What is a clarifier in a Wastewater Treatment Plant?
Clarifiers are tanks built with a mechanism for continuous removal of solids deposited by the sedimentation while filtering the water. Its general use is to remove the solid particles from the liquid for clarification and thickening. The concentrated impurities discharged from the bottom of the tank are known as sludge, and the particles that float on the surface of the liquid are known as scum.
Sedimentation tanks play an essential role in treating wastewater, and the primary treatment includes the removal of floating and settleable solids through sedimentation.
Clarification is an essential step in the wastewater treatment process to remove the solids through gravity settling for providing a clarified and clean liquid. These are also used to remove the materials like oil, grease, solids etc. A clarifier is generally divided into two types:
1. Primary Clarifier: These clarifiers are used to separate the settleable solids from the incoming raw wastewater. They are located the downstream of plant’s screening process. This whole process is known as primary clarification, also known as sedimentation.
2. Secondary Clarifier: These clarifiers are located downstream of biological treatment. Their primary purpose is to separate the treated wastewater from the natural mass. Its main goal is to return the activated sludge. The whole process is known as secondary clarification.
Characteristics of a Clarifier
1. Clarifiers can be installed by modifying the existing facilities, such as a primary sedimentation tank or rainwater tank.
2. The natural flow down process is used in the treatment process, and hence stable operation is possible while depending on the flow rate of fluctuation.
3. Only the maintenance and management cost is needed for electricity due to the availability of the non-flocculation process.
4. It does not require any compulsorily auxiliary tank because washing time for filter media is around 1 minute.
5. The operation management is more accessible. It is because neither a pre-treatment screen nor a bottom screen is needed to prevent the flow out of filter media.