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VFA generation from waste activated sludge: Effect of temperature and mixing

Authors :
Yuan, Q.
Sparling, R.
Oleszkiewicz, J.A.
Source :
Chemosphere. Jan2011, Vol. 82 Issue 4, p603-607. 5p.
Publication Year :
2011

Abstract

Abstract: The success of enhanced biological phosphorus removal (EBPR) depends on the constant availability of volatile fatty acids (VFAs). To reduce costs, waste streams would be a preferred source. Since VFAs were shown to vary in the incoming sewage and fermentate from primary sludge the next available source is waste activated sludge (WAS). The opportunity is particularly good in plants where WAS is stored before shipment. Little information is however available on the rate of VFA release from such sludge, especially at the lower temperatures and under the storage conditions typically found in colder climates. Bench-scale batch tests were performed to investigate the effect of temperature and requirement for mixing on VFA generation from WAS generated in full scale non-EBPR wastewater treatment plant. WAS fermentation was found highly temperature-dependent. Hydrolysis rate constant (k h) values of 0.17, 0.08 and 0.04d−1 at 24.6, 14 and 4°C were obtained, respectively. Arrhenius temperature coefficient was calculated to be 1.07. It took 5d to complete hydrolysis at 24.6°C, 7d at 14°C, and 9d at 4°C. The fermentation lasted for 20d. At 24.6°C the mixed reactor reached 84% of the overall VFA production only in 5d. When temperature dropped to 14 and 4°C, the ratio of VFA production at day 10 to overall VFA production in the mixed reactor were 62% and 48%, respectively. The overall VFA–COD concentration in the non-mixed reactors was much lower than the mixed reactors. The information is important for the designer as there was uncertainty with the effect of temperature and mixing on sludge fermentation. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00456535
Volume :
82
Issue :
4
Database :
Academic Search Index
Journal :
Chemosphere
Publication Type :
Academic Journal
Accession number :
57141956
Full Text :
https://doi.org/10.1016/j.chemosphere.2010.10.084