Experimental and numerical characterization of floc morphology: role of changing hydraulic retention time under flocculation mechanisms

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• 作者：Jun Nan ; Meng Yao ; Ting Chen ; Zhenbei Wang…
• 关键词：Floc breakage ; Floc re ; growth ; Hydraulic retention time ; DLA model
• 刊名：Environmental Science and Pollution Research
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：23
• 期：4
• 页码：3596-3608
• 全文大小：2,643 KB
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• 作者单位：Jun Nan (1)
  Meng Yao (1)
  Ting Chen (1)
  Zhenbei Wang (1)
  Qinggui Li (1)
  Dan Zhan (1)
  
  1. Skate Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, People’s Republic of China
  
• 刊物类别：Earth and Environmental Science
• 刊物主题：Environment
  Environment
  Atmospheric Protection, Air Quality Control and Air Pollution
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  Industrial Pollution Prevention
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1614-7499

文摘

The formation, breakage, and re-growth of flocs were investigated by using modified flocculation tests and numerical simulation to explore the evolution of floc morphology for different hydraulic retention times. The shorter the aggregation time was, the smaller the flocs produced for the same hydraulic conditions were. Another interesting discovery was that broken flocs that formed in shorter aggregation time had the capacity to completely recover, whereas those formed in a longer amount of time had rather worse reversibility of broken flocs. With the addition of the maximum motion step in the representative two-dimensional diffusion-limited aggregation (DLA) model, there was a transition for flocs from isotropic to anisotropic as the maximum motion step increased. The strength of flocs was mainly affected by the distribution of particles near the aggregated core rather than distant particles. A simplified breakage model, which found that broken flocs provided more chances for diffused particles to access the inner parts of flocs and to be uniformly packed around the aggregated core, was first proposed. Moreover, an important result showed that the floc fragments formed with a larger value of the maximum motion step had more growing sites than did those with a smaller msa value, which was a benefit of following the re-forming procedure. Keywords Floc breakage Floc re-growth Hydraulic retention time DLA model