Sedimenting separators lamella separator

This is clearly a word to be used with care in any filtration and sedimentation context. It is used in this Handbook only in the general sense when unmodified, so that the term separator means any form of physical separation equipment. The term only has a specific meaning when preceded by a modifier magnetic separator , lamella separator , or, as is mainly the case in this section, gravity separator or sedimenting separator . 

Lamella settlers are gravity settlers that use a large number of inclined flat plates, closely packed, so that the distance between the plates is small. The gravitational action makes the cells move in the direction of the lower surface of the individual separating space between two plates. Once settled, the particles slide down in a layer towards the plate periphery and then into the sludge hopper. For the same required sedimentation area, lamella settlers are much more compact than vertical ones. Theoretically, their total sedimentation area is the sum of the horizontally projected areas of all plates. In practice, however, only 50% of this total area is effective [137]. The main problem with inclined settlers is that the cells tend to adhere to the plates. Special coating of the plate surface and vibration of the whole lamella pack may alleviate this problem. 

The efficiency of the attachment process depends upon the size of the gas bubbles. Process equations are available for predicting the course of such separations these detign equations require the support of laboratory tests to provide relationsh s between flotation velodties, the volume of air per unit mass of soUds, etc. This chapter also deals with the design of inclined lamella separators vffiich tend to intensify the sedimentation eflfect, thus requiring smaller vessel volumes when conqiared with conventional equqtment. 

The size of the settlement basin is sometimes reduced by employing a series of internally mounted plates inclined at about 60° to the horizontal. In a similar manner to the lamella separator (see Section 1.1.2.3), the effective settling area is increased to allow sedimenting solids to slide down the plates and into the collecting well. Other variants include the vertical flow clarifier, the blanket clarifier and the circular clarifier the latter is similar in form to a conventional circular thickener but of a much lighter construction. 

---