Studies on natural purification mechanism in open channel
1995
Cho, K. (Kagoshima Univ. (Japan). Faculty of Agriculture)
Recently, in public water body, conspicuous water pollution has been prevailing. The self purification mechanism in a water basin makes it possible to clarify such water pollution. But in this occasion, in order to carry out the biochemical decomposing and nitrification of nitrogen, the presence of oxygen is indispensable. Accordingly, unless the amount of oxygen supplied from atmosphere exceeds that of oxygen consumed, it becomes impossible for purification to go on. In this study some experimental examinations were made in order to clarify the relation between the rate of atmospheric reaeration and hydraulic factors of the open channel. The main findings in the present study can be summarized as in the following: 1) Under a uniform flowering, the relation between reaeration coefficients and hydraulic factors of open channel can be expressed by eq.(10). But his it is meant that a production of bulky reaeration can be brought out by making the channel depth shallower and the flowing velocity in the channel faster. 2) Reaeration coefficients derived from atmosphere through hydraulic jump can be expressed by eq.(12). This is to say that reaeration from atmosphere increases in proportion to the increasing of the specific energy in front of hydraulic jump and discharge. In practical channel in which both discharge and specific energy are quite prominent, production of bulky reaeration may be expected
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