Sedimentation Tank Hydraulics

Introduction

The current design of sedimentation tanks in Agua Clara plants consists of plate settlers placed above the inlet manifold that catch flocs formed in the flocculator while allowing water to flow past the settlers into exit launders. The flocs then settle out at the bottom of the sedimentation tank and are removed regularly by a sludge drain. Because of non-uniform flow, 1) flocs accumulate unevenly in the tank which causes difficulty in removal, 2) dead zones are created in the tank that lower the efficiency of the system.

We wish to determine the geometry of sedimentation tanks so that uniform flow is achieved and dead zones are eliminated, which would improve the efficiency of the current tank design and decrease the labor needed to maintain a clean tank. Given a particular upflow velocity, under these hydraulic conditions we may also experiment with floc blanket formation, which we believe will provide a second filtration stage for upward flowing flocs in the sedimentation tank and lower the turbidity of the effluent. Flocs may then be drawn off the blanket with a weir, minimizing the effort needed to clean the tank.

While our team is specifically looking at the floc blanket, some other aspects of the sedimentation tank may also be considered for an overall optimal design such as inlet manifold and the launder. You will be able to find past research on inlet manifold on the side bar.

Sedimentation Tank Hydraulics Documents