Abstract
The purpose of this study is to reveal the effects of power saving via aeration time control on the characteristics of treatment water quality and biota in an activated sludge process of sewage treatment. For this purpose, an anaerobic-aerobic cyclic activated sludge process with different power-off times, i.e. non-aeration time intervals, and sludge circulation ratios were studied comparatively. As a result, when the power-off interval was 6 hr･day-1, the BOD concentration in the effluent was comparable to that in the control, which was obtained via operation with standard full time aeration, whereas when the power-off interval was 12 hr･day-1, the BOD was higher compared to the control. The NH4-N concentration increased and the NOX-N decreased when the power-off interval increased. The T-P for both power-off intervals were lower compared to the control. These results indicated that the BOD consumption and nitrification reaction were inhibited when the indicated DO was less than 1 mg･l-1. When the power-off interval was changed from 12 hr･day-1 to 6 hr･day-1, the total non-aeration time was the same at 12 hr･day-1, and high sludge circulation ratios were maintained, the wastewater treatment performance was as good as that of the control. In all operations, the biota characteristics were not affected by the power-off conditions. The results suggested that sewage treatment with a good treatment water quality could be achieved successfully by selecting appropriate operating conditions with half the power normally supplied to sewage treatment.
