Abstract
Organic suspended solids which settle and concentrate at the bottom of lakes and streams exert an oxygen demand on the overflowing water.
This oxygen demand is examined for bottom sediments of Nihonbashi River in Tokyo. In laboratory studies, the following conclusions are presented ;
1. The oxygen uptake rate was obtained 0.20.4 g-O2/m2· day in the stagnant conditions. But, under the slight mixing conditions, turbulence increases the oxygen demand to 0.81.2 g-O2/m2·day.
2. On the experiments that a fresh supply of water was added to the reaction tank, the oxygen demand of surface of the sludge is obtained 7.011.0 g-O2/g-dry sludge, and its values was constant during experiments.
3. The effect of water temperature on the oxygen demand was observed.
4. On the experiments that the bottom sediments was contacted with water by filtration, the oxygen uptake rate of 0.30.6 g-O2/m2·day/cm and the BOD loading rate of 0.51.6 g-BOD/m2·day/cm were obtained.
