Over 2,000 flocs were involved in the calculations of floc fractal dimensions and floc shape factors to examine the effects of low temperature on floc structures. The 3-D fractal dimension of flocs was found to decrease from 2.48 at 22°C to 2.24 at 2°C, indicating flocs are more compact at the higher temperature. At 22°C, floc fractal dimensions were not significantly affected by flocculation time. However, at the low temperature, 2°C, fractal dimensions were found to increase with flocculation time, indicating that flocs generated at low temperature need more time to be well formed. On the other hand, low temperature did not exert significant influence on floc shape factors. Statistical analyses show that the examined shape factors of the flocs, roundness R and smoothness S, followed probability rules. Around 80% of flocs have an R value ranging from 0.5 to 0.8, and about 75% of flocs have an S value in the same range. The mechanism of floc growth during coagulation of kaolinite suspensions is reaction-limited cluster-cluster aggregation (RLCA).
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February 2009
This article was originally published in
Journal of Water Supply: Research and Technology-Aqua
Article Contents
Research Article|
February 01 2009
Effects of low temperature on floc fractal dimensions and shape factors during alum coagulation
Feng Xiao;
1Department of Civil Engineering, Hong Kong University of Science and Technology, Room 3575, Clear Water Bay, Kowloon, Hong Kong 999077, China
Tel.: +852-2358-8761 Fax: +852-2358-1534 E-mail: [email protected]; [email protected]
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Bao-jie Zhang;
Bao-jie Zhang
2School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China
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Jun Ma;
Jun Ma
2School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China
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Peng Yi;
Peng Yi
2School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China
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Chong-wei Cui
Chong-wei Cui
2School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China
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Journal of Water Supply: Research and Technology-Aqua (2009) 58 (1): 21–27.
Article history
Received:
March 03 2008
Accepted:
June 09 2008
Citation
Feng Xiao, Bao-jie Zhang, Jun Ma, Peng Yi, Chong-wei Cui; Effects of low temperature on floc fractal dimensions and shape factors during alum coagulation. Journal of Water Supply: Research and Technology-Aqua 1 February 2009; 58 (1): 21–27. doi: https://doi.org/10.2166/aqua.2009.019
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