Water Pollution and Control: Sedimentation

Primary Treatment

 Sedimentation:


Sedimentation water treatment uses tanks to remove suspended solids from water or wastewater. The process is based on gravity, which causes heavier particles to settle at the bottom of the tank. 

Construction

·         Shape: Sedimentation tanks can be rectangular, circular, or inverted pyramid-shaped 

·         Floor: The floor of the tank is often sloped to help collect sludge 

·         Size: The size of the tank depends on the amount of water being treated 

·         Mechanical parts: Some tanks use mechanical parts to move sludge 

Working 

1.      Water with suspended solids enters the tank

2.      The water slows down and the solids settle at the bottom

3.      The clean water overflows the tank

4.      The settled solids, called sludge, are removed periodically

Factors that affect sedimentation

·         Flow velocity: The slower the water moves, the more particles settle 

·         Coagulants: Adding coagulants before sedimentation can speed up the settling process 

·         Water temperature: The temperature of the water can affect how quickly particles settle 

·         Particle size: The size of the particles can affect how quickly they settle








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