JPS5615813A - Sludge withdrawal device for sedimentation tank - Google Patents

Abstract

PURPOSE: To eliminate the needs for sludge raker as well as permit the automatic withdrawal of sludge in an equal amount to the transported sludge from the sedimentation tank into a sludge storage tank by keeping the water level of the sludge storage tank constant.

CONSTITUTION: When sludge in the sludge storge tank 2 is transporated by the pump 3, the sludge in an equal amount to the transported sludge is withdrawin into the sludge storage tank 2 through a sludge withdrawal pipe 7 provided to a sludge trap 1a at the bottom of the sedimentation tank 1. The sludge present in the polluted water introducd into the sedimentation tank 1 precipitates to the lower part of the tank and then flows from the aperture between an outer box 6 and an inner box 5 into the inner box 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, goes high, and the amount of overflow is correspondingly increased, resulting in an increase in the amount of sludge to be withdrawn.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3 is reduced and the water level l₂ rises, h is decreased because H₁ becomes small and then the amount of sludge to be withdrawn is decreased. When H₁ becomes H₂, the withdrawal is stopped.

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