Formation, breakage and re-formation of flocs formed by cationic starch

The efficiency of flocculation can be significantly improved through floc breakage and re-formation under appropriate conditions. To obtain a better understanding of the mechanisms involved and to relate floc properties to separation efficiency, the effects of mixing conditions on the formation, bre...

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Bibliographic Details
Published in:Water science and technology 2013-01, Vol.68 (6), p.1352-1358
Main Authors: Lin, Qintie, Peng, Huanlong, Lin, Qinlu, Yin, Guangcai
Format: Article
Language:English
Subjects:
Acidification
Applied sciences
Breakage
Cations
Efficiency
Epoxy Compounds - chemistry
Exact sciences and technology
Flocculation
Hydrogen-Ion Concentration
Jar tests
Kaolin
Kaolin - chemistry
Mechanical Phenomena
Morphology
Nephelometry and Turbidimetry
NMR
Nuclear magnetic resonance
Pollution
Polymers
Quaternary Ammonium Compounds - chemistry
Shear
Shear strength
Starch
Starch - chemistry
Waste Disposal, Fluid
Water Purification
Water treatment and pollution
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Summary:The efficiency of flocculation can be significantly improved through floc breakage and re-formation under appropriate conditions. To obtain a better understanding of the mechanisms involved and to relate floc properties to separation efficiency, the effects of mixing conditions on the formation, breakage and re-formation of flocs formed by kaolin and cationic starch were investigated through conventional jar test procedure and continuous optical monitoring. It has been found that the breakage of flocs was fully reversible and the polymer flocculant could resist strong shear; even having been sheared for four times, the flocculation index (FI) value would be higher than that of the original flocs. The results indicated flocs formed at neutral and alkaline conditions had better shear resistance than those at acidification conditions, and the mode of floc rupture was large-scale fragmentation.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2013.377