Takahiro FUKUMA
Clarification of Removal Performance of Actual Swirl in the Actual Drainage System of Nagaoka City
Tosiya KOMATSUˇˇShuji HIMENO
This study approaches the performance of the swirl in a practical way as countermeasure against combined sewer overflows.
It collects solids in the CSO toward the core of it by the vortex force. The solid concentrated in the core flows out from the outflow pipe of the bottom by gravity, and the treated waste water flows out from the upper overflow weir.
An actual swirl of 1.5m in diameter was set up in a wastewater treatment plant. The performance of the swirl was evaluated by using actual sewage by arbitrary quantity and quality. The swirl was set up on the floor of the wastewater treatment plant without laying underground to facilitate observing the performance.
First of all, the removal performance was evaluated by the change of the influent quality. Through the experiments it was suggested that the removal performance rises by an increase of the influent quality, and moreover the removal performance greatly takes part in the speed of the settling velocity of the solid included in the influent sewage. As a result, the removal rate of the swirl was about 50%. In that case, the influent SS is around 200mg/L, the overflow SS is around 100mg/L, the settling velocity of the solid is 0.6cm/s, the inflow is 8L/s, and overflow discharge is 3L/s.
Through long time observation, the optimal operational conditions of the swirl will be clarified.
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