Estudo da diversidade microbiana metanogênica em reatores UASB tratando esgoto sanitário

• Ano de defesa: 2007
• Autor(a) principal: Erika Ferreira de Abreu
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: FISH; Reator UASB; DGGE; Lodo de esgoto; Engenharia sanitária; Microbiologia sanitaria; Saneamento
• Link de acesso: http://hdl.handle.net/1843/ENGD-7ABPA7

The methanogenic microbial diversity of anaerobic sludge in two UASB reactors (denominated R1 and R2), treating domestic wastewater, was evaluated by molecular techniques (PCR-DGGE and FISH). The reactors were operated under 5 operational phases, with application of different upflow velocities: phase 1 (0,50 m/h), phase 2 (0,71 m/h), phase3 (1,10 m/h), phase 4 (0,50 m/h) and phase 5 (0,71 m/h). The sludge samples were collected at the end of each phase from three different heights of reactors. The results of PCR-DGGE analyses for all samples showed that the archaeal community was mainly constituted by 5 distinct populations and that this diversity was not altered by the imposition of different upflow velocities. However changes were observed in the intensity of the bands, which suggests that the abundance of these microorganisms decreased with the increase of upflow velocity. In addition, there was no difference in diversity of Archaea between the tworeactors, indicating that the presence of a forced screening unit preeceding R2 did not alter the methanogenic types present in the reactor. FISH analyses of samples of phase 5 with ARC915 probe revealed four different morphological types: two were very similar to typical acetoclastic Archaea (rods or filaments of genus Methanosaeta and cocci aggregated of genus Methanosarcina) and other two filaments, different from those of Methanosaeta, probably related to ydrogenotrophic methogens. Methanosaeta-like cells were the most observed archaea and accounted up to 2,29 x 108 cells/mL, comprising about 63 to 87% of total archaeal community. FISH analyses of SMA tests (specific methanogenic activity) incubated with sludge of the same UASB reactors grown with specific substrates showed predominance of Methanosaeta-like cells in two tested substrates (acetate and formate). The filtered COD removal of both reactors was similar which indicates that the estability of the microbial community was followed by estability of reactors performance. The results suggest that both reactors showed a similar archaeal community, constituted mainly by typical rods ofMethanosaeta, confirming the importance of this microbial group in the final chain of anaerobic degradation at UASB reactors.