Submilli-Bubble Dispersion from a Slit Orifice into Water Mixture

概要

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To treat the organic waste water, the biological method is usually used in many industries and water purification plants. The aerobic microorganisms in active sludge decompose organic compounds to low molecular ones with oxygen consumption in aeration tank. On many aeration systems, the oxygen supply into water limits the rate of waste water treatment. To improve the oxygen dissolution into water, it is available that the size of air bubbles is reduced. If bubbles are crushed by some additional power devices such as pump, stirrer and so on, however, the cost must increase. Therefore, in this study, a novel aerator which consumes almost no additional power was developed to generate bubbles that diameter is smaller than 1 mm. When a gas is inputted from a round orifice into water, the bubbles grow very stably that their size is large. On the other hand, when the shape of the orifice is slit-like, instability is caused by the bubble expansion. By using the natural phenomena, a uniform dispersion of submilli-bubble was realized. Moreover, to design submilli-bubble dispersers, a semi-empirical bubble formation model was proposed.