| 研究課題/領域番号 |
16J08523
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| 研究機関 | 東京農工大学 |
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研究代表者 |
謝 理 東京農工大学, 大学院工学府, 特別研究員(DC2)
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| 研究期間 (年度) |
2016-04-22 – 2018-03-31
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| キーワード | High pressure jet device / Cell disruption / Atomic force microscopy / Cavitation / Sludge reduction |
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| 研究実績の概要 |
To reduce excess activated sludge in a cost-effective and high-throughput manner, a high-pressure jet device (HPJD) was developed. Despite the effectiveness, universality of an HPJD as a sludge solubilization device entails further investigation because bacterial community in activated sludge is not identical. Cell robustness against mechanical impacts is likely distinct due to the difference in the cell structures, which plausibly exerts the resultant microbial community compositions after HPJD treatment. Application of an atomic force microscopy (AFM) provided, visualization of bacterial cells with several patterns of damages in a sub-micron level, magnitudes of cell morphological changes and cell wall/membrane conditions were distinct depending on the bacterial species . This may allow one to control microbial community structure depending on cell structure and robustness, adding another unique trait of an HPJD which usually functions as excess activated sludge reduction. Moreover, further improvements in the efficiency are necessary to have an HPJD implemented in full-scale WWTPs. Because of the inherent multiple effects of frictional shear, cavitation and collision, elucidating the dominant mechanism would provide a clue to maximize the performance of excess sludge reduction. Cavitation is proved to be the predominant factor in an HPJD to disrupt bacterial cell, resulting in excess biomass reduction. Optimization of an HPJD based on these findings will pave the way for excess sludge reduction in wastewater treatment plants with high cost-effectiveness and throughput.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
(1) Have completed all of the research plan for 2016, which is to expound the mechanism of cell destruction by a high pressure jet device. (2) Have finished half of the plan for 2017 in advance, which is the determination of dominate effect of HPJD on cell disruption. (3) Have published 2 papers in Chemical engineering journal, which has a high impact factor of 5.3. (4) Have attended the 1st International Conference on Bioresource Technology (BIORESTEC) in 2016, Sitges, Spain.
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| 今後の研究の推進方策 |
(1) Enlargement of cavitation effect on bacterial cell disruption
Cavitation is the dominant effect of HPJD on bacterial cell disruption. Hence, the effect of cavitation should be maximized to improve the sludge reduction efficiency of HPJD. As previous report, inlet pressure and cavitation number affects the intensity and length of cavitational zone, and the height to length ration control the size and collapse rate of cavity. Therefore, these parameters should be optimized to enlarge the cavitation effect.
(2) Enhancing methane production in anaerobic sludge digestion by applying HPJD pretreatment.
With respect to the excellent performance on excess activated sludge reduction, the applicability of an HPJD can be extended to a device for pretreatment of anaerobic sludge digestion.Generally, the hydrolysis is the rate-limiting step in anaerobic digestion of complex particulate waste be decomposed, bacterial cell wall and membrane is recalcitrant to the release and hydrolysis of intracellular polymeric substances, which likewise requires a longer sludge retention time. Our feasibility study has exhibited HPJD treatment increased the biodegradability of sludge and caused the release of intracellular components i.e. DNA, protein and polysaccharide from damaged bacterial cells, which are further decomposed into smaller fractions of organic components.Therefore feasibility of an HPJD toward not only excess sludge reduction but pretreatment for anaerobic digestion needs to be investigated.
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