Enhancement of sludge densification by regulating hydrocyclone inlet flow velocity

CHEN Yasong; LIU Mengmeng; SUN Wan; TAO Xiang; SHAO Yanjun; WANG Yan; WANG Shuo; LI Ji

doi:10.13205/j.hjgc.202509013

Volume 43 Issue 9

Sep. 2025

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Article Navigation > ENVIRONMENTAL ENGINEERING > 2025 > 43(9): 119-126

CHEN Yasong, LIU Mengmeng, SUN Wan, TAO Xiang, SHAO Yanjun, WANG Yan, WANG Shuo, LI Ji. Enhancement of sludge densification by regulating hydrocyclone inlet flow velocity[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(9): 119-126. doi: 10.13205/j.hjgc.202509013

Citation:

CHEN Yasong, LIU Mengmeng, SUN Wan, TAO Xiang, SHAO Yanjun, WANG Yan, WANG Shuo, LI Ji. Enhancement of sludge densification by regulating hydrocyclone inlet flow velocity[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(9): 119-126. doi: 10.13205/j.hjgc.202509013

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Enhancement of sludge densification by regulating hydrocyclone inlet flow velocity

doi: 10.13205/j.hjgc.202509013

1. National Engineering Research Center of Eco-Environment in the Yangtze River Economic Belt, China Three Gorges Corporation, Wuhan 430014, China;
2. Jiangsu Provincial Key Laboratory of Anaerobic Biotechnology, School of Environment and Ecology, Jiangnan University, Wuxi 214122, China;
3. Jiangsu Province University Water Treatment Technology and Materials Collaborative Innovation Center, Suzhou 215009, China

Received Date: 2025-05-14
Available Online: 2025-11-05
Publish Date: 2025-09-01

Abstract

Abstract

The sludge densification technology based on hydrocyclone was expected to address the operational bottlenecks faced by sewage treatment plants due to the increase in treatment load. However， there was still a lack of research on operational optimization and control of hydrocyclone to achieve precise optimization on sludge settling performance. To improve the densification efficiency of this technology， this study systematically compared the differences in particle size distribution and sedimentation performance of wet sludge under low （1 m/s） and high （3 m/s） flow velocity condition. The results showed that， compared with the low flow velocity， the high flow velocity significantly enhanced the separation efficiency of the underflow and overflow sludge， making the proportion of large biological aggregates （≥150 μm） in the underflow 10.6% higher than that in the overflow sludge. After densification enhancement， the SVI₃₀ of the underflow sludge decreased from 101.3 to 89.1 mL/g， and the sedimentation performance was significantly improved （P < 0.05）， while the SVI₃₀ of the rejected overflow sludge was as high as 124.9 mL/g. In terms of functional performance， the nitrification， denitrification and phosphorus release rates of the densified sludge increased by 3.3%， 7.2% and 12.2%， respectively. The analysis of the dominant flora further revealed that the relative abundance of Delftia， which has both a high EPS secretion capacity and simultaneous nitrification and denitrification performance， increased by 3.02% in the densified group， ensuring the aggregation of sludge and improvement of nitrogen removal capacity. In addition， the abundances of Acinetobacter and Dechloromonas with potential for denitrifying phosphorus removal slightly decreased after densification， but they may still play a key role in improving the nitrogen and phosphorus removal function. This study clarified the significant impact of flow rate regulation of the hydrocyclone on sludge densification effect. In the future， it is necessary to combine molecular biological methods and kinetic modelling to promote the development of parameter optimization and intelligent control strategies for hydrocyclone.
- sludge densification system technology,
- hydrocyclone,
- flow velocity,
- settling performance,
- microbial population

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References(30)

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