• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 107
  • 95
  • 43
  • 17
  • 15
  • 15
  • 15
  • 15
  • 15
  • 15
  • 9
  • 7
  • 6
  • 6
  • 5
  • Tagged with
  • 360
  • 360
  • 84
  • 64
  • 61
  • 53
  • 39
  • 38
  • 30
  • 27
  • 27
  • 24
  • 23
  • 23
  • 20
  • 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.
91

Processing of Biodiesel Fuel By-Products into Environmentally Friendly Materials / Biodyzelino gamybos šalutinių produktų perdirbimas į aplinkai draugiškus produktus

Gumbytė, Milda 21 April 2011 (has links)
Effective biocatalysts for the processes of the esterification of free fatty acids with methanol and technical-grade glycerol were selected and optimal conditions of biocatalysis were established. Principle technological design of free fatty acids esterification with methanol and technical-grade glycerol was developed, which can be applied by biofuel producers and other interested enterprises. The formulations of liquid fuel emulsions containing technical-grade glycerol were developed and principle technological design for the production of these emulsions was suggested. Optimal composition of biofilms containing technical-grade glycerol and deoiled rapeseed cake was determined, on the basis of which the industrial scale production of biodegradable composites can be implemented. / Vykdant tyrimus, parinkti efektyvūs biokatalizatoriai ir nustatytos optimalios laisvųjų riebalų rūgščių esterinimo metanoliu ir techniniu gliceroliu taikant biotechnologinį metodą sąlygos. Sukurtos principinės laisvųjų riebalų rūgščių esterinimo metanoliu ir techniniu gliceroliu technologijos, kurias galėtų diegti biodyzelino gamybos ar kitos suinteresuotos įmonės. Sukurta skystojo kuro emulsijų, į kurių sudėtį įeina techninis glicerolis receptūra, parengta principinė technologija šių emulsijų gamybai. Nustatyta optimali bioskaidžių plėvelių, sudarytų iš techninio glicerolio ir nuriebalintų rapsų išspaudų, formavimo mišinio sudėtis, kuria remiantis biologiškai skalių kompozitų gamyba gali būti diegiama pramonėje.
92

Utilisation of bagasse for the production of C5- and C6- sugars.

Trickett, Richard Charles. January 1982 (has links)
Surplus sugarcane bagasse, estimated at a maximum of 0,9x106 tons/year, represents an annual renewable resource which is readily available at the mill site and is a suitable potential source of alternative fuels and chemical feedstocks. This work contains an extensive literature survey which covers the production of C5- and C6- sugars from lignocelluloses by chemical hydrolysis and the pretreatment of cellulosic materials for enzymatic hydrolysis of the cellulose fraction. This survey was then used to determine the final direction of this research into the utilisation of bagasse for the production of fermentable sugars. It was decided that research should be directed at the dilute acid hydrolysis of the bagasse hemicellulose fraction to determine whether this fraction could be selectively hydrolysed from the complex lignocellulose structure and to obtain xylose yields under different hydrolysis conditions. Acids, especially acetic acid, are liberated from bagasse by steaming at elevated temperatures. In this acid medium the hemicelluloses are hydrolysed and become soluble. Autohydrolysis tests on whole bagasse indicate that hemicellulose hydrolysis becomes significant at temperatures above 140°C. However, the autohydrolysis liquor would still require dilute mineral acid hydrolysis to convert the pentose oligomers to their monomeric forms. Dilute sulphuric and batch hydrolysis of whole bagasse hemicellulose has thus been investigated at a solid to liquid ratio of 1:15 over the following temperature and acid concentrations ranges : 80° to 150°C and 3 to 40 g/l acid. Xylose, glucose, furfural and acetic acid formation and sulphuric acid consumption were monitored during these hydrolyses. Hemicellulose hydrolysis to produce mainly xylose is readily achieved over the entire range of acid hydrolysis conditions tested with little removal of the other bagasse components (lignin and cellulose). At the upper end of the temperature range acid concentrations below 20 g/l are sufficient for hemicellulose hydrolysis due to the effect of temperature on reaction rate. The bagasse hemicellulose consists of two fractions, an easily hydrolysable portion containing 165 mg of potential xylose/g bagasse and a resistant fraction containing 105 mg of potential xylose/g bagasse. A first order reaction model has been developed using the batch acid hydrolysis results. It is based on two hemicellulose fractions reacting simultaneously to give a common product (xylose) and predicts total xylose yield as a function of hydrolysis time for a given set of hydrolysis conditions. The encouraging xylose yields obtained during the batch hydrolyses led to the design of a continuous hydrolysis reactor to process bagasse at low liquid to solid ratios to determine whether xylose yields similar to the batch hydrolysis yields could be obtained at the same hydrolysis conditions. The continuous hydrolyses showed that for the conditions tested the xylose yields are unaffected by the decrease in liquid to solid ratio (down to 3,6:1) and it would appear that reactor performance is still controlled by reaction kinetics. A number of reactor configurations for the industrial production of pentoses from bagasse hemicelluloses are also proposed. / Thesis (M.Sc.)-University of Natal. Durban, 1982.
93

Fenolni potencijal uljanih pogača / Polyphenol potential of oil cakes

Krimer Malešević Vera 25 August 2016 (has links)
<p>U okviru disertacije ispitana je mogućnost eksploatacije nusproizvoda (nastalih tokom procesa hladnog presovanja ulja) kao izvora prirodnih fenolnih kiselina. Odabir je obuhvatio uzorke uljane tikve, crnog kima, lana i nara. Radi oslobađanja vezanih fenolnih kiselina i u cilju procene njihovog ukupnog sadržaja i distribucije (u čvrstim uzorcima), primenjena je alkalna hidroliza sa dodatkom L-askorbinske kiseline i EDTA. Dobijeni rezultati pokazuju da se sve analizirane pogače mogu se koristiti za dobijanje vrednih fenolnih kiselina, pri čemu raspodela fenolnih kiselina zavisi od vrste uljane pogače. Koncentracija slobodnih fenolnih kiselina se pokazala značajnom za pogaču uljane tikve, estarski vezanih za pogače nara i lana, a nerastvornih-vezanih za pogače crnog kima i nara. Od svih analiziranih uzoraka kora nara je sadržala najvi&scaron;e estarski vezanih fenolnih kiselina zahvaljujući veoma visokom sadržaju galne kiseline. Nakon određivanja fenolnih kiselina u nusproizvodima, analiza glavnih komponenti (PCA) je omogućila razdvajanje biljnih uzoraka u grupe prema poreklu i smanjila broj fenolnih kiselina neophodnih za njihovu karakterizaciju, &scaron;to može imati potencijalnu primenu u skriningu fenolnih kiselina i određivanju kvaliteta/autentičnosti uljarica i njihovih nusproizvoda.</p> / <p>Within the thesis, the possibility of by-products (formed during the process of cold oil pressing) exploitation as a source of natural phenolic acids was examined. Selection of the samples included pumpkin, black cumin, flax and pomegranate. For the purpose of bonded phenolic acids release and for the total phenolic acids content and distribution (in the solid samples) assessment, the alkaline hydrolysis with the addition of L-ascorbic acid and EDTA was employed. The results show that all analyzed cakes can be used to obtain valuable phenolic acids, while the distribution of phenolic acids depends on the type of oil cakes. The concentration of free phenolic acids proved to be significant for a pumpkin oil cake, ester for pomegranate and flax oil cakes, and insoluble-bound for black cumin and pomegranate oil cakes. Of all analyzed samples, pomegranate hull contains the highest content of ester-linked phenolic acids, due to a very high content of gallic acid. After phenolic acids determination in the by-products, principal components analysis (PCA) allowed the separation of plant samples in groups according to origin and reduced the number of phenolic acids necessary for their characterization, which may have potential application in the screening of phenolic acids and determining the quality/authenticity oilseeds and their by-products.</p>
94

Evaluating the feasibility of converting crude tall oil and tall oil fatty acids into biofuel

Ngcobo, Nkosinathi Cedrick January 2011 (has links)
Submitted in the fulfillment of the requirements for the degree of Master of Technology, Durban University of Technology, Durban, South Africa, 2011. / The main objective of this study was to evaluate the feasibility of conversion of crude tall oil and tall oil fatty acids into biodiesel. During the Kraft pulping process, Crude Tall Oil originates as tall oil soap, which is separated from recovered black liquor. The soap is then converted to Crude Tall Oil by acidulation with sulphuric acid. The Crude Tall Oil is then fractionated by distillation to produce tall oil fatty acids (TOFA), rosin and pitch. There were a number of conversional methods that were considered but proved to be inappropriate. A base-catalyzed method was inappropriate with due to the high free fatty acid content on the feedstock, and the acid-base catalyzed method was inappropriate due to the long reaction times and large excess of methanol required. An enzyme based conversion method was also found to be inappropriate because of the high price attached to the purchasing of the enzymes and the stability of the enzyme. A procedure of choice was the supercritical methanol treatment, due to the fact that it requires no separate catalyst. A procedure was developed for both the feedstocks (i.e. crude tall oil and tall oil fatty acids) using the supercritical methanol treatment. In supercritical methanol treatment, feedstock and methanol were charged to a reactor and were subjected to temperatures and pressures beyond the critical point of methanol (Tc = 240 °C, Pc = 35 bar). The maximum biodiesel yield obtained from Crude tall oil was 66% and was 81% for the tall oil fatty acids that was produced in a single stage process. The temperature and methanol to feedstock ratio effects was also found to yield a maximum biodiesel yield at 325°C and 40:1 respectively. A 20 minutes reaction time was found to be appropriate for the maximum yield of biodiesel. The final biodiesel produced was also evaluated against a commercial biodiesel product and its parameters measured. The biodiesel resulting from the tall oil fatty acid yielded parameters that were acceptable according to ASTM D6751 specifications for biodiesel. The biodiesel produced from the crude tall oil did not meet the ASTM D6751 specification, and this was mostly attributed to the presence of unsaponifiables which hindered the conversion of oil into biodiesel. / M
95

Production of levulinic acid from sugarcane bagasse

Mthembu, Lethiwe Debra January 2016 (has links)
Submitted in fulfillment of the academic requirements for the Masters in Applied Sciences (Chemistry), Durban University of Technology, Durban, South Africa, 2016. / The main aim of this work was to produce levulinic acid (LA) from sugarcane bagasse (SB) and since there is approximately 3 000 000 tons of bagasse produced per annum by 16 factories that are located on the north coast of Kwa-Zulu Natal, after the extraction of sugar. For this project fructose was firstly used for the production of LA, thereafter SB was used to produce LA. Cellulose was extracted from sugarcane bagasse using two types of pre-treatments namely (i) acid-alkali pre-treatment and (ii) liquid hot water (LHW). In the latter method acid hydrolysis and enzymatic hydrolysis was used to hydrolyse cellulose to glucose. For the acid-alkali pre-treatment work, two types of bagasse was used namely (i) mill-run bagasse and (ii) depithed bagasse and for the LHW a mill-run bagasse (pellets form) was used. In both pre-treatment methods the glucose solution was then acid catalysed by two different acids (i) an environment friendly acid, methanesulfonic acid (MSA) and (ii) sulphuric acid, producing levulinic acid. The results showed that MSA and sulphuric acid produced almost the same yield of LA but, MSA is preferred for the production of LA since it is less toxic and less corrosive than sulphuric acid. / M
96

Modélisation prédictive de la formation de sous-produits de chloration dans les ambiances confinées. Applications aux piscines couvertes / Modelling of chlorination by-products formation in indoor swimming pools

Tsamba, Lucie 25 September 2018 (has links)
La formation des sous-produits de chloration dans les piscines couvertes dépend de nombreux paramètres cinétiques et hydrauliques. Cette étude propose le développement d’un modèle de prédiction de la formation de certains sous-produits de chloration et de leur transfert dans l’air. La construction du modèle est basée sur le couplage de constantes cinétiques déterminées à l’échelle laboratoire avec des modèles hydrauliques caractérisant les écoulements dans le bassin. Afin de calibrer et de valider les modèles, un bassin expérimental à l’échelle 1/10ème a été mis en place. Par ailleurs, une méthode de mesure des concentrations des sous-produits de chloration dans l’eau et dans l’air par Membrane Inlet Mass Spectrometry a été évaluée. La représentativité et la reproductivité des expériences réalisées sur le bassin ont été étudiées. À l’échelle laboratoire, les constantes cinétiques de consommation du chlore, de formation du chloroforme et de formation du dichloroacétonitrile par chloration du Body Fluid Analogue utilisé pour mimer les apports organiques des baigneurs ont été déterminées. Le comportement hydraulique du bassin a été modélisé par une série de réacteurs idéaux. Cette modélisation a été validée par la réalisation d’expériences de traçage sur le bassin expérimental. Enfin, les constantes de transfert eau-air des sous-produits de chloration volatils ont été déterminées et comparées avec plusieurs modèles de la littérature. Les résultats obtenus montrent que les modèles permettent de prévoir de façon satisfaisante l’évolution des paramètres modélisés. Le bassin expérimental constitue également un outil prometteur pour la calibration de modèles et l’évaluation de solutions de traitement. / The formation of chlorination by-products in swimming pools depends on many kinetic and hydraulic parameters. This study presents the development of a predictive model for the formation of chlorination by-products as well as their water-to-air transfer. The model is based on the coupling of kinetic rates determined in batch with hydraulic models which describe the flows in the basin. A pilot pool unit has been built in order to collect experimental data for the calibration and validation of the models. Moreover an analytical method by Membrane Inlet Mass Spectrometry has been assessed. The representativeness and the reproducibility of experiments performed on the pilot pool unit have been described. Kinetic rates for chlorine consumption, chloroform formation and dichloroacetonitrile formation have been studied at lab scale, based on chlorination experiments of a Body Fluid Analogue, a mix of chemicals which reproduces human intakes in swimming pools. The hydraulic behavior of the basin has been modeled by a series of ideal reactors. The model has been validated by comparison with tracer-based experiments. Finally, water-to-air transfer rates have been determined and compared with models from the literature. The modeled parameters were satisfactorily modeled. Moreover the pilot pool unit has been demonstrated to be useful in calibrating models or in assessing treatment solutions.
97

Análise econômica da utilização de resíduos agroindustriais em painéis de partículas: produção à base bagaço de cana-de-açúcar / Economic analysis of the use of agro-industrial residues in the production of particle board panel based on the use of sugarcane bagasse

Rodrigues, Rinaldo 11 December 2018 (has links)
Um projeto de investimento foi desenvolvido com o objetivo de avaliar a viabilidade econômica da utilização de resíduo agroindustrial na produção de painéis de partículas (MDP). A unidade de produção foi inicialmente concebida para a utilização em pesquisas na Faculdade de Engenharia de Alimentos da Universidade de São Paulo - Departamento de Engenharia de Biossistemas, sendo que esta tese buscou avaliar a viabilidade econômico-financeira do empreendimento. Foram avaliados dezesseis cenários nos quais utilizou-se, na confecção dos painéis, o bagaço de cana-de-açúcar e resinas à base de ureia-formaldeído e poliuretana à base de óleo de mamona, em diferentes proporções. Os primeiros doze cenários foram definidos a partir da variação de preços dos produtos vendidos e das variações dos desembolsos decorrentes da utilização das diferentes resinas e porcentagem dessas na confecção dos painéis. Para esta avaliação inicial utilizou-se como fonte de financiamento do empreendimento o capital próprio. Nos quatro últimos cenários foram avaliados os efeitos da fonte de financiamento do empreendimento, via operação de crédito junto ao Banco Nacional de Desenvolvimento Econômico e Social (BNDES). Para estes cenários foram avaliados aqueles que apresentaram viabilidade econômica na etapa inicial da avaliação. O método de análise econômica utilizado foi o de Fluxo de Caixa (Cash Flow) e as técnicas aplicadas foram: Payback Simples, Payback Descontado, Valor Presente (VPL) e Taxa Interna de Retorno (TIR). O empreendimento mostrou-se economicamente viável estritamente para os cenários nos quais foram utilizados os preços médios e máximos projetados e com a utilização de resina ureia-formaldeído. A utilização de financiamento via operação de crédito junto ao BNDES não melhorou os índices apurados, porém mostrou-se alternativa para viabilizar a execução do empreendimento. / A study of an investment project was developed with the objective of evaluating the economic viability of agro industrial residue application (sugar cane bagasse) in the production of particle board (MDP). The constructed building production unit was initially designed for researches at the Department of Food Engineering of the University of São Paulo - Department of Biossystems Engineering, and this thesis attempted to evaluate the economic-financial viability of the project. Sixteen scenarios were used, where sugar cane bagasse and resin based on urea-formaldehyde and polyurethane based on castor oil were applied in the preparation of the panels in different proportions. The first twelve scenarios were defined based on the variation of the sold products\' prices and the variations of the payoff resulting from the use of the different resins and their percentage in the preparation of the panels. For the initial evaluation the investment was financing from own researcher\'s capital. In the last four scenarios, the effects of the financing source of the project were evaluated through a credit operation with National Bank for Economic and Social Development (BNDES). For these scenarios, the presented economic feasibility was evaluated on the initial stage of evaluation. The method of economic analysis used was Cash Flow and the applied techniques were: Simple Payback, Discounted Payback, Net Present Value (NPV) and Internal Rate of Return (IRR). The project showed economically feasible strictly for the scenarios in which the average and maximum prices projected used urea-formaldehyde resin. The use of financing through a credit operation along with BNDES bank did not improve the established rates, but it was an alternative to make the accomplishment of the project feasible.
98

Produção e imobilização de lipases produzidas pelo fungo endofítico Cercospora kikuchii para aplicações biotecnológicas / Production and immobilization of lipases produced by the endophytic fungus Cercospora kikuchii for biotechnological applications

Silva, Tales Alexandre da Costa e 16 April 2014 (has links)
O objetivo desse trabalho foi avaliar estratégias de imobilização de lipases produzidas pelo fungo endofítico Cercospora kikuchii através do uso de suportes não convencionais (subprodutos agroindustriais e quitosana). Investigou-se o uso de equipamentos de secagem (estufa, leito de jorro, leito fluidizado, liofilizador e \"spray dryer\") para desidratação dos derivados imobilizados obtidos. A imobilização por ligação covalente, usando glutaraldeído, epicloridrina e metaperiodato de sódio como agentes ligantes, apresentou valores para retenção da atividade enzimática superiores à imobilização por adsorção e encapsulação. Nos ensaios de imobilização utilizando glutaraldeído e secagem em leito de jorro, os melhores valores obtidos foram para a celulose microcristalina com retenção da atividade enzimática de 179,1%, seguido da casca de arroz 173,9%. A palha de milho foi o melhor suporte na imobilização covalente e secagem em estufa, com retenção de mais de 100% da atividade enzimática inicial. Na secagem por liofilização houve destaque para a casca de arroz (163,6%) seguida de palha de milho (157,2%) e cana de açúcar (154,6%). Utilizando quitosana como suporte e secagem em leito fluidizado, o valor para a retenção da atividade enzimática foi de 93,9% empregando-se o glutaraldeído como agente ligante. Na secagem do sistema quitosana-lipase em estufa a retenção da atividade enzimática foi de 68,2% e para secagem por liofilização esse valor foi superior a 80,0%. Realizou-se a caracterização dos materiais utilizados como suportes e estes apresentaram área superficial relativamente alta, elevada porosidade e estrutura constituída de macroporos. Estas características foram importantes por proporcionar a obtenção da enzima imobilizada com alta retenção da atividade catalítica. Alguns parâmetros bioquímicos e cinéticos da lipase na forma livre foram diferentes da lipase imobilizada. A alteração mais evidente foi a afinidade ao substrato (Km), que se mostrou dependente do protocolo de imobilização utilizado. Avaliou-se o potencial de aplicação biotecnológica dos derivados imobilizados que apresentaram maior retenção da atividade enzimática. Para a lipase imobilizada em casca de arroz o rendimento de transesterificação (produção de biodiesel) foi superior a 96,0% após 72 horas de reação enquanto que para as microesferas de quitosana esse valor foi atingido após 120 horas. Os produtos obtidos da transesterificação do óleo de coco estão de acordo com a especificação da Agência Nacional de Petróleo (ANP). Na avaliação da atividade de esterificação, a máxima concentração de butirato de butila foi obtida após 6 horas de reação, correspondendo a uma taxa de conversão de aproximadamente 99,0%, quando utilizou-se quitosana como suporte. Para o uso da casca de arroz, a máxima concentração de butirato de butila foi obtida também após 6 horas de reação, correspondendo a uma taxa de conversão de 92,5%. Este trabalho demonstrou que suportes de baixo custo permitiram a obtenção de derivados imobilizados com características semelhantes àqueles obtidos com o uso de polímeros sintéticos, os quais apresentaram excelente potencial para síntese de biodiesel e de butirato butila. / The objective of this study was to evaluate strategies for immobilization of lipases produced by the endophytic fungus Cercospora kikuchii through the use of unconventional supports (agroindustrial by-products and chitosan). The use of different drying process (oven, spouted bed, fluidized bed, freeze drying and spray drying) for dehydration of immobilized derivatives obtained by adsorption, covalent binding and encapsulation was investigated. The covalent immobilization (using glutaraldehyde, epichlorohydrin and sodium metaperiodate as crosslinking agents) was the best process for the enzymatic activity retention. For covalent immobilization using glutaraldehyde and spouted bed drying, the best values were obtained for microcrystalline cellulose with enzymatic activity retention of 179.1%, followed by rice husk and corn straw with 173.9% and 169.8%, respectively. Corn stover was the best support in the covalent immobilization and oven drying, with retention 100.0% of the initial enzyme activity. For freeze-drying rice husk was the best support (163.6%) followed by corn stover (157.2%), sugar cane bagasse (154.6%) and corn cob (129.5%). Utilizing chitosan as support and fluidized bed drying, the value for the retention of enzymatic activity was 93.9% employing glutaraldehyde as activating agent. For chitosan-lipase drying using oven, the enzymatic activity retention was 68.2% and using freeze-drying the retention of enzymatic activity was higher than 80.0%. The support characterization was carried out and showed high surface area, high porosity and macropore structure. These characteristics were important for providing immobilized derivatives with high catalytic activity retention. Some biochemical and kinetic parameters of lipase in free form were different from the immobilized lipase. The most important changes was the substrate affinity (Km) which was dependent of immobilization protocol used. The last experimental part of this study was the biotechnological applications of the best immobilized derivatives produced. For the immobilized lipase onto rice husk the transesterification yield (biodiesel production) was above 96.0% after 72 hours of reaction while for the use of chitosan microspheres this value was reached after 120 hours. The viscosity values for the biodiesel samples are in accordance with specifications recommended by Brazilian Petroleum Agency (ANP) to be used as biofuel. The immobilized derivatives catalytic power was measured in terms of esterification activity too. The maximum concentration for butyl butyrate was obtained after 6 hours, corresponding to conversion rate of 99.0% when chitosan was used as support. Using rice husk, the maximum butyl butyrate concentration was obtained after 6 hours of reaction, corresponding to conversion rate of 92.5%. This work demonstrated that cheap supports are biocompatible with lipases, rendering immobilized derivatives with characteristics similar to or better than those previously obtained with synthetic polymers. The immobilized derivatives showed excelente potential for biodiesel production and butyl butyrate synthesis.
99

Investigação da toxicidade, tratabilidade e formação de subprodutos tóxicos em efluentes clorados de lagoas de estabilização com e sem pós-tratamento. / Investigation of toxicity, treatability and toxic disinfection by-products formation in chlorinated stabilization ponds effluents with and without post-treatment.

Léo, Luís Fernando Rossi 16 April 2008 (has links)
Entre as principais dificuldades que os sistemas de tratamento de esgotos domésticos compostos por lagoas de estabilização enfrentam para atender as exigências impostas pela Resolução CONAMA 357/2005 podem se destacar as concentrações elevadas de nitrogênio amoniacal, fósforo e coliformes fecais e totais. Estes últimos, quando os sistemas utilizam corpos receptores classe 2 ou 3 geram a necessidade de desinfecção. Dentre as diversas tecnologias disponíveis para a desinfecção dos esgotos, a cloração é bastante atrativa pelo custo reduzido, em relação às outras tecnologias, bem como pela elevada experiência que as companhias e municipalidades possuem neste tipo de sistema, advinda dos sistemas de tratamento de água. Dentre os sistemas de cloração, o uso de hipoclorito de sódio torna-se interessante pela segurança, simplicidade das instalações e de operação. A desvantagem do uso deste tipo de sistema se dá na possibilidade da formação de subprodutos tóxicos, dentro os quais pode-se destacar os trihalometanos (THMs) e os ácidos haloacéticos (AHAs), porém esta formação pode ser teoricamente reduzida pela presença de elevadas concentrações de nitrogênio amoniacal nos efluentes destes sistemas, por sua reação preferencial com o cloro, na formação de cloraminas. Outras possibilidades de redução na formação é reduzir a concentração de precursores, reduzir a dosagem de cloro e utilizar método de descloração dos efluentes após a desinfecção. Este trabalho, ambientado no desenvolvimento das pesquisas do Edital 4 do PROSAB/FINEP (Programa Nacional de Pesquisa em Saneamento Básico), desenvolveu testes de desinfecção em efluentes de lagoas anaeróbias e facultativas utilizando como desinfetante hipoclorito de sódio, em dosagens de 8,0 mgCl/L e 12,0 mgCl/L. Desenvolveu também testes de desinfecção com efluentes anaeróbios e facultativos pós-tratados por meio de coagulação/floculação/sedimentação e coagulação/floculação/flotação com ar dissolvido, com dosagens de 2,0 mgCl/L e 4,0 mgCl/L. Para todos os testes de desinfecção foram realizados também testes de descloração das amostras. Desta forma foi possível estudar, dentro de uma faixa limitada, as possibilidades de reduzir a formação de subprodutos tóxicos na desinfecção de efluentes de lagoas de estabilização com hipoclorito de sódio. Nas amostras foram determinados por meio de cromatografia gasosa as concentrações dos THMs e AHAs. Por meio das metodologias do Standard Methods 20th Edition foram realizadas as análises físico-químicas dos parâmetros pH, temperatura, DQO, DBO, Ntotal, N-NH3, NTK, cloro livre, cloraminas, coliformes e outros microrganismos indicadores. A formação de THMs se mostrou bastante pequena, em média abaixo dos 20,0 µg/L em todos os testes, aparentemente devido às elevadas concentrações de N-NH3, da ordem de 30,0 mg/L. O mesmo não ocorreu com os AHAs. Em muitos testes a concentração encontrada de AHAs totais superou o padrão de 80,0 µg/L preconizados pela USEPA para água potável, e aqui adotado como padrão comparativo. A descloração reduziu em média 52% a concentração de AHAs nos testes, colocando quase todas as amostras dentro do padrão de 80,0 µg/L. Os bioensaios mostraram que a presença de cloro livre nas amostras eleva a toxicidade aguda em Daphnia similis provocada pelos efluentes e que a cloração seguida de descloração produz efluentes com toxicidade inferior à toxicidade dos efluentes apenas clorados e toxicidade também inferior àquela dos efluentes sem cloração. / The main difficulties that the stabilization ponds for sewage treatment systems face to meet the requirements imposed by CONAMA Resolution 357/2005 can highlight the high concentrations of ammonia nitrogen, phosphorus and fecal and total coliform. When the systems use receivers water bodies Class 2 or 3 generate the need for disinfection. Among the different technologies available for the disinfection of sewage, the chlorination is very attractive at reduced cost compared to other technologies, as well as the high experience that companies and municipalities have in this type of system, because the water treatment systems. About the chlorination technologies, the use of sodium hypochlorite becomes interesting for security, simplicity of installation and operation. The disadvantage of using this type of system is given the possibility of formation of toxic by-products, within which you can highlight the trihalomethanes (THMs) and haloacetic acids (AHAs), but this formation can theoretically be reduced by the presence of high concentrations of ammoniacal nitrogen in effluents of these systems, for its preferential reaction with the chlorine in the formation of cloraminas. Other possibilities for reducing the training is to reduce the concentration of precursors (organic matter), reduce the dosage of chlorine and use dechlorination method after disinfection. This work, developed in PROSAB / FINEP (National Program for Research on Sanitation) research announcement number 4, developed tests for disinfection of anaerobic and facultative ponds effluents using sodium hypochlorite as a disinfectant, in concentrations of 8.0 mgCl/L and 12.0 mgCl/L. Were also developed tests for disinfection with anaerobic and facultative ponds effluents post-treated by coagulation / flocculation / sedimentation and coagulation / flocculation / flotation with dissolved air, with concentrations of 2.0 mgCl/L and 4.0 mgCl/L. For all of disinfection tests were also conducted dechlorination tests. This made it possible to study the possibilities of reducing the formation of toxic byproducts of the stabilization ponds effluents disinfection with sodium hypochlorite. The THMs and AHAS concentrations were determined by gas chromatography. Through the methods of Standard Methods 20th Edition analyses were carried out physical-chemical parameters of pH, temperature, COD, BOD, total nitrogen, ammoniacal nitrogen, total Kjeldhal nitrogen, free chlorine, chloramines, coliforms and other indicator microorganisms. The formation of THMs was very low, on average below the 20.0 µg/L in all tests, apparently due to high concentrations of NH3-N, the order of 30.0 mg/L. The same did not occur with AHAs. In many tests found concentrations of AHAs exceeded the standard of 80.0 µg/L recommended by the USEPA for drinking water. Dechlorination reduced 52% of AHAs concentrations, in average. Bioassays showed that the presence of free chlorine in the samples increase the acute toxicity in Daphnia similes. Chlorination followed by dechlorination produces effluents with less toxicity than the toxicity of chlorinated and effluent without chlorination.
100

Recycling of physically refined deodorizer distillate into useful products.

January 2005 (has links)
Wong Yiu Kwong Kenji. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 189-204). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iv / Contents --- p.vi / List of Figure --- p.xii / List of Table --- p.xvi / Introduction --- p.1 / Chapter 1.1. --- Vegetable oil production and their refining --- p.1 / Chapter 1.1.1. --- Vegetable oil production and consumption --- p.1 / Chapter 1.1.2. --- Vegetable oil refining steps --- p.2 / Chapter 1.2. --- Chemical refining vs. Physical refining --- p.3 / Chapter 1.2.1. --- Differences between chemical and physical refining --- p.3 / Chapter 1.2.2. --- Pros and Cons of the two refining practices --- p.4 / Chapter 1.2.3. --- Adoption criteria and popularity of refining methods --- p.6 / Chapter 1.3. --- Deodorizer distillate (DODc vs. DODp) --- p.7 / Chapter 1.3.1. --- Compositions of DODc and DODp --- p.7 / Chapter 1.3.1.1. --- Squalene --- p.9 / Chapter 1.3.1.2. --- Tocopherols --- p.10 / Chapter 1.3.1.3. --- Phytosterols --- p.12 / Chapter 1.3.2. --- Usages of DODc and DODp and purification of phytochemicals --- p.14 / Chapter 1.3.2.1. --- Concentration of tocopherols and phytosterols --- p.15 / Chapter 1.3.2.2. --- Purification of tocopherols and phytosterols --- p.18 / Chapter 1.3.3. --- Alternative usage of DODp --- p.20 / Chapter 1.4. --- Usages of fatty acid mono-alkyl esters --- p.20 / Chapter 1.4.1. --- As intermediate for Bio-surfactants --- p.21 / Chapter 1.4.2. --- Bio-lubricants --- p.21 / Chapter 1.4.3. --- Biodiesel --- p.22 / Chapter 1.5. --- Production of biodiesel and its advantages and disadvantages --- p.23 / Chapter 1.5.1. --- Production of biodiesel --- p.23 / Chapter 1.5.1.1. --- Use of catalyst --- p.25 / Chapter 1.5.1.2. --- "Molar ratios between methanol, sample and catalyst" --- p.26 / Chapter 1.5.1.3. --- Temperature and pressure --- p.27 / Chapter 1.5.1.4. --- Biodiesel purification --- p.27 / Chapter 1.5.2. --- Pros and Cons of using biodiesel --- p.27 / Chapter 1.5.3. --- Sources of Biodiesel production --- p.29 / Chapter 1.6. --- Proposed strategy --- p.33 / Chapter 1.6.1. --- Summary of the literatures reviewed --- p.33 / Chapter 1.6.2. --- Hypothesis making --- p.34 / Chapter 1.6.3. --- Aim and objectives --- p.34 / Chapter 1.6.4. --- Significance of study --- p.34 / Chapter 1.6.5. --- Study scheme --- p.35 / Chapter 2. --- Methodology --- p.36 / Chapter 2.1. --- Characterization of physically refined Deodorizer Distillate (DODp) --- p.36 / Chapter 2.1.1. --- Collection & storage of DODp --- p.36 / Chapter 2.1.2. --- Determination of fatty acids composition --- p.36 / Chapter 2.1.3. --- Determination of acid number (ASTM D 664) --- p.37 / Chapter 2.1.4. --- Determination of free fatty acid contents --- p.38 / Chapter 2.1.5. --- Determination of unsaponifiable matter content --- p.38 / Chapter 2.1.6. --- "Determination of squalene, tocopherol and phytosterol contents." --- p.39 / Chapter 2.1.7. --- Deduction of natural glyceride contents --- p.40 / Chapter 2.1.8. --- "Other physical, chemical and biological analyses" --- p.40 / Chapter 2.1.8.1. --- Elemental analysis --- p.40 / Chapter 2.1.8.2. --- Nitrogen --- p.41 / Chapter 2.1.8.3. --- Water and volatile matter content --- p.41 / Chapter 2.1.8.4. --- Melting point and specific gravity --- p.41 / Chapter 2.1.8.5. --- Microbial counts --- p.42 / Chapter 2.2. --- Production of fatty acid methyl esters (FAMEs) - Protocol A --- p.42 / Chapter 2.2.1. --- Optimization of Esterification --- p.42 / Chapter 2.2.1.1. --- Molar ratio of methanol: DODp --- p.43 / Chapter 2.2.1.2. --- Molar ratio of DODp: sulfuric acid --- p.43 / Chapter 2.2.1.3. --- Reaction temperature --- p.44 / Chapter 2.2.2. --- Optimization of Molecular Distillation --- p.44 / Chapter 2.2.2.1. --- Feed rate --- p.45 / Chapter 2.2.2.2. --- Distillation temperature --- p.45 / Chapter 2.2.2.3. --- Speed of rotary blade --- p.45 / Chapter 2.2.3. --- Crystallization --- p.46 / Chapter 2.3. --- Production of fatty acid methyl esters (FAMEs) - Protocol B --- p.46 / Chapter 2.3.1. --- Optimization of Saponification --- p.47 / Chapter 2.3.1.1. --- Saponification number --- p.47 / Chapter 2.3.1.2. --- Saponification --- p.47 / Chapter 2.3.2. --- Extraction of unsaponifiable matter --- p.48 / Chapter 2.3.3. --- Acidification --- p.49 / Chapter 2.3.4. --- Esterification --- p.49 / Chapter 2.3.5. --- Hot water washing --- p.49 / Chapter 2.3.6. --- Crystallization --- p.49 / Chapter 2.4. --- Quantity and quality assessments of FAMEs --- p.50 / Chapter 2.4.1. --- Determination of purity and yield of FAMEs --- p.50 / Chapter 2.4.2. --- Quality of FAMEs: Biodiesel Specifications in USA --- p.50 / Chapter 2.4.2.1. --- Sulfated Ash (ASTM D 874) --- p.50 / Chapter 2.4.2.2. --- Copper strip corrosion test (ASTM D 130) --- p.51 / Chapter 2.4.2.3. --- Water and Sediment (ASTM D 2709) --- p.52 / Chapter 2.4.2.4. --- Conradson Carbon Residue of Petroleum Products (ASTM D 189) --- p.52 / Chapter 2.4.2.5. --- Determination of Free and Total Glycerine in B-100 Biodiesel Methyl Esters By Gas Chromatography (ASTM D 6584) --- p.53 / Chapter 2.4.2.6. --- Flash point (modified from ASTM D 93) --- p.54 / Chapter 2.4.2.7. --- Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ASTM D 4951) --- p.54 / Chapter 2.4.2.8. --- Kinematic Viscosity --- p.55 / Chapter 2.4.2.9. --- "Cetane index, Cloud Point and Distillation Temperature (ASTM D 613, ASTM D 2500 and ASTM D 90)" --- p.55 / Chapter 2.4.3. --- Toxicity assays of FAMEs --- p.55 / Chapter 2.4.3.1. --- Acute toxicity to mice --- p.56 / Chapter 2.4.3.2. --- Seed germination test --- p.56 / Chapter 2.4.3.3. --- Acute toxicity to aquatic invertebrate --- p.56 / Chapter 2.5. --- Quantity and quality assessments of phytochemical products --- p.57 / Chapter 2.5.1. --- Determination of purity and yield of phytochemicals in phytosterol and desterolized fractions --- p.57 / Chapter 2.5.2. --- Antioxidants activity of desterolized fraction --- p.58 / Chapter 2.5.2.1. --- ABTS scavenging activity --- p.58 / Chapter 2.5.2.2. --- Free radical scavenging activity --- p.58 / Chapter 2.5.3. --- Anti-proliferative effect on cancer cells of phytosterols --- p.59 / Chapter 2.5.3.1. --- Cell culture --- p.59 / Chapter 2.5.3.2. --- Determination of optimal cell density for antiproliferative assays --- p.59 / Chapter 2.5.3.3. --- Anti-proliferative effect of phytosterols on H1299 and Hep G2. --- p.60 / Chapter 2.5.3.4. --- Detection of action mechanism(s) of the anti-proliferative effects of β-sitosterol on H1299 and Hep G2 cancer cells --- p.61 / Chapter 3. --- Result --- p.70 / Chapter 3.1. --- Characterization of Physically Refined Deodorizer Distillate (DODp) --- p.70 / Chapter 3.1.1. --- Free fatty acids composition --- p.70 / Chapter 3.1.2. --- Acid number --- p.75 / Chapter 3.1.3. --- "Free fatty acids, natural glyceride and unsaponifiable matter contents" --- p.75 / Chapter 3.1.4. --- "Squalene, tocopherol and phytosterol contents" --- p.77 / Chapter 3.1.5. --- Other physicochemical and biological analyses --- p.81 / Chapter 3.2. --- Production of fatty acid methyl esters (FAMEs) - Protocol A --- p.83 / Chapter 3.2.1. --- Optimization of Esterification --- p.83 / Chapter 3.2.1.1. --- Methanol to DODp molar ratio --- p.83 / Chapter 3.2.1.2. --- DODp to sulfuric acid molar ratio --- p.85 / Chapter 3.2.1.3. --- Reaction temperature --- p.87 / Chapter 3.2.1.4. --- Calculation of esterification efficiency --- p.87 / Chapter 3.2.2. --- Optimization of Molecular Distillation --- p.89 / Chapter 3.2.2.1. --- Feed rate --- p.89 / Chapter 3.2.2.2. --- Distillation temperature --- p.91 / Chapter 3.2.2.3. --- Rotating blade speed --- p.93 / Chapter 3.2.3. --- Crystallization --- p.97 / Chapter 3.2.3.1. --- Phytosterol preparations --- p.97 / Chapter 3.2.3.2. --- Desterolized fractions --- p.97 / Chapter 3.3. --- Production of fatty acid methyl esters (FAMEs) 一 Protocol B --- p.99 / Chapter 3.3.1. --- Optimization of Saponification --- p.99 / Chapter 3.3.1.1. --- Saponification number --- p.99 / Chapter 3.3.1.2. --- Saponification --- p.99 / Chapter 3.3.2. --- Extraction of unsaponifiable matter --- p.101 / Chapter 3.3.3. --- FAMEs product after esterification --- p.101 / Chapter 3.3.4. --- Crystallization --- p.104 / Chapter 3.3.4.1. --- Phytosterol preparations --- p.104 / Chapter 3.3.4.2. --- Desterolized fractions --- p.104 / Chapter 3.4. --- Quantity and Quality assessments of FAMEs --- p.106 / Chapter 3.4.1. --- "FAMEs yield, purity and appearance" --- p.106 / Chapter 3.4.2. --- Specifications for Biodiesel in U.S.A --- p.106 / Chapter 3.4.3. --- Acute Toxicity assays of FAMEs --- p.109 / Chapter 3.4.3.1. --- Acute toxicity to mice --- p.109 / Chapter 3.4.3.2. --- Seed germination test --- p.109 / Chapter 3.4.3.3. --- Acute toxicity to aquatic invertebrate --- p.109 / Chapter 3.5. --- Quantity and Quality assessments of phytochemicals --- p.113 / Chapter 3.5.1. --- Phytochemicals recoveries and compositions in phytosterol preparations and desterolized fractions --- p.113 / Chapter 3.5.1.1. --- Phytosterols recoveries and compositions in phytosterol preparations --- p.113 / Chapter 3.5.1.2. --- Squalene and tocopherols recoveries and compositions in desterolized fraction --- p.115 / Chapter 3.5.2. --- Antioxidant activities of desterolized fractions --- p.118 / Chapter 3.5.2.1. --- ABTS scavenging activity --- p.118 / Chapter 3.5.2.2. --- Scavenging Activities of DPPH radicals --- p.120 / Chapter 3.5.3. --- Anti-proliferative effect of phytosterols on cancer cells --- p.123 / Chapter 3.5.3.1. --- Determination of optimal cell density for antiproliferative assays --- p.123 / Chapter 3.5.3.2. --- Anti-proliferative effect of phytosterols on H1299 --- p.126 / Chapter 3.5.3.3. --- Anti-proliferative effect of phytosterols on Hep G2 --- p.132 / Chapter 3.5.3.4. --- Further investigation of anti-proliferative mechanism of β-sitosterol --- p.138 / Chapter 4. --- Discussion --- p.149 / Chapter 4.1. --- Characteristics of Physically Refined Deodorizer Distillate (DODp) --- p.149 / Chapter 4.1.1. --- Fatty acid contents and compositions --- p.149 / Chapter 4.1.2. --- "Squalene, tocopherol and phytosterol contents" --- p.153 / Chapter 4.1.3. --- Other physical and chemical analyses --- p.155 / Chapter 4.2. --- Production of fatty acid methyl esters (FAMEs) 一 Protocol A --- p.156 / Chapter 4.2.1. --- Optimization of Esterification --- p.156 / Chapter 4.2.2. --- Optimization of Molecular Distillation --- p.158 / Chapter 4.3. --- Production of fatty acid methyl esters (FAMEs) 一 Protocol B --- p.159 / Chapter 4.3.1. --- Optimization of Saponification --- p.159 / Chapter 4.3.2. --- Extraction of unsaponifiable matter --- p.160 / Chapter 4.3.3. --- Production of FAMEs --- p.161 / Chapter 4.4. --- Purification of phytosterols --- p.162 / Chapter 4.4.1. --- Purity and recovery of phytosterols --- p.162 / Chapter 4.4.2. --- Purity and recovery of squalene and tocopherols in desterolized fractions --- p.163 / Chapter 4.5. --- Quantification of the Loss of Valuable products during Processing --- p.165 / Chapter 4.6. --- Quality assessment of FAMEs and phytochemicals --- p.170 / Chapter 4.6.1. --- Specifications for Biodiesel in USA --- p.170 / Chapter 4.6.2. --- Acute toxicities of FAMEs --- p.171 / Chapter 4.6.3. --- Antioxidant activities of desterolized fractions --- p.172 / Chapter 4.6.4. --- Anti-proliferative effects of phytosterols on cancer cells --- p.173 / Chapter 4.7. --- Comparisons of the two protocols --- p.182 / Chapter 4.7.1. --- Products from protocol A and B --- p.182 / Chapter 4.7.2. --- Characteristics of protocol A and B --- p.183 / Chapter 4.7.3. --- Sustainable recycling technology --- p.184 / Chapter 4.7.4. --- Life cycle analysis --- p.185 / Chapter 4.8. --- Further investigation --- p.186 / Chapter 5. --- Conclusion --- p.187 / Chapter 6. --- Reference --- p.189

Page generated in 0.0592 seconds