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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.
551

Avaliação de um novo protocolo para remoção de retentores metálicos por meio do ultrassom em dentes multirradiculares

Souza, Samir Noronha de 24 February 2014 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-06-16T15:47:05Z No. of bitstreams: 1 Dissertação -Samir Noronha de Souza.pdf: 1429754 bytes, checksum: 835f9975774739f2f3c90832d7100d72 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-16T18:26:30Z (GMT) No. of bitstreams: 1 Dissertação -Samir Noronha de Souza.pdf: 1429754 bytes, checksum: 835f9975774739f2f3c90832d7100d72 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-16T18:27:24Z (GMT) No. of bitstreams: 1 Dissertação -Samir Noronha de Souza.pdf: 1429754 bytes, checksum: 835f9975774739f2f3c90832d7100d72 (MD5) / Made available in DSpace on 2015-06-16T18:27:24Z (GMT). No. of bitstreams: 1 Dissertação -Samir Noronha de Souza.pdf: 1429754 bytes, checksum: 835f9975774739f2f3c90832d7100d72 (MD5) Previous issue date: 2014-02-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The purpose of this paper is to evaluate in vitro a new protocol for intra-radicular posts removal for multi-radicular teeth by applying ultrasonic vibration. Forty lower molars were endodontically treated in order to receive cast posts and cores, being distributed in 4 groups: GI – control without slot; GII – control with slot; GIII – ultrasound application in core without slot; GIV – ultrasound application in core with slot. After the cast posts fixation using zinc phosphate cement, the ultrasonic vibration was applied in group III for 1 minute, dividing 15 seconds on each surface and in group IV 15 seconds on facial and lingual surface, and 30 seconds inside the slot totaling 1 minute. Thereafter, samples were subjected to tensile test in Universal Assay Machine at the speed of 1mm/min. The maximum tensile strength needed for intra-radicular posts removal was registered in Newton and its data were subjected to statistical analysis ANOVA e Tukey-Kramer. The results presented statistically significant differences between the tested groups (GI – 234,34 N; GII – 201,67 N; GIII – 139,57 N; GIV – 83,23 N), with the smallest average of the tensile strength obtained when ultrasonic vibration on the core slotted applied (p<0,05). It is concluded that the implemantation of a slot in the core and ultrasonic application on all the surfaces and inside the slot caused a reduction of force required for removing cast posts and cores fixed with zinc phosphate in multi-radicular teeth. / Este trabalho visa avaliar in vitro um novo protocolo para remoção de retentores intrarradiculares em dentes multirradiculares aplicando a vibração ultrassônica. Quarenta molares inferiores foram tratados endodonticamente para receber retentores intrarradiculares fundidos, sendo distribuídos em 4 grupos: GI – controle sem fenda; GII – controle com fenda; GIII – aplicação ultrassom em núcleo sem fenda; GIV – aplicação de ultrassom em núcleo com fenda. Após a fixação dos retentores com cimento de fosfato de zinco, a vibração ultrassônica foi realizada no grupo III durante 1 minuto, sendo 15 segundos em cada face e no grupo IV 15 segundos nas faces vestibular e lingual, e 30 segundos dentro da fenda, totalizando 1 minuto. Em seguida, os corpos-de-prova foram submetidos ao teste de tração na Máquina Universal de Ensaio com velocidade de 1 mm/min. A força de tração máxima necessária para a remoção do retentor intrarradicular foi registrada em Newton e os dados foram submetidos à análise estatística ANOVA e Tukey-Kramer. Os resultados mostraram haver diferença estatística significante entre os grupos testados (GI – 234,34 N; GII – 201,67 N; GIII – 139,57 N; GIV – 83,23 N), sendo a menor média da força de tração obtida quando se aplicou vibração ultrassônica sobre o núcleo com fenda (p<0,05). Conclui-se que a realização de uma fenda no núcleo e a aplicação ultrassônica em todas as faces e dentro da fenda promoveu a redução da força necessária para a remoção de retentores intrarradiculares metálicos fixados com fosfato de zinco em dentes multirradiculares.
552

Caracterização do cromo presente no lodo de galvanoplastia: avaliação técnica e econômica de processos de remoção / Characteristics of chromium from electroplating sludge: technical and economic evaluation of removal processes

Lucas Campaner Alves 05 February 2016 (has links)
O lodo gerado em processos de galvanoplastia é classificado pela ABNT NBR 10.004/04 como perigoso (classe I). Na literatura encontram-se poucos estudos referentes à recuperação do cromo presente no lodo gerado em sistemas de tratamento de efluentes de indústrias de galvanoplastia. Neste sentido, o presente estudo avaliou a remoção do cromo presente no lodo de galvanoplastia por meio de dois processos, visando avaliar à eficiência técnica e a viabilidade econômica de ambos. O Processo 1 consistiu na remoção do cálcio utilizando o ácido cítrico, seguida de lixiviação ácida. Na etapa de oxidação, variou-se a temperatura em 40ºC, 60ºC e 80ºC e no tempo de 30, 60 e 90 minutos, tendo em vista que a eficiência do processo de oxidação depende da temperatura e tempo. Nesta etapa do processo as concentrações de peroxido de hidrogênio (H2O2) utilizadas foram de 1,50, 3,00 e 4,50 mol.L-1. O Processo 2 realizou a oxidação do cromo sem efetuar as etapas de extração do cálcio e a lixiviação ácida. A oxidação do cromo ocorreu pelo mesmo método apresentado no Processo 1. A caracterização elementar da amostra determinou que o principal elemento constituinte do lodo é o cálcio (20,05% em massa), e que dentre os metais pesados destacam-se o cromo e o níquel (6,52% e 4,33% em massa, respectivamente). A maior eficiência de remoção do cálcio foi obtida na razão mássica de 8,00 (ácido cítrico/hidróxido de cálcio), com 51,76% em massa, seguida pela razão mássica de 5,50 com 36,75% em massa e 2,50 com 24,83% em massa. O melhor resultado de oxidação do cromo no Processo 1 foi obtido com tempo de 30 minutos, temperatura de 60ºC e concentração de peroxido de hidrogênio de 3,00 mol.L-1, com eficiência de 41,09% em massa. No Processo 2, obteve-se a remoção de 37,96% em massa de cromo a temperatura de 80ºC, por uma hora e 3,00 mol.L-1 de peróxido de hidrogênio. Avaliando os custos para remoção do cromo dos dois processos, determinou-se que o Processo 1 foi mais oneroso que o 2, porém ambos não apresentaram viabilidade econômica para aplicação em escala industrial. Nos dois processos efetuou-se a oxidação do cromo presente no lodo de galvanoplastia, permitindo a sua remoção parcial neste resíduo. Com isso obtiveram-se ganhos ambientais, pela diminuição deste elemento no resíduo de galvanoplastia, que na maioria das vezes é disposto em aterros classe I, gerando um passivo ambiental. / The sludge generated in electroplating processes is classified by NBR 10.004/04 as a hazardous material (class I). In the literature, few studies report the recovery of chromium present in the electroplating sludge generated in the industries. In this sense, the present study conducted the removal of chromium in the electroplating sludge through two different processes, aiming to evaluate their efficiency and economic viability. The first process removed calcium through the use of citric acid being performed by varying the ratio of citric acid/calcium hydroxide (2.5, 5.5 and 8.0). Then, were performed the leaching of the samples. According to the literature, the efficiency of the oxidation process varies depending on the reaction temperature, time and concentration of hydrogen peroxide. For this reason, samples were heated to a temperature ranging from 40°C, 60°C and 80°C. Also, were conducted variations in the concentrations of hydrogen peroxide (1.5, 3.0 and 4.5 mol.L-1) and reaction time (30, 60 and 90 minutes). The second Process consisted in the chrome recovery by using the galvanic sludge without removal of the calcium and acid leaching. The chrome oxidation occurred by the same method shown in Process 1. Elemental characterization of the samples determined that the primary sludge constituent was calcium (20.05% by weight), and in terms of heavy metals, the chromium and the nickel (6.52% and 4.33% by mass, respectively). Most of calcium removal efficiency was obtained at a rate of 8 with 51.76% by mass, then the ratio of 5.50 to 36.75% by mass and 2.50 to 24.83% by mass. The best oxidation result of chromium in Process 1 was obtained using a time of 30 minutes, 60°C and hydrogen peroxide concentration of 3 mol.l-1, with 41.09 wt% efficiency. In Process 2 was obtained the removal of 37.96% by mass of chromium temperature of 80°C, for one hour and 3,00 mol.l-1 of hydrogen peroxide. Evaluating the costs for chrome removal of the two processes was determined that the Process 1 was more costly than 2, but both showed no economic feasibility for implementation on an industrial scale. However, in both cases occurred the oxidation of chromium present in the electroplating sludge, allowing its removal from the residue. Thus, environmental gains have been achieved by the reduction of this element in electroplating waste, which mostly is intended for landfill class I, generating an environmental liability.
553

Biofiltro submerso modificado para pós-tratamento do efluente de lagoas de estabilização / Modified submerged biofilter for post treatment of the effluent of stabilization lagoons

Gerson Pavanelli 27 August 2014 (has links)
Esta pesquisa propôs o desenvolvimento de um sistema de biofiltros submersos, modificados com base na configuração de filtros de pedra, visando o pós-tratamento do efluente de lagoas de estabilização, inicialmente para a remoção de algas. A modificação consiste na variação das alturas da camada filtrante e na colocação de tampa na superfície do BS, evitando o acesso da luz. O esgoto tratado captado na lagoa de maturação foi feito em duas profundidades &#8211; a 60 cm de profundidade da superfície da lagoa (denominada zona superficial) e a 180 cm de profundidade da superfície da lagoa (denominada zona intermediárias). O experimento foi composto por 8 BS sendo 4 BS alimentados pelo esgoto captado na zona superficial (60 cm) e outros 4 BS alimentados pela esgoto captado na zona intermediária (180 cm). Foi utilizado, como recheio dos biofiltros submersos, pedra brita nº 3, nas seguintes alturas de camada filtrante: 50 cm, 100 cm, 150 cm e 200 cm, tendo por objetivo avaliar a influência deste fator sobre a eficiência de remoção de algas mediante análise de Clorofila a, e outras 16 variáveis de qualidade associadas neste estudo. Concluiu-se que a extração a partir da zona superficial da lagoa de maturação, e uma profundidade de leito entre 150 cm e 200 cm, foram os parâmetros operacionais que levaram a um melhor desempenho global dos biofiltros submersos modificados, e mais especificamente quanto às seguintes variáveis: Clorofila a, DQO (Demanda Química de Oxigênio), DBO (Demanda Bioquímica de Oxigênio) e sólidos totais. / This research proposed the development of a submerged bio filters system, modified based in rock filters configuration, aiming the post treatment of the effluent of stabilization lagoons, for algae removal first. The modification consists invariance of the heights of the filter layer and the cover placed on the surface of the BS, preventing access of light. The treated sewage captured in the maturation lagoon was made at two depths &#8211; at 60cm depth of the lagoon surface (called superficial zone) and at 180cm depth of the lagoon surface (called intermediary zone). The experiment consisted of 8 BS, with 4 BS being fed by sewage captured in the superficial zone (60 cm) and other 4 BS fed by sewage captured in the intermediary zone (180 cm). It was used, as a stuff of submerged biofilters, rock number three, at the following heights of filtering layers: 50 cm, 100 cm, 150 cm e 200 cm, aiming to evaluate the influence of this factor over algae removal efficiency towards chlorophyll a, and other 16 quality variables associated in this study. It was concluded that the collecting from superficial zone of the maturation lagoon, and a layer depth between 150 cm e 200 cm, were the operational parameters that lead to a better overall performance of modified submerged biofilters, and more particularly to the following variables: Chlorophyll a, COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand) and total solids.
554

Remoção da biomassa algal e determinação da concentração de microcistina pelo Método ELISA em ensaios de coagulação, sedimentação, filtração e adsorção / Removal of algal biomass and determinacy of microcystins concentration through ELISA method in tests of coagulation, sedimentation, filtration and adsorption

Luciana Pallone Hespanholo Ferreira 17 September 2004 (has links)
Nessa pesquisa são relatados os resultados da determinação das concentrações de microcistina e de biomassa algal após as várias etapas de tratamento de amostras de água coletadas junto ao reservatório de Barra Bonita-SP visando obtenção de água potável. O tratamento foi realizado em escala de laboratório com e sem aplicação de carvão ativado em pó (CAP) e as etapas foram: coagulação com aplicação de cloreto férrico, sedimentação, filtração em papel de filtro. Foi possível observar que a pré-clarificação desse tipo de água por coagulação seguida de sedimentação requereu dosagens relativamente elevadas de cloreto férrico (80 mg/L), tendo sido verificada eficiência muito baixa de remoção de microcistina nas etapas de tratamento por sedimentação seguida de filtração, quando não foi aplicado CAP. Apenas com a aplicação de CAP a microcistina foi reduzida à níveis que atendessem os padrões de potabilidade previstos na Portaria 518/04 (concentração menor que 1 &#956g/L). A determinação de microcistina pelo método que utiliza Imunoadsorventes Ligados à Enzima (ELISA) mostrou-se uma ferramenta útil e confiável para detectar e quantificar essa toxina, embora ainda apresente custo relativamente elevado. / This report presents the results of the quantification of microcystins and algae biomass concentrations after treatment of water samples taken from the Barra Bonita reservoir, for production of potable water. Bench-scale tests were carried out with and without powdered activated carbon (PAC) and the treatment processes used were: coagulation with ferric chloride (FeCl3), sedimentation and filtration with paper filter. It was determined that pre-clarification followed by sedimentation required substantial dosages of ferric chloride (80 mg/L). The removal of microcystins using sedimentation followed by filtration was ineffective without PAC. The use of PAC is required to produce water that meets current potability standards for microcystins removal as specified in Decree 518/04 (concentration less than 1 &#956g/L). Analysis of microcystins using the Enzime-Linked Immunosorbent Assay Method (ELISA) has proven to be an effective and reliable procedure to detect and quantify this toxin, although relatively expensive.
555

Engineering a Proteoliposome Transporter to Capture Radioactive Cesium from Water

January 2018 (has links)
abstract: Radioactive cesium (137Cs), released from nuclear power plants and nuclear accidental releases, is a problem due to difficulties regarding its removal. Efforts have been focused on removing cesium and the remediation of the contaminated environment. Traditional treatment techniques include Prussian blue and nano zero-valent ion (nZVI) and nano-Fe/Cu particles to remove Cs from water; however, they are not efficient at removing Cs when present at low concentrations of about 10 parts-per-billion (ppb), typical of concentrations found in the radioactive contaminated sites. The objective of this study was to develop an innovative and simple method to remove Cs+ present at low concentrations by engineering a proteoliposome transporter composed of an uptake protein reconstituted into a liposome vesicle. To achieve this, the uptake protein, Kup, from E. coli, was isolated through protein extraction and purification procedures. The new and simple extraction methodology developed in this study was highly efficient and resulted in purified Kup at ~1 mg/mL. A new method was also developed to insert purified Kup protein into the bilayers of liposome vesicles. Finally, removal of CsCl (10 and 100 ppb) was demonstrated by spiking the constructed proteoliposome in lab-fortified water, followed by incubation and ultracentrifugation, and measuring Cs+ with inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS results from testing water contaminated with 100 ppb CsCl, revealed that adding 0.1 – 8 mL of Kup proteoliposome resulted in 0.29 – 12.7% Cs removal. Addition of 0.1 – 2 mL of proteoliposome to water contaminated with 10 ppb CsCl resulted in 0.65 – 3.43% Cs removal. These removal efficiencies were greater than the control, liposome with no protein. A linear relationship was observed between the amount of proteoliposome added to the contaminated water and removal percentage. Consequently, by adding more volumes of proteoliposome, removal can be simply improved. This suggests that with ~ 60-70 mL of proteoliposome, removal of about 90% can be achieved. The novel technique developed herein is a contribution to emerging technologies in the water and wastewater treatment industry. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018
556

Removal and recovery of metal ions by magnetite-immobilized chitin A.

January 2008 (has links)
Wong, Kin Shing Kinson. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 145-158). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.v / Contents --- p.viii / List of figures --- p.xv / List of plates --- p.xx / List of tables --- p.xxi / Abbreviations --- p.xxiii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Heavy metals --- p.1 / Chapter 1.1.1 --- Characteristics of heavy metals --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Common usage of heavy metals --- p.4 / Chapter 1.1.3.1 --- Copper --- p.4 / Chapter 1.1.3.2 --- Nickel --- p.4 / Chapter 1.1.3.3 --- Zinc --- p.5 / Chapter 1.1.4 --- Toxicity of heavy metals --- p.5 / Chapter 1.1.4.1 --- Copper --- p.6 / Chapter 1.1.4.2 --- Nickel --- p.7 / Chapter 1.1.4.3 --- Zinc --- p.7 / Chapter 1.1.5 --- Treatment techniques for metal ions --- p.8 / Chapter 1.1.5.1 --- Chemical precipitation --- p.9 / Chapter 1.1.5.2 --- Ion exchange --- p.10 / Chapter 1.1.5.3 --- Activated carbon adsorption --- p.10 / Chapter 1.2 --- Biosorption --- p.11 / Chapter 1.2.1 --- Definition of biosorption --- p.11 / Chapter 1.2.2 --- Mechanism --- p.12 / Chapter 1.2.3 --- Advantages of biosorption --- p.13 / Chapter 1.2.4 --- Selection of biosorbents --- p.15 / Chapter 1.3 --- Chitinous materials --- p.17 / Chapter 1.3.1 --- Background of chitin --- p.17 / Chapter 1.3.2 --- Structures of chitinous materials --- p.18 / Chapter 1.3.3 --- Sources of chitinous materials --- p.18 / Chapter 1.3.4 --- Application of chitinous materials --- p.20 / Chapter 1.3.5 --- Mechanism of metal ion adsorption by chitin --- p.22 / Chapter 1.4 --- Activated carbon --- p.25 / Chapter 1.4.1 --- Characteristics of activated carbon --- p.25 / Chapter 1.4.2 --- Applications of activated carbon --- p.26 / Chapter 1.4.3 --- Factors affecting adsorption ability of activated carbon --- p.27 / Chapter 1.4.4 --- Advantages and Disadvantages --- p.28 / Chapter 1.4.4.1 --- Advantages (Adsorption) --- p.28 / Chapter 1.4.4.2 --- Advantages (Regerneration) --- p.28 / Chapter 1.4.4.3 --- Disadvantages (Adsorption) --- p.28 / Chapter 1.4.4.4 --- Disadvantages (Regeneration) --- p.29 / Chapter 1.5 --- Cation exchange resin --- p.29 / Chapter 1.5.1 --- Usages of cation exchange resin --- p.29 / Chapter 1.5.2 --- Characteristics of cation exchange resin --- p.30 / Chapter 1.5.3 --- Disadvantages of using cation exchange resin --- p.30 / Chapter 1.6 --- Magnetite --- p.31 / Chapter 1.6.1 --- Reasons of using magnetite --- p.31 / Chapter 1.6.2 --- Characteristics of magnetite --- p.31 / Chapter 1.6.3 --- Immobilization by magnetite --- p.32 / Chapter 1.6.4 --- Advantages of using magnetite --- p.33 / Chapter 1.7 --- The biosorption experiment --- p.33 / Chapter 1.7.1 --- The batch biosorption experiment --- p.33 / Chapter 1.7.2 --- The adsorption isotherms --- p.34 / Chapter 1.7.2.1 --- The Langmuir adsorption isotherm --- p.34 / Chapter 1.7.2.2 --- The Freundlich adsorption isotherm --- p.36 / Chapter 2. --- Objectives --- p.38 / Chapter 3. --- Materials and methods --- p.39 / Chapter 3.1 --- Adsorbents --- p.39 / Chapter 3.1.1 --- Chitin A --- p.39 / Chapter 3.1.2 --- Pretreatment of chitin A --- p.39 / Chapter 3.1.3 --- Magnetite --- p.39 / Chapter 3.1.4 --- Activated carbon --- p.41 / Chapter 3.1.5 --- Cation exchange resin --- p.41 / Chapter 3.1.6 --- Pretreatment of cation exchange resin --- p.41 / Chapter 3.2 --- Chemicals --- p.43 / Chapter 3.2.1 --- Metal ion solution --- p.43 / Chapter 3.2.2 --- Buffer solution --- p.43 / Chapter 3.2.3 --- Standard solution --- p.43 / Chapter 3.3 --- Immobilization of chitin A by magnetite --- p.44 / Chapter 3.3.1 --- Effect of chitin A to magnetite ratio --- p.44 / Chapter 3.3.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.45 / Chapter 3.3.3 --- Effect of pH --- p.45 / Chapter 3.3.4 --- Effect of immobilization time --- p.46 / Chapter 3.3.5 --- Effect of temperature --- p.46 / Chapter 3.3.6 --- Effect of agitation rate --- p.46 / Chapter 3.3.7 --- Effect of salinity --- p.46 / Chapter 3.3.8 --- Mass production of magnetite-immobilized chitin A --- p.47 / Chapter 3.4 --- Batch adsorption experiment --- p.47 / Chapter 3.5 --- "Optimization of physicochemical condition on Cu2+,Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.48 / Chapter 3.5.1 --- Effect of equilibrium pH --- p.48 / Chapter 3.5.2 --- Effect of amount of adsorbent --- p.49 / Chapter 3.5.3 --- Effect of retention time --- p.49 / Chapter 3.5.4 --- Effect of agitation rate --- p.49 / Chapter 3.5.5 --- Effect of temperature --- p.50 / Chapter 3.5.6 --- Effect of initial metal ion concentration --- p.50 / Chapter 3.5.7 --- Adsorption isotherms --- p.50 / Chapter 3.5.8 --- Dimensionless separation factor --- p.52 / Chapter 3.5.9 --- Kinetic parameters of adsorption --- p.52 / Chapter 3.5.10 --- Thermodynamic parameters of adsorption --- p.53 / Chapter 3.6 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.54 / Chapter 3.6.1 --- Performances of various solutions on metal ion recovery --- p.54 / Chapter 3.6.2 --- Multiple adsorption and desorption cycles of metal ions --- p.55 / Chapter 3.7 --- Statistical analysis of data --- p.55 / Chapter 4. --- Results --- p.56 / Chapter 4.1 --- Immobilization of chitin A by magnetite --- p.56 / Chapter 4.1.1 --- Effect of chitin A to magnetite ratio --- p.56 / Chapter 4.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.59 / Chapter 4.1.3 --- Effect of pH --- p.59 / Chapter 4.1.4 --- Effect of immobilization time --- p.59 / Chapter 4.1.5 --- Effect of temperature --- p.59 / Chapter 4.1.6 --- Effect of agitation rate --- p.64 / Chapter 4.1.7 --- Effect of salinity --- p.64 / Chapter 4.1.8 --- Mass production of magnetite-immobilized chitin A --- p.64 / Chapter 4.2 --- Batch adsorption experiment --- p.67 / Chapter 4.2.1 --- Screening of adsorbents --- p.67 / Chapter 4.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.70 / Chapter 4.3.1 --- Effect of equilibrium pH --- p.70 / Chapter 4.3.2 --- Effect of amount of adsorbent --- p.74 / Chapter 4.3.3 --- Effect of retention time --- p.78 / Chapter 4.3.4 --- Effect of agitation rate --- p.82 / Chapter 4.3.5 --- Effect of temperature --- p.82 / Chapter 4.3.6 --- Effect of initial metal ion concentration --- p.86 / Chapter 4.3.7 --- Summary of optimized conditions for three metal ions --- p.87 / Chapter 4.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.87 / Chapter 4.3.9 --- Performance of reference adsorbents (AC and CER) --- p.87 / Chapter 4.3.10 --- Adsorption isotherms --- p.99 / Chapter 4.3.11 --- Dimensionless separation factor --- p.103 / Chapter 4.3.12 --- Kinetic parameters of adsorption --- p.106 / Chapter 4.3.13 --- Thermodynamic parameters of adsorption --- p.113 / Chapter 4.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.113 / Chapter 4.4.1 --- Performances of various solutions on metal ion recovery --- p.113 / Chapter 4.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.117 / Chapter 5. --- Discussions --- p.121 / Chapter 5.1 --- Immobilization of chitin A by magnetite --- p.121 / Chapter 5.1.1 --- Effect of chitin A to magnetite ratio --- p.121 / Chapter 5.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.121 / Chapter 5.1.3 --- Effect of pH --- p.122 / Chapter 5.1.4 --- Effect of immobilization time --- p.122 / Chapter 5.1.5 --- Effect of temperature --- p.122 / Chapter 5.1.6 --- Effect of agitation rate --- p.123 / Chapter 5.1.7 --- Effect of salinity --- p.123 / Chapter 5.2 --- Batch adsorption experiment --- p.123 / Chapter 5.2.1 --- Screening of adsorbents --- p.123 / Chapter 5.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.124 / Chapter 5.3.1 --- Effect of equilibrium pH --- p.125 / Chapter 5.3.2 --- Effect of amount of adsorbent --- p.126 / Chapter 5.3.3 --- Effect of retention time --- p.127 / Chapter 5.3.4 --- Effect of agitation rate --- p.128 / Chapter 5.3.5 --- Effect of temperature --- p.128 / Chapter 5.3.6 --- Effect of initial metal ion concentration --- p.129 / Chapter 5.3.7 --- Summary of optimized conditions for three metal ions --- p.130 / Chapter 5.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.132 / Chapter 5.3.9 --- Performance of reference adsorbents (AC and CER) --- p.133 / Chapter 5.3.10 --- Adsorption isotherms --- p.133 / Chapter 5.3.11 --- Dimensionless separation factor --- p.135 / Chapter 5.3.12 --- Kinetic parameters of adsorption --- p.136 / Chapter 5.3.13 --- Thermodynamic parameters of adsorption --- p.139 / Chapter 5.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.140 / Chapter 5.4.1 --- Performances of various solutions on metal ion recovery --- p.140 / Chapter 5.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.141 / Chapter 6. --- Conclusions --- p.143 / Chapter 7. --- References --- p.145
557

Influência do tamanho molecular aparente das substâncias húmicas aquáticas na eficiência da coagulação com sulfato de alumínio e cloreto férrico / Influence of apparent molecular size from aquatic humic substances in the coagulation efficiency with aluminium sulfate and ferric chloride

Sloboda, Eliane 01 November 2007 (has links)
Existem muitos mananciais usados como fonte de abastecimento de água que apresentam cor verdadeira relativamente alta, devido à presença de substâncias húmicas (SH). Muitas estações de tratamento de água (ETA) apresentam problemas no processo de coagulação decorrentes da presença das SH. Com isso é necessário o uso de pré-oxidantes para reduzir a cor verdadeira da água. Quando emprega-se o cloro como oxidante ocorre a formação de subprodutos halogenados, que são prejudiciais a saúde humana. Para este estudo coletou-se água no Rio Itapanhaú - Bertioga/SP, a qual apresentou cor verdadeira na ordem de 400 uH. Para a extração das SHA empregou-se a resina XAD 8. Os extratos de SHA foram filtrados em membrana com poros de 0,45 µm e após utilizou-se a técnica de ultrafiltração (UF) para o fracionamento do material húmico em diferentes tamanhos moleculares aparente. As frações empregadas na caracterização foram: F1: menor que 0,45 µm, F2: entre 100 kDa e 0,45 µm, F3: entre 30 e 100 kDa, F4: entre 10 e 30 kDa, F5: entre 5 e 10 kDa. As frações foram caracterizadas por meio das técnicas de análise elementar, espectroscopia de ultravioleta/visível, infravermelho e ressonância magnética nuclear de 13C (RMN de 13C). Os resultados mostraram que as frações de menor tamanho molecular aparente (F3, F4 e F5) possuem maior conteúdo de carbonos alifáticos do que carbonos aromáticos e uma porcentagem relativamente alta de oxigênios ligados a grupamentos alquílicos e a ácidos carboxílicos. As frações de maior tamanho molecular aparente (F1 e F2) apresentaram maior grau de condensação de grupamentos aromáticos. No caso dos espectros de RMN de 13C, não foi possível verificar diferenças significativas nas diferentes frações de SHA. Verificou-se picos mais intensos na região de grupos carboxil e alifáticos e menos intenso na região dos aromáticos. Isso indica que nas SHA há maior conteúdo de grupamentos oxigenados e carbonos alifáticos. As amostras de água de estudo foram preparadas com água de poço artesiano e com as frações de diferentes tamanhos moleculares aparentes das SHA (F1: menor que 0,45 µm, F2: entre 100 kDa e 0,45 µm e F3: entre 30 e 100 kDa e F4\': menor que 30 kDa) com cor verdadeira aproximadamente de 100 uH e turbidez em torno de 0,5 uT. Para avaliar a influência dos diferentes tamanhos moleculares aparentes das SHA na eficiência da coagulação foram feitos ensaios em jartest empregando filtração direta descendente. Os coagulantes empregados neste estudo foram, o sulfato de alumínio e cloreto férrico, ambos como produto comercial líquido. Os diagramas de coagulação evidenciaram a influência do tamanho molecular aparente das SHA no processo de coagulação, quando empregou-se os coagulantes sulfato de alumínio e cloreto férrico. Para as águas de estudo preparadas com as frações de menor tamanho molecular aparente, foi necessário maior dosagem de coagulante para se obter remoção da cor aparente da água e mesmo assim, a remoção foi menor. A fração de menor tamanho molecular aparente (F4\') apresenta maior porcentagem de ácidos fúlvicos, e estes apresentam maior quantidade de grupos com carga negativa. Por isso, há necessidade de maior dosagem de coagulante para que ocorra uma eficiente remoção de cor aparente. / Water sources used to supply the public water system frequently have a relatively high true color intensity due to dissolved aquatic humic substances (AHS). In this study, water samples were collected from the Itapanhaú River (Bertioga, SP, Brazil), which exhibited a true color intensity in the order of 300 Hanzen units. XAD-8 resin was used to extract AHS. The AHS extract was filtered through a membrane with 0.45 µm pores, giving fraction F1, and this was separated by ultrafiltration into 4 apparent molecular size fractions of humic material: F2 from 100 kDa to 0.45 µm, F3 from 30 to 100 kDa, F4 from 10 to 30 kDa and F5 from 5 to 10 kDa. The fractions were characterized by elemental analysis and UV/Vis, infra-red (IR) and carbon 13 nuclear magnetic resonance (13C-NMR) spectroscopy. In general, the results showed that the smaller molecular size fractions (F3, F4 and F5) had a higher proportion of aliphatic than aromatic carbon atoms and a relatively high percentage of oxygen atoms bonded to alkyl groups and in carboxylic acids. Conversely, the apparently larger molecules (fractions F1 and F2) showed a higher content of aromatic groups. In the case of the 13C-NMR spectra, no significant differences could be detected among the fractions. There were stronger peaks in the carboxyl group and aliphatic carbon region and weaker peaks in the aromatic region, indicating that in the AHS as a whole, there is a greater content of oxygenated groups and aliphatic carbon atoms. Water from an artesian well was used to prepare experimental samples of the following molecular size fractions of AHS: F1 < 0.45µm, F2 from 100 kDa to 0.45 µm and F3: from 30 kDa to 100 kDa and F4\': < 30 kDa, with true color intensity around 100 Hazen units and turbidity around 5.0 NTU. To assess the influence of the apparent molecular size on the efficiency of coagulation, jar test were carried out, using direct filtration. The coagulants employed were aluminum sulfate and ferric chloride. The coagulation diagrams obtained with these products revealed the effects of the molecular size of the AHS on the coagulation process. For the experimental samples, fractions F3 e F4 \', a greater dose of coagulant was needed to remove the apparent water color around 5.0 Hanzen units and, even then, the amount removed was smaller. F4\' also had a higher proportion of fulvic acids, which exhibited a larger number of negatively-charged groups. For these reasons, a high dose of coagulant is necessary to achieve an efficient removal of apparent color.
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Biofilms de microalgues pour l'élimination des nutriments des eaux usées industrielles / Microalgal biofilms for nutrients removal from industrial wastewater

Moreno Osorio, Jairo 29 October 2018 (has links)
La recherche visait à développer une technologie de biofilm à base de biofilms de microalgues pour le traitement des effluents riches en phosphore en vue de la production de produits de valeur secondaires, tels que la récupération du phosphore.Des recherches fondamentales ont été menées pour sélectionner des souches de microalgues efficaces en termes de traitement efficace des eaux usées et de production de biomasse algale, afin de mettre au point un procédé avec une faible addition d'électricité et de réactifs chimiques. Au total, 21 souches de microalgues ont été sélectionnées et sept souches ont été sélectionnées en fonction de leur taux de croissance. Le taux de croissance et l'efficacité d'élimination des éléments nutritifs de six souches ont été évalués dans différentes conditions de traitement des eaux usées synthétiques. Chlorella vulgaris ACUF_809 a montré une efficacité d'élimination du phosphate supérieure à celle des souches sélectionnées. Chlorella sp. ACUF_802 a également été caractérisé par l'effet des conditions limitant l'azote et le phosphore dans le milieu de croissance. Des expériences en laboratoire ont été effectuées pour évaluer les performances de formation de biofilm sur des tissus. L’activité photosynthétique, le pourcentage de colonisation et la croissance de la biomasse ont été étudiés pour deux Chlorella spp. Les différences dans les performances de formation de biofilm étaient observées entre les souches. Il a été constaté que l’analyse combinée de méthodes optiques non destructives est une méthode efficace pour surveiller les premières étapes du développement d’un biofilm. L'épaisseur moyenne du biofilm (106,37 ± 47 µm) a été mesurée. En outre, la distribution et la localisation des phosphates au cours du développement des biofilms C: pyrenoidosa ACUF_808 et C. vulgaris ACUF_809 ont été examinées au fil du temps, tout en préservant le contexte spatial. En utilisant des mesures physiologiques combinées, des techniques microscopiques, spectroscopiques et spectrométriques de masse ont été déterminées pour déterminer la croissance cellulaire, l'adhésion cellulaire, la performance physiologique, l'élimination des nutriments (phosphate et nitrate) et l'accumulation de phosphate visualisée au niveau des cellules dans les biofilms.La production de biomasse et l'efficacité d'élimination des nutriments par les microalgues Scenedesmus vacuolatus et C. vulgaris ACUF_809 à partir d'eaux usées synthétiques dans un nouveau photobioréacteur (PBR) de biofilm en laboratoire ont été étudiées. Le développement de biofilms sur du tissu de coton a été suivi dans le PBR dans des conditions semi-discontinues pendant 41 jours. S. vacuolatus ACUF_053 a obtenu l’élimination complète des éléments nutritifs et cinq étapes de développement du biofilm ont été identifiées: 1) fixation, 2) formation de biofilm, 3) maturation I, 4) sélection / adaptation et 5) maturation II. En revanche, le développement du biofilm de C. vulgaris ACUF_809 a montré une croissance de la biomasse plus régulière et une efficacité d'élimination constante. Cette recherche offre de nouvelles informations fondamentales dans le domaine de la formation de biofilms de microalgues pouvant être utilisées dans un plus large éventail d'applications scientifiques, notamment la possibilité d'un traitement couplé des eaux usées avec une récupération potentielle du phosphate / The aim of this Ph.D. research was to develop a bench scale microalgae biofilm technology for phosphorus rich effluents treatment toward the production of secondary valuable products, i.e. phosphorus recovery.Fundamental research was conducted to select efficient microalgae strains in terms of successful wastewater treatment and algal biomass production, in order to develop a process with low addition of electricity and chemical reagents. A total of 21 microalgae strains were screened and seven strains were selected according to their growth rate. The growth rate and nutrient removal efficiency of six strains were evaluated under different synthetic wastewater conditions, Chlorella vulgaris ACUF_809 showed superior efficiency of phosphate removal compared with the strains screened. Chlorella sp. ACUF_802 was characterized additionally by the effect of nitrogen and phosphorus limitating conditions in the growth medium. Laboratory scale experiments were done to evaluate the biofilm formation performance on textile fabrics. Photosynthetic activity, colonization percentage and biomass growth were investigated for two isolated Chlorella spp. Diffferences in biofilm formation performance were obswerved between the strains. It was found that combined analysis of non-destructive optical methods is an effective methodology for monitoring the early stages of biofilm development. Biofilm average thickness (106.37 ± 47 µm) was measured. Furthermore, as a promising valuable recovery product, phosphate distribution and localization during C: pyrenoidosa ACUF_808 and C. vulgaris ACUF_809 biofilms development were examined over time and keeping the spatial context unaltered. Using physiology measurements combined to advance microscopic, spectroscopic and mass spectrometric techniques were determined cellular growth, cell adhesion, physiological performance and nutrient (phosphate and nitrate) removal and visualized phosphate accumulation at single-cell level within the biofilms.Biomass production and nutrient removal efficiency by the microalgae Scenedesmus vacuolatus and C. vulgaris ACUF_809 from synthetic wastewater in a new laboratory configuration biofilm photobioreactor (PBR) was studied. Biofilm development on cotton fabric was followed in the PBR under semi-batch conditions during 41 days. Complete nutrient removal was obtained by S. vacuolatus ACUF_053 and five stages in the development of the biofilm were identified: 1) attachment, 2) biofilm formation, 3) maturation I, 4) selection/adaptation and 5) maturation II. In contrast, C. vulgaris ACUF_809 biofilm development showed a more regular biomass growth and constant removal efficiency. This research offers novel fundamental information in the field of microalgae biofilms formation with a scope for a wider range of scientific applications, including the possibility of coupled wastewater treatment with potential recovery of phosphate
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Impacts hydromorphologiques et sédimentaires du décloisonnement de l'Yerres : identification, quantification, spatialisation / Effects of small dam lowering on fluvial geomorphology in the Yerres River, France : processes identification, quantification and mapping

Michler, Luc 16 November 2018 (has links)
Le bassin-versant de l’Yerres (1030 km²) est localisé au sud-est de l’agglomération parisienne et s’étend sur le plateau de Brie au relief très modéré. Ses caractéristiques physiographiques et sa situation géographique confèrent au lit de l’Yerres une très faible pente (0,009 %), entravée par une forte segmentation longitudinale (0,5 ouvrage/km). Cette dernière est ancienne (moulins hydrauliques) ou plus récente (barrages mobiles) et s’est généralement accompagnée d’une chenalisation du lit. Les perturbations engendrées par ces ouvrages et les modifications morphologiques du lit ont provoqué une altération considérable de la dynamique fluviale et de la diversité morphologique du cours d’eau. Dans ce contexte d’un cours d’eau de faible énergie (< 10 W/m²) fortement artificialisé, notre recherche s’est attachée à évaluer l’efficience de l’effacement de trois barrages à clapets mobiles (h < 3 m) sur la restauration hydromorphologique du lit. À cet effet, des suivis topographique et sédimentologique à haute résolution spatio-temporelle ont été mis en œuvre entre 2015 et 2017 afin d’appréhender les réajustements du système fluvial à partir de l’évolution des caractéristiques morphologiques et granulométriques de son lit. Ils ont dévoilé un remblaiement alluvial se produisant principalement sous la forme de banquettes latérales de vases, à l’exception du site d’Ozouer (le plus en amont). Sur ce dernier le remblaiement alluvial sableux est plus généralisé. À la suite des abaissements hivernaux, celui-ci a fait l’objet des changements morphologiques les plus prononcés, caractérisés par une érosion marquée du fond du lit de la retenue et un faible alluvionnement en aval. Les réajustements morphologiques restent toutefois modérés compte tenu des débits exceptionnellement forts sur la période de suivi et semblent par ailleurs être subordonnés à la présence de substrats sableux. Ainsi, si les abaissements améliorent indubitablement les conditions hydro-éco-morphologiques (i.e. la diversité des faciès d’écoulement), la restauration physique du lit fortement dégradé de l’Yerres se limite au rétablissement du transport du matériel de fond sableux. / The Yerres catchment (1030 km²) is located at the southeast border of the Paris conurbation and spreads on the low relief Brie Plateau. Topographical characteristics and geographical location provide the Yerres River with a very low gradient (0,009 %) and a high longitudinal partitioning (0,5 dam/km). Cross-structures are either ancient (medieval watermills) or more recent (mobile dams) and often associated with river channelling. Dam perturbation on sediment fluxes and bed morphological modifications have led to a significant degradation of the river fluvial dynamic and morphological diversity. In this context of a much artificialized low-energy river (< 10 W/m²), we aimed at assessing the efficiency of three mobile dam (h < 3 m) lowering on bed hydromorphological restoration. For that purpose, high spatial and temporal resolution monitoring of bed topography and sediment-size were carried out between 2015 and 2017, in order to document fluvial system adjustment to dam lowering through morphological and grain-size change. Before dam lowering, fine sediment had mainly deposited in channel margins forming mud banks, except for Ozouer impoundment (the more upstream study site). For the latter, sand sedimentation had been extended to the whole channel width. After dam lowering, it also experienced the more pronounced morphological change, characterised by significant bed erosion upstream and little bed aggradation downstream. However, morphological response to dam lowering remained moderate given the high discharges over the monitoring period. Channel adjustments also appeared to be linked to sand-bed. Thus, while dam lowering undoubtedly improve hydro-eco-morphological conditions (i.e. flow facies diversity), physical restoration of the highly degraded Yerres riverbed is restricted to the sand bed material transport restoration.
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Effects of selenium in the intracellular peroxide-removal system

Bian, Weipeng 01 December 2011 (has links)
No description available.

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