The Characteristics of Stratified Dissolved Oxygen and the Aeration Efficiency at the Midstream of Tanshui River and the Lover River
Date Issued
2008
Date
2008
Author(s)
Chuang, Kai-Ming
Abstract
The dissolved oxygen（DO）is nearly none at the bottom of water at the midstream of Tanshui river. Therefore, this study is applying an air-lift column to deal with low DO condition of water and investigating hydraulic characteristic of Dadaocheng Basin as air-lift column design reference resources. In this study, the air-lift column is a low energy costing and intermittently operating device which can mix different water layers. Field experiments in summer and winter are operated to measure the oxygen consumption rate of the sediment. And the air-lift column efficiency of the increased oxygen rate、the water mixing ability and the oxygen spread of ability are fast. Standard experiment of air-lift column is carried out in static state water. And compare the efficiency of the two types of column design. In addition, this study measures the increased oxygen efficiency and diffusive ability of the aeration boat to build up the database for river renovation.esults show DO below 3ppm and without-delaminating during the period of flood tide and only about 1ppm in the ebb tide in the Dadaocheng watershed. The oxygen consumption rate of the sediment are 9±6 mg/m2/min in summer (water temp. 26℃) and 5±5 mg/m2/min in winter (water temp. 19℃). The standard aeration efficiency (SAE) of air-lift column is 1.50 kgO2/kw/hr, up-welled water volume is 621~629 ml. when it is applied to the low speed flow watershed, the agitated range is about 3 m、the increased oxygen rate at the outlet is 0.86mg/l and the electric cost is 0.38 NT dollar/mgO2/l/hour. The increased oxygen rate of the aeration boat in Kaohsiung is 1.8mg/l and electric cost is 6.99 NT dollar/mgO2/lhour. omparing water quality improvement ability and the oxygen spread of ability between indirect oxygen increasing air-lift column and continuous aeration boat, indirect oxygen increasing method has better performance than continuous oxygen increasing method. To sum up, the air-lift column can be one of the physics methods to effect oxygen increasing.
Subjects
air-lift column
oxygen consumption rate of the sediment
oxygen increased method
water quality improvement
dissolved oxygen.
Type
thesis
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