The good composition and activity of biofilms are very important for successful operation and control of fixed-film biological reactors employed in liquid effluents treatment. During the last decade, microsensors have been applied to study microbial ecology. These sensors could provide information regarding the microbial activity concerning nitrification and denitrification that occur inside biofilms. Other techniques of molecular biology, such as fluorescence in situ hybridization (FISH), have also contributed to this matter because their application aids in the identification of the bacterial populations that compose the biofilms. The focus of this paper was to study the loading rate and surface velocity to promote the development of nitrifying biofilms in three distinct flow cells that were employed in the post treatment of a synthetic wastewater simulating the effluent from a UASB (Upflow Anaerobic Sludge Blanket) reactor. Using the FISH technique, it was found that the population of ammonia-oxidizing-bacteria was greater than that of nitrite-oxidizing-bacteria; this was also supported by the lower production of nitrate determined by physicochemical and microsensor analyses. It was verified that the loading rate and surface velocity that promoted the greatest nitrogen removal were 0.25 g N-amon m(-2)biofilm day(-1) and 1 m h(-1), respectively.

Protozooplankton is an important component of the aquatic microbial food webs and its composition, density, and distribution reflect the chemical, physical, and biological aspects of the environment. Considering the scarce literature on freshwater protozoans in Brazil and on protozoan ecology in subtropical environments, we listed the ciliates and amoebae taxa found in 13 water bodies in São Paulo State and analyzed their abundance in relation to the environmental variables. We collected two samples in each environment, fixed immediately with mercuric chloride and stained with bromophenol blue. After microscopical analysis, 74 protozoan genera were identified and the Ciliophora were dominant in the majority of the environments. The Stichotrichia, represented mostly by the genus Halteria, occurred in all environments, and was the dominant subclass in five of them. The canonic correspondence analysis of the most frequent genera and the environmental variables showed that nitrite and nitrate were the variables that better explained the distribution of Limnostrombidium, Urotricha, and Vorticella. The densities of the genera Halteria, Coleps, and of the species Cinetochilum margaritaceum were positively affected by increasing concentrations of dissolved oxygen, particulate phosphate, conductivity, and temperature. C. margaritaceum were also negatively affected by increasing concentrations of nitrite and nitrate. Considering that we made only one sampling in each environment, the richness was high compared to the mean diversity of lakes in the São Paulo State. The Diogo Lake, located in an ecological reserve, was the richest one, confirming the need of more research on the biodiversity of more preserved environments.

pela orientação e incentivo durante a realização desse trabalho.Ao Técnico Antônio Wagner Lamon pela amizade e ajuda com os microssensores e operação do reator. À Dra. Eloisa Pozzi pela grande amizade, apoio e ajuda com a parte microbilógica.À Beatriz Cruz Gonzalez, pela amizade, companheirismo e parceria durante o nosso trabalho.Ao Paulo "Jalaska", pela amizade e ajuda com os gráficos e formatações. O pós-tratamento de efluentes de reatores anaeróbios, tais como o Upflow Anaerobic Sludge Blanket (UASB), na maior parte de suas aplicações, faz-se necessário, já que esse tipo de tratamento biológico promove remoção de DBO na faixa de 60 a 75% e tem baixa eficiência na remoção de nitrogênio e fósforo. A remoção de nitrogênio geralmente é feita de forma convencional pela nitrificação, seguida da desnitrificação. Tanto a nitrificação, como a desnitrificação podem ser efetuadas em reatores com crescimento suspenso ou crescimento aderido, contudo é conhecido que sistemas baseados em biofilmes exercem influência direta na taxa da degradação de substrato e facilitam a retenção de bactérias nitrificantes em reatores. O principal objetivo deste trabalho é o de acompanhar o desenvolvimento de biofilmes aeróbios em reatores do tipo célula de fluxo para a nitrificação de substrato sintético simulando efluente de UASB, submetidos a diferentes velocidades superficiais (1, 4 e 8 m.h -1 ) e taxas de carregamento (0,25; 0,5 e 1,0 g N.m -2 biofilme.dia). O desenvolvimento dos biofilmes nitrificantes foi acompanhado mediante perfis de microssensores e estimativa do número mais provável de bactérias nitrificantes (NMP). Nas células de fluxo operadas com taxa de carregamento mais baixa (0,25 g N.m -2 biofilme.dia), foram obtidas as melhores eficiências de remoção de NTK, a qual representa valor menor que as taxas de carregamento empregadas na literatura para reatores de crescimento aderido usados na nitrificação. Considerando as células de fluxo com taxa de carregamento mais baixa, a célula que apresentou remoção de NTK próxima a 100% foi a de menor velocidade superficial de (1 m.h -1 ). Porém, esses sistemas apresentaram baixa eficiência para a nitrificação completa, obtendo maior produção de nitrito do que de nitrato; poderiam ser usados então na remoção de nitrogênio pela via curta. Os microssensores de OD foram eficientes para as análises de perfis de OD no interior dos biofilmes nitrificantes, mostrando grandes variações, à medida que o biofilme se desenvolvia, nas concentrações de OD do líquido circundante e do fundo do biofilme The post-treatment of anaerobic reactor effluents, such as the Upflow Anaerobic Sludge Blanket (UASB), in most applications, is necessary, since this kind of biological treatment promotes BOD removal ranging from 60 to 75% and it has low efficiency in nitrogen and phosphorous removal. Nitrogen removal is usually carried out in a conventional way through nitrification, followed by denitrification. Nitrification, as well as denitrification, can be achieved in suspended growth reactors, or in adhered growth...

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