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What is a Lamella Clarifier?

11/7/2013 8:25:26 AM | by Anonymous

Clarifiers


A lamella clarifier also typically known as an inclined plate clarifier is designed to remove particles from liquids. They are usually employed in the primary water treatment such as places with conventional settling tanks. They are also used in industrial water treatments. Unlike the conventional clarifiers, they utilize a series of inclined plates. These inclined plates seemingly provide a large effective setting area for a relatively small foot print. The inlet stream is stilled upon entry into the clarifier. Solid particles will then begin to settle onto the plates and begin to accumulate in collection hoppers at the bottom of the clarifier unit. The sludge is then drawn off at the bottom of these hoppers and the clarified liquid proceeds to exit the unit at the top by the weir.

 

Lamella clarifiers can be used in various industries for various reasons. Some examples of the industries and reasons would include, metal finishing, mining to treat groundwater, industrial process water and backwash from the various sand filters. Lamella clarifiers are ideal for applications whereby the solids loading are variable and the solids sizing is fine. They are more common than conventional clarifiers at industrial sites also due to their smaller foot print that are in comparison to others.


One specific application of the Lamella Clarifiers is that it acts as pre-treatment stage for effluent entering membrane filters. Lamella clarifiers are also considered to be the better options for pre-treatment ahead of membrane filters. For them being made of all steel means that there is a lower chance that part of the inclined plate will chip off and be carried over to the membrane. This is especially in comparison to tube settlers that are constructed of plastic. Further lamella clarifiers are also able to maintain the water quality required to the membrane without the use of any chemicals. This is a huge saving cost measure that is utilized for purchasing the chemicals and limiting the damage done to the membrane. This is also because membranes do not work well with the large particles contained in coagulants and flocculants.


On top of that, lamella clarifiers are also used in the municipal waste water treatment process. The most common waste water application for lamella clarifiers is at the tertiary treatment stage. Lamella clarifiers are integrated into the treatment process or stand alone units can also be used to increase the flow through existing water treatment plants. The reason for integrating lamella clarifiers into existing plants is for the sludge blanket or conventional clarifiers to be upgraded. This is done by attaching a bundle of inclined plates or tubes before the overflow in the clear water zone. This helps to increase the settling area by two folds, thus, resulting in a decrease in the solids that are loading in the overflow.


Typical lamella clarifier design usually consists of a series of inclined plates inside the vessel. The untreated water stream will enter from the top of the vessel and proceeds to flowing down a feed channel underneath the inclined plates. It is then followed by water flowing up inside the clarifier between the inclined plates. During this time, the solids will settle onto the plates and eventually fall to the bottom of the vessel. The next route a particle will take would be dependent upon the flow rate of the suspension and the settling rate of the particle.


At the bottom of the vessel, there will be a funnel to collect the particles as sludge. Sludge may be intermittently discharged. Now, the particles that have settled can be found above the inclined plate and the clarified water is produced which is drawn off into an outlet channel. The clarified water then exits the system in an outlet stream.

 

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