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Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering)  2010, Vol. 11 Issue (9): 638-655    DOI: 10.1631/jzus.A0900651
Civil Engineering     
Effect of vacuum degree and aeration rate on sludge dewatering behavior with the aeration-vacuum method
Yu-feng Gao, Yuan Zhou
Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China, Geotechnical Research Institute, Hohai University, Nanjing 210098, China, The Science and Technology Division, Hohai University, Nanjing 210098, China
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Abstract  Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the adsorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (Δm) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.

Key wordsHigh water content dredged sludge      Sludge dewatering with aeration-vacuum (SDAV)      Vacuum degree      Aeration rate      Arch structures     
Received: 28 October 2009      Published: 07 September 2010
CLC:  TU4  
Cite this article:

Yu-feng Gao, Yuan Zhou. Effect of vacuum degree and aeration rate on sludge dewatering behavior with the aeration-vacuum method. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(9): 638-655.

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http://www.zjujournals.com/xueshu/zjus-a/10.1631/jzus.A0900651     OR     http://www.zjujournals.com/xueshu/zjus-a/Y2010/V11/I9/638

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