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Conditioning of excess activated sludge by freezing and thawing: changes in the settling characteristics of the sludge floc.

Author(s) : KAWASAKI K., et al.

Type of article: Article

Summary

An excess activated sludge from a wastewater treatment plant, which was very difficult to filter, was subjected to freezing and thawing at various freezing rates, and the relationship between the density of the sludge floc and the solid-liquid separation characteristics was studied. The rate of settling of the sludge supernatant-liquid interface was correlated, using the equation of Richardson and Zaki; and the settling velocity of the single floc and the volumetric fraction increased in the order: unfrozen, fast-frozen, slowly-frozen sludge, showing that the gravitational settling characteristics could be greatly improved and the density of the flow increased by freezing and thawing. The solids concentration of the sludge sediment after gravitational settling was highest under slow freezing.

Details

  • Original title: Conditioning of excess activated sludge by freezing and thawing: changes in the settling characteristics of the sludge floc.
  • Record ID : 1993-0505
  • Languages: English
  • Source: Int. chem. Eng. - vol. 31 - n. 4
  • Publication date: 1991/10
  • Document available for consultation in the library of the IIR headquarters only.

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