Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
[0001] Wastewater Treatment System With De-Nitrification
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application claims the priority benefit of U.S. Provisional Patent
Application
Number 61/239,868 filed on September 4, 2009 and U.S. Provisional Patent
Application
Number 61/239,874 filed on September 4, 2009, the disclosures of which are
expressly
incorporated herein in their entireties by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0003] Not Applicable
PARTIES TO JOINT RESEARCH AGREEMENT
[0004] Not Applicable
REFERENCE TO APPENDIX
[0005] Not Applicable
FIELD OF THE INVENTION
[0006] The present invention generally relates to residential and commercial
sewage
treatment systems and, more particularly, to aerobic waste treatment systems.
BACKGROUND OF THE INVENTION
[0007] One type of sewage treatment system operates using an aerobic bacterial
process that
breaks down waste materials into carbon dioxide and water. This aerobic
treatment system has
distinct advantages over the much more common anaerobic septic systems. The
aerobic
process is much faster and its products are less objectionable with regard to
odor and
flammability. U.S. Patent Numbers 3,923,656 and 4,246,114, the disclosures of
which are
expressly incorporated herein in their entireties by reference, each disclose
an aerobic waste
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treatment facility or system in which waste (often referred to as
"wastewater") is treated under
aerobic conditions to transform the waste to an essentially clear effluent.
Despite the efficiency
of these aerobic waste treatment systems, nuisance and maintenance issues may
result from
user habits and detract from customer acceptance of the treatment systems.
[0008] U.S. Patent Number 7,077,952, the disclosure of which is expressly
incorporated
herein in it entirety by reference, discloses an aerobic wastewater treatment
system that utilizes
pretreatment and flow equalization to resolve these issues. Such an aerobic
wastewater
treatment system is a great solution for sensitive environments, restricted
sites, and seasonal or
intermittent uses. However, these treatment systems may not be the ideal
solution for other
applications such as a non-sensitive environment with steady use.
[0009] Additionally, there is ongoing demand in the market for wastewater
treatment systems
with increased performance and/or reduced cost and maintenance. Accordingly,
there is a need
in the art for improved waste treatment systems.
SUMMARY OF THE INVENTION
[0010] The present invention provides an aerobic wastewater treatment system
that
overcomes at least some of the issues of the related art. Disclosed is an
aerobic wastewater
treatment system comprising, in combination, an outer tank, a deck located
within the outer
tank and forming an aeration chamber therebelow and an effluent chamber, and a
plurality of
porous bags hanging from the deck into the aeration chamber. The deck has
openings
communicating interiors of the bags with the effluent chamber. A submersible
aerator is
located within the aeration chamber. An inlet communicates an exterior of the
outer tank with
the aeration chamber so that influent can enter into the aeration chamber. An
outlet
communicates the effluent chamber with the exterior of the outer tank so that
effluent can exit
out of the outer tank. A controller is adapted to operate the submersible
aerator in a timed on-
off sequence so that dissolved oxygen can be controlled to create times of
anoxic conditions.
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[0011] Also disclosed is an aerobic wastewater treatment system comprising, in
combination,
an outer tank, a deck located within the outer tank and forming an aeration
chamber therebelow
and an effluent chamber, and a plurality of porous bags hanging from the deck
into the aeration
chamber. The deck has openings communicating interiors of the bags with the
effluent
chamber. A submersible aerator is located within the aeration chamber. An
inlet
communicates an exterior of the outer tank with the aeration chamber so that
influent can enter
into the aeration chamber. An outlet communicates the effluent chamber with
the exterior of
the outer tank so that effluent can exit out of the outer tank. Retainers are
threaded into the
deck to secure the porous bags to the deck and expanders extend from the
retainers and into the
porous bags to hold the bags open.
[0012] Further disclosed is an aerobic wastewater treatment system comprising,
in
combination, an outer tank, a deck located within the outer tank and forming
an aeration
chamber therebelow and an effluent chamber, and a plurality of porous bags
hanging from the
deck into the aeration chamber. The deck has openings communicating interiors
of the bags
with the effluent chamber. A submersible aerator is located within the
aeration chamber. An
inlet communicates an exterior of the outer tank with the aeration chamber so
that influent can
enter into the aeration chamber. An outlet communicates the effluent chamber
with the exterior
of the outer tank so that effluent can exit out of the outer tank. There is a
central opening in the
deck and a vertical wall extending about the central opening and a surge bowl
has a lower edge
resting on the vertical wall and has substantially vertical walls.
[0013] From the foregoing disclosure and the following more detailed
description of various
preferred embodiments it will be apparent to those skilled in the art that the
present invention
provides a significant advance in the technology of aerobic wastewater
treatment systems.
Particularly significant in this regard is the potential the invention affords
for providing an easy
to install, reliable, effective, low maintenance, aerobic wastewater treatment
system.
Additional features and advantages of various preferred embodiments will be
better understood
in view of the detailed description provided below.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00141 These and further features of the present invention will be apparent
with reference to
the following description and drawings, wherein:
FIG. 1 is a cutaway perspective view of an aerobic wastewater treatment system
according to the present invention;
FIG. 2 is an exploded, cutaway perspective view of the aerobic wastewater
treatment
system of FIG. 1;
FIG. 3 is a diagrammatic view of the aerobic wastewater treatment system of
FIGS. 1
and 2;
FIG. 4 is a block diagram of a control system of the aerobic wastewater
treatment
system of FIGS 1 to 3;
FIG. 5 is a fragmented, sectional view of a flange interface for an outer tank
of the
aerobic wastewater treatment system of FIGS. 1 to 4;
FIG. 6 is an exploded perspective view a filter membrane assembly of the
aerobic
wastewater treatment system of FIGS. 1 to 5;
FIG. 7 is fragmented, sectional view of an alternative filter membrane holder;
FIG. 8 is a perspective cut-away view of the filter membrane holder of FIG. 7;
FIG. 6 is an exploded perspective view an alternative access lid assembly of
the aerobic
wastewater treatment system of FIGS. 1 to 6, wherein a riser is provided; and
FIG. 5 is an exploded perspective view an alternative surge bowl assembly of
the
aerobic wastewater treatment system of FIGS. 1 to 6, wherein a riser is
provided.
[00151 It should be understood that the appended drawings are not necessarily
to scale,
presenting a somewhat simplified representation of various preferred features
illustrative of the
basic principles of the invention. The specific design features of the
wastewater treatment
systems as disclosed herein, including, for example, specific dimensions,
orientations,
locations, and shapes will be determined in part by the particular intended
application and use
environment. Certain features of the illustrated embodiments have been
enlarged or distorted
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relative to others to facilitate visualization and clear understanding. In
particular, thin features
may be thickened, for example, for clarity or illustration. All references to
direction and
position, unless otherwise indicated, refer to the orientation of the
treatment systems illustrated
in the drawings. In general, up or upward refers to an upward direction within
the plane of the
paper in FIG. 1 and down or downward refers to a downward direction within the
plane of the
paper in FIG. 1.
DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS
[0016] It will be apparent to those skilled in the art, that is, to those who
have knowledge or
experience in this area of technology, that many uses and design variations
are possible for the
improved wastewater treatment methods and devices disclosed herein. The
following detailed
discussion of various alternative and preferred embodiments will illustrate
the general
principles of the invention with reference to preferred embodiments. Other
embodiments
suitable for other applications will be apparent to those skilled in the art
given the benefit of
this disclosure.
[0017] Referring now to the drawings, FIGS. 1 to 4 illustrate an improved
aerobic wastewater
treatment system 10 according to the present invention. The improved aerobic
wastewater
treatment system 10 is based on the treatment systems described in U.S. Patent
Numbers
3,923,656 and 4,246,114, the disclosures of which are expressly incorporated
herein in their
entireties by reference. The illustrated aerobic wastewater treatment system
10 includes an
outer tank 12, a deck or plate 14 located within the outer tank 12 and forming
an aeration
chamber 16 therebelow and an effluent chamber, a plurality of porous filter
bags 20 hanging
from the deck 14 into the aeration chamber 16, a submersible aerator 22
located within the
aeration chamber 16, a controller 24 adapted to operate the submersible
aerator 22 in a timed
on-off sequence so that dissolved oxygen can be controlled to create times of
anoxic conditions
an inlet 26 communicating an exterior of the outer tank 12 with the aeration
chamber 16 so that
influent can enter into the aeration chamber 16, and an outlet 28
communicating the effluent
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chamber 18 with the exterior of the outer tank 12 so that effluent can exit
out of the outer tank
12.
[0018] The illustrated outer tank 12 includes a substantially cylindrical
holding tank or lower
portion 30 having an upwardly facing open mouth terminating at an outwardly
turned lip or
flange 32. A generally dome-shaped outer shell or upper portion 34 has a
downwardly facing
mouth terminating at an outwardly turned lip or flange 36. As shown in FIG. 5,
the flanges 32,
36 are secured together with mechanical fasteners 38 and sealant 40 is
provided between the
flanges 32, 36 to seal the joint. The illustrated joint is provided with Butyl
sealant but any
other suitable sealant can alternatively be utilized. The illustrated flanges
32, 36 form a void or
pocket 42 for the sealant to ensure sealant compression. The upper end of the
outer shell 34 is
provided with an upward facing access opening 44 terminating at inwardly
turned upper lip or
flange 46.
[0019] A mechanically fastened, vented access cover or lid 48 removably closes
the access
opening 44. As the only at grade access for service and maitenance of the
system, the
illsutrated lid assembly 48 is designed both durable and tamper resistant.
Four stainless steel,
recessed, allen head bolts fasten into cage nuts on the outer tank top flange
46 to secure the lid
assembly 48 thereto. The cage nuts are preferably stainless steel and
permanently secured to
the outer tank top flange 46. Removal can only be accomplished with special
tools provided by
the manufacturer. To allow air to be drawn into the system 10 by the
submersible aerator 22,
four louvered vents 50 with weep holes 52 have been cast into the lid assembly
48. To prevent
insect infiltration and potential oder outgassing, the lid assembly 48
contains internal charcoal-
filters 54, preferably in the form of sheets, behind the louvered weep holes
52 and within the
outer tank 12.
[0020] The illustrated weir deck 14 is located within the outer tank 12 and
rests on the upper
flange 32 of the holding tank 30. It is noted that the weir deck 14 can
alternatively be secured
within the outer tank 12 in any other suitable manner. The weir deck 14 forms
the aeration
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chamber 16 therebelow and the effluent chamber 18 thereabove as described in
more detail
hereinafter. The weir deck 14 has a centrally located opening 56 which is
surrounded by a
vertically extending wall 58. The upper end of the wall forms an opening
terminating at
inwardly turned upper lip or flange 60. The weir deck 14 forms an upwardly
extending weir
62 near the outer edge of the weir deck 14. The illustrated weir 62 extends a
full 360 degrees
about the central opening 56 in the weir deck 14. A plurality of openings 64
are formed
through the weir deck 14 outward of the vertical wall 58 and inward of the
weir 62 for the filter
bags 20 as described in more detail hereinafter.
[0021] A removable surge bowl 66 is mounted on the upper flange 60 of the
vertical wall 58.
As the filter membranes 20 mature and grow a biomass on their exterior, flow
through the
system 10 will gradually slow until equalized. Given that the system's output
is equal the
amount input, as flow slows, a reserve capacity is needed as the system
matures. The surge
bowl 66 accounts for this extra volume by providing the reserve capacity to
store influent until
it can slowly discharge out of the system 10. The illustrated surge bowl 66
has a substantially
horizontal wall 68 which engages the upper flange 60 of the vertical wall 58
and a substantially
vertical outer wall 70 which forms an open upper mouth which terminates at an
outwardly
turned lip or flange 72 which rests on the upper flange 46 of the outer shell
34. The lower wall
68 has an opening sized to cooperate with the upper opening of the vertical
wall 58. Outer wall
70 is substantially vertical and has a diameter as large as possible in order
to keep operating
head pressures in a mature system at a minimum and still be removable out of
the access
opening 44. Lower head pressures have proven to extend service intervals and
reduce
hydraulic failure due to overloading the system. The lower and upper ends of
the surge bowl
66 are secured with mechanical fasteners and gaskets to seal the joints.
[0022] The surge bowl 66 can be provided with a foam baffle or plate 74 that
generally closes
the upper end of the surge bowl 66. The foam plate 74 can sit on top of the
surge bowl 66 so
that the access lid 48 seals the foam plate 74 to the surge bowl 66 when the
access lid 48 is
installed. A hole is provided in the center of the foam plate 74 so it slides
over an aerator
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intake pipe 76. The foam plate 74is desirable because the system 10 will foam
during periods
of stress (drastic change in temperature that occur in the spring and fall).
With prior designs,
this foam blows out under the cover and pools around the top of the system.
The foam plate 74
seals the top of the surge bowl 66, as well as the entire tank 12, and forces
the foam back inside
the sewer line through the inlet 26. The foam plate 74 can be produced of
fiberglass or any
other suitable material and can have a thickness of about 3/16 or any other
suitable thickness.
[0023] The plurality of porous filter bags 20 hang from the weir deck 14 into
the aeration
chamber 16 and are located at the openings 64 in the weir deck 14. The
illustrated system 10
utilizes thirty of the porous filter bags 20 but any other suitable quantity
can alternatively be
utilized. The illustrated filter bags 20 comprise 100 micron polyester felt
filter membranes and
provide about 132 sq. ft of surface area. It is noted that any other suitable
filter membrane can
alternatively be utilized and any other suitable quantity of surface area can
alternatively be
utilized.
[0024] As best shown in FIG. 6, illustrated filter membrane assemblies 78 each
include a
filter membrane expander 80 and one of the porous filter bags 20. The expander
80 includes a
retainer or retaining portion 82 and an open body or open cage portion 84
downwardly
extending from the retainer 82. The illustrated retainer 82 is generally
cylindrical shaped and
has a central passage therethrough. A central portion of the outer surface is
provided with
external threads 86 adapted to cooperate with internal threads provided at the
openings 64 in
the weir deck 14 to removably secure the retainer 82 to the weir deck 14 and
prevent the
passage of untreated effluent therethrough. The upper portion of the retainer
82 is provided
with a pair of opposed radially facing openings 88 which form hand holds for
threading and
unthreading the retainer 82 into the weir deck 14. The lower portion of the
retainer 82 is
adapted for receiving the upper end of the porous filter bag 20. The upper end
of the filter bag
20 contains an internal stainless-steal ring 90 which acts as a stop to
prevent the filter bag 20
from passing through the weir deck 14 and threads onto the retainer 82 to
prevent the passage
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of untreated effluent therethrough. Because the filter bags 20 are generally
cylindrical shaped,
they require the internal open cage 84 to prevent collapse, loss of surface
area, and potential
biomass bridging. The illustrated open cage 84 includes three vertically
spaced-apart ring
members 92 which are connected together by a pair of opposed vertically
extending connecting
members 94. The ring members 92 are sized to fully expand the filter bags 20.
The vertical
members 94 are sized to extend substantially the entire length of the filter
bags 20 and are
secured to the ring members 92 and the retainer 82 at their upper ends. It is
noted that the
illustrated expander 80 is utilized to both secure the filter bags 20 to the
weir deck 14 and hold
the filter bags 20 open. The open cage 84 of the expander 80 allows for free
flow through the
membrane and provides a settling/clarification area inside the membrane for
oxidized organic
matter (pin floc). The expander 80 also allows for membrane cleaning without
removal from
the weir deck 14. The expander 80 can comprise polyethylene or any other
suitable material.
[0025] FIGS. 7 and 8 illustrate an alternative retainer 96 for the filter bags
20. The retainer
96 is ring shaped and has a generally-S-shaped cross section. The retainer 96
includes an
inward facing recess 98 sized for receiving and retaining therein a stainless
steel ring 100 at the
upper end of the filter bag 20 and an outward facing recess 102 sized for
receiving and
retaining therein the edges of the opening 64 in the weir deck 14. The
illustrated ring 100 is
sized so that it cannot pass through the opening 64 in the weir deck 14. The
illustrated recess
102 for the weir deck 14 is provided with a plurality of webs 104 for ensuring
against the
passage of untreated effluent therethrough. The illustrated recess 102 for the
weir deck 14 is
also sized for an interference fit with the weir deck 14 to secure the
retainer 96 to the weir deck
14 with a friction grip. The illustrated retainer 96 is formed of rubber but
can alternatively be
formed of any other suitable material. This alternative retainer 96 has the
advantage that it can
be produced very inexpensively by extruding a web, cutting it to length and
then forming the
ring shape. It also has the advantage that it can be easily utilized in
retrofit applications.
[00261 The illustrated submersible aerator 22 is located within the aeration
chamber 16 near
the bottom of the holding tank 30. The air inlet line or pipe 76 vertically
extends from the
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aerator 22 through the central opening 56 in the weir deck 14 and the surge
bowl 66 to a
location near the access lid 48 where air entering through the access lid 48
is available for the
aerator 22. It is noted at any suitable submersible aerator 22 can be
utilized. Operation of the
aerator 22 is controlled by the controller 24 as described in more detail
hereinafter.
[00271 The controller 24 is preferably adapted to operate the submersible
aerator 22 in a
timed on-off sequence to improve nutrient reduction. Note that this is
different than the
continuous operation utilized by the prior art systems. By cycling the aerator
22 on and off,
dissolved oxygen can be controlled to create extended times of anoxic, or near
anoxic,
conditions. In the absence of free oxygen the bacteria utilize nitrogen in the
wastewater for
respiration (if oxygen was present they would use that instead because it
requires less energy)
and convert it to nitrogen gas. It is believed that about 3 hours on followed
by about 2 hours
off is desirable for a 500 gpd system in warm weather. However, other on and
off durations
may be desirable depending on site conditions (specific wastewater
characteristics,
temperature, ph, alkalinity etc.) and design flow. It is believed that the key
is keeping dissolved
oxygen to about 2 Mg/L. Below about 2 Mg/L, ammonia increases and above 2 Mg/L
there is
too much oxygen for the process to work efficiently. The controller 24
preferably incorporates
a programmed PLC control which monitors water temperature and pressure inside
the outer
tank 12 to cycle the submersible aerator 22 as required. Suitable temperature,
pressure and/or
oxygen sensors 106, 108, 110 are preferably provided within the tank 12 and in
communication
with the controller 24. The aerator 22 is preferably provided with an
integrated loss of air
sensor 112 for stopping the aerator 22 and/or activating an alarm when air is
not available to
the aerator 22.
[00281 The illustrated inlet 26 communicates an exterior of the outer tank 12
with the aeration
chamber 16 so that influent can enter into the aeration chamber 16. The
illustrated inlet 26 is in
the form of a four inch pipe that horizontally extends from the exterior of
the tank 12 through
the wall of the outer shell 34 and the vertical wall 58 of the weir deck 14.
The exit opening of
the inlet 26 is thus in communication with the aerobic chamber 16 through the
central opening
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56 and with the surge bowl 66 through the upper opening. It is noted that the
inlet 26 can
alternatively have any other suitable size and/or can alternatively have any
other suitable
location.
[0029] The illustrated outlet 28 communicates the effluent chamber 18 with the
exterior of
the outer tank 12 so that effluent can exit out of the outer tank 12. The
illustrated outlet 28 is in
the form of a four inch pipe that horizontally extends from the exterior of
the tank 12 through
the wall of the outer shell 34. The opening in the outer she1134 is preferably
drilled on site
a\during installation and there are preferably a plurality of predefined
locations that can be
selected for drilling the outlet opening. For example, there can be three
predefined locations;
one opposite the inlet (180 degrees from the inlet), and two at 90 degrees
from the inlet in
opposite directions. The entrance opening of the outlet 28 is thus located in
the effluent
chamber 18. It is noted that the outlet 28 can alternatively have any other
suitable size and/or
can alternatively have any other suitable location.
[0030] Household wastewater enters the system 10 through the inlet 26 where it
enters the
aerobic chamber 16 through the central opening 56 in the weir deck 14. The
wastewater is
cyclically mixed by the submersible aerator 22. Organic matter is broken down
via aerobic and
anaerobic digestion. The wastewater passes through the membranes of the filter
bags 20 which
separate treated from untreated waste. The flow then travels up the inside of
the filter bags 20,
through the openings 64 in the weir deck 14, and discharges over the 360
perimeter weir 62 in
the effluent chamber 18. Once in the effluent chamber 18, the treated effluent
exits the tank 12
through the outlet 28. It is noted that the illustrated system 10is a one pass
system.
[0031] A best illustrated in FIGS. 9 and 10, in the event site conditions
require a deeper depth
of bury, a tank riser 114 can be installed on the outer tank 12. between the
outer shell 34 and
the access lid 48. The tank riser 114 is provided with a rubber gasket and is
mechanically
fastened to the top of the outer shell upper flange 46. In these circumstances
a surge bowl riser
116 can also be utilized to ensure the system flow, head and basic operation
remain unchanged.
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The surge bowl riser 116 is provided with a rubber gasket and is mechanically
fastened to the
top flange 72of the surge bowl 66.
[0032] From the foregoing disclosure, it can readily be seen that the aerobic
wastewater
treatment system 10 according to the present invention incorporates 100 micron
positive
filtration, cycled aerobic digestion/media scrubbing via a submersible
aerator, and a 360
perimeter discharge weir to effectively treat typical residential wastewater
in an improved
manner. For example, the present invention has reduced from 15-20 Mg/L total
nitrogen in a
comparable prior art system down to 5Mg/L total nitrogen. No other wastewater
treatment
system has been able to do this effectively in a single pass system (most have
to recirculate
(multiple pass) or add a second process tank following initial treatment).
[0033] From the foregoing disclosure and detailed description of certain
preferred
embodiments, it will be apparent that various modifications, additions and
other alternative
embodiments are possible without departing from the true scope and spirit of
the present
invention. The embodiments discussed were chosen and described to provide the
best
illustration of the principles of the present invention and its practical
application to thereby
enable one of ordinary skill in the art to utilize the invention in various
embodiments and with
various modifications as are suited to the particular use contemplated. All
such modifications
and variations are within the scope of the present invention as determined by
the appended
claims when interpreted in accordance with the benefit to which they are
fairly, legally, and
equitably entitled.
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