Upflow water clarifier with central pier

Details Upflow water clarifier with central pier Upflow water clarifier with central pier

1998-03-10

2001-01-09

Reifsnyder, David A. (Department: 1723)

Liquid purification or separation

Tangential flow or centrifugal fluid action

C210S207000, C210S220000, C210S522000, C210S523000, C210S532100, C210S540000

Reexamination Certificate

active

06171498

ABSTRACT:

This invention relates generally to apparatus and methods for treating liquids to remove dissolved or suspended solids, such as for treating water so it may be used for potable or industrial use. In particular, the invention relates to clarifiers in which the liquid flows in an upward helical path, gradually decreasing in velocity until precipitated or suspended solids separate from the rising water to create a rotating sludge blanket beneath a region of clarified water.
BACKGROUND OF THE INVENTION
An upflow water clarifier, such as those disclosed in Wyness U.S. Pat. Nos. 4,146,471 and 4,765,891, is a specific type of clarifier that has a prominent conical portion with the larger diameter at the upper end. Typically, the walls of the clarifier are angled at between about 40 degrees and 60 degrees with respect to the horizontal, although angles outside of this range can also be used. Contaminated water enters the clarifier near the lower end, while clarified effluent is removed from near the upper end. Inside, the water is given a rotational movement, often in part by feeding it into the clarifier in a tangential direction, resulting in a generally upward helical flow of the water within the clarifier.
The increasing diameter of the clarifier toward its upper end causes a decrease in velocity of the flow of liquid as it moves upwardly. As the velocity decreases, suspended solids having a higher density than water agglomerate and separate from the water, forming a revolving sludge blanket that remains behind as clarified water continues upward until being withdrawn as clarified effluent.
Conventionally, the effluent has been removed from the clarifier over weirs, and collected at one or more drop boxes at the periphery of the upper end of the clarifier, while sludge is periodically removed through a sludge concentrator located on the central axis of the clarifier. Traditionally, the sludge concentrator has taken the form of a cone suspended from an overhead observation deck that traverses the top of the clarifier, and has been used to concentrate and reduce the volume of the sludge before it is removed.
SUMMARY OF THE INVENTION
Like other upflow clarifiers, the clarifier has a lower chamber into which contaminated water is fed through a conduit; an upper zone from which clarified water is removed through an outlet; and a conical zone extending upwardly and outwardly from the lower chamber toward the upper zone. Unlike conventional upflow clarifiers with a conical zone, the clarifier includes a central pier extending through the lower chamber, the conical zone, and the upper zone.
The pier bears at least part of the weight of an observation and access deck that spans at least a portion of the clarifier. The use of a central pier allows significant cost savings to be realized by using only a half-span deck, instead of the full-span decks conventionally used with upflow clarifiers, or by reducing the size of the beams in a full-span deck.
Like conventional clarifiers, the present clarifier includes a mechanism for discharging sludge from the clarifier. Unlike conventional clarifiers, the new clarifier includes this mechanism on the central pier. This use of a central pier further reduces the load requirements on the observation deck (which, in many conventional upflow clarifiers, must support the weight of a sludge concentrator). In addition, the interior of the pier can be used to temporarily hold and thicken the sludge before it is discharged, permitting the sludge concentrator cone to be reduced in size or even eliminated altogether. The interior of the pier can also be used as a sludge discharge line.
A central pier can also be designed to accommodate a central effluent withdrawal line. Such a design allows radial troughs to be used to collect and channel effluent to a central collection point, eliminating the need for a series of external collection drop boxes on the outer periphery of the clarifier. Further, routing an effluent withdrawal line through a central pier can provide thermal insolation, resulting in a reduced risk of freezing in the line.
The presence of a central pier in the lower chamber may also improve mixing in that part of the clarifier, which is believed to have a beneficial impact on water clarification.
A central pier can also be used as an aid during construction, allowing the clarifier to be built less expensively and more precisely.
Further advantages should be apparent to those skilled in the art upon reviewing the following detailed description and accompanying drawings, in which:


REFERENCES:
patent: 4146471 (1979-03-01), Wyness
patent: 4765891 (1988-08-01), Wyness
patent: 5804062 (1998-09-01), Wyness

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