Lamella Design Program

Lamella Design Program Algorithm

Lamella Program Inputs
Lamella Program Outputs

Critical velocity is the rate at which a particle must fall to ensure that it settles out in the plate settlers. If the critical velocity is too large, flocs will not settle out. However a small critical velocity comes at the expense of area (so it is not practical to have an unnecessarily small velocity).
We are designing our tanks to have an upward velocity of 100 m/day. We've found that this is the velocity allows for the formation of a sludge blanket in the bottom of the tank. Since a portion of the tank's length is rendered unusable due to the sloping of the lamella, the actual length of the tank is greater than the active length. Explain the dual constraints of critical velocity and upflow velocity and detail how both constraints could be met simultaneously or how they could both be set as maximum values.

Sedimentation is a basic step of most traditional water treatment processes. In our plant it comes between flocculation and chlorination. It uses gravity to separate water from the particles - particles settle to the bottom of the tank while the clean water rises to the top. Any particle settling faster than the critical velocity of the tank should settle out. Critical velcoty is a function of the flow rate and setting area of the tank. A particle's settling velcotiy depends on its size and density. Larger particles settle faster and therefore are thereby easier to separate from the clean water. Our design employs plate settlers which lessen the distance a particle must fall in order to settle out. This increases the tanks efficiency.