• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 27
  • 6
  • 4
  • 2
  • 1
  • Tagged with
  • 107
  • 45
  • 36
  • 33
  • 17
  • 17
  • 15
  • 14
  • 14
  • 13
  • 13
  • 12
  • 10
  • 10
  • 9
  • 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.
51

Analyse der RDF-Produktion in Vietnam / Analyze of RDF-production in Vietnam

Schulenburg, Sven 02 August 2010 (has links)
A simplified RDF production was made, together with a waste characterization of MSW from Hanoi area. Three experiments were done, two with active aeration and one without. A high water content was determined at all RDF, which has a negative influence on the lower heating value and a saving-effect. A accumulation of the heating value to the higher class (>40mm), was not completely possible, also no complete transfer of mineral contents to the lower class (<10mm). The RDF reach in most cases the criteria for a fuel for different limit values, heavy metals, chloride and sulfur. An economic benefit could be possible with a surplus income by using RDF instead of coal (lignite), also by avoiding landfill gas and sell emission rights via CDM. More and detailed investigations seem to be necessary to confirm these results.:I. Index I II. Abbreviations III III. List of Tables IV IV. Figures VII V. Acknowledgements VIII VI. Summary IX 1. Introduction 1 2. Materials and methods 3 2.1 Waste Composition Analyze 3 2.2 Sample analyze 4 2.2.1 Water Content 4 2.2.2 Size reduction 5 2.2.3 Carbon content 5 2.2.4 Chloride and Sulfur 7 2.2.5 Heavy metals 7 2.2.6 fossil and biogenic carbon 9 2.2.7 Ash content / Los of Ignition 11 2.3 biological Stabilization 11 2.3.1 Active Aeration 12 2.3.2 Passive aeration 12 2.4 Clean Development Mechanism 13 2.4.1 Kyoto Protocol 13 2.4.2 International emission trading 14 2.4.3 Clean Development Mechanism 15 2.4.4 Avoidance potential of emissions from waste through RDF production 22 2.5 Economic calculation 27 2.6 Comparison to the usage of primary energy sources 28 3. Results 30 3.1 Waste characterization 30 3.2 Mass Balance of RDF Production 33 3.3 Water content 34 3.3.1 Waste from Characterization 34 3.3.2 RDF 35 3.4 Heating value 36 3.4.1 Waste from Characterization 36 3.4.2 RDF 37 3.5 Heavy metals 38 3.5.1 Waste from Characterization 38 3.5.2 RDF 39 3.6 Chloride and Sulfur content 41 3.6.1 Waste from Characterization 41 3.6.2 RDF 42 3.7 Total carbon content 42 3.8 Biogenic / fossil carbon content / Ash 43 3.9 Methane avoidance potential 44 3.10 CO2e emission through RDF usage 45 3.11 Economic comparison 46 3.12 Comparison to coal 47 4. Discussion 48 4.1 1st Thesis 48 4.2 2nd Thesis 53 4.3 3rd Thesis 61 4.3.1 Mechanical requirements 62 4.3.2 Caloric requirements 63 4.3.3 Chemical requirements 64 4.4 4th Thesis 71 4.4.1 Environmental benefit 71 4.4.2 Economical benefit 74 5. Conclusion 77 References 79 Annex I - Tables I Affidavit – Eidesstattliche Erklärung I
52

Environmental and Economic Modelling for MSW Management Strategies and Reverse Logistic System

Xu, Zonghua January 2020 (has links)
No description available.
53

Co-Pyrolysis of Fruit Waste and High Density Polyethylene: Effect of Composition, Temperature and CO2 Environment on Pyrolysis Products

Nooh, Abdullah 06 1900 (has links)
Waste recycling is gaining prominence and acceptance compared to landfilling to reduce greenhouse gas emissions. Municipal solid waste (MSW), the largest source of solid waste, is primarily composed of food waste, plastics packaging and papers. Thermochemical recycling technique, such as pyrolysis, is considered as a promising alternative for producing value-added products. Pyrolysis is a process occurring in inert environments at moderate temperatures controlled by parameters such as the reaction temperature, heating rate and residence time to produce bio-oil and biochar. It is also known for its high tolerance for mixed waste stream. In this thesis, fruit waste (FW) consisted of bananas, apples, oranges and cucumbers peels and commercial high density polyethylene (HDPE) as co-pyrolysis feedstock were investigated. Co-pyrolysis experiments were performed in a tubular furnace reactor to investigate the effect of polymer composition, temperature and CO2 atmosphere. HDPE composition was varied between 33–67% to investigate the effect of feedstock composition at 500 ˚C. A composition was fixed and then effect of temperature was assessed in the range 500–700 ˚C. Finally, in CO2 atmosphere, co-pyrolysis experiments were performed with 50% HDPE at 600 ˚C. The collected bio-oil and biochar were thoroughly characterized via different analytical techniques. The effect of different process parameters on bio-oil was studied by gas chromatography-mass spectrometry (GC/MS), proton nuclear magnetic resonance (1H NMR) and Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). Biochar samples are analyzed using scanning electron microscopy (SEM), CHNS elemental analysis and Fourier-transform infrared (FTIR). Detailed product composition revealed that formation of hydrocarbons was promoted with increasing HDPE, while significant deoxygenation was observed with increased temperature. In addition, heavier molecules in the bio-oil were studied via FT-ICR MS. HDPE loading and CO2 atmosphere stabilized the biochar by reducing the oxygen content. The results demonstrated the potential use of HDPE as a co-feed with FW in a pyrolysis system to produce valuable products.
54

Slope Stability Analysis Of Class I Landfills With Co Disposal Of Bios

Vajirkar, Mrutyunjay 01 January 2004 (has links)
Land filling provides a major, safe, and economical disposal route for biosolids and sludges. With an expanding world, the demand for larger and higher capacity landfills is rapidly increasing. Proper analysis and design on such fills have pushed the boundaries of geotechnical engineering practice, in terms of proper identification and assessment of strength and deformation characteristics of waste materials. The engineering properties of Municipal Solid Waste (MSW) with co-disposal of biosolids and sludges with regards to moisture characteristics and geotechnical stability are of utmost importance. Significant changes in the composition and characteristics of landfill may take place with the addition of sludges and biosolids. In particular, the stability of waste slopes needs to be investigated, which involves the evaluation of the strength properties of the mixture of the waste and biosolids. This thesis deals with impact of the addition of biosolids on the geotechnical properties of class I landfill as determined from field investigations. The geotechnical properties are evaluated using an in-situ deep exploration test, called the Cone Penetration Test (CPT). CPT provides a continuous log of subsurface material properties using two measuring mechanisms, namely, tip resistance and side friction. The areas receiving biosolids are compared with areas without, to evaluate the effect of landfilling of biosolids. The required geotechnical shear strength parameters (angle of internal friction and cohesion) of MSW and biosolids mixture are determined by correlation with CPT results similar to the procedure followed in evaluating soil properties. The shear strength parameters obtained from the CPT data are then used to study the stability of different slope configurations of the landfill. The slope stability analysis is conducted on the various landfill models using the computer software SLOPE/W. This software was designed for soils but was found to be suitable for modeling landfills, as the waste is assumed to act similar to a cohesionless soil. Based on the field investigations, the angle of internal friction was found to be about 29° and the determination of any cohesion was not possible. It was concluded that the most suitable practical solution to adding biosolids into the landfill was in the form of trenches. From the slope stability study, it was found that the factor of safety reduces significantly with the introduction of biosolids due to a reduction in shear strength and increase in the overall moisture content. From a parametric study, the stability of a 1:2 side slope with an angle of friction lower than about 20° was found to be less than the safe limit of 1.5. In addition, the factors of safety for landfills with trenches extending close to the edges of the slopes were also found to be unsafe and this situation needs to be avoided in practice.
55

Determining Florida Landfill Odor Buffer Distances Using Aermod

Figueroa, Veronica 01 January 2008 (has links)
As U.S. landfills continue to grow in size, concerns about odorous gas emissions from landfills are increasing. For states that are expanding in population, such as Florida, odors from landfills are a major concern because new housing developments, needed to accommodate the rapid population growth, are creeping closer and closer to the existing landfills. As homes get closer to landfills, odor complaints are likely to become more frequent, causing landfill managers increased problems with public interactions. Odor buffer zones around landfills need to be established to give municipalities tools to help prevent the building of future homes too close to landfills. Using the latest air dispersion model, AERMOD, research predicted downwind odor concentrations from a Central Florida landfill. Accurate estimates of methane emissions throughout a Central Florida landfill were determined using a new technique developed as part of this research that uses hundreds of ambient air VOC measurements taken within a landfill, as receptors. Hundreds of point sources were placed on the landfill, and the standard Gaussian dispersion equations were solved by matrix inversion methods. The methane emission rates were then used as surrogates for odor emissions to predict downwind odor concentrations via AERMOD. By determining a critical zone around a landfill with regards to odor, stakeholders will be able to meet regulatory issues and assist their communities. Other beneficial uses from this research include: determination of existing gas collection system efficiencies, calculation of fugitive greenhouse gas emissions from municipal solid waste (MSW) landfills, and improved landfill gas management.
56

Investigation of Temperature, Solution Strength, and Applied Stress Effects on Cation Exchange Processes in Geosynthetic Clay Liners

Katzenberger, Kurt 01 December 2022 (has links) (PDF)
A laboratory test program was conducted to investigate the effects of temperature, solution strength, and applied stress over increasing conditioning durations on cation exchange processes in sodium bentonite (Na-B) geosynthetic clay liners (GCLs). The test program was intended to determine if the variables of temperature, solution strength, and applied stress had beneficial or detrimental effects on the engineering behavior of Na-B GCLs in municipal solid waste (MSW) landfills and laboratory testing applications. Needlepunched-reinforced, double non-woven Na-B GCL specimens were conditioned in fluids of increasing ionic strength (DI water, 2 mM CaCl2, 50 mM CaCl2, and 200 mM CaCl2 representing control, pore water, mild MSW leachate, and harsh MSW leachate, respectively), temperatures of 5 degrees C, 20 degrees C, 40 degrees C, and 60 degrees C, and overburden stresses (30 kPa and 500 kPa representing stresses experienced by cover and bottom liner systems, respectively) which are all representative of geoenvironmental conditions observed in MSW landfill barrier systems. Cation exchange in the bentonite component of all conditioned Na-B GCL specimens was quantified by measuring the bound cation (BC) complexes and cation exchange capacities (CEC) of the specimens using inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis and by conducting index tests to determine the dimensional characteristics, swell index, and gravimetric moisture content of the specimens. For zero stress conditions, periodic measurements of electrical conductivity, total dissolved solids, sodium and calcium cation concentration, and temperature of the conditioning fluids were recorded to supplement bound cation complex data. For applied stress conditions, electrical conductivity, total dissolved solids, and temperature of the conditioning fluid were recorded. For zero stress conditions, 152 mm x 152 mm Na-B GCL specimens were conditioned in all conditioning fluids and temperatures over increasing time durations ranging from 4 hours to 32 days. For applied stress conditions, 60-mm-diameter Na-B GCL specimens were conditioned in 50 mM CaCl2 conditioning fluid at all temperatures for 4 to 16 days under the applied overburden stresses of 30 kPa and 500 kPa. Temperature, solution strength, and applied stress were all observed to affect cation exchange in the bentonite component of Na-B GCLs. Cation exchange processes were observed to increase with increasing temperature, increasing solution strength, and decreasing applied overburden stress. The majority of cation exchange processes were observed to occur within 8 to 10 days for specimens conditioned under zero stress. Cation exchange processes were observed to have a higher sensitivity to changes in solution strength (up to 625% increase in the change of Na+ BC from DI water to 200 mM CaCl2) compared to changes in temperature (up to 52% increase in the change of Na+ BC from 5 degrees C to 60 degrees C) in zero stress conditions. Changes in the bound cations of the Na-B GCL specimens over time were not reflected in the periodic electrical conductivity measurements taken of the high strength conditioning fluids. The results of this study can be used for quality assurance evaluations of in-service GCLs using thresholds developed for index properties. From the numerical thresholds determined in this study, hydrated Na-B GCL specimens sampled from the field conditioned under zero stress that exhibit swell indices greater than or equal to approximately 70% of the swell index reported by the manufacturer and gravimetric moisture contents of greater than or equal to approximately 200% will likely exhibit adequate hydraulic barrier performance. Hydrated Na-B GCL specimens sampled from the field conditioned under zero stress that exhibit swell indices of less than or equal to approximately 20% of the swell index reported by the manufacturer and gravimetric moisture contents of less than or equal to approximately 100% will likely exhibit inadequate hydraulic barrier performance. The Na-B GCL component of cover liner systems may be susceptible to high rates of cation exchange due to experiencing low overburden stress and elevated temperatures compared to typical earth temperatures. The Na-B GCL component of bottom liner systems may exhibit low rates of cation exchange due to experiencing high overburden stress and cooler temperatures.
57

A proposed walkway system constructed from selected combustion residues

Hillabrand, James L 02 May 2009 (has links)
This thesis studies a new more affordable way to build sidewalks in the U.S. Typical sidewalks are often impractical on many roads because of a steep runoff slope and/or close proximity to the drainage ditch. Also, if future road widening is required, the sidewalk must be removed. This thesis proposes a structure called a Lanwalk which is an elevated sidewalk made of precast units. A Lanwalk could simultaneously serve as a sidewalk and potentially as a guardrail. It can be placed over drainage areas if necessary without obstructing the flow of water. Lanwalks can be easily installed and relocated if necessary. This thesis examines the possibility of using high amounts of waste ash as an admixture during the construction of Lanwalks or sidewalks to lower cost and save landfill space. The two waste products examined are municipal solid waste incinerator bottom ash (IBA) and coal fly ash (CFA).
58

Enhanced Biodegradation in Landfills

Shearer, Brad David 29 May 2001 (has links)
The objective of this paper is to evaluate the effectiveness of leachate recirculation and bioreactor landfills at enhancing biodegradation, and to optimize the operation of a bioreactor. Waste Management has been examining leachate recirculation landfills for several years. Samples of Municipal Solid Waste (MSW) from existing leachate recirculation (LR) landfills were collected and analyzed for several physical and biochemical properties. These parameters of interest were moisture content, pH, density, temperature, volatile solids, cellulose/lignin ratios, and biological methane potential (BMP). Leachate recirculation increased the dry density 55% faster and decreased the BMP 125% more rapidly. Moisture content was the biggest factor influencing overall degradation. Therefore, leachate reciculation effectively increases biodegradation of MSW in landfills. Waste Management built a pilot-scale bioreactor in Franklin, WI, which was sampled for one year. It contained a bioreactor side and a control side. The volatile solids, cellulose, and BMP degradation rates for the bioreactor were increased by 56%, 87%, and 271% versus the control, respectively. Moisture content was the biggest factor influencing overall degradation. The column study is designed to optimize three parameters under the control of an operator: moisture content, initial aeration period, and biosolids addition. The optimum moisture content is above 45%, but it is not safe to operate heavy equipment on refuse with greater than 45% moisture. Initial aeration did not speed up the overall degradation, but it did shorten the acidogenic phase. Finally, biosolids did not have a significant effect on degradation rates. The columns maintained an average temperature of 70oF. / Master of Science
59

[en] POTENTIAL OF A NEUTRINO DETECTOR AT THE ANDES UNDERGROUND LABORATORY FOR THE STUDY OF SUPERNOVA NEUTRINOS / [pt] POTENCIAL DE UM DETECTOR DE NEUTRINOS NO LABORATÓRIO SUBTERRÂNEO DE ANDES PARA O ESTUDO DE NEUTRINOS DE SUPERNOVAS

THIAGO MUHLBEIER 20 September 2018 (has links)
[pt] A oportunidade ímpar da construção do primeiro laboratório subterrâneo no Hemisfério Sul precisa ser alicerçada com importantes objetivos científicos, de maneira a competir com os demais laboratórios já existentes ao redor do planeta. Assim, no intuito de auxiliar na solidificação desta ideia, esta tese tem o propósito de verificar o potencial de um detector de neutrinos no futuro laboratório de ANDES para a observação de neutrinos vindos da próxima Supernova Galáctica. A observação de tais partículas é de fundamental importância para a compreensão do mecanismo de explosão de estrelas e para inferir ou desvendar propriedades dos neutrinos. Para tal, simulamos o número de eventos para o decaimento Beta inverso e para o espalhamento elástico v - p que seriam obtidos com a próxima supernova com o detector de ANDES considerando diferentes tipos de cintiladores líquidos, levando em conta o efeito MSW. Mostramos que através do espalhamento elástico v - p é possível reconstruir o fluxo total de todos os sabores de neutrinos, energia média e total liberados por neutrinos não-eletrônicos. Além disso, a comparação da razão dos números de eventos que vem de corrente carregada (depende da oscilação) e de corrente neutra (independente de oscilação), nos permite inferir a hierarquia de massa para alguns casos. Adicionalmente, estudamos a contribuição do laboratório de ANDES para a observação do efeito de matéria da Terra ao compararmos dados com outros detectores do Hemisfério Norte. Finalmente, investigamos a precisão angular para determinar a direção de uma supernova apenas usando o registro de neutrinos, que pode ser o caso de Supernovas que formam buracos negros ou sofram efeito de obscurecimento devido a poeira interestelar. / [en] The unique opportunity of construction of the first underground laboratory in the Southern Hemisphere must be grounded with important scientific goals in order to compete with others already existing laboratories around the word. In order to compete with idea as much as possible, this PhD Thesis aims to investigate the potential of a future neutrino detector at the ANDES laboratory to the observation of such particles is of fundamental importance to understanding the mechanism and starbust inferred or unravel properties of neutrinos as mass hierarchy, for example. To this end, we simulate the number of events for inverse beta decay and the elastic scattering of v - p that would be obtained with nearby supernova at the ANDES detector taking into account different types of liquid scintillator ande the phenomenon of MSW effect. We show that through the v - p elastic scattering is possible to reconstruct the total flux of all flavors of neutrinos, total and average energy released by non-electron neutrinos. furthermore, comparison of the ratio of observed and theoretical prediction, the number of the ANDES laboratory to the Northern Hemisphere. Finally, we investigate the angular precision for determining the direction of the supernova only using its neutrinos, which can be the situation when either supernovae collapses forming black holes or obscuration due to interstellar dust.
60

Reliability Based Approach for Evaluation of MSW Landfill Designs and Site Selection using GIS

Santhosh, L G January 2016 (has links) (PDF)
Dumping of municipal solid waste (MSW) generated due to anthropogenic activities in any barren land or out fields causes severe hazards to human populations, ecosystems and the environment. In order to avoid this, it is required to design landfills in an engineered and scientific manner. Therefore, it is necessary to understand the behaviour of landfills over a period of time, to design landfills for site specific conditions. In this thesis such an attempt is made to evaluate performance of conventional landfill system using a large scale anaerobic reactor in the laboratory. The performance of the containment (bottom liner and final cover) systems is evaluated through numerical modelling and reliability based analysis. Response Surface Methodology (RSM) is used to develop linear regression models. Influence of various parameters and their uncertainty on the reliability of the containment systems are studied for various scenarios and conditions. Reliability assessment of containment systems play a decisive role in taking remedial measures in order to reduce its adverse affects on the environment and human health in the vicinity of landfill sites. On the other hand, pre-assessment of risk guides the engineers, planners and decision makers in achieving the goal of sustainable solid waste management as well as safe landfills. The thesis also includes assessment of vulnerability of groundwater to contamination, identification and ranking of suitable sites for municipal solid waste (MSW) disposal in the Bengaluru district, using remote sensing and Geographic information system (GIS) integrated with analytical hierarchy process (AHP), a multi criteria decision making tool. The study considers various land use, geological, hydrogeological and environmental factors as criteria. As a result, two most suitable locations are identified around the Bengaluru city and their descriptions are provided. Further, reliability analysis of the suitability of sites is evaluated considering criteria as random variables. The proposed reliability based approach helps the decision makers and planners to choose site locations having low probability of environmental pollution. The provided methods in the thesis can be effectively used for engineered design of landfills.

Page generated in 0.026 seconds