Settling behaviour of polymer flocculated water-treatment sludge II : effects of floc structure and floc packing

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Title: Settling behaviour of polymer flocculated water-treatment sludge II : effects of floc structure and floc packing
Authors: Zhao, Y.Q.
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Date: Mar-2004
Abstract: On the basis of experiments carried out using an image analysis system and static zone settlement, the alum sludge floc structure and the floc packing status with varied polymer dosages were examined in greater detail to reveal the link with the settling behaviour manifested in the “CML30 method”. The results of image analysis lead to the findings of the floc size with a pattern in initially great increase with low polymer dose and finally a plateau being reached at higher amount of polymer addition. Meanwhile, a polymer dosage in the range of 2.0 – 20.0 mg/l (for sludge SS = 4,595 mg/l) can result in the increase of the floc fractal dimension (DF) up to an average value of 1.72 (raw sludge DF being 1.06), indicating greater compactness of the floc solids. These floc features control the settling behaviour of the “CML30 method”, especially in small polymer dosages. However, in large polymer doses, the controlling factor is derived from the floc 'packing' status (referring to the inter – floc contact manner). This 'packing' status may associate with viscosity of settling medium (supernatant) and the excess polymer in bulk solution. All these affect the sludge floc networked structure in overdosing range.
Funding Details: Not applicable
Type of material: Journal Article
Publisher: Elsevier
Copyright (published version): 2004 Elsevier Ltd.
Keywords: Alum sludgeFloc packingFloc sizePolymerSettlementStructureTheoretical prediction
Subject LCSH: Water treatment plant residuals
DOI: 10.1016/s1383-5866(03)00133-3
Language: en
Status of Item: Peer reviewed
Appears in Collections:Centre for Water Resources Research Collection
Urban Institute Ireland Research Collection
Critical Infrastructure Group Research Collection
Civil Engineering Research Collection

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