Liquid purification or separation – Particulate material type separator – e.g. – ion exchange or... – With rehabilitation means
Reexamination Certificate
2001-02-14
2004-05-11
Popovics, Robert James (Department: 1724)
Liquid purification or separation
Particulate material type separator, e.g., ion exchange or...
With rehabilitation means
C210S275000, C210S293000
Reexamination Certificate
active
06733670
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to traveling bridge filter systems. In general, the invention is directed toward an improved system of installing porous media support plates and/or replacing plates which are failing or leaking. More particularly, the improvement is a prefabricated plate support system, which allows the direct installation of porous media support plates or replacement of porous media support plates in an existing filter. In addition, the present invention is directed to providing a cell structure that enhances the backwash process.
2. Description of the Related Technology
Water treatment often involves a filtering process to remove solids from water being treated. During a water filtering process, a layer of solids develops on the surface of a filter media. At is optimum the layer results in beneficial and substantial removal of solids from the water being filtered. However, as the quantity of material forming the layer increases, the permeability of the filter bed decreases. In order to overcome an excessive reduction in permeability, conventional filter systems backwash the entire filter area, thus requiring large flow rates and large volumes of backwash water, i.e., the waste by-product of filtering. The success of traveling bridge filters, on the other hand, depends to a large extent on the filter system's ability to backwash small, individual sections, often referred to as cells, of granular filtration media with water to periodically clean the filtration media using a cell structure to minimize the area of the filtration media to be cleaned reduces the amount of waste by-product. Traveling bridge filter systems are well known in the field of waste water management. These systems are exemplified in U.S. Pat. Nos. 3,239,061, 4,152,265, and 5,234,600 the disclosures of which are expressly incorporated by reference herein.
FIG. 1
shows a perspective view of a typical prior art traveling bridge filter
10
. A concrete tank having a slab
20
, influent wall
21
, and effluent wall
22
, contains a plenum section
13
having a plurality of cells
12
separated by cell dividers
121
. Media
25
is placed on media retention plates
145
in each cell of the plenum section. Commonly, sand is used as a filtration media, but other materials such as anthracite, garnet, or carbon, may also be used. Traveling bridge
101
travels along tracks
15
installed at the top of the influent and effluent walls.
In both the prior art and the present filter systems, during filtering, influent water is delivered to the filter compartment through influent openings
211
in the influent wall
21
. The influent water maintains a level over the surface of the granular filter media
25
such that the downward flow of influent water is more or less uniform across the entire surface area of the filter media. Solids in the influent water are deposited on the surface of the media
25
, and the filtered water enters through the media retention plates
145
at the top of the plenum section
13
and exits through filtrate effluent openings
221
installed in the effluent wall
22
.
During backwashing of the prior art traveling bridge filter, backwash water pump
26
located near filtrate effluent openings
221
forces backwash water into a particular cell of the plenum section
13
through a filtrate effluent opening. The water is forced up through the media retention plates
145
of the cell, and it loosens solids from the surface of the media
25
. Waste water pump
27
mounted on washwater hood
28
removes the loosened solids, suspended in the backwash water, at the surface of the media
25
via a waste water pipe in the hood. Traveling bridge
101
and supports
11
are used to transport backwash water pump
26
, waste water pump
27
, and washwater hood
28
from one cell to the next cell during the backwash cycle.
The individual cells, which are required for the traveling bridge filter, may be constructed using fiberglass-reinforced polyester (FRP) sheets as cell dividers, plastic end sections, FRP support angles (either integral to cell dividers or attached separately), FRP hold down angles, porous media support plates, adhesive/sealant, a variety of hardware types, and leveling channels. This equipment is used to construct individual cells that are substantially hydraulically separated from other cells. In the present art, the cell dividers are used to:
1. divide the filtration media into individual compartments;
2. form the sidewalls of the plenum compartments; and
3. support the porous plates.
This multiple utility requires that great care be taken to avoid installation errors so that all the required purposes are properly met.
The installation of prior filters requires many steps and hardware; some steps require the presence of a technician. The details of installing a filter underdrain system made be found in U.S. patent application Ser. No. 09/122,801, filed Jul. 27, 1998, entitled Underdrain Filter With Prefabricated Cells, which is hereby incorporated by reference.
In the past, the rehabilitation of an existing filter underdrain is very labor intensive, and the filter must be taken out of service for a substantial amount of time. The repair work is tedious and typically requires both factory supervision and skilled, properly equipped, workers. Referring to
FIG. 2
in the prior art, replacement of existing porous media support plates involves the following steps:
1. removing the existing media (
25
);
2. removing existing retention angles (
205
) and porous plates (
204
);
3. cleaning the plate support ledge thoroughly (
203
);
4. applying sealant/adhesive (
206
) to plate support ledge (
203
);
5. installing new porous plates (
204
);
6. applying sealant/adhesive (
207
) around the periphery of the plate (
204
);
7. performing a “light test”;
8. installing new retention angle (
205
);
9. installing new media.
After installing the porous plates, a “light test” is performed. This test must be performed when the sun is down, preferably at the darkest time of the night. During the test, a bright light is inserted into the plenum under the porous plates. As the light is withdrawn from a cell, an observer on the top side of the porous plates watches for any light to shine through, which indicates a leak that filtration media could pass through. The light spots, which commonly occur even with careful workmanship, must be repaired by topically applying additional sealant/adhesive. Finally, the filtration media may be replaced in the cell compartments to complete the construction of the filter's underdrain. These requirements are similar to the original installation requirements, as described in the references cited above.
As with installation, this method of reconstruction has numerous drawbacks, such as the amount of time required to rehabilitate the filter. In addition, this method requires that a technician be present during installation. Furthermore, due to the environmental conditions during installation, the adhesive used to create a seal around the porous plate may be weaken. Moreover, the use of sealants/adhesives during installation results in component breakage when attempting to disassemble the filter. Great care must be taken to avoid installation errors so that all the parts function properly and as intended.
SUMMARY OF THE INVENTION
An object of the invention is to provide an underdrain rehabilitation system for traveling bridge filters.
Another object of the invention is to reduce the time a filtration system is out of commission for repairs.
Another object of the invention is to permit a portion of a filter to be rehabilitated without disrupting other sections of the filter.
Another object of the invention is to provide a rehabilitation system that allows builders flexibility in budgeting by eliminating the “all or nothing” replacement of a filter underdrain.
Another object of the invention is to provide a porous plate module that reduces the amount of care required in demolishing or removing existing pla
Baker & Botts L.L.P.
Parkson Corporation
Popovics Robert James
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