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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desempenho de reatores anaeróbios de leito fixo no tratamento de águas residuárias da lavagem e descascamento/despolpa dos frutos do cafeeiro / Performance of the anaerobic fixed-bed reactors in the treatment of wastewater from the washing and pulping/husking the cherries of the coffee shrub

Luiz, Fátima Aparecida Resende 27 February 2007 (has links)
Made available in DSpace on 2015-03-26T13:24:01Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3612082 bytes, checksum: 149afc8c39e12bc41cc161a29373f800 (MD5) Previous issue date: 2007-02-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Three anaerobic fixed-bed reactors with upflow and containing immobilized biomass were operationally evaluated for the treatment of wastewater from the coffee cherries processing (WCP). Because the performance of those reactors are related to the supportive medium providing adherence and growth to the biofilm, the following materials were studied: blast furnace scum, polyurethane foam and crushed stone #2 with porosity 53, 95 and 48%, respectively. The reactors were made with PVC and total volume for 139.5L. They were operated under environmental temperature varying from 6.4 to 32.9ºC, with average value 17.2ºC. Their operations consisted of increasing the organic load, that was quantified in terms of COD (1000, 2500 and 5000 mg L-1) flowing to reactors, by keeping a stable hydraulic residence time (HRT) around 1.3 days. The reactors were monitored, by collecting both the affluent and effluent samples of the reactors, and quantifying the variables: COD, BOD, phenolic compounds, TS, TVS, TSS, VSS, total nitrogen, phosphorus, sodium, potassium, pH, alkalinity, volatile acids and electric conductivity. At the end of the evaluated conditions, the WCP samples were collected along the height of the reactors for kinetic study, as well as those of the formed biofilm for microscopic observations. For an affluent COD value around 5000 mg L-1, the reactor infilled with foam showed an average removal efficiency of 80 and 83% for the total and filtered COD respectively. This fact is due to its higher porosity, that provided higher retention and fixation of the biomass, that when quantified under the TVS form was 1,301 mg g-1 foam. By the other hand, the reactor infilled with scum generated effluents with lower concentrations of phenolic compounds that were statistically different (P <0.05) from those obtained in the other reactors. The increase in the COD flowing to the reactors also made possible the development and growth of the adhered microbial biofilm that showed wide variety of species, as been registered some morphologies similar to bacilli, curved bacilli, coccus, filaments, Methanosaeta sp. and Methanosarcina sp., this last one with lower frequency. Based on the results, it is concluded that the reactors showed satisfactory performance, which make them a viable alternative to be used in the treatment of WCP, as emphasizing the polyurethane foam as supportive material. / No presente trabalho, objetivou-se efetuar a avaliação operacional de três reatores anaeróbios de leito fixo e com fluxo ascendente, contendo biomassa imobilizada, no tratamento da água residuária do processamento dos frutos do cafeeiro (ARC). Como o desempenho desses reatores está relacionado com o meio suporte, o qual proporciona a aderência e crescimento do biofilme, foram estudados três materiais: escória de alto-forno, espuma de poliuretano e brita n.2, com porosidade de 53, 95 e 48%, respectivamente. Os reatores, confeccionados em PVC e volume total de 139,5 L, foram operados sob temperatura ambiente, que variou de 6,4 a 32,9ºC, com valor médio de 17,2ºC. A operação dessas unidades consistiu no aumento da carga orgânica, quantificada em termos de DQO (1.000, 2.500 e 5.000 mg L-1), afluente aos reatores, mantendo-se o tempo de residência hidráulica (TRH) constante, em torno de 1,3 dias. O monitoramento dos reatores foi feito com a coleta de amostras afluente e efluente dos reatores, quantificando-se as variáveis DQO, DBO, compostos fenólicos, ST, SVT, SST, SSV, nitrogênio total, fósforo, sódio, potássio, pH, alcalinidade, ácidos voláteis e condutividade elétrica. No final de cada condição avaliada, foram coletadas amostras de ARC, ao longo da altura dos reatores, para estudo cinético, bem como, amostras do biofilme formado, para observações microscópicas. Para um valor de DQO afluente em torno de 5.000 mg L-1, o reator preenchido com espuma apresentou eficiência média de remoção de DQO total e filtrada de 80 e 83%, respectivamente, atribuídas a sua maior porosidade, a qual proporcionou maior retenção e fixação da biomassa que, quantificada na forma de SVT, foi de 1.301 mg g-1 de espuma. Por outro lado, o reator preenchido com escória gerou efluentes com menores concentrações de compostos fenólicos, que foram estatisticamente diferentes (P<0,05) das obtidas nos outros reatores. O aumento na DQO afluente aos reatores também possibilitou o desenvolvimento e crescimento do biofilme microbiano aderido que apresentou grande variedade de espécies, tendo sido registradas morfologias semelhantes a bacilos, bacilos curvos, cocos, filamentos, Methanosaeta sp. e Methanosarcina sp., este último com menor freqüência. Pela análise dos resultados, pode-se concluir que os reatores apresentaram desempenhos satisfatórios, tornando-os alternativa viável para ser aplicada no tratamento da ARC, com destaque para espuma de poliuretano como material suporte.

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