181 resultados para Marais filtrant artificiel


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OS TÉCNICOS NA PRODUÇÃO DOS RIBEIRINHOS DO AMAZONAS, estuda principalmente a relação educação/trabalho dos egressos da Escola Agrotécnica Federal de Manaus e dos pequenos produtores (ribeirinhos) de várzea de Manacapuru - AM. Trabalha-se a contextualização abordando-se as políticas públicas de desenvolvimento pós-l964 na amazônia. Essas políticas tinham como objetivo a integração da região ao País, pois a amazônia apresentava descompasso frente ao processo de desenvolvimento que caracterizou a década de 70. Mas o que se constata após cuidadoso exame é tão-somente sua inserção (particularmente do setor rural) nas relações capitalistas de produção. As análises mostram que o Estado - como viabilizador dessas relações que têm como fundamento, explícita ou implicitamente, a acumulação via modernização da agricultura. - tem necessidade de formar agentes para disseminar suas idéias desenvolvimentistas e dissimular as contradições daí advindas. Estuda-se a produção desses agentes formados pelo estado na Escola Agrotécnica Federal de Manaus, através de sua proposta educativa teórico-prática; a educação é, assim, chamada pelo Estado para respaldar sua política econômica. O pressuposto que norteia todas as práticas educativas da escola leva a pensar que o aluno é uma mercadoria que deve sair ajustada aos desígnios do mercado capitalista. A partir dos conhecimentos teórico-metodológicos que mostram como os trabalhadores são produzidos no sistema capitalista, construíram-se na prática concreta em Manacapuru diretrizes para apreender como esses produtores ribeirinhos se reproduzem e se organizam para resistirem à dominação do capital. Trata-se, portanto, de identificar as relações educação/trabalho do técnico agropecuário (assistência técnica) junto aos pequenos produtores de várzea do município de Manacapuru.

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Stabilization pond system consisting in more sewage treatment used in Rio Grande do Norte (RN), Brazil, representing about 90% of all systems. Fecal bacteria are removed mainly facultative ponds and in maturation ponds. Many factors influence bacterial decay, such as the levels of pH and DO, temperature, light intensity, HDT and nutrient availability. The bacterial decay rate (Kb) is calculated considering many variables, but the hydraulic regime is a significant influence for microorganisms removal, and the dispersed flow which best characterizes a stabilization pond. However, some authors developed equations for the Kb accordant plug flow and complete mixing. This research study aimed to evaluate the bacterial decay of fecal coliform and Enterococcus sp. in stabilization ponds designed to treat domestic sewage, full-scale, in RN. All systems have assessed pretreatment, a facultative pond (LF) followed by two maturation (LM1 and LM2). The parameters availed were: temperature, pH, DO, BOD5, COD, fecal coliform, Enterococcus sp., Chlorophyll a, total suspended solids, fixed and volatile. In general, there were not significant differences for pH, DO and temperature in the ponds, except for the new systems, since they have low flow and hydraulic loads. The removal of organic matter in the ponds was low, about 70%, and nearly all are overloaded organic and operational problems. The bacterial removals were low, with average 96% for LF for fecal coliform, and 98% for Enterococcus sp.; LM1 were in itself a removal for fecal coliform about 71%, and 81% for Enterococcus sp.; LM2 have efficiency of 69% for fecal coliform, and 68% for Enterococcus sp. The equation proposed by Von Sperling (1999), according to the dispersed flow regime, generated empirical values of Kb more approximate to calculated values of Kb. On average, the calculated Kb to coliforms in the LF was 0.31 d-1, and for both maturation ponds were 0.35 d-1. For Enterococcus sp. the average was 0.40 d-1 for LF, 0.55 d-1 for LM1, and 0.58 d-1 for LM2. These results also showed that the Kb obtained in full-scale systems are smaller than those found in pilot-scale ponds. Moreover, one can say that the equation proposed by Marais (1974), according to the complete-mix regime, overestimates Kb. Actual results of Kb indicated that fecal coliforms are more resistant to adverse conditions present in stabilization ponds than Enterococcus sp., therefore, an indicator of microbiological safety and efficiency. The factors significant interventions in the rate of bacterial decay were concentrations of COD, the organic loading and HDT. The few Kb relationship between pH, DO and temperature were not significant. Finally, we conclude that it s essential to correct operation and maintenance, for not performing these activities is one of the main factors contributing to low rates of bacterial decay.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The suite of environments and anthropogenic modifications of sub-Antarctic islands provide key opportunities to improve our understanding of the potential consequences of climate change and biological species invasions on terrestrial ecosystems. The profound impact of human introduced invasive species on indigenous biota, and the facilitation of establishment as a result of changing thermal conditions, has been well documented on the French sub-Antarctic Kerguelen Islands (South Indian Ocean). The present study provides an overview of the vulnerability of sub-Antarctic terrestrial communities with respect to two interacting factors, namely climate change and alien insects. We present datasets assimilated by our teams on the Kerguelen Islands since 1974, coupled with a review of the literature, to evaluate the mechanism and impact of biological invasions in this region. First, we consider recent climatic trends of the Antarctic region, and its potential influence on the establishment, distribution and abundance of alien insects, using as examples one fly and one beetle species. Second, we consider to what extent limited gene pools may restrict alien species' colonisations. Finally, we consider the vulnerability of native communities to aliens using the examples of one beetle, one fly, and five aphid species taking into consideration their additional impact as plant virus vectors. We conclude that the evidence assimilated from the sub-Antarctic islands can be applied to more complex temperate continental systems as well as further developing international guidelines to minimise the impact of alien species.

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