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Influence of support material on the immobilization of biomass for the degradation of linear alkylbenzene sulfonate in anaerobic reactors

OLIVEIRA, Lorena Lima de; DUARTE, Iolanda Cristina Silveira; SAKAMOTO, Isabel Kimiko; VARESCHE, Maria Bernadete Amancio
Fonte: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD Publicador: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.51443%
Two horizontal-flow anaerobic immobilized biomass reactors (HAIB) were used to study the degradation of the LAS surfactant: one filled with charcoal (HAIB1) and the other with a mixed bed of expanded clay and polyurethane foam (HAIB2). The reactors were fed with synthetic substrate supplemented with 14 mg l(-1) of LAS, kept at 30 +/- 2 degrees C and operated with a hydraulic retention time (HRT) of 12 h. The surfactant was quantified by HPLC. Spatial variation analyses were done to quantify organic matter and LAS consumption along the reactor length. The presence of the surfactant in the load did not affect the removal of organic matter (COD), which was close to 90% in both reactors for an influent COD of 550 ring l(-1). The results of a mass balance indicated that 28% of all LAS added to HAIB1 was removed by degradation. HAIB2 presented 27% degradation. Molecular biology techniques revealed microorgan isms belonging the uncultured Holophaga sp., uncultured delta Proteobacterium, uncultured Verrucomicrobium sp., Bacteroides sp. and uncultured gamma Proteobacterium sp. The reactor with biomass immobilized on charcoal presented lower adsorption and a higher kinetic degradation coefficient. So, it was the most suitable support for LAS anaerobic treatment. (c) 2008 Elsevier Ltd. All rights reserved.

Biohydrogen production in anaerobic fluidized bed reactors: Effect of support material and hydraulic retention time

BARROS, Aruana Rocha; AMORIM, Eduardo Lucena Cavalcante de; REIS, Cristiane Marques; SHIDA, Gessia Momoe; SILVA, Edson Luiz
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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This study evaluated two different support materials (polystyrene and expanded clay) for biohydrogen production in an anaerobic fluidized bed reactor (AFBR) treating synthetic wastewater containing glucose (4000 mg L(-1)). The AFBRs contained either polystyrene (R1) or expanded clay (R2) as support materials were inoculated with thermally pre-treated anaerobic sludge and operated at a temperature of 30 degrees C and a pH of approximately 5.5. The AFBRs were operated with a range of hydraulic retention times (HRTs) between 1 and 8 h. For R1 with an HRT of 2 h, the maximum hydrogen yield (HY) was 1.90 mol H(2) mol(-1) glucose, with 0.805 mg of biomass (as total volatile solids, or TVS) attached to each g of polystyrene. For R2 operated at an HRT of 2 h, the maximum HY was 2.59 mol H(2) moll glucose, with 1.100 mg of attached biomass (as TVS) g(-1) expanded clay. The highest hydrogen production rates (HPR) were 0.95 and 1.21 L h(-1) L(-1) for R1 and R2, respectively, using an HRT of 1 h. The H(2) content increased from 16-47% for R1 and from 22-51% for R2. No methane was detected in the biogas produced throughout the period of AFBR operation. These results show that the values of HY, HPR, H(2) content, and g of attached biomass g(-1) support material were all higher for AFBRs containing expanded clay than for reactors containing polystyrene. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.; FAPESP; CNPq; CAPES

Anaerobic fluidized bed reactor with expanded clay as support for hydrogen production through dark fermentation of glucose

AMORIM, Eduardo Lucena Cavalcante de; Barros, Aruana Rocha; Damianouic, Márcia Helena Rissato Zamariolli; Luiz, Edson da Silva
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.09468%
This study evaluated hydrogen production in an anaerobic fluidized bed reactor (AFBR) fed with glucose-based synthetic wastewater. Particles of expanded clay (2.8-3.35 mm) were used as a support material for biomass immobilization. The reactor was operated with hydraulic retention times (HRT) ranging from 8 to 1 h. The hydrogen yield production increased from 1.41 to 2.49 mol H(2) Mol(-1) glucose as HRT decreased from 8 to 2 h. However, when HRT was 1 h, there was a slight decrease to 2.41 mol H(2) Mol(-1) glucose. The biogas produced was composed of H(2) and CO(2), and the H(2) content increased from 8% to 35% as HRT decreased. The major soluble metabolites during H(2) fermentation were acetic acid (HAc) and butyric acid (HBu), accounting for 36.1-53.3% and 37.7-44.9% of total soluble metabolites, respectively. Overall, the results demonstrate the potential of using expanded clay as support material for hydrogen production in AFBRs. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.; CNPq[141197/2007-2]; CNPq[130551/2007-4]; CNPq[152215/2007-7]; FAPESP[05/51702-9]; FAPESP[07/58564-6]

Influência do material suporte na degradação de alquilbenzeno linear sulfonado (LAS) em reator anaeróbio ; Influence of material support in degradation of linear alquilbenzene sulphonate (LAS) in anaerobic reactor

Oliveira, Lorena Lima de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/03/2006 PT
Relevância na Pesquisa
47.51443%
Neste trabalho foi estudada a degradação anaeróbia do alquilbenzeno linear sulfonado (LAS), um surfactante largamente utilizado na fabricação de detergentes e presente em águas residuárias domésticas e industriais. Para isso, foram utilizados dois reatores anaeróbios horizontais de leito fixo (RAHLF) preenchidos com diferentes materiais suporte para imobilização da biomassa: carvão vegetal (RAHLF1) e leito misto de argila expandida e espuma de poliuretano (RAHLF2). O inóculo usado foi lodo proveniente de reator anaeróbio de fluxo ascendente e manta de lodo (UASB) utilizado no tratamento de águas residuárias de suinocultura. Os reatores foram alimentados, numa primeira etapa, com esgoto sintético e, posteriormente, suplementados com 14 mg/L de LAS. O tempo de detenção hidráulica (TDH) utilizado foi de 12 horas. Foi possível constatar que a presença do surfactante na alimentação não afetou a remoção de matéria orgânica (DQO), próxima a 90% em ambos os reatores para afluente com DQO de 550 mg/L. Com o balanço de massa constatou-se que os reatores foram aptos a remover LAS em 30% no RAHLF1 e 35% no RAHLF2. Desse total, 28% e 27%, respectivamente, foram degradados biologicamente, após 343 dias de operação. O restante manteve-se adsorvido nos materiais suportes. O pH no efluente dos RAHLFs manteve-se constante e próximo a 7...

Remoção de alquilbenzeno linear sulfonado (LAS) e caracterização microbiana em reator anaeróbio de leito fluidificado; Removal of linear alkylbenzene sulfonate (LAS) and microbial characterization in anaerobic fluidized bed reactor

Oliveira, Lorena Lima de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/02/2010 PT
Relevância na Pesquisa
47.873633%
Nesse trabalho foi estudado a degradação anaeróbia do alquilbenzeno linear sulfonado (LAS), um surfactante amplamente utilizado na fabricação de detergentes e presente em esgoto doméstico e águas residuárias industriais. Para isso foi utilizado reator anaeróbio de leito fluidificado em escala de bancada (1,2 L) preenchido com material suporte para imobilização da biomassa. Quatro diferentes suportes foram testados previamente em reatores de leito fluidificado em menor escala (350 ml): carvão ativado (R1), argila expandida (R2), pérolas de vidro (R3) e areia (R4). Todos os reatores foram inoculados com lodo proveniente de reator UASB utilizado no tratamento de dejetos de suinocultura e alimentados com substrato sintético acrescido de LAS. Os reatores foram mantidos a 30°C e operados com tempo de detenção hidráulica (TDH) de 18 horas. Foi possível constatar que os quatro reatores foram aptos na remoção de matéria orgânica (acima de 84%) e LAS (acima de 81%), respectivamente para concentração inicial média de 550 mg/L e 16,5 mg/L. No entanto, carvão ativado e argila expandida sofreram processo de fragmentação durante a operação do reator. Assim, areia foi o material escolhido para preencher o reator em escala de bancada devido aos bons resultados de remoção do LAS (99%)...

Agregado leve de argila calcinada para uso em concreto estrutural: viabilidade de cerâmica vermelha do Estado de São Paulo; Calcined clay lightweight aggregate for use in structural concrete: viability of the red ceramic from the state of São Paulo

Santis, Bruno Carlos de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/11/2012 PT
Relevância na Pesquisa
48.054546%
Este trabalho tem por objetivo o estudo da viabilidade da utilização de cerâmica vermelha para a confecção de agregados leves de argila calcinada para utilização em concretos estruturais. Inicialmente, foram coletadas amostras de solo de cinco diferentes empresas produtoras de cerâmica vermelha do estado de São Paulo. As massas cerâmicas foram caracterizadas por meio das técnicas de limites de liquidez (LL) e plasticidade (LP), análise granulométrica, análise química e difração de raios X (DRX). Os corpos de prova confeccionados com essas massas cerâmicas, queimados à temperatura de 900ºC, foram caracterizados por meio da avaliação da retração linear, absorção de água, porosidade aparente, massa específica aparente, expansão por umidade e resistência à compressão. Após a caracterização dos corpos de prova de cerâmica vermelha, foram escolhidas duas amostras para a confecção dos agregados leves de argila calcinada. Em seguida, foram confeccionados corpos de prova de concreto com agregados leves de argila calcinada, argila expandida e brita. Os corpos de prova de concreto leve foram caracterizados pelos ensaios de slump, massa específica fresca, teor de ar incorporado, resistência à compressão...

Matéria-prima da formação Corumbataí na região do pólo cerâmico de Santa Gertrudes, SP, com características naturais para fabricação de argila expandida

Moreno, M. M. T.; Zanardo, A.; Rocha, R. R.; Roveri, C. D.
Fonte: Associação Brasileira de Cerâmica Publicador: Associação Brasileira de Cerâmica
Tipo: Artigo de Revista Científica Formato: 342-348
POR
Relevância na Pesquisa
47.83296%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Estudou-se um material da base da Formação Corumbataí, proveniente de uma mineração de argila, que apresenta restrições de uso em cerâmica devido à sua dureza e, principalmente, ao alto conteúdo de matéria orgânica. Verificou-se que o material apresenta características naturais ótimas para a fabricação de argila expandida diretamente a partir de fragmentos de rocha, mostrando comportamento piroplástico com expansão significativa se submetido à queima rápida. A caracterização da matéria-prima e do produto foi realizada mediante análise de carbono orgânico, difração de raios X, microscopia ótica e testes de queima. Foram determinadas as condições de queima para obter argila expandida utilizando forno de queima rápida e forno a rolos, ambos de laboratório, obtendo corpos com densidade variável (que podem chegar a valores menores que 0,5 g.cm-3) até o limite de expansão. Esta densidade é obtida devido à formação de poros fechados e uma película externa vítrea, que proporcionam uma resistência mecânica alta aos fragmentos expandidos.; This paper refers to the study of the material of the base of the Corumbataí formation (Parana Basin...

The effect of biomass immobilization support material and bed porosity on hydrogen production in an upflow anaerobic packed-bed bioreactor

Fernandes, Bruna Soares; Saavedra, Nora Katia; Maintinguer, Sandra Imaculada; Sette, Lara Durães; Oliveira, Valéria Maia de; Varesche, Maria Bernadete Amâncio; Zaiat, Marcelo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1348-1366
ENG
Relevância na Pesquisa
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H2 mol−1 sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation...

Obtenção de nanocompositos poliprolipeno-argila compatibilizados com organossilano; Obtaining of polypropylene-clay nanocomposites compatibilized with organosilanes

Adair Rangel de Oliveira Junior
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/10/2006 PT
Relevância na Pesquisa
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Este trabalho teve como foco principal a obtenção de argilas expandidas por meio da modificação de argila natural com organossilanos, e depois sua incorporação em uma resina de polipropileno em extrusora de rosca dupla para a obtenção de nanocompósitos. As argilas usadas neste estudo foram as argilas montmoriloníticas sódicas Polenita e GelMax, bem como a argila organofílica Viscogel. Os organossilanos empregados no tratamento químico das argilas naturais foram o aminopropiltrimetoxissilano, glicidoxipropiltrietoxissilano e o metacriloxipropiltrietoxissilano. A obtenção da argila expandida foi fortemente influenciada pelas condições reacionais, como tipo e concentração do silano, solvente e pH do meio. As análises de difração de raios X revelaram que os melhores resultados de expansão da argila foram alcançados ao usar o silano aminopropiltrimetoxissilano em meio aquoso na faixa de pH entre 8 e 10. Segundo os dados de análise térmica, esta argila apresentou uma estabilidada térmica bem superior às tradicionais argilas organofílicas. Antes da incorporação da argila à matriz de polipropileno, primeiramente fez-se um estudo de otimização das condições de mistura, usando-se para isto a argila organofílica Viscogel...

Desempenho de um sistema de filtração lenta de água em argila expandida e geotêxtil; Performance of the slow filtration of water in expanded clay and geotextile

Rodrigues, André da Silva
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Trabalho de Conclusão de Curso
Publicado em //2014 POR
Relevância na Pesquisa
68.09468%
Dissertação de mestrado integrado em Engenharia Civil; A filtração lenta é um processo de tratamento de água com uma vasta aplicação desde há bastantes anos a esta parte. A presente dissertação destina-se a estudar o desempenho de um filtro lento de argila expandida com mantas geotêxtil, mais concretamente avaliar a variação de alguns parâmetros indicadores da qualidade da água, antes e após a filtração. A instalação experimental foi realizada no Laboratório de Hidráulica e Recursos Hídricos do Departamento de Engenharia Civil da Universidade do Minho, em Azurém, Guimarães. Os parâmetros de qualidade da água medidos foram a turvação, o pH, a condutividade elétrica, a temperatura e o oxigénio dissolvido. A turvação da água foi conseguida pela adição de lodo ao sistema. O caudal médio do filtro foi de cerca de 0,37 m3/h, variando entre 0,22 e 0,73 m3/h. A taxa de filtração manteve-se entre 4,13 e 13,90 m/dia. Relativamente à turvação medida, obteve-se eficiências de redução máximas superiores a 90%, mas a eficiência de redução mínima foi apenas 37%, aproximadamente. O maior pico de turvação da água recirculada foi cerca de 64 UNT, mantendo-se a média deste parâmetro em cerca de 8 UNT. Apesar da turvação elevada do tanque de água bruta...

Biodegradation of 2-fluorobenzoate in upflow fixed bed bioreactors operated with different growth support materials

Emanuelsson, Maria A.E.; Henriques, Isabel S.; Jorge, Ruben M Ferreira; Castro, Paula ML
Fonte: Wiley Blackwell Publicador: Wiley Blackwell
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
47.51443%
Three upflow fixed bed bioreactors treating an aqueous stream containing 2-fluorobenzoate were operated for a period of 7months, during which they were exposed to high organic loading rates and starvation. The reactors contained granular activated carbon (GAC), polyethylene (PE) particles and expanded clay (EC) respectively as growth support for microbial biofilms. The performance of the reactors was compared and the biofilm microbial population was followed by cell counting and denaturing gradient gel electrophoresis (DGGE). The reactor containing GAC always had 100% removal efficiency owing to the adsorption properties of thematerial combined with biodegradation. The GAC reactor also recovered better after starvation periods in the sense that it showed more stable behaviour than the reactors containing EC and PE. The highest biological elimination capacity was observed for the reactor containing EC, which reached 200mg day−1 L−1 during reactor start-up, but during long-termoperation the reactor containing GAC showed the highest biological elimination capacity, 140mg day−1 L−1. DGGE analysis indicated that starvation periods seemed to be responsible for shifts in the microbial population.

Evaluation of different substrates to support the growth of Typha latifolia in constructed wetlands treating tannery wastewater over long-term operation

Calheiros, Cristina S. C.; Rangel, António O. S. S.; Castro, Paula M. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /03/2008 ENG
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The aim of this study was to investigate the performance of horizontal subsurface flow constructed wetlands planted with Typha latifolia treating tannery wastewater under long-term operation. Two expanded clay aggregates (Filtralite® MR3–8-FMR and Filtralite® NR3–8-FNR) and a fine gravel-FG were used as substrate for the constructed wetland units plus one unit with FMR was left as an unvegetated control. The systems were subject to three hydraulic loadings, 18,8 and 6cm d⁻¹, and to periods of interruption in the feed. The relationship between the substrate, plant development and removal efficiency, especially of organic matter, was investigated. Organic loadings up to 1800 kg BOD5 ha⁻¹ d⁻¹ and 3849 kg COD ha⁻¹ d⁻¹ were applied leading to mass removals of up to 652 kg BOD₅ ha⁻¹ d⁻¹ and 1869 kg COD ha⁻¹ d⁻¹, respectively. The three different substrates were adequate for the establishment of T. latifolia, although the clay aggregates allowed for higher plant propagation levels. The units with FNR and FMR achieved significantly higher COD and BOD₅ removal when compared to the FG and to the unplanted units. The systems proved to be tolerant to high organic loadings and to interruptions in feed suggesting this technology as a viable option for the biological treatment of tannery wastewater.

Using clay materials to remove pharmaceuticals from waters

Dordio, Ana V.; Palace Carvalho, A. J.; Estêvão Candeias, A. J.; Pinto, Ana P.; Costa, Cristina
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Aula Formato: 10823 bytes; application/pdf
ENG
Relevância na Pesquisa
47.83296%
Pharmaceutical active compounds (PhACs) have an important role in the treatment and prevention of disease in both human and animals. Ingested drugs are only partially absorbed by the organisms and studies have shown that the excreted compounds are only partially removed in the sewage treatment plants (STPs) [1]. Contaminated effluents are being released from the STPs and trace amounts of PhACs have been detected in wastewaters, surface and groundwaters worldwide [1]. Acidic pharmaceuticals like diclofenac, ibuprofen and clofibric acid are some of the most frequently detected compounds [1]. The concentrations detected are low (ng/L - μg/L) but, due to the very nature of these compounds, studies have shown damaging effects on the aquatic ecosystems [1]. Several different processed natural materials can be used as filter media in water and wastewater treatment systems. Some of these materials can additionally present functions which extend beyond the simple process of filtration. Their surface areas can constitute a support for microbial population growth in biofilters as well as support matrix for the development of macrophytes in sub-surface flow constructed wetland systems (SSF-CWS) [2] which are increasingly being used in sewage tertiary treatment. The efficiency of these biological systems in the removal of xenobiotics can be significantly enhanced by a greater capability of the support matrix to retain contaminants by sorption phenomena...

Removing pharmaceutical residues from contaminated wastewaters using expanded clay aggregates

Dordio, Ana V.; Pinto, Ana P.; Estêvão Candeias, A. J.; Palace Carvalho, A. J.; Costa, Cristina
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Aula Formato: 41788 bytes; application/pdf
ENG
Relevância na Pesquisa
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Pharmaceutical compounds (PhCs) are ingested in large quantities by humans in treatment and prevention of disease, but they are only partially absorbed by the organisms being excreted together with their metabolites. The sewage treatment plants (STP) are only able to partially remove some of these compounds and, despite the low concentrations present in the wastewaters (ng-μg/L), these xenobiotics can still pose a serious threat to the aquatic environments. Sub-surface flow constructed wetland systems (SSF-CWS) are biological systems used in wastewater treatment, and clay materials can be used as support matrices for these systems. Clay materials act not only as filters but they also can potentially remove organic pollutants due to its sorption properties. In this study a processed clay material, light expanded clay aggregates (LECA), was tested for their sorption capacity towards three widespread water polluting pharmaceuticals, namely clofibric acid (CA), ibuprofen (IB) and carbamazepine (CB). Sorption assays were done with aqueous solutions of the individual compounds and with their mixture at different concentrations from 1.0 to 50.0 mg L-1. The sorptive properties of LECA were also investigated using wastewater spiked with a mixture of the three compounds at the same concentrations tested for the aqueous solutions. Reversed phase HPLC with UV-Vis detection at 210...

Improving thermal performance of rammed earth walls using expanded clay aggregate

Correia-da-Silva, José; Pereira, João
Fonte: Universität Graz Publicador: Universität Graz
Tipo: Aula
ENG
Relevância na Pesquisa
68.54978%
The use of earth as a building material dates back to the beginning of our civilization. In the South of Portugal there is still a large number of buildings with rammed earth walls, but this technology has been falling into disuse since the middle of last century. The earth construction is highly sustainable since earth is a local material and is 100% reusable. The buildings with rammed earth walls have a high thermal inertia which, given the climate characteristics Portugal, improves its thermal behaviour. However, it is desirable that the thermal conductivity of the rammed earth were lower. Environmental concerns related to energy consumption associated with comfort in housing and construction, transportation and application of materials used in construction, has led us to seek new solutions in building typologies on earth. Considering these aspects and improving the energy efficiency in buildings, this paper presents the results of tests performed in the laboratory on building new solutions on earth. Geotechnical characterization of the soil used was made and various compositions prepared with the incorporation of expanded clay. The expanded clay was chosen as a thermal insulator made from raw materials available in the regions of Alentejo and Algarve (South of Portugal)...

Effect of vegetation on the performance of horizontal subsurface flow constructed wetlands with lightweight expanded clay aggregates

Mesquita, Maria da Conceição; Albuquerque, Antonio; Amaral, Leonor; Nogueira, Regina
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /05/2013 ENG
Relevância na Pesquisa
47.51443%
This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m(-2) day(-1). The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.

Estudo da adição de argila expandida na formulação de concretos leves

Pereira, Maurício Rodrigues
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
48.35257%
Lightweight concrete has been the subject of several studies towards the development of new building materials. Emphasis has been given on the particle size effect and nature of aggregates used as raw materials. The present study includes an analysis of the materials that make this kind of concrete, analyzes of mechanical properties such as compressive and tensile strength, in addition to assessments of the interface concrete aggregate/matrix interface, porosity and absorption profile of chloride ions in lightweight concrete based on expanded clay. The experiments were carried out by molding cylindrical samples 100 mm in diameter and 200 mm in height. The dosage experiments were performed without additives or with the addition of minerals: (T1) 1: 2.01: 1.10: 0.78 (T2) 1: 2.00: 1.32 : 0.62 - (T3) 1 :1.93 :1.54: 0.47 (cement : sand : expanded clay 0500 : expanded clay 1506).The water to cement ratio was set to 0.43. Expanded clay minerals with different average particle sizes were used, i.e., 9.5 mm/0500 and 19 mm/1506. The larger aggregate was coated by a glassy layer, yielding lower water absorption characteristics to the concrete. The results showed that the use of light expanded clay aggregates is a technically interesting solution to the production of lightweight concrete for construction applications; Considerando-se as tendências de novos materiais na Construção Civil...

Efeito da adição de argila expandida e adições minerais na formulação de concretos estruturais leves autoadensáveis

Borja, Edilberto Vitorino de
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Mecânica; Tecnologia de Materiais; Projetos Mecânicos; Termociências Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Mecânica; Tecnologia de Materiais; Projetos Mecânicos; Termociências
Tipo: Tese de Doutorado Formato: application/pdf
POR
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The search for alternative materials with lower density, reduction in heat transfer and propagation of noise associated with the ease of handling and application in concrete structures, represents an enormous challenge in the formulation and knowledge of the performance of self-compacting lightweight concrete, which has technology little known nationally, and appears on the international scene as an innovative material and alternative to conventional concrete. Based on these, this study set out to study self-compacting lightweight concrete made with two distinct grades of expanded clay associated with the addition of plasticizing/superplasticizers additives and mineral additions of metakaolin and bagasse ash of sugar cane. There is also an object of study, evaluation of pozzolanic activity of mineral admixtures and their influence on the durability characteristics of concrete. The rheological, physical, mechanical and microstructural analysis in this study served as basis in the classification of concretes autoadensáveis, targeting the national technical requirements for their classification in the category autoadensável and lightweight structural. The inclusion of mineral admixtures (metakaolin and bagasse ash of sugar cane), partial replacement of cement...

Evaluation of almond shell as a culture substrate for ornamental plants. I. Characterisation: (with 4 figures & 6 tables)

Lao,MT; Jiménez,S
Fonte: Phyton (Buenos Aires) Publicador: Phyton (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
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47.873633%
Some technical and economic problems currently limit the use of substrates. The main problems include the lack of reciprocal adaptation of the cultivation technics and the substrate, the possible presence of pathogens, and the cost involved. To these we must add the ecological problems of the extraction areas, since there are no short-term renewable resources, especially in the case of peat, the classic substrate. This has motivated the search for substitutes, especially amongst indigenous materials and those easily obtained locally, such as cereals straw, rice husk and cork residues. The use of these substrates should be evaluated agronomically for: physical (total porosity, available water, air content, distribution of particles size, apparent density), chemical (cation exchange capacity, assimilable elements, salinity, pH, C/N ratio) and cultural properties. The characterisation and use of almond shell (Prunus dulcis) as a horticultural substrate substitute for growing ornamental plants were studied. The study involved the characterisation of the physical and chemical properties of 4 almond shell and peat mixtures (20:80,40:60, 60:40 and 80:20 in almond shell and peat volume respectively), as well as those of a control mixture consisting of peat and expanded clay (33.3: 66.6 in volume of expanded clay and peat respectively). The almond shell in the substrate increased aeration...

Evaluation of almond shell as a culture substratefor ornamental plants. II. Ficus benjamina: (with 3 tables & 2 figures)

Lao,MT; Jiménez,S
Fonte: Phyton (Buenos Aires) Publicador: Phyton (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
Relevância na Pesquisa
47.873633%
Some technical and economic problems currently limit the use of substrates. The main problems include the lack of reciprocal adaptation of the cultivation technics and the substrate,the possible presence of pathogens, and the cost involved. To these we must add the ecological problems of the extraction areas, since there are no short-term renewable resources, especially in peat, the classic substrate. This has motivated the search for substitutes, especially amongst indigenous materials and those easily obtainable locally, such straws cereals, rice husk and cork residuous. The use of these substrates should be evaluated agronomically for: physical, chemical and cultural properties. The characterisation and use of almond shell (Prunus dulcis) as a horticultural substrate substitute for growing ornamental plants were studied. The study involved 4 almond shell and peat mixtures (20:80,40:60, 60:40 and 80:20 in almond shell and peat volume respectively), as well as those of a control mixture consisting of peat and expanded clay (33.3: 66.6 in volume of expanded clay and peat respectively). The evaluated plant was Ficus benjamina. The plants crop in mixture 20:80 present hight height, dry and fresh weight aerial and root zone and nitrogen foliar level.