Abstract
For the control of COD load in Lake Kojima, this study was performed to estimate dissolved COD inflows from domestic effluent and paddy field which were considered as main COD source.
Degradation and remaining of fractions of the dissolved COD substances were discussed by the gel chromatography.
By calculation with the increase of lake water level, water inflows were 7.6×105m3·d-1 in the clear non-irrigation period and 12.1×105m3·d-1 in the clear irrigation period, and annual average run-off ratio of precipitation was 0.46 from Apr. '91 to Mar. '92.
Dissolved COD remaining through the process of sewage treatment and natural purification from domestic effluent showed about 21% of COD load factor (20g·person-1·d-1) in estimation with UV absorbance and dissolved COD pattern of domestic effluent and downstream river water by Sephadex G-15 gel chromatography.
On the basis of synthesis of UV absorbance pattern and dissolved COD concentration of waters sampled at lake, paddy field, forest and urban area, dissolved COD inflow from paddy field was estimated at 7,200kg·km-2·y-1.
