| Summary: | 碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 95 === Water areas have temperature and dissolved oxygen dividing layer. We use air-lift equipments with aerated ability to exchange upper and lower water to break the layer and increase the water’s dissolved oxygen. Air-lift equipments was assembled of PVC tubes. Regard air-lift pump as equipments’ motive force. Utilizing gas buoyancy that wells up the water in equipments and raises the water periodically to the surface, causing the water to exchange. Equipments increase dissolved oxygen in water to enhance the water quality.
According to the design of the equipments, two kinds of specifications of the device are designed. The experiment methods and designs and results are clearly propositioned to standardize more product of equipment to set up. This research analyses two kinds of specifications for air-lift equipments and confirming its movement characteristic. Oxygen increasing efficiency and range were recorded as well for identifying applicable conditions and clarifying operation methods. We design the numbers of oxygenation device to be used in order to apply different water areas.
The standard aeration efficiency (SAE) with air-lift equipments typeⅠis 0.56 kgO2/kw/hr, typeⅡis 0.72 kgO2/kw/hr. The latter is more efficient than type Ⅰ. The equipments showed outstanding effect in deep water since the oxygen diffused area expanded as the depth increased. The experiments showed that the oxygen diffused area can access to 8 meters in radius when the equipments was placed at 1 meter underwater,and 15 meters when it was placed at 5 meters .
The results confirmed that air-lift equipments can aerate more effective of whole bottom water in ponds, and it should enhance the organic matter digestion. It benefits water quality improvement when we aerate the water for a long time in succession.
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