Factual analysis of granule flotation in brewery wastewater treatment plants by the fluorescence in situ hybridization method.
The factors that change the microbial distribution and consequently the flotation of brewery granules were investigated using laboratory-scale upflow anaerobic sludge blanket (UASB) reactors and the fluorescence in situ hybridization (FISH) method. The startup operations of laboratory-scale UASB reactors fed with acetate-based synthetic wastewater, in which the loading rate was maintained at 0.1 gCOD/gVSS/d (Run 1) and increased in a stepwise manner from 0.1 gCOD/gVSS/d to 1.0 gCOD/gVSS/d (Run 2), generated methanogen colonies near the granule surface, while the overloading operation at 1.0 gCOD/gVSS/d from the startup (Run 3) resulted in the formation of methanogen colonies deep in the granules. In each run, a proportion of the granules floated when overloaded at 2.0 gCOD/gVSS/d and circulation was stopped. The ratio of floating granules increased as the methanogen-growing region increased. On the other hand, the Bacteria layer on the granule surface, which is also considered as a possible cause of granule flotation, was not formed by the inflow of other organic acids such as propionate and lactate. Glucose caused formation of a 5-microm-thick surface Bacteria layer, but the granules were still resistant to flotation. Interfusing of air under glucose feeding caused the formation of a Bacteria layer over 50 microm thick leading to granule flotation.
Saiki
Yuko
Y
Fundamental Research Laboratory, Asahi Breweries, Ltd., 1-1-21 Midori, Moriya 302-0106, Japan. yuko.saiki@asahibeer.co.jp
Katami
Akiko
A
Kitagawa
Yasushi
Y