoil, the trials where a cover of topsoil was used performed better than the combination trials. This indicated that topsoil placement on post-operational phase shaped subsoils during the mining operation to be the most desirable treatment. Initial results of the trials were used as a basis for developing the rehabilitation techniques that were rolled out across the Chemfos landscape. The approaches were refined as indications of trial responses became evident. Lessons learned were incorporated in the adaptive management approach that was followed and the rehabilitation techniques (Chapter 6) were continually re-evaluated and adjusted. This resulted in a significant step towards achieving the overall research objective of finding cost-effective approaches to rehabilitation. Components such as refinement of the seed collection and processing techniques (Chapter 7) where the post-harvest processing cost was significantly reduced by introducing specially designed drying racks. Processing techniques were adjusted to suit the different species, and a variety of mechanical processing options were explored. The scale of the Chemfos project led to the development of new techniques of manufacturing a smoke-derived germination stimulant (Chapter 8) since commercial availability of these products was very limited. The development of FireGrow assisted in the overall aim of reducing cost by increasing germination of seed in the rehabilitation sites using a very cost-effective smoke concentrate. Socio-economical aspects were considered during the implementation as well as the post-closure phases of the rehabilitation and BHPBilliton invested through the agency of the SAMANCOR Trust. This led to the development of livelihoods of the staff that remained in the area and that lived in the mine village. The demography of the population has changed over time in the Green Village as well as the skills that the inhabitants have developed. Thus, the new economic opportunities that were pursued have brought a new lease on life beyond the lifespan of the mine (Chapter 9) once the closure certificate had been issued.
464

Cost-benefit analysis of land restoration in the Assegaaibos Catchment Area with regard to water yield and tourism benefit

Currie, Bianca January 2007 (has links)
With the emergence of the new field of resource economics, one now has the ability to value and to include natural resources in decision making. This thesis aims to explore the valuation of natural resources by reviewing the economic values, techniques, methods and ecological aspects of restoration. Assegaaibos mountain catchment in the Western Cape Province has been used as a case-study example. A cost-benefit analysis of the restoration of the mountain catchment, in terms of the direct benefits of water and tourism, has been performed. The costs of restoration were observed to see whether they outweighed the benefits (income) derived (water and tourism). The results show that the water and tourism benefits did outweigh the costs of a basic restoration scenario. However, the basic restoration scenario did not fulfil the ecological requirements of the project. The results also illustrated that in the moderate restoration scenario, costs only outweighed the benefits when a three percent discount rate was applied. With the optimistic restoration scenario, costs outweighed benefits only when an eight percent discount rate was used. In the comprehensive restoration scenario, costs were shown to outweigh by far the water and tourism benefits over a thirty-year time frame. However, it should be noted that the deterioration of the environment (accelerated erosion, reinvasion, reduced water quality) was not factored into the costs of failure to rehabilitate.
465

Analýza počtu reklamací a procesu vyřizování reklamací ve společnosti LASSELSBERGER, a.s. / The analysis of the number of reclamations and of the reclamations handling process in the LASSELSBERGER, a.s. company

Davídková, Veronika January 2009 (has links)
Main subject of the thesis is customer satisfaction. The introductory theoretical parts of the thesis are devoted right to the customer and his/her satisfaction, to its measuring methods and to the way how to handle complaints, eventually reclamations in corporations. The practical part of the thesis focuses on the analysis of qualitative reclamations and of reclamations and complaints handling and customer satisfaction evaluating processes in the LASSELSBERGER, a.s. company producing ceramic wall and floor surfaces. The objective and the outcome of the thesis is formulating a set of recommendations arising from elaborated analysis and also from theoretical findings. These recommendations should improve actual run of analysed processes considering the quality of output of those processes and for sure considering the customer satisfaction.
466

Aftrekbaarheid van omgewingsherstel uitgawes vanuit 'n belasting-oogpunt

Swart, Willem Jacobus 07 October 2014 (has links)
M.Com. / Please refer to full text to view abstract
467

Study of canopy variability and irrigable potential of rehabilitated and virgin mine lands by means of remote sensing and spatial analysis

Narciso, Giovanni 01 August 2005 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Agronomy))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted
468

Návrh využití šedých vod v plaveckém areálu Kraví hora s ohledem na dostavbu wellness centra / Proposal for the use of gray water in the swimming area "Kraví hora" with a view to completion of the wellness center

Běloušková, Pavla January 2013 (has links)
Greywater is the leftover water from baths, showers, hand basins and washing machines only, what implies that it is free of faeces and urine. Greywater can be recycled as processing water (whitewater) for toilet and/or urinal flushing or landscape irrigation. Energy recovery from greywater looks also very promising. The subject of this thesis is short research on the issue of the use of greywater in the first part, the following chapter provides examples of the use of greywater in practice. Practical part of thesis provides suggestion of use of greywater and their heat potential in swimming area Kraví hora with regard to completion of wellness centre. This part also includes economical analysis of suggested recycling.
469

Analýza procesu veřejné autobusové dopravy / Bus transport process analysis

Růčka, Josef January 2008 (has links)
The diploma dissertation deals with the bus transport process analysis. More specifically, it deals with a proposition of the reclamation subprocess control. The dissertation contains the description of subprocess of the main process of bus transport. Moreover, it contains the analysis of the original state of the reclamation subprocess control and a set of measures and recommendations that lead to the more effective evaluation of this subprocess.
470

A Decision-making Framework for Hybrid Resource Recovery Oriented Wastewater Systems

Rezaei, Nader 28 June 2019 (has links)
Water shortage, water contamination, and the emerging challenges in sustainable water resources management (e.g., the likely impacts of climate change and population growth) necessitate adopting a reverse logistics approach, which is the process of moving wastewater from its typical final destination back to the water supply chain for reuse purposes. This practice not only reduces the negative impacts of wastewater on the environment, but also provides an alternative to withdrawal from natural water resources, forming a closed-loop water supply chain. However, the design of such a supply chain requires an appropriate sustainability assessment, which simultaneously accounts for economic, environmental, and social dimensions. The overall aim of this work was therefore to contribute to the literature by evaluating the impacts of water reclamation and reuse according to the triple-bottom-line sustainability indicators (i.e., economic, environmental, and social) and to develop frameworks and mathematical models to help decision-makers, stakeholders, and officials with the design of sustainable water reclamation and reuse systems. The applicability of the developed frameworks and models was examined using real case studies and hypothetical scenario analyses. This enactment also revealed the tradeoffs and thresholds associated with the design of sustainable water reclamation and reuse systems. To conquer the mentioned goal, the research was conducted in three major sections. The first part of the research was outlined to design possible scenarios for water reuse based on water reuse guidelines and evaluate the different types of end-use based on the three major dimensions of sustainability (i.e., economic, environmental and social aspects), simultaneously. The different reuse types considered include unrestricted urban reuse, agricultural reuse, indirect potable reuse (IPR), direct potable reuse (DPR), distributed unrestricted urban reuse, as well as some degree of decentralization of treatment plants for distributed unrestricted urban reuse. The tradeoff investigation and decision-making framework were demonstrated in a case study and a regret-based model was adopted as the support tool for multi-criteria decision-making. This study revealed that although increasing the degree of treatment for water reuse required implementation of advanced treatment options and it increased the implementation, operation, and maintenance (O&M) costs of the design, it increased the value of resource recovery significantly, such that it can offset the capital and O&M costs associated with the treatment and distribution for DPR. Improving the reclaimed water quality also reduced the environmental footprint (eutrophication) to almost 50% for DPR compared to the other reuse scenarios. This study revealed that the distance between the water reclamation facility and the end use plays a significant role in economic and environmental (carbon footprint) indicators. In the second part of this research, a multi-objective optimization model was developed to minimize the costs and environmental footprint (greenhouse gas emissions), and maximize social benefits (value of resource recovery) of the water reclamation systems by locating the treatment facility, allocating treatment capacity, selecting treatment technology, and allocating customers (final reclaimed water users). The expansion of the water reclamation system in Hillsborough County, Florida was evaluated to illustrate the use of the model. The impacts of population density and topography (elevation variation) of the water service area on the model outputs were also investigated. Although the centralization of treatment facilities takes advantage of the economies of scale, the results revealed that simultaneous consideration of economic and environmental indicators favored decentralization of treatment facilities in the study area. This was mainly due to the significant decrease in water transfer requirements, especially in less populous areas. Moreover, the results revealed that contribution of population density to the optimal degree of decentralization of treatment facilities was significant. In the last part of this work, hypothetical scenarios for a water service area were generated to evaluate the impacts of external variables on the design of water reclamation and reuse systems. Although the conducted sensitivity analyses in the previous sections revealed the tradeoffs and thresholds associated with the design of water reclamation systems, the concept of a hypothetical study helped with the elimination of case-specific factors and local conditions that could possibly influenced the outcomes. These factors, which were specific to the case studies (e.g., the location of candidate sites for implementation of water reclamation facilities and special population distribution patters) made barriers to the conclusions and hurdled the interpretation of findings. Two major factors, which were found to be significant among the factors influencing the design of water systems (i.e., elevation variation and population density), were selected for the evaluation. Accordingly, three different topographies (i.e., flat region, medium elevation variation, and hilly) and three types of population density (i.e., low, medium, and high) were considered for the design of hypothetical cases and the previous model developed in the second section was modified and used to evaluate the impacts. The results revealed that although decentralization of water reclamation facilities decreases the costs and environmental impacts associated with water transfer phase (i.e., wastewater collection and reclaimed water distribution), there were tradeoffs between the impacts of decentralization of treatment plants and the benefits from economies of scale for treatment. The results showed that when the population density is high and there is moderate to high elevation variations in the water service area, decentralization of treatment facilities is the beneficiary option. However, if the population density is low, economies of scale for treatment becomes more influential and lower degrees of decentralization of treatment facilities is preferred.

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