1. An effective start-up of thermophilic UASB reactor by seeding mesophilically-grown granular sludge
- Author
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Suzuki, H., Ohashi, A., Harada, H., and Syutsubo, K.
- Subjects
SEWAGE sludge ,UPFLOW anaerobic sludge blanket (UASB) reactor ,DIGESTION ,BIODEGRADATION ,WASTEWATER treatment - Abstract
After seeded with mesophilically-grown (35 deg. C) granular sludge, a laboratory-scale UASB reactor was thermophilically (55 deg. C) operated over 8 months by feeding with an alcohol distillery wastewater. Use of mesophilically-grown granules as a seed material proved to be more advantageous for rapid and stable start-up of thermophilic UASB process, compared with the use of suspended-growth sludge taken from a thermophilic anaerobic digester. The reactor accommodated successfully a COD loading 30 kgCOD7m
-3 7d-1 , with a COD removal efficiency of 85%. However, during a period of 30 kgCOD7m-3 7d-1 , propionate accumulated in the effluent up to 300-600 mgCOD7l-1 . Thermophilic cultivation caused a drastic increase of methanogenic activities (55 deg. C) of the retained sludge: 4.4 times for acetate, 4.6 times for propionate, and 3.5 times for hydrogen as large as those of the seed sludge. A considerably low value of propionate-fed methanogenic activity, i.e. only 1/5 of acetate-fed activity and only 1/23 of hydrogen-fed activity, suggested that the propionate degradation is subject to be a rate-limiting stepin thermophilic anaerobic processes. [ABSTRACT FROM AUTHOR]- Published
- 1997
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