Table 11154 Important Sedimentation Data Needs

Data Need

Purpose

Viscosity of

High viscosity hinders

aqueous waste

sedimentation

Oil and grease

Not applicable to

content of

wastes containing

waste stream

emulsified oils

Specific gravity of

Must by greater than 1

suspended solids

for sedimentation to occur

can be accomplished using a batch process or a continuous removal process. Several physical arrangements where the sedimentation process is applied are shown in Figure 11.15.1.

The top diagram illustrates a settling pond. Aqueous waste flows through while suspended solids are permitted to gravitate and settle out. Occasionally the settling particles (sludges) are removed, so this system is considered a semibatch process.

The middle diagram shows a circular clarifier equipped with a solids-removal device. This facilitates continuous clarification, resulting in a lower solid content outlet fluid.

The sedimentation basin is shown in the bottom diagram. It uses a belt-type solids collector mechanism to force solids to the bottom of the basin's sloped edge, where they are removed.

The efficiency of sedimentation treatment depends upon the depth and surface area of the basin, settling time (based

Settling Pond

Inlet Liquid

Overflow Discharge Weir

Inlet Liquid

Overflow Discharge Weir

Accumulated Settled Particles Periodically Removed by Mechanical Shovel

Circular Clarifier

Inlet Liquid

Accumulated Settled Particles Periodically Removed by Mechanical Shovel

Circular Baffle

. Annular Overflow Weir

Settling Zone -

Inlet Zone > X

Revolving Collection Mechanism

Outlet Liquid Settling Particles

Settled Particles

Collected and Periodically Removed Sludge Drawoff

Sedimentation Basin Baffles to Maintain Inlet Zone Quiescent Conditions

Inlet Liquid

Settled Particles Collected and Periodically Removed

Sedimentation Basin Baffles to Maintain Inlet Zone Quiescent Conditions

Inlet Liquid

Settled Particles Collected and Periodically Removed

Outlet Liquid

Belt-Type Solids Collection Mechanism

FIG. 11.15.1 Representative types of sedimentation.

Outlet Liquid

Belt-Type Solids Collection Mechanism

FIG. 11.15.1 Representative types of sedimentation.

on the holding time), solid particle size, and the flow rate of the fluid.

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