U.S. patent application number 14/252819 was filed with the patent office on 2014-10-09 for filter for removing sediment from water.
This patent application is currently assigned to IMBRIUM SYSTEMS LLC. The applicant listed for this patent is IMBRIUM SYSTEMS LLC. Invention is credited to Roland Dubois, Bob Gallucci, Joel Garbon, Perry Scott, Gregory Williams.
Application Number | 20140299553 14/252819 |
Document ID | / |
Family ID | 48168584 |
Filed Date | 2014-10-09 |
United States Patent
Application |
20140299553 |
Kind Code |
A1 |
Dubois; Roland ; et
al. |
October 9, 2014 |
FILTER FOR REMOVING SEDIMENT FROM WATER
Abstract
A system for removing sediment from water is disclosed. The
exemplary embodiments described herein disclose a system comprising
a filter chamber, having a deck positioned inside to divide it into
an upper chamber and a lower chamber. The deck may have a plurality
of holes to hold filtration elements and also may have a ridge or a
skirt or both. The filtration elements may be filter cartridges
with multiple elongated filter elements that extend down into the
lower chamber.
Inventors: |
Dubois; Roland; (Denver,
NC) ; Williams; Gregory; (London, CA) ; Scott;
Perry; (Mount Airy, MD) ; Garbon; Joel;
(Portland, OR) ; Gallucci; Bob; (Rockville,
MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IMBRIUM SYSTEMS LLC |
West Chester |
OH |
US |
|
|
Assignee: |
IMBRIUM SYSTEMS LLC
West Chester
OH
|
Family ID: |
48168584 |
Appl. No.: |
14/252819 |
Filed: |
April 15, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2012/062205 |
Oct 26, 2012 |
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14252819 |
|
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13283000 |
Oct 27, 2011 |
8287726 |
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PCT/US2012/062205 |
|
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12014888 |
Jan 16, 2008 |
8123935 |
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13283000 |
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Current U.S.
Class: |
210/747.3 ;
210/170.03; 210/323.1; 210/333.01 |
Current CPC
Class: |
E03F 1/00 20130101; B01D
29/15 20130101; B01D 2201/4015 20130101; B01D 2201/301 20130101;
B01D 29/72 20130101; B01D 29/114 20130101; E03F 5/14 20130101; B01D
2201/0453 20130101; B01D 29/52 20130101; B01D 29/54 20130101; B01D
29/74 20130101; B01D 35/10 20130101; B01D 29/66 20130101; B01D
2201/291 20130101; B01D 2201/4038 20130101; B01D 29/21 20130101;
B01D 2201/0446 20130101; B01D 2201/0461 20130101 |
Class at
Publication: |
210/747.3 ;
210/170.03; 210/323.1; 210/333.01 |
International
Class: |
E03F 1/00 20060101
E03F001/00 |
Claims
1. A water runoff system for removing suspended particles from a
liquid, the system comprising: a filter vessel defining an internal
chamber; a deck positioned within the internal chamber and dividing
the internal chamber into an upper chamber and a lower chamber, the
deck having a plurality of holes formed therein, each hole having a
filtration element therein; an inlet line for introducing a liquid
into the internal chamber; an outlet above the deck for permitting
liquid to exit the upper chamber; a ridge positioned atop the deck,
the ridge forming an outlet weir atop the deck; a plurality of the
filtration elements positioned upstream of the ridge; and at least
one the filtration elements positioned downstream of the ridge;
wherein when flow subsides from the inlet, liquid that has
accumulated above the deck and behind the ridge flows downward
through the filtration elements located upstream of the ridge,
flowing downward and into the lower chamber and up through the
filtration element positioned downstream of the ridge, thereby
backwashing filter elements located upstream of the ridge with
filtered liquid.
2. The system of claim 1 wherein the filtration element located
downstream of the ridge has a lid with at least one hole sized to
induce a pulsing/vibration effect during backwashing to assist in
maintaining cleanliness of the filtration elements, wherein
pressure caused by the downward flow causes the water flowing
through said at least one hole in the lid of the filter element
positioned downstream of the ridge to pulse, thereby creating a
vibration that shakes the filtration elements.
3. The system of claim 1, wherein at least one of the filtration
elements comprises a filtration cartridge.
4. The system of claim 1, further comprising a skirt that is
positioned below the deck and surrounds the filtration
elements.
5. A system for removing suspended particles from a liquid, the
system comprising: a filter chamber defining an internal chamber; a
deck positioned within the internal chamber and dividing the filter
chamber into an upper chamber and a lower chamber, the deck having
a plurality of holes formed therein, each hole having a filtration
cartridge therein; an inlet line for communicating an influent
liquid to the filter chamber; and a ridge positioned atop the deck,
wherein the ridge acts as an outlet weir atop the deck, at least
one of the filtration cartridges is positioned so that liquid that
moves upward through the filtration cartridge for filtration exits
the filter chamber by passing over the ridge to reach an outlet of
the filter chamber, and when flow into the filter chamber subsides,
liquid that has accumulated above the deck behind the ridge then
flows backward through the filtration cartridge to backwash the
filtration cartridge, causing liquid in the lower chamber to flow
upward through another opening in the deck downstream of the ridge
and then to the outlet of the filter chamber.
6. The system of claim 5 wherein the another opening in the deck
contains an additional filtration cartridge, and when flow into the
filter chamber subsides, liquid that flows upward through the
another opening passes through the additional filtration
cartridge.
7. The system of claim 5, further comprising: a skirt positioned on
a bottom surface of the deck and extending below the deck into the
lower chamber.
8. The system of claim 7, wherein the skirt surrounds at least one
of the filtration cartridges.
9. The system of claim 7, wherein the skirt surrounds all of the
filtration cartridges.
10. The system of claim 6 wherein the additional filtration
cartridge has a lid with at least one hole sized to induce a
pulsing/vibration effect such that during backwash water flowing
upward through the at least one hole in the lid creates a
vibration.
11. The system of claim 5 wherein each of the filtration cartridges
comprises a plurality of elongated filter elements extending
downward into the lower chamber, each filter element comprising a
pleated filter member disposed around an internal frame to help
retain a form of the pleated filter member and to define an
internal flow space within the filter element.
12. The system of claim 11 wherein each filter element further
comprises an upper cap engaged with a top portion of the pleated
filter member and a lower cap engaged with a bottom portion of the
pleated filter member.
13. A method of removing sediment from stormwater, the method
comprising: introducing sediment-laden stormwater into a filter
chamber that defines an internal chamber, a deck positioned within
the internal chamber and dividing the filter chamber into an upper
chamber and a lower chamber, the deck having a plurality of holes
formed therein, each hole holding a filtration cartridge therein,
and a ridge positioned atop the deck, wherein the ridge acts as on
outlet weir atop the deck that is positioned between multiple
filtration cartridges and an outlet of the filter chamber, the
sediment-laden stormwater directed into the lower chamber;
filtering the sediment-laden stormwater by passing the stormwater
from the lower chamber upward through the multiple filtration
cartridges into the upper chamber; passing the filtered stormwater
over the ridge to reach the outlet of the filter chamber; and when
introduction of sediment-laden stormwater into the filter chamber
subsides, filtered stormwater that has accumulated above the deck
behind the ridge then flows backward through the multiple
filtration cartridges to backwash the multiple filtration
cartridges and thereby causes liquid in the lower chamber to flow
upward through another opening in the deck at a downstream side of
the ridge and then to the outlet of the filter chamber.
14. The method of claim 13 wherein the another opening in the deck
contains an additional filtration cartridge, and when flow into the
filter chamber subsides, liquid that flows upward through the
another opening passes through the additional filtration
cartridge.
15. The method of claim 13 wherein a skirt positioned on a bottom
surface of the deck and surrounds the multiple filtration
cartridges.
16. The method of claim 15 wherein sediment-laden stormwater swirls
around the skirt, passes under the skirt and then upward through
the filtration cartridges for filtering.
17. The method of claim 14 wherein the additional filtration
cartridge has a lid with at least one hole sized to induce a
pulsing/vibration effect such that during backwash water flowing
upward through the at least one hole in the lid creates a
vibration.
18. The method of claim 13 wherein each of the filtration
cartridges comprises a plurality of elongated filter elements
extending downward into the lower chamber, each filter element
comprising a pleated filter member disposed around an internal
frame to help retain a form of the pleated filter member and to
define an internal flow space within the filter element.
19. The method of claim 18 wherein each filter element further
comprises an upper cap engaged with a top portion of the pleated
filter member and a lower cap engaged with a bottom portion of the
pleated filter member.
Description
[0001] This is a continuation of International Patent Application
No. PCT/US2012/062205 filed Oct. 26, 2012, which claims priority to
U.S. patent application Ser. No. 13/283,000 filed on Oct. 27, 2011,
now U.S. Pat. No. 8,287,726, which is a continuation-in-part of
U.S. patent application Ser. No. 12/014,888 filed on Jan. 16, 2008,
now U.S. Pat. No. 8,123,935, the entire disclosures of which are
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to an apparatus,
system, and method for removing sediment from water, and, more
particularly, to an elongated filtratable element used for removing
sediment from stormwater.
[0004] 2. Description of the Related Art
[0005] Stormwater runoff is rainfall or snowmelt that travels over
the ground or impervious surfaces--roofs of buildings, homes and
sheds, roadways, parking lots, sidewalks and driveways--and drains
into natural or manmade drainage ways. In some cases, stormwater
runoff drains directly into bodies of water. Stormwater runoff does
not usually receive any treatment before it enters streams, lakes,
and other surface waters, and it is a major source of water
pollution. For example, various harmful pollutants, such as
pesticides, fertilizer, litter, car oil, bacteria, trace metals,
and sediment, are washed off with stormwater runoff into storm
drains, or directly into streams, rivers, and lakes.
[0006] One of the harmful pollutants of major concern is sediment.
Sediment is soil particles from stream banks, construction sites,
and other areas, that are dislodged by stormwater runoff and
deposited into streams, lakes, and rivers. Sediment accumulates in
water bodies and destroys feeding grounds for aquatic life, clogs
fish gills, blocks light, increases water temperature, and can
cause other adverse environmental impacts.
[0007] Currently, sedimentation-based tanks are used to remove the
majority of sediment that is dislodged by stormwater runoff.
Sedimentation-based tanks, however, cannot completely remove all of
the fine sediment from stormwater because of the required settling
time needed for fine sediment to be removed from stormwater. For
example, settling out the fine sediment in stormwater would require
a large and uneconomical sedimentation-based tank. Therefore, in
addition to sedimentation-based tanks, granular media filter
systems are used downstream of sedimentation-based tanks to remove
fine sediment. Granular media filter systems utilize different
types of granular media to trap fine sediment in the interstitial
gaps formed between the granular media. However, as the fine
sediment continues to accumulate, the interstitial gaps eventually
clog and must be frequently recharged. Granular media filter
systems can be partially recharged through pressurized backwashing,
but pressurized backwashing piping and controls are complicated and
expensive.
[0008] In addition to granular media filter systems, a variety of
other filter systems are available for filtering contaminated
fluids. For example, filter cloths consisting of pile threads may
be used, U.S. Pat. No. 6,103,132, which is incorporated by
reference herein. While these types of filters and others like them
have their merits, they also have their drawbacks. For example, the
filters have a small amount of surface area available for trapping
fine sediment. As a result, during high flow events, the filter
systems quickly clog, causing the stormwater runoff to back up. In
addition to filter cloths, flexible hose-type filter elements have
been used, U.S. Pat. No. 4,163,724, which is incorporated by
reference herein. Such hose-type filter elements, however, rely on
pressurized flow to effect separation.
SUMMARY OF THE INVENTION
[0009] A system for removing sediment from water is disclosed.
According to one embodiment of the present invention, the system
comprises a filter chamber defining an internal chamber; a deck
positioned within the internal chamber and dividing the filter
chamber into an upper chamber and a lower chamber, the deck having
a plurality of holes formed therein, each hole adapted to receive a
filtration element therein; and an inlet line for communicating an
influent liquid to the filter chamber at a location that is below
the deck; wherein the inlet line is positioned such that the
influent liquid is introduced tangentially into the filter
chamber.
[0010] According to another embodiment of the present invention,
the system comprises a filter chamber defining an internal chamber;
a deck positioned within the internal chamber and dividing the
filter chamber into an upper chamber and a lower chamber, the deck
having a plurality of holes formed therein, each hole adapted to
receive a filtration element therein; an inlet line for
communicating an influent liquid to the filter chamber; and a ridge
positioned on a top surface of the deck, wherein the ridge forms a
perimeter on the top surface of the deck.
[0011] According to another embodiment of the present invention,
the system comprises a filter chamber defining an internal chamber;
a deck positioned within the internal chamber and dividing the
filter chamber into an upper chamber and a lower chamber, the deck
having a plurality of holes formed therein, each hole adapted to
receive a filtration element therein; an inlet line for
communicating an influent liquid to the filter chamber; and a skirt
positioned on a bottom surface of the deck.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a more complete understanding of the present invention,
the objects and advantages thereof, reference is now made to the
following descriptions taken in connection with the accompanying
drawings.
[0013] FIG. 1A is a perspective view of an elongated filtratable
element according to one embodiment of the present invention.
[0014] FIG. 1B is a perspective view of an elongated filtratable
element according to one embodiment of the present invention.
[0015] FIG. 1C is a perspective view of each component that
comprises a filtratable element according to one embodiment of the
present invention.
[0016] FIG. 1D is a perspective view of a partially assembled
filtratable element according to one embodiment of the present
invention.
[0017] FIG. 1E is a perspective view of fully assembled filtratable
element according to one embodiment of the present invention.
[0018] FIG. 2 is a perspective view of a preassembled filter mat
according to one embodiment of the present invention.
[0019] FIGS. 3A-3C are perspective views of magnified sections of a
filter mat according to one embodiment of the present
invention.
[0020] FIGS. 4A-4B are perspective views of a filtration cartridge
according to one embodiment of the present invention.
[0021] FIG. 5A-5B are perspective views of a filtration cartridge
according to one embodiment of the present invention.
[0022] FIGS. 5C-5D are perspective views of a lid for the
filtration cartridge according to one embodiment of the present
invention.
[0023] FIGS. 6A-6D are perspective views of a shaking mechanism
according to one embodiment of the present invention.
[0024] FIG. 7 is a perspective view of a filtering system according
to one embodiment of the present invention.
[0025] FIG. 8 is a perspective view of the inlet device according
to one embodiment of the present invention.
[0026] FIGS. 9A-9B are perspective views of the filtration system
according to one embodiment of the present invention.
[0027] FIGS. 10A-10B are perspective views of a filtration system
according to one embodiment of the present invention.
[0028] FIG. 11 is a perspective view of a filtration system with a
backwashing mechanism according to one embodiment of the present
invention.
[0029] FIGS. 12A-12B are perspective views of a valve assembly
according to one embodiment of the present invention.
[0030] FIG. 13 is a perspective view of a filtration system with a
backwashing mechanism with a partition, where accumulated filtrate
is above each valve assembly according to one embodiment of the
present invention.
[0031] FIG. 14 is a perspective view of a filtration system with a
backwashing mechanism where each elongated filtratable element has
been backwashed according to one embodiment of the present
invention.
[0032] FIG. 15 is a perspective view of a deck for a filtration
system according to one embodiment of the present invention.
[0033] FIG. 16 is a side perspective view of a filtration system
according to one embodiment of the present invention.
[0034] FIG. 17 is a top perspective view of a filtration system
according to one embodiment of the present invention.
[0035] FIG. 18 is a bottom perspective view of a filtration system
according to one embodiment of the present invention.
[0036] FIG. 19 is a cutaway side view of a filtration system
according to one embodiment of the present invention.
[0037] FIG. 20 is a cutaway isometric view of a filtratable element
according to one embodiment of the present invention.
[0038] FIG. 21 is an isometric view of a filtration system
according to another embodiment of the present invention.
[0039] FIG. 22 is a partially cutaway isometric view of a filter
backflush unit according to one embodiment of the present
invention.
[0040] FIGS. 23A-C are cutaway side views of the filter backflush
unit of FIG. 22 shown in three stages of operation.
[0041] FIGS. 24A-C are plan, and side elevation views of another
embodiment of a filtration system, with FIG. 24B being a view along
line B-B of FIG. 24A, and FIG. 24C being a view along line C-C of
FIG. 24A.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0042] Although the present invention is described in the context
of stormwater filtration, the invention is not so limited. Rather,
the present invention has application as a filter media for many
types of liquid, including water. Stormwater runoff generally has
an "organic portion" and an "aqueous portion." The organic portion
of stormwater runoff typically has a relatively high amount of
sediment, which includes, for example, dislodged soil particles
from stream banks, construction sites, and other areas, as well as
other suspended particles that may or may not be organic. The
aqueous portion of stormwater is primarily water. As used herein,
the term "downstream" in a process system means later in the
direction of general process or fluid flow, and the term "upstream"
means earlier in the direction of general process or fluid
flow.
[0043] Disclosed embodiments of the present invention and their
advantages may be understood by referring to FIGS. 1-14, wherein
like reference numerals refer to like elements.
[0044] In accordance with an embodiment of the present invention
described herein is an elongated filtratable element that has a
large amount of surface area for filtering a substantial amount of
fine sediment from stormwater. The disclosed filtratable element
can be used individually or in combination with other filtratable
elements. And, the filtratable elements can be combined with
current stormwater filtering systems to improve efficiency.
[0045] According to one embodiment of the present invention, the
elongated filtratable element may be a tubular element or hollow
tube with a permeable fiberglass filter media that surrounds a
flexible inner core. The fiberglass filter media may have a
porosity such that it allows the aqueous portion of stormwater to
pass through, while trapping sediment.
[0046] Referring to FIGS. 1A-1E, perspective views of elongated
filtratable element 100 and its components are shown. Referring to
FIG. 1A, according to one embodiment, each elongated filtratable
element 100, or tentacle, includes three general components:
support member 101, filter mat 102, and outer casing 103. In
general, support member 101 prevents the surrounding filter mat 102
from collapsing. Filter mat 102 consists of any permeable
filtratable material that surrounds inner core 101. Filter mat 102
may be adapted to filter a substantial amount of fine sediment from
stormwater runoff. Outer casing 103 protects filter mat 102 from
abrasion. Each component will be described in greater detail
below.
[0047] In one embodiment, support member 101 may be adapted to be
an inner core that serves as a frame for elongated filtratable
element 100, and may be provided to prevent elongated filtratable
element 100 from collapsing upon itself. Support member 101 may
comprise a flexible support tube made of any water permeable
member, such as a polymer membrane. While any water permeable
polymer materials may be used, in one embodiment, support member
101 may be made of a plastic, such as polyurethane, acrylate,
polypropylene or polyethylene.
[0048] In another embodiment, support member 101 may be made of any
water impermeable member. Support member 101 may be adapted so that
it has a negligible effect on sediment removal and has negligible
head loss associated with it under typical flows.
[0049] In another embodiment, support member 101 may comprise a
more rigid, even an inflexible, support structure made of metal or
plastic that is adapted to allow for the passage of stormwater.
Support member 101 may be manufactured by way of plastic injection
molding, as is well known in the art.
[0050] In still another embodiment, support member 101 may be an
inner frame comprised of support rings or rods, or a combination of
both. In still another embodiment, support member 101 may be formed
as an integral component of filter mat 102. Support member 101 may
be of any suitable shape, and for example, may be round, square, or
rectangular in shape. Support member 101 may be made of a
corrosion-resistant material, as is well known in the art. Other
sizes, shapes, or materials may be used for support member 101 as
necessary and/or desired.
[0051] Referring to FIG. 1B, support member 101 is shown according
to another embodiment of the present invention. In this embodiment,
support member 101 may be a flexible coil that serves as the
foundation for the elongated filtratable element 100.
[0052] Filter mat 102 serves to filter and trap sediment and other
particles in stormwater. In one embodiment, filter mat 102 may
comprise a tube of non-woven filtration media that surrounds
support member 101, if provided. In one embodiment, shown in FIG.
2, filter mat 102 may be comprised of two parts: backing mesh 202
and fiberglass batting 201. Backing mesh 202 may include a
comparatively course, non-woven plastic support layer, and
fiberglass batting 201 may include a plurality of individual
fiberglass fibers.
[0053] The use of fiberglass batting 201 provides several
advantages. For example, fiberglass batting 201 may be high in
surface area, self-cleanable, easily maintained, durable, and
economical.
[0054] In order to create filter mat 102, a plurality of fiberglass
fibers, of the same or different diameters and/or lengths, may be
attached to backing mesh 202. In another embodiment, filter mat 102
may be comprised of any natural filaments or synthetic filaments.
For example, filter mat 102 may also comprise graphite filaments,
metallic filaments, glass filaments, polymer fibers, or any other
suitable material as necessary and/or desired.
[0055] In one embodiment, filter mat 102 may have a relatively high
porosity (i.e., it allows relatively large particles to pass). For
example, backing mesh 202 may be comprised of 10-20 .mu.m plastic
fibers that form openings of more than about 200 .mu.m, and
fiberglass batting 201 may be comprised of less than 1 .mu.m
fiberglass fibers that are loosely packed.
[0056] In another embodiment, filter mat 102 may have a relatively
low porosity (i.e., it allows only relatively small particles to
pass). In this embodiment, backing mesh 202 may be comprised of
10-20 .mu.m plastic fibers that form openings of less than about
200 .mu.m, and fiberglass batting 201 may be comprised of less than
1 .mu.m fiberglass fibers that are tightly packed.
[0057] One of ordinary skill in the art can readily determine
appropriate fiber length, diameter, and percentage of porosity for
filter mat 102 depending on the expected stormwater flow rate and
sediment particle size.
[0058] Referring to FIG. 3A, a magnified portion of filter mat 102
is shown, according to one embodiment of the present invention. In
one embodiment, individual filter media filaments 301, made of any
suitable material, are attached to backing mesh 202. In the
aggregate, individual filaments 301 comprise fiberglass batting
201. When filter mat 102 is exposed to stormwater flow, as shown in
FIG. 3B, fiberglass batting 201 may be pressed against backing mesh
202 to create a compact, yet permeable, filter bed. When filter mat
102 is backwashed, as shown in FIG. 3C and described in greater
detail below, filtrate flows through each filtratable element 100
in the opposite direction, causing filaments 301 of fiberglass
batting 201 to be forced away from backing mesh 202. Backwashing
regenerates each element 100 by removing a substantial amount of
trapped sediment.
[0059] Referring to FIGS. 1C-1E, filter mat 102 may be formed into
a tube. Filter mat 102 may be adapted to surround support member
101 so that backing mesh 202 faces or contacts support member 101.
Filter mat 102 may consist of two half-cylinders. The
half-cylinders may be connected by a hinge. As an example, filter
mat 102 may be snap-fitted over support member 101, as best shown
in FIG. 1D. Filter mat 102 may also be adapted such that it is not
a rigid element, and it may be folded over support member 101.
Outer casing 103 may be adapted to surround filter mat 102. In one
embodiment, outer casing 103 may consist of two half-cylinders. The
half-cylinders may be connected by a hinge. As an example, outer
casing 103 may be snap-fitted over filter mat 102, as best shown in
FIG. 1E.
[0060] Referring back to FIGS. 1A and 1B, spacers 105 may be
disposed between support member 101 and filter mat 102. Spacers 105
may be used to fasten or attach filter mat 102 to support member
101. Spacers 105 may also allow for the aqueous portion of the
stormwater to freely permeate through filter mat 102. Spacers 105
may be made of the same material as support member 101, or any
other suitable material. The size, shape, number, and location of
spacers 105 may be varied as necessary and/or desired.
[0061] Outer casing 103, according to one embodiment of the present
invention, protects filter mat 102 and fiberglass batting 201 from
abrasion. Because stormwater runoff may contain a substantial
amount of sediment, it has a tendency to abrade and destroy
unprotected filter media as it permeates through. Outer casing 103
may also protect filter mat 102 from abrasion that may be caused by
large debris or occur during normal handling of the filtratable
element 100 or groups of elements, such as during typical
packaging, transportation, and installation activities. In one
embodiment, outer casing 103 may be a wire mesh screen. In another
embodiment, outer casing 103 may be a nylon screen. The mesh size
of outer casing 103 may be adapted such that the screen does not
trap sediment, nor become clogged. One of ordinary skill in the art
can readily determine the appropriate mesh size. Further, in
addition to protecting filter mat 102 from abrasion, outer casing
103 adds to the stability and strength of the elongated filtratable
element 100.
[0062] In one embodiment, elongated filtratable element 100 may be
constructed without outer casing 103. Under some flow conditions
and depending on the amount of sediment expected in the stormwater
runoff, outer casing 103 may be unnecessary. Moreover, filter mat
102 may be constructed of a material that reduces the risk of
abrasion and eliminate the need for outer casing 103. One of
ordinary skill in the art can readily determine the need for outer
casing 103.
[0063] In one embodiment, support member 101, filter mat 102, and
outer casing 103 may be coated or treated with an antimicrobial
agent. Antimicrobial agents are materials that are able to reduce
or eliminate the microbial growth, e.g., bacteria, yeasts, molds.
Microbes, if left untreated, may reduce the separation efficiency
of filtratable elongated element 100, and eventually clog the
filter media. In one embodiment, chitosan may be introduced into
the stormwater or used to coat filtratable element 100 to prevent
or reduce microbial degradation. Chitosan causes the fine sediment
particles to bind together and may also remove phosphorus, heavy
minerals, and oils from stormwater. Other antimicrobial agents may
also be used as necessary and/or desired.
[0064] Elongated filtratable element 100 may be adapted to increase
the available surface area for removing sediment. In one
embodiment, this may involve pleating, crimping, or finning the
surface of elongated filtratable element 100. Other constructions
that increase the surface area may be used as necessary and/or
desired.
[0065] In one embodiment, elongated filtratable element 100 may be
provided with a packing or granular filtration media, for example,
sand, polyethylene beads, clay, perlite, etc., in order to adsorb
contaminants that might be present in stormwater.
[0066] Referring to FIGS. 4A and 4B, filtration cartridge 400 is
shown, according to embodiment of the present invention. Filtration
cartridge 400 may include two general components: central manifold
401 and a plurality of elongated filtratable elements 100. Central
manifold 401 may be a deck with a plurality of holes 402, adapted
to receive a plurality of elongated filtratable elements 100.
Central manifold 401 may also be considered a plate. Central
manifold 401 may also be a tube having top and bottom plates that
are separated by a gap. The tube may be of any suitable shape. For
example, it may be cylindrical or cubical.
[0067] In one embodiment, central manifold 401 may be comprised of
an impermeable plastic, and it may be of any suitable shape. For
example, central manifold may be round, square, or rectangular in
shape. In one embodiment, the shape of central manifold 401 may be
selected to correspond to the opening in which it is to be
placed.
[0068] In one embodiment, central manifold 401 may also be coated
with an antimicrobial agent to prevent unwanted microbe growth, as
discussed above.
[0069] Central manifold 401 may include a plurality of holes 402,
with each hole 402 being sized and adapted to receive at least one
elongated filtratable element 100.
[0070] Referring to FIGS. 5A and 5B, according to one embodiment of
the present invention, central manifold 401 of filtration cartridge
400 may have a sidewall with at least one notch 403. Notch 403 may
be provided so that central manifold 401 may be easily fitted into
stormwater filtration systems.
[0071] Referring to FIGS. 5C and 5D, filtration cartridge 400 may
be fitted with a lid 404. Lid 404 may have at least one hole 406
for restricting flow through elongated filtratable elements 100
that are attached to central manifold 401. In one embodiment, lid
404 may have only one hole 406. In another embodiment, lid 404 may
have two holes 406. Other numbers and arrangements of holes 406 may
be used as necessary and/or desired.
[0072] Lid 404 may have threaded walls. Each filtration cartridge
400 may have a ring (not shown) that fits around cartridge 400 so
that lid 404 may be attached to cartridge 400. Each filtration
cartridge 400 with lid 404 attached thereto may be installed into a
filtration system. Lid 404 may be of any suitable shape. Further,
the amount of space between the top of filtration cartridge 400 and
the bottom of lid 404 may be changed as necessary and/or
desired.
[0073] With reference to FIGS. 1, 4A, 4B, 5A and 5B, each elongated
filtratable element 100 may be fitted with a cap 104 for attaching
each elongated filtratable element 100 to central manifold 401. For
example, in one embodiment, holes 402 may be sized to hold 1''
diameter elongated filtratable elements 100. In another embodiment,
each hole 402 may be adapted to hold more than one elongated
filtratable element 100. Further, the shape of holes 402 may vary
to accommodate differently shaped elongated filtratable elements
100.
[0074] In one embodiment, holes 402 are open and uncovered so as to
reduce the chance of additional clogging. Although, in another
embodiment, holes 402 can be provided with a filter, for example, a
layer of porous media, to provide an additional filtration. The
porous media may also be able to adsorb or to react with dissolved
components in the water.
[0075] In one embodiment, filtration cartridge 400 may include a
substantial number of filtratable elements 100. For illustration
only, more than 100 elongated filtration elements 100 may be
provided. More or fewer filtration elements 100 may be provided.
Each elongated filtration element 100 may be about 1'' in diameter,
although each filtration element 100 may have a different diameter,
length, and/or shape.
[0076] Filtration cartridge 400 may be of any size and shape to
accommodate different operating conditions. Filtration cartridge
400 may be assembled such that elongated filtration elements 100
dangle freely from cartridge 400. Because each elongated element
100 may be flexible and dangle freely from cartridge 400, filter
cartridge 400 may be easily maintained by mechanical means, such as
vibration and/or shaking. Moreover, if one elongated filtratable
element 100 becomes clogged or damaged, filtration cartridge 401
allows for it to be individually replaced.
[0077] Referring to FIGS. 6A-6D, a shaking mechanism for filtration
cartridge 400 is shown, according to an embodiment of the present
invention. In one embodiment, shaking mechanism 600 may be an
accessible, manually-operated mechanism that includes a hand crank
601, a shaft 602, a base 603, and a bar 604. Shaking mechanism 600
may be designed such that it causes at least one filtration
cartridge 400 to rotate, thereby removing any trapped sediment from
each elongated element 100. Hand crank 601 may be adapted so that
it extends above filtration cartridge 400 and may be easily turned.
Turning hand crank 601 causes shaft 602 to rotate base 603. Bar 604
connects base 603 to a deck in which filtration cartridge 400 may
be installed. The rotating motion of filtration cartridge 400
causes the freely dangling elongated filtratable elements 100 to
shake, which may remove trapped sediment. In another embodiment,
shaking mechanism 600 may be automated. Other shaking and/or
vibration mechanisms may be used as necessary and/or desired.
[0078] Referring to FIG. 7, a filtration system 700 is shown,
according to one embodiment of the present invention. Filtration
system 700 may include five general components: a filtration
chamber 701, an inlet line 702, an inlet device 703, one or more
filtration cartridges 400, and an outlet line 704. In general, one
or more filtration cartridges 400 may be placed inside filtration
chamber 701. If more than one filtration cartridge 400 is placed
inside filtration chamber 701, a deck may be used. Inlet line 702
introduces stormwater into filtration chamber 701 through inlet
device 703, and outlet line 704 discharges the filtrate.
[0079] In one embodiment, filtration chamber 701 may house a single
filtration cartridge 400. Filtration chamber 701 may either be open
to the atmosphere, or it may be enclosed. Further, filtration
chamber 701 may either be located above-ground or underground.
Filtration chamber 701 may be of any conventional type or shape and
may be constructed from steel, fiberglass, concrete, or plastic, or
other suitable materials.
[0080] Filtration cartridge 400 may be flush with the walls of
filtration chamber 701 so as to prevent stormwater from seeping
upwards between filtration cartridge 400 and filtration chamber
701. Filtration cartridge 400 may be fitted with a conformable seal
to contact the sidewalls of filtration chamber 701 to prevent
seepage.
[0081] In another embodiment, filtration chamber 701 may house a
plurality of filtration cartridges 400, using a deck. One of
ordinary skill in the art can readily determine the number of
filtration cartridges, and, correspondingly, the number of
elongated filtratable elements 100 needed for a given operation.
One advantage to filtration chamber 701 having a plurality of
filtration cartridges 400 is that more filtration cartridges 400
provides for more filtratable surface area, increasing the
operating life of and flow rate through filtration system 700. In
another embodiment, filtration cartridge 400 may be configured or
fitted in a different arrangement. For example, filtration
cartridge 400 may be adapted to be horizontal or inverted. Further
filtration cartridge 400 may be located inside inlet line 702.
Other configurations and locations for filtration cartridge 400 may
be used as necessary and/or desired.
[0082] Referring to FIG. 8, inlet device 703 is shown, according to
one embodiment of the present invention. Inlet device 703 consists
of a mesh screen 804, a deck 805, a weir 803, and a base 801. Base
801 may be comprised of a buoyant, impermeable material. Base 801
may have a hole 807 formed through it to allow stormwater to fill
filtration chamber 701. In another embodiment, base 801 may be made
of a porous material instead of having a hole. In one embodiment,
weir 803 may be attached to and extend upward from base 801. Weir
803 may be comprised of a water-impermeable material. Mesh screen
804 may be attached to base 801 and may extend upwardly above and
outside of weir 803. Mesh screen 804 forms a porous wall. In one
embodiment, mesh screen 804 may be a wire or nylon mesh screen,
with a mesh size that is larger than the expected sediment particle
size. Impermeable deck 805 may be attached to mesh screen 804 above
the top of weir 803. Deck 805 forms an impermeable deck and has a
small inlet hole 806, in which stormwater flows through. The
stormwater may be introduced from inlet line 702, through inlet
device 703, and into filtration chamber 701. In one embodiment,
deck 805 may be sloped so that the influent stormwater is directed
toward hole 806.
[0083] Inlet device 703 may be adapted so that it moves with the
level of the stormwater in filtration system 700. During operation,
inlet device 703 may be positioned such that the top of base 801
may be level with the bottom of inlet line 702. In this
arrangement, the influent stormwater may be directed into the
filtration chamber 701 through hole 807. Weir 803 may prevent
unfiltered stormwater from bypassing inlet device 703. Weir 803 may
also prevent unfiltered stormwater from backing up into inlet
device 703. During high flow events--which generally correspond to
infrequent operating conditions, such as those during flooding or a
thunderstorm or other high-intensity runoff events--water may pass
over inlet device 703, through mesh screen 804, and flow
downstream, to prevent the filtration system from backing up.
[0084] Referring to FIGS. 8 and 9A, inlet device 703 may also be
positioned such that deck 805 may be level with the bottom of inlet
line 702. In this arrangement, the influent stormwater flows
simultaneously through hole 806 into filtration chamber 701, and
also through mesh screen 804, through elements 100 and into
filtration chamber 701, thus backwashing elements 100. Referring to
FIGS. 8 and 9B, as the level of water in the filtration chamber
rises, the inlet device 703 may rise until the top of base 801 may
be level with the bottom of influent line 702. The influent
stormwater may be directed into the filtration chamber 701 through
hole 807, and normal filtration operation proceeds.
[0085] In normal operation, stormwater is introduced into
filtration system 700 via inlet line 702. The stormwater flows
through inlet device 703 and fills filtration chamber 701. As
filtration chamber 701 fills with water, the aqueous portion of the
stormwater permeates through each elongated filtration element 100.
Fiberglass batting 201, which is exposed to the stormwater, traps a
substantial amount of the sediment in the stormwater. As the
aqueous portion flows through each elongated filtratable element
100, fiberglass batting 201 is pressed against backing mesh 202,
forming a permeable filter bed. A deck 1000 separates filtration
system 700 into two parts: a lower housing and an upper housing. In
one embodiment, deck 1000 may be impermeable. After the lower
housing of filtration system 700 fills completely with stormwater,
influent stormwater accumulates on inlet device 703 creating the
driving forces for stormwater to permeate through each elongated
filtratable element 100. The aqueous portion, after permeating
through filter mat 102, travels upward through elongated filtration
element 100 and out holes 402 in filtration cartridge 400. Deck
1000 separates the influent stormwater from the filtrate. The
filtrate then flows downstream away from the filtration system
700.
[0086] Referring to FIG. 10A, a filtration system with a
backwashing mechanism is shown, according to one embodiment of the
present invention. In this embodiment, filtration system 700 has an
inlet impermeable weir 1001 and an outlet impermeable weir 1002. In
operation, the stormwater flows through an inlet opening created by
impermeable weir 1001 and fills filtration chamber 701. Impermeable
weir 1001 separates the influent stormwater from the filtrate. As
filtration chamber 701 fills with water, the aqueous portion of the
stormwater permeates through each elongated filtration element 100.
The filtrate then accumulates above deck 1000 until it overflows
outlet impermeable weir 1002 and exits system 700. Outlet
impermeable weir 1002 allows for a level of filtrate to accumulate
above deck 1000. When flow stops, the stormwater that remains in
lower chamber of filtration system 700 drains down through
infiltration, connection to a dry well, or any other drain-down
mechanism. As the water level in the lower chamber drops, the
filtrate that is accumulated above deck 1000 flows downward through
each filtration cartridge 400, backwashing each elongated
filtratable element 100 and removing any trapped sediment.
[0087] Referring to FIG. 10B, in another embodiment, inlet line 702
may feed directly into filtration chamber 701 beneath deck 1000. In
this embodiment, inlet line 702 would be positioned, in relation to
filtration chamber 701, so that a sufficient hydraulic head is
created to cause stormwater to flow through elongated filtratable
elements 100 and out outlet line 704. In general, this will require
inlet line 702 to be positioned at a height above filtration
chamber 701 and outlet line 704. For example, inlet line 702, at
some point upstream of filtration chamber 701, may be elevated
above filtration chamber 701 and then slope downward and connect to
filtration chamber 701 below deck 1000.
[0088] Referring to FIG. 11, a filtration system with a backwashing
mechanism is shown, according to another embodiment of the present
invention. In this embodiment, filtration system 700 has a
plurality of filtration cartridges 400 with each cartridge 400
being equipped with its own backwashing valve assembly 1200.
Referring to FIG. 12A, valve assembly 1200 may generally include
five components: a cartridge cover 1201, a release valve 1202, a
float 1203, a hole 1204, and a tether 1205. In general, valve
assembly 1200 enables each elongated filtratable element 100 to be
backwashed between rain events in order to remove trapped
sediment.
[0089] Cartridge cover 1201 may be adapted so that it sealably and
removably covers each filtration cartridge 400 in filtration system
700. Tether 1205 attaches release valve 1202, which may be
pivotally attached to cartridge cover 1201, to float 1203. Release
valve 1202 may have a plug that fits into hole 1204. Valve assembly
1200 has two primary operating positions: a generally closed
position, as shown in FIG. 12A, and an open position, as shown in
FIG. 12B.
[0090] Referring to FIGS. 13 and 14, filtration system 700 is in an
operating position where stormwater has completely filled the lower
housing and a small amount of filtrate has accumulated above each
valve assembly 1200. In normal operation, not the backwashing
operation, release valve 1200 may be slightly forced open by the
filtrate flowing upward through filtration cartridge 400 so that
filtrate accumulates on deck 1000 before it flows out of filtration
system 700 via outlet 704. In one embodiment, as shown in FIG. 13,
each valve assembly 1200 may be separated using a partition 1300 so
that each filter cartridge 400 may have its own "tank" of filtrate
for later use during backwashing. In this embodiment, outlet line
704 (not shown) may be at the level of the top of partition
1300.
[0091] During normal operation, filtrate flows up through each
elongated filtratable element 100 as usual. When the flow of
influent stormwater stops, release valve 1202 closes to prevent any
of the filtrate that has accumulated on the upper housing of
filtration system 700 from draining down through each filtration
cartridge 400. When flow stops, the stormwater that remains in
lower chamber of filtration system 700 drains down through
infiltration, connection to a dry well, or any other drain-down
mechanism. Float 1203 travels downward as the stormwater in the
lower housing is drained. When the water level in the lower chamber
drops to the desired level, release valve 1202 may be pulled open
by float 1203 via tether 1205. In one embodiment, tether 1205 may
be long enough to allow float 1203 to reach a level below each
elongated filtratable element 100. When release valve 1202 opens,
the "tank" of accumulated filtrate above each filtration cartridge
400 flushes downward, backwashing each filtratable element 100 and
removing any trapped sediment.
[0092] Referring to FIG. 15, deck 1000 for filtration system 700 is
shown according to one embodiment. In this embodiment, deck 1000
may be generally described as an insert that securely fits into
filtration chamber 701. Deck 1000 may divide filtration chamber 701
into an upper chamber above deck 1000, and a lower chamber below
deck 1000. Deck 1000 may have one or more holes for mounting one or
more filtration cartridges (not shown). Further, deck 1000 may have
a ridge 1404 attached to or integrally formed with the top surface
of impermeable deck 1000. Ridge 1404 may form perimeter on deck
1000. Ridge 1404 may generally surround holes 1402. Ridge 1404 acts
as an outlet weir for the filtered water that filters through each
filtration cartridge 400. Ridge 1404 may be of any suitable height
and thickness. Water may exit filtration system 700 by flowing over
ridge 1404 and onto another portion of deck 1000, proceeding
downstream via outlet line 704.
[0093] Deck 1000 may also have a skirt 1406. Skirt 1406 may be
attached to or integrally formed with the bottom surface of deck
1000. Skirt 1406 may extend below deck 1000 at some distance. Skirt
1406 may substantially surround or entirely surround elongated
filtratable elements 100 that reside in the lower chamber of
filtration system 700. Skirt 1406 may be of any suitable length; it
may extend beyond, be of the same length, or be shorter than
elongated filtratable elements 100.
[0094] Referring to FIG. 16, another embodiment of filtration
system 700 is shown according to one embodiment. In this
embodiment, deck 1000, having ridge 1404 and skirt 1406, may be
installed into filtration chamber 701. Deck 1000 may have a
substantially circular outer perimeter and may be sized to fit
within the walls of filtration chamber 701. Deck 1000 may also be
shaped to provide access for maintenance. The access way may be of
any shape and depth. The access way may allow for inspecting and
maintaining filtration system 700. For example, a ladder, or ladder
rungs, may be located within the access way.
[0095] In this embodiment, inlet line 702 may be located below deck
1000. Inlet line 702 may be located above the bottom of skirt 1406.
Inlet line 702 may be tangential to filtration chamber 701.
Therefore, influent may be introduced tangentially into filtration
chamber 701 below deck 1000. Influent may be directed in a circular
path around skirt 1406, which may allow coarse sediments to settle
at the bottom of filtration chamber 701, and floatable pollutants
to rise and be trapped underneath deck 1000 and outside of skirt
1406. In other words, influent is introduced into filtration system
700 via tangential inlet line 702. This arrangement causes the
influent to "swirl" around skirt 1406, eventually flowing under
skirt 1406, then upward and through elongated filtration elements
100. In this embodiment, each filtration cartridge 400 is shown as
being covered by lid 404. The aqueous portion flows through each
elongated filtratable element 100, through hole 406 in lid 404, and
onto deck 1000. Filtered water accumulates above deck 1000 until it
reaches a level to overflow ridge 1404. Water then exits filtration
system 700 through outlet line 704.
[0096] Referring to FIG. 17, one or more filtration cartridges 400
may be installed outside ridge 1404. For example, filtration
cartridge 410 may be located outside of ridge 1404. This embodiment
al lows for backwashing of elongated filtratable elements 100. When
flow subsides from inlet 702, water that has accumulated above deck
1000 and inside of ridge 1404 then flows backwards through
filtration cartridges 400 located inside of ridge 1404. The water
flows downward, through each elongated filtratable elements 100 and
into the lower portion of filtration chamber 701. Because there is
one or more filtration cartridges 400 located outside of ridge
1404, water then flows upward through one or more filtrations
cartridges 400 installed outside of ridge 1404. Therefore, this
embodiment allows for filtration cartridges 400 that are located
inside of ridge 1404 to be backwashed with filtered water.
[0097] Referring to FIG. 18, a bottom view of one embodiment of
filtration system 700 is shown. This embodiment shows that skirt
1406 surrounds elements 100 from each filtration cartridge 400,
even the one or more filtration cartridges 400 that may be
installed outside of ridge 1404. In another embodiment, skirt 1406
may not surround the filtratable elements 100 from each filtration
cartridge. A portion of skirt 1406 may also define the access
way.
[0098] Referring to FIG. 19, a side view of the filtration system
700 of FIG. 16 is provided, showing various features that may be
incorporated into this or other embodiments. The filtration system
700 includes a filtration chamber 701 having an inlet 702 and an
outlet 704. A deck 1000 divides the chamber 701 into an upper
region 1902 and a lower region 1904. Access between the two regions
may be provided by a service passage 1906 and ladder 1908. A number
of filtration cartridges 400 pass through the deck 1000 into the
lower region 1904. Each filtration cartridge 400 includes a
plurality of elongated filtratable elements 100 (elements in the
background are shown in dotted lines for clarity). The filtratable
elements 100 of each filtration cartridge 400 are mounted to a
manifold 401, which may be covered by a lid 404. An orifice 406
through the lid regulates the flow through each filtration
cartridge 400. As explained herein, the orifices 406 can be sized
such to induce various pulsing effects and vibrations during
operation to assist in maintaining cleanliness of the filterable
elements 100, and extending the frequency between required
maintenance or replacement.
[0099] Below the deck 1000, a skirt 1406 surrounds the filtratable
elements 100. As shown here and in FIG. 16, the skirt 1406 may
surround all of the filtratable elements 100. As explained
previously, the skirt helps prevent floating debris and lighter
fluids from contacting the filtratable elements 100. The skirt 1406
also assists in creation of a flow path to extend the time for
particulates to settle and floating debris and lighter fluids to
rise and be captured within the channel that is created between the
skirt and lower portion of the deck and structure wall.
[0100] Above the deck 1000, an overflow ridge 1404 surrounds one or
more filtration cartridges 400. The overflow ridge 1404 collects
water during high water events, and releases the water back down
through the filters at the end of the event. In order for such
backflushing to occur, a flow path must be provided to allow the
water to go backwards through the filtration cartridges. One way of
accomplishing this is to leave one or more filtration cartridges
outside the overflow ridge 1404, as shown in FIGS. 16 and 19. Using
this arrangement, water flows down through the filtration
cartridges within the confines of the ridge 1404, and up through
the filtration cartridge(s) located outside the ridge.
[0101] It is believed that a further backflushing effect may be
created by the selection of the location and size of the hole(s)
406 through the filtration cartridge lid 404. As explained with
reference to FIGS. 5A-D, the filtration cartridge 400 may have a
number of filtratable elements 100 connected to a common manifold
401, and the manifold 401 may be covered by a lid 404 having one or
more holes 406. Filtered water passes through the filtratable
elements 100, through the manifold 401, and then through the hole
406. It has been found that when a single hole 406 is used, the
water passing through the hole 406 forms a small vertical spout
that cyclically rises and falls, in some cases generating a
palpable vibration. Without being bound to any theory of operation,
it is believed that the water being forced upwards by momentum
through the hole 406 as a column, periodically falls back down onto
itself, creating a pressure pulse that is conveyed through the
incompressible water. In use, this pulsing vibration is believed to
generate a small, but functional, backflow through the filtratable
elements 100, or at least a vibration that tends to shake the
filtratable elements 100. It is believed that this backflow or
vibration helps prevent the accumulation of sediment and other
debris on the filtratable element 100.
[0102] It is believed that the foregoing pulsing backflush effect
may be enhanced by positioning the holes 402 through the manifold
such that they are not equidistant from the hole 406 through the
lid 404, possibly causing the water flowing through the various
filtratable elements 100 to mix in a turbulent pulsing flow before
it reaches the hole 406 through the lid. This effect also may be
enhanced by forming the deck 1000 of rigid material, such as
fiberglass, that can convey the pulsing vibrations. It also might
be possible to reduce or enhance the backflush effect by resizing
the hole, forming it with rounded or beveled edges, adding a pipe
or other extension to the hole, reshaping the hole to something
other than round, and so on.
[0103] This pulsing backflush effect also may be enhanced in
embodiments in which the filtratable elements 100 have relatively
high hydraulic conductance (i.e., are capable of passing relatively
large volumes of water through them with relatively little head
loss). In such embodiments, the hole 406 through the lid 404 may be
sized to provide a substantial flow restriction to prevent high
flow rates through the filtratable elements 100, which may be
desirable to slow the flow through the system to encourage
precipitation of sediment and to prevent blinding of the filters
with large amounts of entrained sediment. In such embodiments, the
many relatively unrestricted flows from the filtratable elements
100 converge at the hole 406, which acts as an restricting orifice
that may generate reversed pulses or vibrations through the
water.
[0104] In other embodiments the filtration cartridge outside the
ridge 1404 may be omitted and replaced by a simple weep hole
through the deck 1000 that allows the water to flow to the outlet
704, or a drain-down feature to allow the water to flow out through
the bottom (or side) of the lower chamber 1904. If a drain-down
feature is provided, it may facilitate backflushing and partially
or wholly empty the contents of the filtration system 700 between
storm events or upon control of a service technician. Drain-down
may be provided through infiltration, connection to a dry well, or
any other drain-down mechanism, as noted above. For example, a
drain-down hole 1910 may be provided through the bottom of the
filtration chamber 701, or the bottom of the filtration chamber 701
may simply be open. A filter 1912 optionally may be placed over the
drain-down hole or other opening to remove pollutants from the
water as it drains back into the soil. As the water level in the
lower chamber 1904 drops, the filtrate that is accumulated above
deck 1000 flows downward through each filtration cartridge 400,
backwashing each elongated filtratable element 100 and removing
trapped sediment. If the drain-down also substantially empties the
liquid contents of the filtration chamber 701 between storm events,
this may reduce the incidence of bacteria and insect growth. The
flow rate through the drain-down feature may be controlled by using
an orifice or the like. If desired, the drain-down feature may
include a valve to open or close it, or to regulate the flow rate
therethrough.
[0105] As will be appreciated from the foregoing explanation, the
inclusion of an overflow ridge 1404 along with some mechanism to
allow the liquid to drain back down through the filtration
cartridges provides an automatic backflushing mechanism that
operates whenever the fluid level recedes below the deck height.
However, while such an automatic backflushing mechanism is
desirable, it is not required of all embodiments.
[0106] The deck 1000 in the filtration system 700 may be
constructed integrally with the chamber 701 (e.g., as a concrete
slab), but instead may be made as a separate part that is installed
into a simple cylindrical chamber 701. For example, in the shown
embodiment, the deck 1000 may comprise a fiberglass insert that may
have the ridge 1404, skirt 1406 and service passage attached to or
formed as part of the deck 1000. Around its outer edge, the deck
1000 has upper and lower perimeter walls 1914, 1916, such as the
walls shown in FIG. 1 5. The perimeter walls 1914, 1916 are
configured to fit relatively closely within the chamber 701, so
that connectors such as bolts can be passed through the walls 1914,
1916 to secure the deck 1000 to the chamber 701. The upper and
lower perimeter walls 1914, 1916 also may be generally water-tight
to create a double wall (in conjunction with the wall of the
chamber 701) around the top of the lower chamber 1904 and the
bottom of the upper chamber 1902. This double wall construction is
expected to help reduce the release of hydrocarbons or other
pollutants through the walls of the chamber 701, which may be
particularly beneficial if the chamber 701 is formed of concrete,
which may not fully resist such pollutants. The location of the
double wall at the top of the lower chamber 1904 and bottom of the
upper chamber 1902 may be particularly desirable, as these are the
locations at which hydrocarbons are likely to accumulate. In the
shown embodiment, the upper perimeter wall 1914 may be cut out at
the outlet pipe 704 to permit the flow of fluid through the outlet
704. Also, the upper and lower perimeter walls 1914, 1916 may be
omitted around the service passage 1906, as shown, or they may be
continued all the way around the perimeter of the chamber 701.
[0107] Still referring to FIG. 19, embodiments of a filtration
system 700 may position the elongated filtratable elements 100
above and spaced from the bottom wall of the chamber 701. This
arrangement allows dirt and sediment to accumulate below the
filtratable elements 100 without touching them, and without
interfering with their filtration function. A large space is
expected to permit greater sediment storage volume, and reduce the
likelihood that an influx of water will entrain the sediment and
raise it up to contact the filtratable elements 100.
[0108] It also may be desirable to mount the filtratable elements
100 to the manifold 401 without any supports or other structures
along the lengths of the filtratable elements 100. Such supports
might provide a space for sediment or debris to collect and remain
in contact with the filtratable elements 100, and may interfere
with the downward movement of dirt and debris during backflushing
and by natural precipitation. An arrangement of filtratable
elements 100 that lacks any kind of intermediate supports is shown,
for example, in FIGS. 11 and 19. Where no intermediate supports are
used, it may be desirable to reinforce the filtratable elements 100
to prevent them from moving excessively, but alternatively such
movement may enhance natural cleaning of the filtratable elements
100. It has been found that omitting any kind of intermediate
support along the length of the filtratable elements 100 may
contribute to increased service life of filters used in the
filtration system 700 by preventing any substantial localized
accumulation of sediment of debris on the filtratable elements
100.
[0109] Referring now to FIG. 20, an example of another filtratable
element 100 is illustrated and described. As noted above, the
surface area of the filtratable elements 100 may be increased by
pleating them. The filtratable element 100 in FIG. 20 comprises a
filter medium 2002 that has been formed into pleats and rolled into
a cylindrical shape. The filter medium 2002 may comprise any
suitable filter material, or combination of material s, and may
also include antimicrobial agents, sorbtive media, or other
features. The filter medium 2002 may surround an internal frame
2004 to help retain the structure of the filter medium 2002. The
filter medium 2002 also may be secured at its ends to upper and
lower end caps 2006, 2008. In this embodiment, the upper end cap
2006 includes an outlet passage 2010 through which the filtrate
passes. The outer surface 2012 of the outlet passage 2010 may
include fastening elements (e.g., threads, bayonet fastener prongs
or slots, etc.) for securing the element 100 to the manifold 401.
For example, the outer surface 2012 may be threaded, so that it can
be passed through a corresponding opening in the manifold and
secured by tightening a nut onto the threads, the lower end cap
2008 may be closed to prevent fluid from bypassing the filter
medium 2002. It is expected that closing the lower end cap 2008
also may help prevent an upward current of fluid at the bottom of
the filtratable element 100, which may help prevent sediment from
being entrained and rising up into contact with the filter medium
2002. The use of a closed lower end cap 2008 may be particularly
beneficial in embodiments such as FIG. 19, where the filtratable
elements 100 are elevated above the bottom of the chamber 701.
[0110] A pleated filtratable element 100 such as the embodiment in
FIG. 20 might provide a significantly larger filtration surface
area than a non-pleated element. This may be beneficial to increase
service life, provide more tolerance for surface occlusion, and
provide a higher hydraulic conductance that allows faster flows
through the filtration system. For example, it is believed that a
filtration system such as shown in FIG. 21 that uses pleated
filtratable elements such as shown in FIG. 20 may have about ten
times the flow rate for the footprint of the filtration system than
conventional devices. The higher hydraulic conductance may allow
the filtration system to operate at a relatively low head. If
faster flows are not desired, one or more orifices or other flow
restrictions may be used in conjunction with the pleated
filtratable element 100. The orifices may be associated with the
individual filtratable elements 100 (e.g., sizing or providing an
orifice on the outlet passage 2010 to restrict flow), or with a
manifold that collects the flow from multiple filtratable elements
100 (e.g., an orifice hole 406 through a lid 404 over a manifold
401).
[0111] FIG. 20 also illustrates how the filtratable element 100 may
be divided into subparts 100', 100'' that connect to one another to
increase the length of the filtratable element 100. In this
embodiment, an upper subpart 100' has a hole through its lower end
cap 2008', and a lower subpart 100'' has an outlet passage 2010'
through its upper end cap 2008' that fits into the hole. The two
subparts 100', 100'' may be secured by any suitable means, such as
threaded fasteners, adhesive, ultrasonic bonding, or the like.
[0112] FIG. 21 illustrates another embodiment of a filtration
system. This embodiment includes a deck assembly 2100 that is
positioned adjacent an inlet 2102. The chamber has been omitted
from FIG. 21 to better visualize the remaining parts of the system.
It will be appreciated that the shown parts can be fit into a
chamber having an outlet and a sediment reservoir located below the
deck assembly 2100, such as the chambers illustrated elsewhere
herein.
[0113] The deck assembly 2100 includes a deck 2104 that divides the
corresponding chamber into upper and lower portions. The deck 2104
is bounded by upper and lower perimeter walls 2106, 2108 by which
the deck assembly 2100 may be connected to the chamber walls to
secure it in place. The upper perimeter wall 2106 may include a
cutout 2017 that partially surrounds the chamber outlet (not
shown). A number of filter cartridge openings 2110 pass through the
deck 2104 and each opening 2110 is configured to receive a
respective filter cartridge such as the ones described previously
herein. The deck 2104 may include an overflow ridge 2112 that
segregates one of the filter cartridge openings 2110' to act as a
bypass for backflushing the remaining filter cartridges. In this
exemplary embodiment, the inlet 2102 is located above the deck,
although a sub-deck location would be equally possible. The inlet
2102 is positioned over a deck inlet opening 2114. The deck opening
2114 may serve as a service passage. Alternatively, the service
passage may be omitted, made separate from the inlet opening 2114,
or be configured otherwise. The inlet opening 2114 may be
surrounded by a barrier wall 2116 that directs incoming fluid below
the deck 2104. A skirt 2120 (portions of which are visible through
the cartridge openings 2110) may depend from the bottom of the deck
2104 to help segregate the filter cartridges from floating debris
or relatively light liquids, as described previously herein.
[0114] In use, fluid enters through the inlet 2102, drops down
through the deck inlet opening 2114, rises up through the filter
cartridges, and exits through the outlet. Backflushing is provided
by the overflow ridge 2112 such as described herein. During
particularly high flows, the incoming fluid may rise up in the
barrier wall 2116. The barrier wall 2116 may act as a weir that
permits bypass flow when the flow rate exceeds the flow rate
capacity of the filter cartridges, however it has been found that
under such circumstances floating debris retained by the barrier
wall 2116 can flow over the barrier wall 2116 and be carried out of
the filtration system. To inhibit or prevent this from happening,
the deck 2104 may include one or more bypass pipes 2118 that
provide a fluid flow path through the deck 2104. The bypass pipes
2118 may be located within the skirt 2120 that depends from the
bottom of the deck 2104, to thereby reduce the amount of floating
or light fluid debris that is flushed out during bypass conditions.
Alternatively, the bypass pipes 2118 may be located outside the
skirt 2120, but may extend some distance from the bottom of the
deck 2104 to position their inlets where they are less likely to
permit the passage of floating debris and light fluids. Still
another alternative would be to simply have the bypass pipes feed
directly from just below the deck 2104, in which case they might be
more susceptible to passing lighter fluids and floating debris.
[0115] Under some circumstances, it may be desirable to provide
additional filtration or water cleaning devices in a filtration
system. Examples of such additional devices are shown in FIG. 21,
but it will be appreciated that similar devices may be used in
other embodiments. As shown in FIG. 21, in one embodiment, a simple
debris trap 2122 may be located below the inlet 2102. The debris
trap 2122 is a relatively large mesh screen that catches
particularly large debris that might be carried in through the
inlet 2102. In other embodiments, a debris trap may be placed over
the outlet, over the top of the inlet 2102 to prevent debris from
rising over the barrier wall 2116, or at other locations.
[0116] Another device that may be used in this or other embodiments
is a supplemental filter cartridge or sack 2124, such as a granular
media filter that polishes the fluid, adsorbs pollutants that may
be dissolved constituents such as nitrogen, phosphorus or metals,
or otherwise contributes to cleaning the passing water. The
supplemental filter cartridge or 2124 may be located such that all
of the fluid is forced through it, but it is expected that simply
having a supplemental adsorbent filter cartridge somewhere in the
filtration system can be beneficial. For example, the shown
supplemental filtration cartridge 2124 is located on the deck 2104
where some, but not all, of the fluid will pass through it. In
another embodiment, the supplemental filtration cartridge may be a
flexible tubular member 2126 that is located in the space between
the overflow ridge 2112 and the upper perimeter wall 2106. In still
another embodiment, the supplemental filtration cartridge may be
formed as a rigid or flexible cover over some or all of the
overflow ridge 2112. In still another embodiment, a supplemental
filtration media may be provided inside the elongated filtratable
elements 100 (e.g., inside the open space within the pleated filter
shown in FIG. 20 or the filter shown in FIGS. 1A and 1B), or
between the manifold 401 and the lid 404. The supplemental
filtration cartridge may comprise a rigid chamber, or a permeable
bag, or other suitable constructions. Regardless of the location,
it may be desirable to ensure that the supplemental filtration
cartridge 2124 cannot be dislodged and conveyed downstream during
high flows. These or other supplemental cleaning devices preferably
have sufficient capacity or service life that they can be serviced
on the same schedule as the filter cartridges, but this is not
strictly necessary.
[0117] An exemplary embodiment of a portable backflush unit 2200
for servicing stormwater filtration devices is shown in FIG. 22.
The backflush unit 2200 comprises a vertical tube 2202 having an
open top 2204 and a bottom floor 2206. A valve 2208 is mounted on
the floor 2206 to selectively cover or expose an opening 2302 (FIG.
23C) through the floor 2206. The valve 2208 may be any suitable
kind of valve. For example, the valve 2208 may comprise a sealing
plate 2210 that is pivotally mounted to the floor 2206 by an arm
2212. The exemplary valve 2208 may be operated remotely by lifting
a rope 2214 or chain that is connected to the sealing plate 2210 or
arm 2212.
[0118] Referring to FIGS. 23A-C, the backflush unit 2200 is
configured to cover a filtration cartridge 400. The unit 2200 may
cover one or more filtration cartridges, but for ease of
manipulation and use it may be desirable to be sized to fit over a
single filtration cartridge. The backflush unit 2200 may include
one or more seals (not shown) that help form a water-tight seal
around the top of the filtration cartridge 400, but this is not
strictly required. The backflush unit 2200 is operated by lowering
it in to place above a filtration cartridge 400 (FIG. 23A), and
then filling it with water 2304. Once the backflush unit 2200 is
filled, the operator pulls up on the robe 2214 to open the valve
2208 and allow the water 2304 to flow backwards through the filter
cartridge 400. To enhance the backflushing effect, the operator may
drain or partially drain the filtration system below the level of
the deck so that the backflush water does not need to displace and
surrounding water to flow through the filter cartridge 400.
[0119] It is expected that a portable backflush unit 2200, such as
the illustrated embodiment, will have particular utility for
backflushing operations performed in installed filtration systems.
The backflush unit 2200 can be constructed of lightweight
materials, and can be dimensioned to fit through relatively small
openings, making it easy to handle and use. To assist with its use,
one or more handles 2306 may be provided.
[0120] It will be appreciated that many modifications and
variations can be made to the illustrated backflush unit 2200. For
example, it can have any suitable shape instead of being
cylindrical. Also, the valve can be replaced by any suitable fluid
control device, and can be operated by any suitable mechanism
(e.g., a lever or pushrod). These and other variations will be
apparent to persons of ordinary skill in the art in view of the
present disclosure.
[0121] FIGS. 24A-C illustrate another embodiment of a filtration
system 2400. Here, the filtration system 2400 includes a catch
basin 2402 and a filtration chamber 2404 that are located adjacent
one another in a side-by-side arrangement. The catch basin receives
incoming flow either from a curb inlet 2406 or from an opening 2408
through the top wall 2410. A suitable grate or other screen may be
placed over either the inlet 2406 or the opening 2408. The opening
2408 may be used to access the catch basin 2402, and may be closed
during normal use (i.e., to only receive flow from the curb inlet
2406). A similar covered opening may be provided over the
filtration chamber 2404 for service access.
[0122] The filtration chamber 2404 is divided into upper and lower
portions by a deck 2412. A number of filtration cartridges 2414
provide a fluid flow path through the deck 2412. A ridge 2416 may
be provided on the deck 2412, with one or more filtration
cartridges 2414' located on the downstream side of the ridge 2416
to act as a drain-down filter to permit backwashing of the
remaining filters, such as described previously herein. A bypass
2418 also may be provided through the deck 2404 to allow flow
during high flow events. An outlet 2420 is located above the deck
2404 to receive and remove filtered water. A skirt 2422 divides the
catch basin 2402 from the filtration chamber 2404. The skirt 2422
extends downward from the top of the chamber (or from a height
where the fluid level is not expected to reach during any typical
conditions), to an elevation spaced from the bottom of the chamber,
leaving a space for water to flow laterally from the catch basin to
the filtration chamber. A drain-down or other features may be
provided, if desired.
[0123] It will be appreciated that a filtration system as described
herein or having other constructions may be used in conjunction
with other water treatment devices. For example, an embodiment such
as the embodiment of FIG. 16 may be used downstream of a gravity
separation system, and upstream of a sorbtive media filtration
system. Embodiments also may be reconfigured to fit into catch
basin systems that have a catch basin and a filtration system
integrated into a single chamber. Embodiments also may be modified
to fit into pre-existing water treatment devices. For example a
deck assembly similar to the one shown in FIG. 21 may be modified
to fit into a pre-existing well (that was either empty or
previously contained some other separation or filtering system), or
to be integrated as part of a preexisting separation or filtration
device (e.g., shaped to fit into a downdrain of a gravity
separation system). Other modifications and uses will be apparent
in view of the present disclosure.
[0124] Example. An experiment was conducted using five filtration
cartridges, each having eighteen elongated filtratable elements,
for a total of 90 elements. Each elongated filtratable element was
constructed by wrapping filter mats around a flexible inner core,
and enclosing the filter mats in a nylon screen. Each filtratable
element was 0.75'' in diameter and 48'' long. The elongated
filtratable elements tested had a surface area of about 90 square
feet. The filtration cartridges were placed inside a 3' diameter
filtration chamber. With less than 5 inches of head loss, the
prototype filtration system was able to remove over 5 kg of
sil-co-sil 106 (a standard fine sediment mixture) from the influent
water having a flow rate of 1 L/s and a sediment concentration of
300 mg/L. The filter cartridge occupied approximately 1 square foot
of area in an impermeable deck separating the unfiltered and
filtered water. The effluent water stream had a sediment content
less than 20% of the influent concentration. It is reasonable to
assume, based on these results, that this type of device could
remove fine sediment for the runoff generated by an acre of
impervious area, be contained in a chamber less than 10 feet in
diameter, and last for over 1 year before the filter had clogged or
needed to be replaced. The total suspended solid removal, or
sediment removal, efficiency was 90-92%.
[0125] It will be readily understood by those persons skilled in
the art that the present invention is susceptible to broad utility
and application. Many embodiments and adaptations of the present
invention other than those herein described, as well as many
variations, modifications and equivalent arrangements, will be
apparent from or reasonably suggested by the present invention and
foregoing description thereof, without departing from the substance
or scope of the invention.
[0126] Accordingly, while the present invention has been described
here in detail in relation to its exemplary embodiments, it is to
be understood that this disclosure is only illustrative and
exemplary of the present invention and is made to provide an
enabling disclosure of the invention. Accordingly, the foregoing
disclosure is not intended to be construed or to limit the present
invention or otherwise to exclude any other such embodiments,
adaptations, variations, modifications or equivalent
arrangements.
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