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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.
1

Effects of paper mill sludge on tree growth and competition in young red pine plantations /

Young, Michael Joseph, January 1991 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 84-93). Also available via the Internet.
2

Microchemical characterization of ash from fuel production /

Brock, Melissa Kay. January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Abstract. Includes bibliographical references (leaves 63-64). Also available via the Internet.
3

Effects of paper mill sludge on tree growth and competition in young red pine plantations

Young, Michael Joseph 05 December 2009 (has links)
The disposal of pulp and paper industry sludge has become a significant problem in recent years. Increasing costs and regulatory constraints associated with landfilling and incineration have caused the industry to look for viable alternatives for the disposal of their wastes. In September of 1988, a nutrient-enriched, combined (primary/secondary) paper mill sludge was surface applied to a 4-year-old and a 6-year-old red pine (Pinus resinosa Ait.) plantation in central Wisconsin at rates of 10, 20 and 40 dry Mg ha⁻¹. Red pines measured 10 and 22 months following sludge application did not show a significant volume growth response to increasing sludge rates. Nonetheless, some biologically significant trends did occur following the first growing season, namely, diameter growth in the younger plantation decreased by 27%, 36% and 39% with increasing rates of sludge application. Reductions in height, crown width and volume growth were seen as well. Increased absorption of moisture among the heavier application rates coupled with already dry conditions is believed to be the cause of the growth reduction. Tree growth in the older plantation was more variable, possibly reflecting the greater degree of establishment and reduced susceptibility to moisture deficits. By the end of the second growing season, there was some indication that the trees were responding to sludge application in both plantations, with the greatest growth occurring among the 40 Mg ha TM treatment plots for all growth parameters. Red pine fascicles examined 12 months following sludge application showed significant increases in foliar concentrations of N, P, Ca, Mg and S with increasing rate of sludge application. This corresponded with a significant increase in fascicle biomass relative to application rate in the younger plantation. Fascicle biomass was not affected by sludge application in the older plantation. Analysis of nutrient response, in general, indicated luxury consumption taking place among all nutrients with the exception of boron, which decreased in foliar concentration, to low or deficient levels, and content in sludge amended plots in both plantations. Analysis for nutrient concentrations and dry matter production of Carex spp. (sedge), the predominant herbaceous understory component, showed increasing foliar N levels with sludge application 21 months following treatment in above-ground tissue, with a corresponding increase in above-ground biomass relative to controls of 22%, 33% and 85% among the 10, 20 and 40 Mg/ha treatments, respectively. An assessment of woody vegetation using a competing vegetation assessment system (CVAS) showed essentially no response by hardwood competition to sludge application for either study site. Total weed control, consisting of 0.140 kg ha⁻¹ a.i. of Oust™ and 1.3 kg ha⁻¹ a.i. of Garlon™ was performed in August of 1989 and resulted in significantly reduced coverage of herbaceous and woody competing vegetation in both plantations the following growing season. Analysis of red pine volume growth between weed control treatments did not show a significant response relative to sludge application for either plantation one year following herbicide application. Additionally, there was evidence of reduced weed control efficacy with increasing sludge application rate in the younger plantation. This suggests that weed control efficacy may be greater if weed control is performed prior to sludge application; however, given the apparent sequestering ability of the herbaceous vegetation, removal of this component may contribute to elevated levels of undesirable leachates in soilwater and groundwater. / Master of Science
4

Estudo da influência da cinza de lodo de esgoto como material não-convencional na produção de geopolímeros à base de metacaulim /

Istuque, Danilo Bordan. January 2017 (has links)
Orientador: Mauro Mitsuuchi Tashima / Resumo: A constante preocupação com o meio ambiente, principalmente, em relação à emissão de gases de efeito estufa na atmosfera, é uma das grandes razões pelas quais pesquisadores buscam por aglomerantes alternativos ao cimento Portland. Associado a este fato, está também a geração e o manejo dos resíduos sólidos urbano e industriais. Neste sentindo, os aglomerantes ativados alcalinamente têm sido apontados como “os novos cimentos do futuro”, uma vez que proporcionam uma redução na emissão CO2 pelo menor consumo de cimento Portland e pelo potencial de absorção dos resíduos, já que estes tem sido muito empregado como precursores na produção dos aglomerantes ativados alcalinamente, além de apresentarem melhores propriedades que o cimento Portland. Diante disto, o objetivo desta pesquisa foi avaliar a viabilidade e os efeitos da utilização da cinza de lodo de esgoto (CLE) em geopolímeros à base de metacaulim. Sistemas binários compostos por metacaulim (MK) e CLE foram confeccionados e submetidos a diferentes condições de cura – temperatura ambiente (25°C) e banho térmico (65°C) usando como solução alcalina a mistura de NaOH e uma solução de silicato de sódio. A CLE foi empregada como substituição parcial do MK em proporções de 0-20%. As amostras foram avaliadas por difração de raios – X, microscopia eletrônica de varredura e por resistência à compressão. Os resultados mostraram a formação de zeólitas (Faujasita) nas amostras curadas em banho térmico, que provocou uma redução de até 16,... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre
5

Avaliação do método respirométrico pelo acompanhamento e controle de processo de compostagem de lodo de esgoto

Scoton, Edvaldo José [UNESP] 17 August 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:26:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-17Bitstream added on 2014-06-13T19:13:23Z : No. of bitstreams: 1 scoton_ej_me_bauru.pdf: 11700204 bytes, checksum: 4b50447a64f592bc0b8288e6d2b3ee17 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O desenvolvimento econômico e a necessidade de proporcionar melhor qualidade de vida a toda a população, constituem alguns aspectos responsáveis para que a produção de residuos sólidos seja cada dia maior, aumentando a necessidade da busca de soluções ambientais corretas, para sua destinação. A compostagem consiste em importante ferramenta para o tratamento da fração orgânica dos resíduos sólidos, através do uso de tecnologias que processam os resíduos originados da agricultura, agroindústria, silvicultura, dos domicílios e, ainda, do loda da estação de tratamento de esgoto, adequando-os para serem incorporados ao solo e contribuindo para redução de adubos químicos. No Brasil, o emprego do processo de compostagem, é ainda bastante restrito, pelo alto grau de empirismo utilizado no controle e avaliação do processo e por falta de conhecimento técnico. Este estudo aborda o problema do tratamento de resíduos sólidos orgânicos provenientes das estações de tratamento de esgoto, através de pesquisa experimental de co-compostagem com outros resíduos orgânicos. No processo desenvolvido, denominado de método respirométrico, utilizou-se metodologia na qual os parâmetros de degradação biológica dos resíduos são quantificados na fase gososa. Os parâmetros avaliados, nesse trabalho, na fase gasosa de processos de co-compostagem do lodo de esgoto, possibilitaram a determinação do consumo de O2 e a geração de CO2 e da demanda bioquímica de oxigênio (DBO). Ao obter valores em substância totalmente homogênia, seu emprego apresentou como vantagens maior representatividade, precisão e confiabilidade, representando uma evolução quando comparados aos métodos tradicionais, permitindo o acompanhamento on line e contínuo. Os resultados foram muito superiores, quando... / Economic development and the need to provide better quality of life for the entire population, are responsible for some aspects of the production of solid waste each day is greater, increasing the need to search for environmental solutions right to your destination. Composing is an important tool for the treatment of the organic fraction of solid waste throgh the use of technologies that process the waste generated from agriculture, agribusiness, forestry, households, and also sludge from sewage treatment plant, adapting them to be incorporated into the solid and contribuing to reduction of chemical fertilizers. In Brazil the use of traditional composting process is still very limited, the high degree of empirism used in the control and evaluation of the process and lack of technical knowledge. This study addressed the problem of the treatment of organic solid waste from the sewage treatment plants, through experimental research of co-composting with other organic waste. In the process developed, called respirometric method was used methodology in which the parameters of biological degradation of waste are quantified in the gas phase. The parameters evaluated in this study, in the gas phase of the co-composting of sewage sludge, allowed the determination of O2 consumption and CO2 generation and biochemical oxygen demand (BOD). By obtaining values in totally homogeneous substance, its use had advantages as greater representation, accuracy and reliability, representing an evolution when compared to traditional methods, enabling monitoring on line and continuous. The results were far superior when compared to the traditional method, obtaining data lines 1440/day, while in the conventional process, these data are sun up to a daily measurement of temperature, which makes the respirometric method an... (Complete abstract click electronic access below)
6

Estudo da influência da cinza de lodo de esgoto como material não-convencional na produção de geopolímeros à base de metacaulim / Study of the behaviour of sewage sludge ash as nonconventional material in the production of metacaulim-based geopolymers

Istuque, Danilo Bordan [UNESP] 10 March 2017 (has links)
Submitted by Danilo Bordan Istuque null (daniloistuque@gmail.com) on 2017-04-19T14:38:55Z No. of bitstreams: 1 Danilo - Dissertação_Versão Final.pdf: 2470053 bytes, checksum: 5127673dbd7df0cf93ae3c8e6b962c6a (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-04-19T17:04:23Z (GMT) No. of bitstreams: 1 istuque_db_me_ilha.pdf: 2470053 bytes, checksum: 5127673dbd7df0cf93ae3c8e6b962c6a (MD5) / Made available in DSpace on 2017-04-19T17:04:23Z (GMT). No. of bitstreams: 1 istuque_db_me_ilha.pdf: 2470053 bytes, checksum: 5127673dbd7df0cf93ae3c8e6b962c6a (MD5) Previous issue date: 2017-03-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A constante preocupação com o meio ambiente, principalmente, em relação à emissão de gases de efeito estufa na atmosfera, é uma das grandes razões pelas quais pesquisadores buscam por aglomerantes alternativos ao cimento Portland. Associado a este fato, está também a geração e o manejo dos resíduos sólidos urbano e industriais. Neste sentindo, os aglomerantes ativados alcalinamente têm sido apontados como “os novos cimentos do futuro”, uma vez que proporcionam uma redução na emissão CO2 pelo menor consumo de cimento Portland e pelo potencial de absorção dos resíduos, já que estes tem sido muito empregado como precursores na produção dos aglomerantes ativados alcalinamente, além de apresentarem melhores propriedades que o cimento Portland. Diante disto, o objetivo desta pesquisa foi avaliar a viabilidade e os efeitos da utilização da cinza de lodo de esgoto (CLE) em geopolímeros à base de metacaulim. Sistemas binários compostos por metacaulim (MK) e CLE foram confeccionados e submetidos a diferentes condições de cura – temperatura ambiente (25°C) e banho térmico (65°C) usando como solução alcalina a mistura de NaOH e uma solução de silicato de sódio. A CLE foi empregada como substituição parcial do MK em proporções de 0-20%. As amostras foram avaliadas por difração de raios – X, microscopia eletrônica de varredura e por resistência à compressão. Os resultados mostraram a formação de zeólitas (Faujasita) nas amostras curadas em banho térmico, que provocou uma redução de até 16,8% na resistência à compressão das argamassas ativadas alcalinamente. No entanto, a presença de CLE ofereceu uma menor redução da resistência à compressão das argamassas (9,1%). Além disso, à temperatura ambiente, foram obtidas resistências à compressão similares tanto para as argamassas com MK (28,8 MPa) quanto para as argamassas com MK e CLE (27,9 MPa). Portanto, de acordo com os resultados obtidos nesta pesquisa, a CLE é um precursor mineral não-convencional com potencial para a produção de geopolímeros via substituição parcial do MK. / One of the explanations for the increases research numbers about the alternative binders to Portland cement is the concern about the environment, especially in relation to the emission of greenhouse gases in the atmosphere. Moreover, the generation and management of urban solid waste and industrial are another concern about the environment. In this sense, alkali-activated binders have been denominated as "the future cements". Alkali-activated binders provide a reduction in CO2 emissions due to lower consumption of Portland cement and the waste absorption potential. The aims of this research were to evaluate the feasibility and effects of sewage sludge ash (SSA) on metakaolin-based geopolymer mortars. Binary systems metakaolin/SSA were prepared and exposed to different curing conditions - room temperature (25 °C) and thermal bath (65 °C). The alkaline solution of NaOH and sodium silicate was used for the preparation of geopolymer mortars. SSA was used in partial replacement of MK to 020% proportions. The samples were evaluated by X - ray diffraction of, scanning electron microscopy and compressive strength. The results showed the formation of zeolites (faujasite) in cured samples in a thermal bath, which caused a decrease of 16,8% in the compressive strength of alkali-activated mortars. However, the presence of SSA caused a lower reduction in the compressive strength of mortars (9,1%). In addition, at room temperature, similar mechanical strength was achieved for both MK and MK/SSA geopolymer mortar (28,8 MPa and 27,9 MPa, respectively. Therefore, according to the results presented in this study, the SSA is a suitable non-conventional mineral precursor for replacement of MK in geopolymer production.
7

Continuous leaching of phosphorus from sewage sludge ash / Kontinuerlig lakning av fosfor från avloppslamsaska

Göransson, Sofie January 2022 (has links)
The global demand for food is increasing. Different nutrients are used to increase growth in agriculture and are thus essential for the world ́s food supply. An important and common nutrient is phosphorus. It can be mined, in the form of phosphate, from phosphate rock. The problem is that mining causes environmental problems and phosphate rock is a non-renewable resource. A risk is that phosphorus will become a scarce commodity in about 100 years.  Sewage sludge from wastewater treatment plants (WWTP) is rich in phosphorus. In Sweden and other European countries, a stricter legislation is expected with consideration of an increased recovery of phosphorus from sewage sludge. A ban on the spread of hazardous substances like drug residues and heavy metals from the sludge is also expected. Incineration of the sludge can be done to eliminate hazardous substances and at the same time recover phosphorus and metals. Development of technologies to recover phosphorus from incinerated sewage sludge is therefore topical.  EasyMining is a company that invents new technologies to close nutrient cycles. One of their present projects is about recycling phosphorus, iron, and aluminium from incinerated sewage sludge. Hydrochloric acid (HCl) is used to leach the ash and in the following steps metals and phosphorus are recovered, and heavy metals are removed. Batch experiments have been performed and EasyMining examines the process in a continuous stirred tank reactor (CSTR).  The aim with this project is to compare the batch and continuous process for the ash leaching step. The study was limited to investigate different residence times and liquid to solid ratios (L/S ratios) for the ash leaching step in the CSTR. To accomplish the aim, mainly experimental studies have been performed. A total of 14 runs have been conducted to investigate the continuous process. The residence times 10, 30 and 60 min and the L/S ratios 2.5, 3 and 3.5 ml/g were evaluated. The lab-set up consisted of a peristaltic pump to pump diluted HCl solution, a conveyor belt to dose the ash and a CSTR. The filtrate was analysed for phosphorus, iron, and aluminium with a spectrophotometer. Interpretation of the result was conducted after each run and the data was then compared to previous batch data from within the company. A paired t-test was used to evaluate if there was a significant difference in the mean values between different residence times and L/S ratios.  The result shows that the leching is very fast and longer residence times or higher L/S ratios do not result in higher yields for phosphorus, iron, or aluminium. There is no significant difference between the examined residence times or L/S ratios in the paired t-test. Data from the batch process shows that the investigated residence times and L/S ratios do not affect the yield. A more even distribution of the yields is obtained in the batch process compared to the continuous process. The less even distribution in the continuous process, probably depends on errors in the method and the equipment used in the process. For example, there were some problems with the ash dosing, which led to an inconstant L/S ratio in the runs. This affected the calculated yields significantly. Overall, the batch process results in slightly higher yields. This is especially the case when excluding high calculated yields in the continuous process, probably obtained because of an overdosing of the ash. / Den globala efterfrågan på mat ökar. Olika näringsämnen används för att få en högre tillväxt i jordbruket och dessa är essentiella för världens livsmedelsproduktion. Ett viktigt och vanligt näringsämne är fosfor och det bryts i form av fosfat från fosfatmineral. Problemet är att brytningen förorenar miljön och dessutom är fosfat-sten en icke förnyelsebar resurs. Det finns en risk att fosfor blir en bristvara om cirka 100 år.  Avloppsslam från vattenreningsverk innehåller höga fosfatkoncentrationer. I Sverige samt i andra europeiska länder förväntas en striktare lagstiftning, som kräver en ökad återvinningsgrad av fosfor från avloppsslam. Även ett förbud mot spridningen av giftiga substanser som läkemedelsrester och tungmetaller förväntas införas. Slammet kan förbrännas för att eliminera farliga substanser samtidigt som fosfor och olika metaller kan återvinnas. Utvecklingen av nya tekniker för återvinning av fosfor från bränt avloppsslam är därför väldigt aktuell.  EasyMining är ett innovationsföretag som utvecklar nya tekniker för att erhålla slutna näringskretslopp. Ett av deras pågående projekt handlar om att återvinna fosfor, aluminium och järn från förbränt avloppsslam. Saltsyra används för att laka askan och i nästkommande steg återvinns fosfor och metaller, samtidigt som tungmetaller separeras. Satsvisa försök har genomförts och EasyMining vill nu undersöka processen i en tankreaktor.  Syftet med projektet är att jämföra resultat från den satsvisa driften med resultat från en kontinuerlig process för ask-lakningssteget. Studien begränsades till att endast undersöka olika uppehållstider och förhållandet mellan vätskan och askan (L/S-förhållande) i lakningssteget. För att uppnå syftet genomfördes huvudsakligen experimentella studier. 14 körningar genomfördes totalt för undersökning av den kontinuerliga processen. Undersökta uppehållstider var 10, 30 och 60 min och undersökta L/S-förhållandena var 2,5, 3 och 3,5 ml/g. Laborationsuppställningen bestod av en peristaltisk pump för tillförsel av utspädd saltsyralösning, ett rullband för dosering av askan samt en tankreaktor. Filtratet analyserades för fosfor, järn och aluminium i en spektrofotometer. Efter varje körning tolkades resultatet och jämfördes därefter med data från de av företaget tidigare utförda satsvisa försöken. Ett parat t-test användes för att utvärdera om det fanns någon signifikant skillnad i medelvärden mellan olika uppehållstider och L/S-förhållanden.  Resultatet visar att lakningen är väldigt snabb och längre uppehållstider eller högre L/S-förhållanden ger inte högre utbyten för fosfor, järn eller aluminium. Ingen signifikant skillnad erhålls mellan undersökta uppehållstider eller L/S-förhållanden i de parade t-testen. Data från de satsvisa försöken visar att de undersökta uppehållstiderna och L/S-förhållandena inte påverkar utbytet. En mindre spridning av utbyten erhålls i den satsvisa driften jämfört med den kontinuerliga. Den större spridningen i den kontinuerliga processen beror förmodligen på felkällor i processens metod/utrustning. Exempelvis var det en del problem med askdoseringen, vilket medförde icke konstanta L/S-förhållanden. Detta påverkade det beräknade utbytet signifikant. Generellt erhålls något högre utbyten i den satsvisa processen. Framförallt då höga beräknade utbyten exkluderas i den kontinuerliga processen på grund av en överdosering av askan.
8

Microchemical characterization of ash from fuel production

Brock, Melissa Kay 10 November 2009 (has links)
Millions of tons of ash and slag are produced each year as a result of energy production. This study looks at the mineralogy and textures in the ash resulting from the gasification of a 25% Passaic Valley sewage sludge, 75% Pittsburgh #8 coal slurry in a Texaco gasification facility and at ash resulting from the incineration of municipal solid waste at several facilities in Virginia and North Carolina. This information is then compared with similar studies done on ash and slag from coal-burning power plants and a study done on petroleum coke slag which was produced at a Texaco gasification facility. Lastly, a comparison of bulk chemistries of ashes to those of soil and crustal rocks is made. A general understanding of the stability of elements, especially metals, in terms of the phases in which they are contained as well as the textures, was hoped to be gained from this study. Samples for this study were polished sections which were 2.54 em in diameter that were set in cold-setting epoxy then ground and polished. Samples were then studied under a reflected light microscope before being carbon coated for study on a SEM and an electron microprobe. Photos of textures and analyses were made throughout. At least 50% of the ash from all sources was a Si-Al oxide rich glass which had varying amounts of Fe, Ca, K, P, Mg, and Ti and other trace elements. Fe oxides and spinels were common phases found. Pb and Zn were rarely encountered, but were found as both oxides and sulfides. Cr was found in the form of spinels, often covered by a protective AI enriched outer rim. The heavy metals found were successfully bound as mineral analogs or as a glass phase. The only phase found to be reactive was an AIC matrix containing subhedral SiC crystals. The AI phase effervesced when placed in contact with water, changing from tan to greenlblue/violet in color, releasing a gas (probably CO₂, C2H2, or CH4) in the process. / Master of Science
9

Avaliação do método respirométrico pelo acompanhamento e controle de processo de compostagem de lodo de esgoto /

Scoton, Edvaldo José. January 2012 (has links)
Resumo: O desenvolvimento econômico e a necessidade de proporcionar melhor qualidade de vida a toda a população, constituem alguns aspectos responsáveis para que a produção de residuos sólidos seja cada dia maior, aumentando a necessidade da busca de soluções ambientais corretas, para sua destinação. A compostagem consiste em importante ferramenta para o tratamento da fração orgânica dos resíduos sólidos, através do uso de tecnologias que processam os resíduos originados da agricultura, agroindústria, silvicultura, dos domicílios e, ainda, do loda da estação de tratamento de esgoto, adequando-os para serem incorporados ao solo e contribuindo para redução de adubos químicos. No Brasil, o emprego do processo de compostagem, é ainda bastante restrito, pelo alto grau de empirismo utilizado no controle e avaliação do processo e por falta de conhecimento técnico. Este estudo aborda o problema do tratamento de resíduos sólidos orgânicos provenientes das estações de tratamento de esgoto, através de pesquisa experimental de co-compostagem com outros resíduos orgânicos. No processo desenvolvido, denominado de método respirométrico, utilizou-se metodologia na qual os parâmetros de degradação biológica dos resíduos são quantificados na fase gososa. Os parâmetros avaliados, nesse trabalho, na fase gasosa de processos de co-compostagem do lodo de esgoto, possibilitaram a determinação do consumo de O2 e a geração de CO2 e da demanda bioquímica de oxigênio (DBO). Ao obter valores em substância totalmente homogênia, seu emprego apresentou como vantagens maior representatividade, precisão e confiabilidade, representando uma evolução quando comparados aos métodos tradicionais, permitindo o acompanhamento "on line" e contínuo. Os resultados foram muito superiores, quando... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Economic development and the need to provide better quality of life for the entire population, are responsible for some aspects of the production of solid waste each day is greater, increasing the need to search for environmental solutions right to your destination. Composing is an important tool for the treatment of the organic fraction of solid waste throgh the use of technologies that process the waste generated from agriculture, agribusiness, forestry, households, and also sludge from sewage treatment plant, adapting them to be incorporated into the solid and contribuing to reduction of chemical fertilizers. In Brazil the use of traditional composting process is still very limited, the high degree of empirism used in the control and evaluation of the process and lack of technical knowledge. This study addressed the problem of the treatment of organic solid waste from the sewage treatment plants, through experimental research of co-composting with other organic waste. In the process developed, called respirometric method was used methodology in which the parameters of biological degradation of waste are quantified in the gas phase. The parameters evaluated in this study, in the gas phase of the co-composting of sewage sludge, allowed the determination of O2 consumption and CO2 generation and biochemical oxygen demand (BOD). By obtaining values in totally homogeneous substance, its use had advantages as greater representation, accuracy and reliability, representing an evolution when compared to traditional methods, enabling monitoring "on line" and continuous. The results were far superior when compared to the traditional method, obtaining data lines 1440/day, while in the conventional process, these data are sun up to a daily measurement of temperature, which makes the respirometric method an... (Complete abstract click electronic access below) / Orientador: Rosane Aparecida Battistelle / Coorientador: Jorge Akutsu / Banca: Erich Kellner / Banca: Adilson Renofio / Mestre
10

Utilización de geopolímero para la mejora de las propiedades en morteros cal-puzolana y su empleo en países en desarrollo.

Villca Pozo, Ariel Rey 02 September 2021 (has links)
[ES] El descubrimiento del cemento Portland ha cambiado nuestra forma de construir, pero también es el responsable de grandes emisiones de CO2 a la atmósfera durante su fabricación (~1450 ᴼC), agravando la crisis actual que está sufriendo nuestro planeta debido al cambio climático y sus consecuencias en todo el medio ambiente. Por lo tanto, una alternativa más sostenible en la construcción es la utilización de la cal que necesita menor temperatura para su fabricación (~900 ᴼC). Si bien la introducción de puzolanas naturales o artificiales en morteros de cal han mejorado sus propiedades mecánicas y de durabilidad, estas aún tienen el inconveniente de ganar resistencias a edades largas de curado. Es por esta razón que en la presente tesis se pretende eliminar este inconveniente técnico, buscando la asociación de la cal con nuevos conglomerantes más sostenibles a partir de residuos para obtener morteros mixtos denominados cal/puzolana-geopolímero. Los residuos estudiados fueron: el catalizador gastado de craqueo catalítico, la ceniza de cascara de arroz, la tierra diatomea de origen residual y la ceniza de lodo de depuradora. También se estudia una puzolana natural proveniente de la República de Guatemala. En los morteros cal/puzolana (cal/FCC, cal/CCA, cal/CLD) se ha realizado sustituciones en peso hasta un 50 % de la mezcla cal/puzolana por geopolímero. El geopolímero se obtiene por una combinación del FCC como precursor y diferentes activadores alcalinos siendo estos la mezcla de: NaOH/Na2SiO3, NaOH/CCA, NaOH/TDN y NaOH/TDR. Los últimos tres sustituyen al silicato comercial como fuente de sílice alternativa. Asimismo, se realizaron estudios a nivel mecánico y microestructural. Para los estudios microestructurales, tanto de muestras endurecidas como de materiales de partida, se emplearon como técnicas: FRX, ADL, TG, DRX y FESEM. Los resultados han demostrado con éxito que añadir pequeñas cantidades de geopolímero sobre el sistema cal/puzolana fue notable, debido a que este potenció la formación de los nuevos productos de reacción, lo que mejoró la resistencia mecánica de los morteros desde las primeras horas de curado, llegando a obtener 7 veces más de resistencia que un mortero control cal/puzolana en 1 día de curado. El reemplazo del silicato de sodio comercial por CCA, TDN, TDR, como fuente de sílice, condujo a mejores desempeños del mortero en términos de resistencia a la compresión. Además, redujo el coeficiente de absorción de agua por capilaridad y aumento el tiempo de exposición a los ciclos hielo-deshielo frente a los morteros activados con activadores comerciales. Finalmente, los conglomerantes desarrollados en este estudio podría beneficiar tanto a la gestión de residuos como al desarrollo de materiales de construcción más sostenibles, aportando a los objetivos propuestos en la agenda 2030. / [CA] El descobriment del ciment Portland ha canviat la nostra manera de construir, però també és el responsable de grans emissions de CO¿ a l'atmosfera durant la seva fabricació (~1450 ᴼC), agreujant la crisi actual que està patint el nostre planeta degut al canvi climàtic i les seves conseqüències en tot el medi ambient. Per tant, una alternativa més sostenible en la construcció és la utilització de la calç que necessita menor temperatura per a la seva fabricació (~900 ᴼC). Si bé la introducció de putzolanes naturals o artificials en morters de calç han millorat les seves propietats mecàniques i de durabilitat, aquestes encara tenen l'inconvenient de guanyar resistències a edats llargues de curat. És per aquesta raó que en la present tesi es pretén eliminar aquest inconvenient tècnic, buscant l'associació de la calç amb nous conglomerants més sostenibles a partir de residus per a obtenir morters mixtos denominats calç/putzolana-geopolímer. Els residus estudiats van ser: el catalitzador gastat del craqueig catalític, la cendra de closca d'arròs, la terra diatomea d'origen residual i la cendra de llot de depuradora. També es va estudiar una putzolana natural provinent de la República de Guatemala. En els morters calç/putzolana (calç/FCC, calç/CCA, calç/CLD) s'ha realitzat substitucions en pes fins a un 50 % de la barreja calç/putzolana per geopolímer. El geopolímer s'obté per una combinació del FCC com a precursor i diferents activadors alcalins, sent aquests la mescla de: NaOH/Na2SiO3, NaOH/CCA, NaOH/TDN i NaOH/TDR. Els últims tres substitueixen al silicat comercial com a font de sílice alternativa. Així mateix, es van realitzar estudis a nivell mecànic i microestructural. Per als estudis microestructurals, tant de mostres endurides com de materia primera, es van emprar tècniques com: FRX, ADL, TG, DRX i FESEM. Els resultats han demostrat amb èxit que afegir petites quantitats de geopolímer sobre el sistema calç/putzolana va ser notable, pel fet que aquest va potenciar la formació dels nous productes de reacció, la qual cosa va millorar la resistència mecànica dels morters des de les primeres hores de curat, arribant a obtenir 7 vegades més de resistència que un morter control calç/putzolana en 1 dia de curat. El reemplaçament del silicat de sodi comercial per CCA, TDN, TDR, com a font de sílice, va conduir a millors acompliments del morter en termes de resistència a la compressió. A més, va reduir el coeficient d'absorció d'aigua per capil·laritat i va augmentar el temps d'exposició als cicles gel-desgel enfront dels morters activats amb activadors comercials. Finalment, els conglomerants desenvolupats en aquest estudi podrien beneficiar tant a la gestió de residus com al desenvolupament de materials de construcció més sostenibles, aportant als objectius proposats en l'Agenda 2030. / [EN] The discovery of Portland cement has changed the way we build; however, it is also responsible for large CO2 emissions into the atmosphere during its manufacturing (~ 1450 ᴼC), thereby aggravating the current crisis that our planet is suffering due to climate change and its consequences in the environment. Thus, a more sustainable alternative in construction is the use of lime that requires a lower temperature for its manufacturing (~ 900 ᴼC). The introduction of natural or artificial pozzolans in lime mortars has improved their mechanical properties and durability. Nevertheless, they present some technical disadvantages, as the low compressive strength, especially at early curing time. This thesis aims to eliminate this technical disadvantage by mixing lime with new more sustainable binders derived from waste, obtaining mixed mortars called lime/pozzolan-geopolymer The waste materials studied included fluid catalytic cracking residue (FCC), rice husk ash (CCA), residual diatomite (TDR) and sewage sludge ash (CLD). A natural pozzolan from the Republic of Guatemala was also studied. In the experimental procedure, in lime/pozzolan mortar mixtures (lime/FCC, lime/CCA, lime/CLD), up to 50% of their weight was substituted by geopolymer. The geopolymer is obtained by combining FCC as a precursor, and different alkaline activator mixtures including NaOH/Na2SiO3 (commercial waterglass), NaOH/CCA, NaOH/TDN, and NaOH/TDR, with the last three being an alternative silica source to commercial waterglass. In the same way, both mechanical and microstructural studies were carried out. The following techniques were used: XRF, ADL, TG, XRD and FESEM to assess the microstructural properties of both the raw materials and the hardened samples. The results have demonstrated that adding small amounts of geopolymer to the lime/pozzolan system was remarkable; it enhanced the formation of new reaction products, which improved the mechanical strength of the mortar from the first hours of curing, obtaining 7 times more strength than the lime/pozzolan control mortar in 1 day of curing. The replacement of commercial waterglass by CCA, TDN, TDR, as a source of silica, led to better performance of the mortar in terms of compressive strength. In addition, the coefficient of water absorption by capillarity was reduced and the exposure time during freezing-thawing cycles was increased compared to mortars activated with commercial activators. Finally, the binders developed in this study could benefit both waste management and the development of more sustainable construction materials, contributing to the objectives proposed in the 2030 Agenda. / Gracias al programa ADSIDEO-COOPERACIÓN de la Universitat Politècnica de València, que me ha brindado financiación para la presente investigación. / Villca Pozo, AR. (2021). Utilización de geopolímero para la mejora de las propiedades en morteros cal-puzolana y su empleo en países en desarrollo [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172663

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