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Wastewater treatment tips: Sedimentation

Source:     Time:11 September 2020


There are many professional words in the wastewater treatment industry, such as sedimentation, sludge concentration, reclaimed water, etc. To facilitate everyone's understanding and a better understanding of our industry, we will introduce the definition and classification of sedimentation.

Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration or electromagnetism. 

Classification of sedimentation:

1. Unhindered settling. Sedimentation is characterized by particles that settle discretely at a constant settling velocity. They settle as individual particles and do not flocculate or stick to other during settling.

Example: sand and grit material.

2. Settlement of flocculent particles. Sedimentation is characterized by particles that flocculate during sedimentation and because of this their size is constantly changing and therefore their settling velocity is changing.

Example: alum or iron coagulation

3. Zone sedimentation. In this process the particles are at a high concentration (greater than 1000 mg/L) such that the particles tend to settle as a mass and a distinct clear zone and sludge zone are present. Zone settling occurs in lime-softening, sedimentation, active sludge sedimentation and sludge thickeners.

4. Compression settling. The settling particles can contact each other and arise when approaching the floor of the sedimentation tanks at very high particle concentrations. In compression zone, the settled solids are compressed by gravity.

Envset is a professional wastewater treatment solution provider and knows a lot about wastewater treatment. If you are interested in sedimentation, you can contact us.

Tag: sedimentation definition, classification of sedimentation