Abstract
Since the easily decomposable organic matter is necessary for denitrification by denitrifying bacteria, in the previous study dextrose was mixed in the incoming water to make a C/N ratio of 12. But the secondary treated water from the sewage treatment plant includes little organic matter, hence a new experiment was carried on with the same conditions of the previous study but without carbon source.
The analytical results of purification rate, adsorption rate and denitrification rate by using the data of two experiments (incoming water with and without dextrose) are summarized as follows:
1. The effective factors for purification rate were carbon source, the kind of soil, N concentration of the incoming water and soil water condition. The mean purification rate without dextrose was 27%, which was 15% less than that with dextrose.
2. The kind of soil, N concentration and soil water condition have an effect on adsorption rate.
3. For denitrification rate, carbon source was the effective factor, and the kind of soil and N concentration seems to be significant. The mean denitrification rate without dextrose was 21%, less than 16% compared with the mean value of mixing dextrose.
