1. Changes of microbial characteristics of retained sludge during low-temperature operation of an EGSB reactor for low-strength wastewater treatment.
- Author
-
Syutsubo, K., Yoochatchaval, W., Yoshida, H., Nishiyama, K., Okawara, M., Sumino, H., Araki, N., Harada, H., and Ohashi, A.
- Subjects
- *
CHEMICAL oxygen demand , *ANAEROBIC digestion , *SEWAGE sludge digestion , *BIOLOGICAL nutrient removal , *LOW temperature engineering , *METHANOGENS , *METHANE - Abstract
In this study, a lab scale EGSB reactor was operated for 400 days to investigate the influence of temperature-decrease on the microbial characteristic of retained sludge. The EGSB reactor was started-up at 15°C seeding with 20°C-grown granular sludge. The influent COD of synthetic wastewater was set at 0.6-0.8 gCOD/L. The process-temperature was stepwise reduced from 15°C to 5°C during 400 days operation. Decrease of temperature of the reactor from 15°C to 10°C caused the decline of COD removal efficiency. However, continuous operation of the EGSB reactor led the efficient treatment of wastewater (70% of COD removal, 50% of methane recovery) at 10°C. We confirmed that the both acetate-fed and hydrogen-fed methanogenic activities of retained sludge clearly increased under 15 to 20°C. Changes of microbial profiles of methanogenic bacteria were analyzed by 16S rDNA-targeted DGGE analysis and cloning. It shows that genus Methanospirillum as hydrogen-utilizing methanogen proliferated due to low temperature operation of the reactor. On the other hand, genus Methanosaeta presented in abundance as acetoclastic-methanogen throughout the experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF