In the primary sedimentation stage, sewage flows through large tanks, commonly called “pre-settling basins”, “primary sedimentation tanks” or “primary clarifiers”. The tanks are used to settle sludge while grease and oils rise to the surface and are skimmed off. Primary settling tanks are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank where it is pumped to sludge treatment facilities.
- To produce a liquid effluent of suitably improved quality for the next treatment stage (i.e.) secondary biological treatment.
- To active a solids separation resulting in a primary sludge that can be conveniently treated and disposed of.
Benefits of Primary Treatment
The benefits of primary treatment include
- Reduction in suspension solids
- Reduction in BOD
- Reduction in the amount of waste activated sludge (WAS) in the activated-sludge plant.
- Removal of floating materials (oil and geese).
- partial equalization of flow rates and organic load.
Types of Sedimentation Tanks that WATEQ can offer:
- Rectangular Horizontal Flow Tanks
- Rectangular grit and scum clarifier
- Circular Radial Flow Tanks and Up Flow Tanks
- Circular half and full bridge clarifier
- Non metallic rectangular chain scraper