TY - JOUR
T1 - The optimization on distributions of flow field and suspended solids in a full-scale high-rate clarifier using computational fluid dynamics
AU - Xu, Qi
AU - Xiao, Keke
AU - Wu, Qiongxiang
AU - Wang, Hui
AU - Liang, Sha
AU - Yu, Wenbo
AU - Tao, Shuangyi
AU - Hou, Huijie
AU - Liu, Bingchuan
AU - Hu, Jingping
AU - Yang, Jiakuan
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/3/15
Y1 - 2020/3/15
N2 - Suspended solids (SS) are one of major pollutants that deteriorate water quality. The high-rate clarifier is commonly used as the tertiary treatment by coagulation to agglomerate particles, thus achieving a high SS removal and making effluents acceptable for discharge. Currently the control of average residence time in operation of high-rate clarifier is challenging: With limited residence time, the particles fail to form flocs in the mixing tank, causing inefficient solid/liquid separation; while with prolonged residence time, SS sedimentation would accumulate at the bottom of the tank. In this study, a liquid-solid two-phase computational fluid dynamics (CFD) model has been developed to simulate the distributions of flow field and SS in a high-rate clarifier. The CFD model was successfully validated against experimental results in a full-scale operation, with the normalized standard error on SS less than 1.24 %. The results showed that the height of under-through channel affected the flow field more significantly rather than its width. This study also indicated that with the height of under-through channel decreasing from 2000 to 500 mm and the height of baffle increasing from 3300 to 5213 mm, the average SS concentration at the bottom of reaction tank would decrease by 34.95 % and the average residence time would be shortened by 4.77 %, which can be helpful for prolonging dredging cycle and avoiding unnecessary dredging costs.
AB - Suspended solids (SS) are one of major pollutants that deteriorate water quality. The high-rate clarifier is commonly used as the tertiary treatment by coagulation to agglomerate particles, thus achieving a high SS removal and making effluents acceptable for discharge. Currently the control of average residence time in operation of high-rate clarifier is challenging: With limited residence time, the particles fail to form flocs in the mixing tank, causing inefficient solid/liquid separation; while with prolonged residence time, SS sedimentation would accumulate at the bottom of the tank. In this study, a liquid-solid two-phase computational fluid dynamics (CFD) model has been developed to simulate the distributions of flow field and SS in a high-rate clarifier. The CFD model was successfully validated against experimental results in a full-scale operation, with the normalized standard error on SS less than 1.24 %. The results showed that the height of under-through channel affected the flow field more significantly rather than its width. This study also indicated that with the height of under-through channel decreasing from 2000 to 500 mm and the height of baffle increasing from 3300 to 5213 mm, the average SS concentration at the bottom of reaction tank would decrease by 34.95 % and the average residence time would be shortened by 4.77 %, which can be helpful for prolonging dredging cycle and avoiding unnecessary dredging costs.
KW - Computational fluid dynamics
KW - High-rate clarifier
KW - Hydrodynamics
KW - Suspended solids distribution
KW - Two-phase flow
UR - http://www.scopus.com/inward/record.url?scp=85077650705&partnerID=8YFLogxK
U2 - 10.1016/j.bej.2020.107489
DO - 10.1016/j.bej.2020.107489
M3 - 文章
AN - SCOPUS:85077650705
SN - 1369-703X
VL - 155
JO - Biochemical Engineering Journal
JF - Biochemical Engineering Journal
M1 - 107489
ER -