| DOI: | 10.1016/j.watres.2018.09.041
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| Scopus记录号: | 2-s2.0-85054293170
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| 论文题名: | Selection of media for the design of ballasted flocculation processes |
| 作者: | Lapointe M.; Barbeau B.
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| 刊名: | Water Research
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| ISSN: | 431354
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| 出版年: | 2018
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| 卷: | 147 | | 起始页码: | 25
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| 结束页码: | 32
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| 语种: | 英语
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| 英文关键词: | Ballast media
; Ballasted flocculation key criteria
; Floc size
; Specific gravity
; Surface concentration
; Turbidity removal
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| 英文摘要: | Conventional clarification processes imply specific facility footprints that translate into important capital costs. Ballasted flocculation, consisting of injecting ballast medium to increase floc specific gravity and size, is being increasingly used in the water industry owing to its potential for design with very high superficial velocities. However, no systematic approach has yet been proposed to compare and select an appropriate ballast medium with respect to its specific gravity and size. In order to facilitate this procedure, this research project explores the hypothesis that flocculation performance is controlled by the surface area of the medium available for ballasted flocculation. This hypothesis was tested at laboratory scale by evaluating five ballast media with differing specific gravity and size: granular activated carbon, anthracite, silica sand, ilmenite, and magnetite sand having specific gravities of 1.24, 1.45, 2.62, 3.70, and 5.08, respectively. Flocculation kinetics were monitored by measuring floc size through microscopy and with a camera installed directly on the jar-test beaker. Settling performance was monitored using turbidity measurements. This study shows that all ballast media, when expressed as total surface available during flocculation, required similar surface concentrations to achieve settled water turbidity near 1 NTU and lower. In addition, the effects from the ballast media size and specific gravity were lowered for settling time longer than 3 min. Inversely, for settling time of 12 s, larger and denser media produced lower settled water turbidity. For certain applications, lighter ballast media may be more economical because they offer more available surface area for a given mass concentration, hence reducing the amount of ballast media required in the flocculation tank. Finally, the ballast media point of zero charge and shape were not identified as key criteria for ballasted flocculation. © 2018 Elsevier Ltd |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/112378
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| Appears in Collections: | 气候减缓与适应
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作者单位: | Department of Civil, Geological and Mining Engineering, Polytechnique MontrealQuebec H3C 3A7, Canada
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| Recommended Citation: | |
Lapointe M.,Barbeau B.. Selection of media for the design of ballasted flocculation processes[J]. Water Research,2018-01-01,147
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