XIAODan,NANJun,HEWei-peng,et al.Analysis of Lag Effect during Combined Flocculation and Sedimentation Processes Based on Evolution of Turbid Particle Size Distribution[J].China Water & Wastewater,2025,41(7):24-32.
Analysis of Lag Effect during Combined Flocculation and Sedimentation Processes Based on Evolution of Turbid Particle Size Distribution
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第41卷
Number:
第7期
Page:
24-32
Column:
Date of publication:
2025-04-01
- Keywords:
- water treatment plant; flocculation and sedimentation; coagulant dosage; turbidity; particle size distribution; lag effect
- Abstract:
- In order to address the lag characteristics associated with flocculant dosing, the trends and variations in floc particle numbers across different size ranges were investigated under varying influent conditions and dosages. The analysis emphasized the spatiotemporal changes in floc particle distribution to facilitate rapid dosing responses at water treatment plants, thereby enhancing operational stability. The results indicated that fluctuations in influent flow rate could be quickly reflected by changes in the number of floc particles within the size range of 15-25 μm. Specifically, when the influent flow rate decreased, the number of particles in this size range in the pre-flocculation water demonstrated minimal lag during the early flocculation phase, typically around 8 min, accompanied by a rapid decline in particle numbers. Conversely, when the influent flow rate increased, the number of floc particles in this range in the pre-flocculation water began to rise approximately 4 min into the early flocculation phase. In the circumstances of sudden changes in influent turbidity, the number of floc particles in the range of 10-15 μm also exhibited rapid fluctuations during the early flocculation phase, with minimal lag, generally reflecting abrupt changes in influent turbidity within 4 min. Moreover, a strong correlation existed between the turbidity removal rate after sedimentation and the number of particles greater than 10 μm at the conclusion of flocculation, and a lower count of particles exceeding 10 μm was associated with higher turbidity removal rates.
Last Update:
2025-04-01