抄録
A biological method is usually used in many industries and water purification plants to treat organic waste water. Aerobic microorganisms in active sludge decompose organic compounds to lower molecular weight compounds 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, the size of air bubbles may be reduced. If bubbles are crushed by some additional power devices such as pump or stirrer, however, the cost increases. Therefore, in this study, a novel aerator which consumes almost no additional power was developed to generate bubbles having a diameter smaller than 1 mm.
When a gas is inputted from a round orifice into water, the bubbles grow very stably and their size is large. On the other hand, when the shape of the orifice is slit-like, instability is caused by bubble expansion. By using this natural phenomena, a uniform dispersion of submilli-bubbles was realized. Moreover, to design submilli-bubble dispersers, a semi-empirical bubble formation model is proposed.
