Sedimentation tank, also called settling tank are made of Glassfibre Reinforced Plastic/Polymer (GRP), component of a modern system of water supply or wastewater treatment. A sedimentation tank allows suspended particles to settle out of water or wastewater as it flows slowly through the tank, thereby providing some degree of purification. A layer of accumulated solids, called sludge, forms at the bottom of the tank and is periodically removed. In drinking-water treatment, coagulants are added to the water prior to sedimentation in order to facilitate the settling process, which is followed by filtration and other treatment steps. In modern sewage treatment, primary sedimentation must be followed by secondary treatment (e.g., trickling filter or activated sludge) to increase purification efficiencies.

Solid liquid separation process in which a suspension is separated into two phases –

• Clarified supernatant leaving the top of the sedimentation tank (overflow).
• Concentrated sludge leaving the bottom of the sedimentation tank (underflow).

The sedimentation tanks are partitioned to adequately remove suspended particles from water depending on the capacity of the sedimentation tank.

It is designed to adequacy remove the settled sludge formed at the bottom of the tank.

They are made up of GRP for durability. The GRP has the advantage of non corrosion and chemical resilience.