Wastewater Treatment Equipment:Lamella Clarifier Graver

Removable Plates - Individual plates in the GRAVER lamella are easily removable, even when the unit is in operation.  This design permits a single operator to easily inspect, clean, or remove plates without the assistance of mechanical lifting devices, making the unit easier to maintain than competitive designs.  This feature also offers the flexibility needed to handle changes in influent characteristics.

Effluent Weir Take off - An adjustable weir launder is used to provide a level and more effective weir length than other designs.  The weir is of the orifice type with orifices placed so that each plate is serviced by two orifices, one on each side of the plate.  This insures uniform collection of the clarified effluent and thus higher quality.

Flow Entry - Inlet flow enters from the bottom of both sides of the lamella plates, thus maintaining distribution velocities at a minimum.  This optimizes the hydraulic flow regime resulting in a higher projected effective surface area (PESA) through more efficient utilization of the available PSA. 

FEATURES & ADVANTAGES

Standard units can be manufactured for flows from 25 gpm up to 3000 gpm (5 to 680 m3/hr) and above, in single above-grade tanks, limited only by shipping requirements. One-piece prefabricated tanks are available in a range to process 1500 gpm (340 m3/hr) with 3000 ft2 (280 m2) of PESA. Larger units are also prefabricated and shipped knocked down in match-marked pieces for final fit-up and erection in the field. Optionally, a concrete tank design can be used with prefabricated internals to treat unlimited flow rates. If headroom is a problem, a standard unit can be customized into a low profile design by modifying the internals to change overall tank dimensions.

Since the circular thickener section is an integral part of the lamella, the released water moves upward along with the clarified water, eliminating any decanting or repumping requirements. The thickener height and diameter are designed to maximize the dry concentration. The bottom floor is concentrically sloped to a center pit to ensure positive sludge removal.

slowly agitates the sludge to release a larger percentage of mechanically removable water while providing positive movement and removal.

Whenever a higher dry solids concentration is desired or required, the lamella can be combined with a thickener, which replaces the sludge collection hopper. The thickener
 
THE GRAVER LAMELLA CLARIFIER (CONTD)

The hopper is also designed with a hold-up volume to allow liquid sludge to accumulate. This usually eliminates having to continuously operate the sludge blowdown system and results in higher dry solids concentrations. By accumulating sludge, the water is squeezed (compressed) from the liquid sludge, decreasing the daily volume of blowdown.

Since liquid sludge removal is important, the sludge collection area must also be designed with inclined walls to keep the liquid sludge moving to the point of discharge. An effective
arrangement for a majority of applications is in inverted pyramid type hopper in which all walls are sloped a minimum of 60