Optimization of multi-stage velocity gradients in a cylindrical fluidized bed flocculator--颗粒学报PARTICUOLOGY

Lu, Y., Wang, J., Zhou, D., Xu, Z., & Bi, X. T. (2015). Optimization of multi-stage velocity gradients in a cylindrical fluidized bed flocculator. Particuology, 19, 118–123. https://doi.org/10.1016/j.partic.2014.05.006

Optimization of multi-stage velocity gradients in a cylindrical fluidized bed flocculator

Yamei Lu ^{a b}, Jun Wang ^a, Dandan Zhou ^a *, Zhengxue Xu ^a, Xiaotao T. Bi ^c

a Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China
b Changchun Urban Sciences Institute, Changchun 130062, China
c Department of Chemical and Biological Engineering, University of British Columbia, Vancouver V6T 1Z3, BC, Canada

10.1016/j.partic.2014.05.006

Volume 19, April 2015, Pages 118-123

Received 17 December 2013, Revised 12 April 2014, Accepted 2 May 2014, Available online 18 August 2014.

E-mail: zhoudandan415@163.com

Highlights

• Multi-stage velocity gradients were set up in a cylindrical fluidized bed.

• Multi-stage velocity gradients fluidized bed (MGF) was beneficial to protection of flocs.

• The required velocity gradients could be achieved by formulating solid phase.

• Suspended solids and dispersed dyes could be removed more efficiently in MGF.

Abstract

Flocculation time is conventionally believed to be proportional to the flocculation efficiency of a cylindrical fluidized bed flocculator. However, in a single-stage velocity gradient situation, the flocculation efficiency decreases when the optimal flocculation time is exceeded. A multi-stage velocity gradient was established in a cylindrical fluidized bed flocculator, based on the hydraulic classification theory. This multi-stage velocity gradient fluidized bed flocculator (MGF) created a more suitable environment for floc growth and protection, which was confirmed by the size distribution of flocs along the bed height. Correspondingly, the abatement efficiencies for Kaolin slurry and dyed wastewater treatment in the MGF were enhanced by 5–10%, and by 7–20%, respectively, compared with those in the single-stage velocity gradient fluidized bed flocculators (SGFs). The initial bed height distribution ratio along the velocity gradients was an important factor for MGF optimization.

Graphical abstract

Keywords

Abatement efficiency; Floc protection; Fluidized bed flocculator; Multi-stage velocity gradient; Optimization

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