JPS5615812A - Sludge withdrawal device for sedimentation tank - Google Patents

Abstract

PURPOSE: To withdraw automatically a sludge in an amount equal to the amount of the sludge transported from a sedimentation tank into a sludge storage tank by keeping the water level of the sludge storage tank constant.

CONSTITUTION: When sludge in the sludge storage tank 2 is transported by a pump 3, the sludge in an equal amount to the transported sludge is withdrawn into the sludge storage tank 2 by the sludge withdrawal device 4 provided to a sludge trap 1a at the bottom of the sedimentation tank 1. the sludge in polluted water sent to the sedimentation tank 1 is precipitated to the lower part of the tank and then flows through an aperture between an outer cylinder 6 and an inner cylinder 5 into the inner cylinder 5. When the amount of sludge transported by the pump 3 is increased and the water level l₂ is lowered, H₁ is increased, H₁-H₂, or h, is increased, and the amount of overflow is correspondingly increased, resulting in an increase in the amount of sludge to be withdrawn. On the other hand, when the amount of sludge transported by the pump 3 dicreases and the water level l₂ rises, H₁ is decreased, h is also decreased, and the amount of sludge to be withdrawn is correspondingly reduced. Then, when H₁ becomes H₂, the withdrawal is stopped.

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