2006 Fiscal Year Final Research Report Summary
Development of waste activated sludge solubilization treatment by simultaneous use of ultrasonic and electrolytic processes
| Project/Area Number |
17560482
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | Gunma University |
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Principal Investigator |
WATANABE Tomohide Gunma University, Department of Civil Engineering, Professor, 工学部, 教授 (60251120)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Tsukasa Gunma University, Department of Civil Engineering, Assistant Professor, 工学部, 講師 (80431708)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Sludge disintegration / Sonication / Electrolysis / Anaerobic sludge digestion / Waste activated sludge / sludge volume reduction |
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| Research Abstract |
The sludge solubilization treatment by the simultaneous use of ultrasound and electrolysis processes was investigated experimentally. A lab-scale diaphragm cell with irradiation of ultrasound was used as a reactor. The following results were obtained.
1.Compared to the sonication alone, the simultaneous use of ultrasound and electrolysis processes significantly increased the generation rate of soluble COD and reduced the specific energy consumption for sludge solubilization. This was exclusively observed in cathodic compartment. The pH adjustment of the sludge to a moderate alkaline condition as a pre-treatment further contributed to the improvement of the solubilization performance in the simultaneous treatments.
2.The specific energy consumption for sludge solubilization could be reduced by about 50% at optimum condition of the initial solid concentration in sludge, ultrasonic density and electric current for electrolysis, compared to that of sonication alone. The sludge solubilization
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performance was approximately similar, regardless of different sources of sludge within the experimental range.
3.The soluble nitrogen/total nitrogen ratio and soluble phosphorus/total phosphorus ratio were comparable with degree of solubilization based on soluble COD release. The soluble nitrogen components consisted of 60 to 70% organic nitrogen, 15 to 20% ammonium nitrogen and 15 to 20% nitrate.
4.The specific methane production rate considerably increased by the proposed sludge solubilization treatment, especially in first several days of fermentation. Methane conversion of soluble COD was approximately constant, regardless of degree of solubilization. The percentage of readily biodegradable substrates on the basis of aerobic degradability tended to be higher than that by the sonication alone.
5.Nitrate and phosphate ions generated in cathodic compartment during sludge solubilization could be migrated to anodic compartment, indicating that potentiality for the separation and enrichment of these components. Less
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Research Products
(4 results)
