Efficient separation of suspended solids or sedimentation is an important and essential aspect in effluent treatment, since it not only reduces considerably suspended solids loading, but also helps in reducing the COD/BOD loading, thereby contributing in reducing the sizing of subsequent processes viz. that of biological treatment etc.
The clarification/sedimentation is the process to remove suspended solids. Suspended solids removal of up to 70% and settleable solids removal up to 90% to 98% and COD removal as high as up to 40% are achievable with the proper design of the clarifier unit.
The process is purely gravity separation. This is achieved by the reduction in velocity of the fluid and nearly 180° change in the direction of flow. The separated solids would flow downward and settle on the tapered floor.
The slow moving scraper arm scrapes the floor and brings the settled sludge to the central sludge well. The velocity of the movement is designed in such a way that the sedimentation process is not disturbed at all.
There are two basic types of the clarifier mechanisms which are manufactured.
- End Drive/Traction Drive type clarifier with central RCC column for support.
- Centre-Drive clarifier.
in Central Drive Clarifier. Central Drive Clarifier have low running/operating cost, and hence are more economical. For the same diameter of the clarifier,
the HP required for the End Drive Clarifier is more than the HP required for Central Drive Clarifier.
From maintenance point of view, there are more wearing parts in End Drive Clarifier and hence result in more maintenance expenditure.
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