HEWei-peng,LUOTian-hao,SHIZhou,et al.Impact of Turbidity Characteristics under Varying Flow Directions on Sand Filtration Efficiency and Head Loss Distribution[J].China Water & Wastewater,2025,41(19):22-28.
Click Copy

Impact of Turbidity Characteristics under Varying Flow Directions on Sand Filtration Efficiency and Head Loss Distribution

China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU] volume: 第41卷 Number: 第19期 Page: 22-28 Column: Date of publication: 2025-10-01
Author(s):
HE　Wei-peng1; 2;  LUO　Tian-hao1; 2;  SHI　Zhou1; 2;  NAN　Jun3;  MA　Jing-wei1; 2;  SUN　Xiang-hui1; 2
（1. College of Civil Engineering， Hunan University， Changsha 410082， China； 2. Hunan Engineering Research Center of Water Security Technology and Application， Changsha 410082， China； 3. School of Environment， Harbin Institute of Technology， Harbin 150090， China）
Keywords:
upflow filtration;  downflow filtration;  filtered water turbidity;  head loss distribution;  synergistic removal of pollutants
Abstract:
There remains a lack of systematic understanding regarding the influence of turbidity characteristics (e.g., particle morphology and surface charge) in the influent on the filtration process under different flow directions. To address this issue, polyaluminium chloride (PAC) was selected as the coagulant to prepare influent containing turbidity particles with controlled characteristics through coagulation regulation. Subsequently, pilot-scale comparative experiments were conducted to investigate the differences in pollutants removal efficiency and head loss distribution between downflow and upflow filtration processes. Based on these experimental results, the filtration mechanisms under both flow conditions were systematically analyzed. Compared with downflow filtration, upflow filtration reached the stable stage more rapidly under the same dosage of PAC. Furthermore, with an increase in PAC dosage, the effluent turbidity during the breakthrough phase of upflow filtration rose at a faster rate, ultimately resulting in higher final turbidity. Under both flow conditions, the UV254 value of the filtered water decreased with increasing PAC dosage. However, at the same PAC dosage, the UV254 value in upflow filtration was higher than that in downflow filtration, indicating a relatively weaker synergistic removal efficiency of humic acid in upflow filtration. Additionally, upflow filtration exhibited a more uniform head loss distribution and a slower growth rate of total head loss compared to downflow filtration.
Last Update: 2025-10-01