Size-dependent anaerobic digestion rates of flocculated activated sludge: Role of intrafloc mass transfer resistance

JOURNAL OF ENVIRONMENTAL MANAGEMENT

卷:76

Article

Chu, CP ; Tsai, DG ; Lee, DJ ; Tay, JH

关键词: anaerobic digestion;    activated sludge;    mass transfer resistance;    CLSM;   

DOI  :  10.1016/j.jenvman.2005.01.022

来源: Elsevier

【 摘 要 】

The anaerobic digestion rate for flocculated sludge has been considered to be lower than that of original sludge, particularly in the later stages of digestion; Chu et al. (2003) attributed this relatively slower rate to the increased mass transfer resistance for reactants through the large flocs after flocculation. This study confirmed that methane production was retarded by flocculation. The structure of the floc was identified with fluorescence in situ hybridization (FISH) and a confocal laser scanning microscope (CLSM) technique. To verify the mass transfer resistance induced by flocculation, microsensors were applied to assess the response of oxygen concentration distribution inside the floes that are subjected to sudden changes in ambient oxygen levels. Response time for the electrode at a floc's center was five times greater than the response time in original sludge flocs. Although the effective diffusivity of oxygen in the floc increased by 2.3 times after flocculation, the increased size of the flocculated floc was the major contributor to the total mass transfer resistance to oxygen. (c) 2005 Elsevier Ltd. All rights reserved.

【 授权许可】

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