Biofilmes aeróbios para remoção de nitrogênio em células de fluxo, submetidos a diferentes velocidades superficiais e taxas de carregamento
Data
2017-11-15
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
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) e taxas de carregamento (0,25; 0,5 e 1,0 g N/\'M POT.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 POT.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). 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 reactors, however it is known that systems based on biofilms exert direct influence in substrate degradation rates and ease the retention of nitrifying bacteria in reactors. The main objective of this work is to follow the development of aerobic biofilms in flow cell type reactors for the nitrification of synthetic substrate simulating an UASB effluent, submitted to different superficial velocities (1, 4 and 8 m/h) and loading rates (0.25; 0.5 and 1.0 g N/\'M POT.2\' biofilm.day). The development of nitrifying biofilms was followed by microsensors profiles and an estimative of the most probable number of nitrifying bacteria (MPN). The best NTK removal efficiencies were obtained in flow cells operated with a lower loading rate (0.25 g N/\'M POT.2\' biofilm.day), which represents a lower level than the levels applied in literature for adhered growth reactors used for nitrification. Considering the flow cells with a lower loading rate, the cell that presented NTK removal close to 100% was the one with the lowest superficial velocity (1 m/h). However, these systems present low efficiency for complete nitrification, obtaining higher nitrite than nitrate production; they could then be used in nitrogen removal by short way. The DO microsensors were efficient for analyses of DO profiles inside nitrifying biofilms, showing great variations, while the biofilm developed itself, in the DO concentrations in the contiguous liquid and at the bottom of the biofilm.
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 reactors, however it is known that systems based on biofilms exert direct influence in substrate degradation rates and ease the retention of nitrifying bacteria in reactors. The main objective of this work is to follow the development of aerobic biofilms in flow cell type reactors for the nitrification of synthetic substrate simulating an UASB effluent, submitted to different superficial velocities (1, 4 and 8 m/h) and loading rates (0.25; 0.5 and 1.0 g N/\'M POT.2\' biofilm.day). The development of nitrifying biofilms was followed by microsensors profiles and an estimative of the most probable number of nitrifying bacteria (MPN). The best NTK removal efficiencies were obtained in flow cells operated with a lower loading rate (0.25 g N/\'M POT.2\' biofilm.day), which represents a lower level than the levels applied in literature for adhered growth reactors used for nitrification. Considering the flow cells with a lower loading rate, the cell that presented NTK removal close to 100% was the one with the lowest superficial velocity (1 m/h). However, these systems present low efficiency for complete nitrification, obtaining higher nitrite than nitrate production; they could then be used in nitrogen removal by short way. The DO microsensors were efficient for analyses of DO profiles inside nitrifying biofilms, showing great variations, while the biofilm developed itself, in the DO concentrations in the contiguous liquid and at the bottom of the biofilm.
Palavras-chave
Biofilmes aeróbios, Microssensores, Nitrificação, Pós-tratamento, Aerobic biofilms, Microsensors, Nitrification, Post-treatment