Aerobic biofilms for nitrogen removal in flow cells, submitted to different superficial velocities and loading rates / Biofilmes aeróbios para remoção de nitrogênio em células de fluxo, submetidos a diferentes velocidades superficiais e taxas de carregamento

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

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.2biofilm.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.2biofilm.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.

ASSUNTO(S)

aerobic biofilms nitrificação nitrification pós-tratamento microsensors microssensores post-treatment biofilmes aeróbios

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