Abstract
In order to determine the optimum treatment conditions for reducing the retention time in the nitrogen removal treatment with intermittent aeration, investigations at 20°C were carried out in small treatment tanks. In these tanks, various concentrations of artificial wastewater were used as influents and the aeration intervals and strengths were changed.
The results showed that in the treatments of the high, middle, and low concentrations of wastewaters the high rates of nitrogen removal of ca. 90, 80, and 70%, respectively, could be achieved under the rather short retention times of 3, 1.5 and 0.25 days, without the addition of methanol as an energy source for denitrification and without the occurrence of excess sludge in the effluent.
Some excess sludge, which remarkably reduced the removal rate of nitrogen in effluent, occurred occasionally in the effluent after the treatment of high concentration wastewater. But such effluent with the excess sludge could be prevented by treating the wastewater with a continuous aeration during one day, once every 3-4 weeks.
