Inclined plate clarifiers

Blanket clarifier Circular clarifier inclined plate clarifier Rectangular clarifier Vertical flow clarifier... 

Inclined plate clarifiers, also known as Lamella clarifiers, use several inclined plates (or sometimes tubes) to maximize the settling area for a given floor area (Lamella is a registered trademark of Parkson Corporation, Ft. Lauderdale, FL). Figure 8.5 shows a diagram of an inclined-plate clarifier. Inclined-plate clarifiers have five treatment zones ... 

There are three basic designs for clarifiers (also known as "gravity clarifiers") solids-contact, inclined-plate settlers, and sedimentation. The advantages of each type of unit are ... 

Rise Rate Rise rate of water is the flow rate (total hydraulic load) divided by the surface area of the clarifier. Most clarifiers operate between 0.75 gpm/ft2 and 1.25 gpm/ft2, with the exceptions of inclined-plate... 

Rake The purpose of the rake is twofold direct the settled solids to the blowdown and to control the character of the sludge bed. High rake speed results in a fluffier bed while low speed hinders the contact between newly-formed floe (agglomerated suspended solids) and the bed. Note that most inclined-plate clarifiers do not have this feature. 

Figure 8.5 Inclined-plate clarifier. Courtesy ofParkson Corporation.

Inclined-plate clarifiers have five treatment zones ... 

Selection of Type of Thickener or Clarifier Selection of the type of unit thickener or clarifier depends primarily on the optimization of performance requirements, installation cost and operating cost. For example, the inclined-plate type of clarifier provides for less solids-holding capacity than a circular or rectangular clarifier, but at a lower installation cost. The high-density thickener maximizes underflow solids concentration, requiring a higher torque rating than conventional thickeners. 

Inclined plate clarification is a traditional separation technology that has been used for decades to remove suspended solids from a liquid stream in various types of systems including traditional precipitation [12]. In the semiconductor industry, the clarifier is commonly used in fluoride waste treatment systems where calcium fluoride precipitate is concentrated prior to dewatering in a press, or in assembly/test operations to separate silicon fines from backgrind operations. The clarifier will concentrate the solid phase of slurry like a UF, but unlike the UF or MF, the clarifier may require the addition of a chemical polymer to facilitate the agglomeration of the suspended solids so that they settle and concentrate. Polymer addition adds another level of complexity to the waste treatment system. The clarifier does not provide a physical barrier to prevent the transport of solids to downstream equipment, so it may be necessary to install a UF or MF downstream of the clarifier to capture extraneous particles or to protect the downstream equipment from clarifier upsets. 

Inclined plate clarifiers. KWM Wastewater Technologies, Evanston, Illinois, www.koch-water.com/clar.html. 

Inclined-Plate Clarifiers Lamella or inclined-plate separators have achieved increased use for clarification. They contain a multiplicity of plates inchned at 45 to 60° from the horizontal. Various feed methods are employed so that the influent passes into each inclined channel. The geometry of the plates results in the solids having to settle only a short distance in each channel before sliding down the base to the collection zone beneath the plates. The clarified liquid passes in the opposite direction beneath the ceiling of each channel to the overflow connection. 

FIG. 18-102 Basic concept of the inclined-plate type of clarifier. 

A variation on the inclined-plate principle uses inverted triangular elements mounted above each other [108]. The fact that there are so many elements in this type of clarifier translates into a very low upward fluid velocity and a horizontal projected clarification area that is up to 20 times as great as the floor area of the unit. 

Clarifiers used for removal of settleable solids and readily floating oils and greases are either rectangular or circular basins (Figs. 4.73 and 4.74). Clarifiers are sized on the basis of settling rate (area) and detention time (volnme). Inclined plates can be inclnded to increase the effective settling area of a clarifier and rednce space reqnirements. 

---