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篇目详细内容 |
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【篇名】 |
Enhancement of sludge gravitational thickening with weak ultrasound |
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【刊名】 |
Frontiers of Environmental Science and Engineering |
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【刊名缩写】 |
Front.Environ.Sci.Eng. |
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【ISSN】 |
2095-2201 |
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【EISSN】 |
2095-221X |
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【DOI】 |
10.1007/s11783-011-0368-5 |
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【出版社】 |
Higher Education Press and Springer-Verlag Berlin
Heidelberg |
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【出版年】 |
2012 |
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【卷期】 |
6
卷5期 |
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【页码】 |
753-760
页,共
8
页 |
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【作者】 |
Panyue ZHANG;
Tian WAN;
Guangming ZHANG;
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【关键词】 |
activated sludge; sonication; settlability; dry weight; extracellular polymeric substances; polyelectrolyte |
【摘要】 |
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Gravitational thickening is the prevailing method to reduce sludge volume but the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the sludge gravitational thickening with very low energy dose, so called “weak ultrasound”. Results showed that weak sonication significantly changed the sludge settlability and the main mechanism was release of the loosely bounded extracellular polymeric substances. The changes in sludge behaviors by sonication were strongly influenced by power density and sonication duration. Lower sound frequency was slightly better than higher frequency. Weak sonication (<680？kJ·kg？1 DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15？W·mL？1, 7？s, and 25？kHz. Under such conditions, the energy dose was only 155？kJ·kg？1 DS, much lower than literature reports, and the sludge settling time was shortened from 24？h to 12？h. Weak sonication could substitute expensive polyelectrolyte coagulant for sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6？h. The final water content of the thickened sludge was not changed after sonication or polyelectrolyte addition. |
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