Practical design of flocculator for new polymeric inorganic coagulant - PSI

Physical characteristics of flocs formed by new polymeric inorganic coagulant, polysilicato-iron coagulant (PSI) were investigated using kaolinite clay suspended water as test water. Floc density was determined by measuring floc settling velocity and spherical equivalent floc diameter. The floc dens...

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Bibliographic Details
Published in:Water science & technology. Water supply 2004-01, Vol.4 (1), p.67-75
Main Authors: Ohno, K, Uchiyama, M, Saito, M, Kamei, T, Magara, Y
Format: Article
Language:English
Subjects:
Alum
Aluminum
Clay
Coagulants
Density
Design parameters
Flocculation
Kaolinite
Physical properties
Sedimentation
Settling velocity
Size distribution
Stirring
Turbidity
Vadose water
Water purification
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Summary:Physical characteristics of flocs formed by new polymeric inorganic coagulant, polysilicato-iron coagulant (PSI) were investigated using kaolinite clay suspended water as test water. Floc density was determined by measuring floc settling velocity and spherical equivalent floc diameter. The floc density function proposed by Tambo and Watanabe could be applied to PSI. Flocs formed by PSI showed higher floc density than those formed by alum at the same floc size. Floc size distribution after the rapid mixing as also determined. PSI could produce well-grown flocs at the stirring speed of 300 rpm. Stirring at 300 rpm for 7 minutes, residual turbidity after 15 minute sedimentation became lower than rapid mixing at 120 rpm for 5 minutes followed by slow mixing at 40 rpm for 25 minutes. Flocs formed by PSI was much stronger than those formed by alum. Using the data obtained, the design parameters of flocculator by use of PSI were estimated following Tambo and WatanabeÕs procedure. According to the estimation, it was suggested that rapid mixing process alone can make well-grown flocs and slow mixing process, which is essential for the conventional water purification system using aluminium coagulants, can be eliminated by use of PSI.
ISSN:1606-9749
1607-0798
DOI:10.2166/ws.2004.0008