Influência da intensidade de aeração na formação do floco de lodo ativado e na eficiência de remoção de matéria orgânica

In wastewater treatment, activated sludge systems have been a technology widely applied as secondary treatment. During this step, which has a strong biological aspect, it is necessary to introduce oxygen supply for the maintenance of metabolic activity of the bacteria through the aerators. Aeration devices are responsible for most of the energy consumption in this stage. In this background, the influence of three aeration intensities (atmospheric air flow 3.5, 7.0 and 10.5 L.min-1) and the concentration of dissolved oxygen (DO) on the dimension of activated sludge flocs as well as on the efficiency of organic matter removal were assessed using a traditional activated sludge system which was fed with synthetic domestic wastewater. Samples were taken weekly from the three units that make up the system feed, aeration and storage tank in order to verify the Chemical Oxygen Demand (COD). It was established the process efficiency through a comparison between the initial and final COD. Besides the parameters already mentioned, this monitoring work on activated sludge batch system was also observed by Mixed Liquor Suspend Solids (MLSS), Volatile Suspend Solids (VSS), pH and temperature measures. The results have showed a maximum removal efficiency around 75% in the first aeration sequence and approximately 85% for the second and third one. For the first aeration, the DO concentration remained higher than 3.0 mg.L-1 and a diameter range from 10 to 60 μm was observed. In the second e third sequence, the DO concentration remained higher than 4.0 mg.L-1 with a diameter range of 10 until 200 μm. Although the sequence 1 and 2 have presented similar performances for organic matter removal, the sequence 2 promoted a regular floc size distribution and with lower values of Sludge Volumetric Index (SVI) meaning a better flocculating ability. In addition, the results reaffirmed what the literature has reported: higher DO concentrations produce flocs with greater dimensions

História da matemática na formação do professor: dificuldades e sugestões

This work is the result of a study that aimed to start scoring difficulties that the math teacher is trying to get a historical formation. Considering that the textbook is the material with which the teacher has more contact, start with reading historical texts present in these books. Choose a theme and choose from that we observed limitations ranging from the search for sources of research in relation to the actual historical content. There are many studies that show the importance of the history of mathematics in teacher education and also in the teaching and learning of mathematics. These works , in particular the work of Feliciano (2008 ) entitled : " The use of history of mathematics in the classroom " , along with the information , experiences and opinions given by Professor Anderson Luís de Azevedo Paulo , in some meetings , point to need for materials for teaching , since they show that recognizes the importance of this knowledge and the ability to use it in the classroom , but several factors have pushed aside , even the texts present in textbooks. From the analysis of some of the work and contributions of Professor Anderson Paulo we pointed out some of the factors that make historical texts being ignored by teachers and among them are characteristics in appearance and content in the text. To assist in the preparation of materials that meet the expectations of the teacher, we present a manual with suggestions and / or features to choose or produce a good text. These suggestions can make the history books more enjoyable and thus approach the teacher of historical knowledge and later encouraged to seek, in fact, a historical formation

Alterações dos parâmetros climáticos no município de Apodi-RN, antes e após a construção da barragem Santa Cruz do Apodi, e formação do lago

Este trabalho teve como objetivo principal analisar as mudanças ocorridas no clima local onde o município de Apodi/RN está inserido, em virtude da construção da Barragem Santa Cruz do Apodi. Foram utilizadas para o tratamento dos dados climáticos precipitação pluviométrica, umidade relativa do ar e temperatura técnicas estatísticas como Desvio Padrão, Teste T, Coeficiente de Variação e Média aritmética, além do modelo matemático. Para o balanço hídrico foi aplicado o método de Thornthwait (1948), considerando dois períodos em análise: o anterior e posterior a construção da Barragem Santa Cruz do Apodi, respectivamente 1995 e 2005. os resultados obtidos permitiram inferir que a hipótese inicial levantada se confirma, ou seja, a construção da Barragem Santa Cruz do Apodi, está influenciando diretamente numa alteração no que concerne à condição atmosférica local, especialmente no parâmetro umidade relativa do ar. Quanto ao balanço hídrico, observou-se a predominância do déficit hídrico especialmente entre os meses de junho a janeiro, período de estiagem; um excedente ocorrente entre os meses de maio e junho, conseqüente do período chuvoso; e uma reposição hídrica antecedendo e sucedendo este período, chuvoso, ou seja, compreendendo os meses de fevereiro a junho. Todas as considerações e análises poderão contribuir para o planejamento de abastecimento d´água, a irrigação, auxílio na previsão de enchentes e estiagens, bem como o manejo do uso da água subterrânea

Papel da extensão e do trabalho junto à comunidade na formação médica

SILVA, Thiago Demétrio Nogueira Costa e; CORRÊA, Edison José; MARANHÃO, Técia Maria de Oliveira. O papel da extensão e do trabalho junto à comunidade na formação Médica. Revista Eletrônica Pesquisa Médica, v.1, n.3, p.9-13, jul./set. 2007