Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
8001033-2/88247739
APPARATUS FOR AND METHOD OF WASTEWATER TREATMENT
FIELD
This disclosure relates generally to wastewater treatment.
RELATED ART
Wastewater may require treatment under aerobic conditions. It may be desirable
for
aerobic treatment of wastewater to occur in a moving bed biofilm reactor.
SUMMARY
In one embodiment there is provided a wastewater treatment apparatus. The
apparatus
includes a first container defining an anaerobic treatment chamber operable to
treat wastewater
anaerobically, a second container defining an aerobic treatment chamber
operable to treat the
wastewater aerobically, and a third container defining a clarifying chamber.
The anaerobic
treatment chamber is in fluid communication with the aerobic treatment
chamber. The aerobic
treatment chamber and the second container are disposed within the clarifying
chamber. The
aerobic treatment chamber has a bottom. The bottom of the aerobic treatment
chamber is in
fluid communication with the clarifying chamber.
The apparatus may further include a screen at an interface between the bottom
of the
aerobic treatment chamber and the clarifying chamber.
The apparatus may further include an air supply system attached to the screen
and
operable to provide air to the aerobic treatment chamber.
The air supply may be positioned below the screen.
The aerobic treatment chamber may have media carriers therein.
The screen may have openings sized to prevent the media carriers from entering
the
clarifying chamber.
The media carriers may be operable to grow microorganisms.
Each of the media carriers may provide a surface for a biofilm to grow.
The second container may include a media reactor.
The second container may include a moving bed biofilm reactor.
In another embodiment there is provided a method of treating wastewater. The
method
involves treating the wastewater anaerobically in an anaerobic treatment
chamber and treating
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the wastewater aerobically in an aerobic treatment chamber defined by a
container disposed
within a clarifying chamber. The anaerobic treatment chamber is in fluid
communication with
the aerobic treatment chamber. The aerobic treatment chamber has a bottom. The
bottom of
the aerobic treatment chamber is in fluid communication with the clarifying
chamber.
Treating the wastewater anaerobically may occur before treating the wastewater
aerobically.
The method may further involve providing air to the aerobic treatment chamber.
The air may be provided from below the bottom of the aerobic treatment
chamber.
The aerobic treatment chamber may have media carriers therein.
The media carriers may be operable to grow microorganisms.
The method may further involve allowing a biofilm to grow on a surface of each
of the
media carriers.
The method may further involve using a screen at an interface between the
bottom of
the aerobic treatment chamber and the clarifying chamber to prevent the media
carriers from
entering the clarifying chamber.
The container defining the aerobic treatment chamber may include a media
reactor.
The container defining the aerobic treatment chamber may include a moving bed
biofilm reactor.
Other aspects and features will become apparent to those ordinarily skilled in
the art
upon review of the following description of illustrative embodiments in
conjunction with the
accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a wastewater treatment apparatus according to
one
embodiment, with a tank lid of the apparatus removed.
FIG. 2 is a perspective view of the wastewater treatment apparatus of FIG. 1
with a
portion of the tank wall cut away to show the interior of the treatment
apparatus and with the
tank lid of the apparatus removed.
FIG. 3 is a top view of the wastewater treatment apparatus of FIG. 1, with the
tank lid
of the apparatus removed.
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FIG. 4 is a cross-sectional side view of the wastewater treatment apparatus of
FIG. 3,
taken along the section line marked FIG. 4 in FIG. 3.
FIG. 5 is a fragmentary bottom perspective view of a bottom of a reactor
structure of
the wastewater treatment apparatus of FIG. 1.
FIG. 6 is a perspective view of a media carrier according to one embodiment.
FIG. 7 is a front view of the media carrier of FIG. 6.
FIG. 8 is a flow chart of a method of treating wastewater according to one
embodiment.
DETAILED DESCRIPTION
Referring to FIGS. 1 to 4, a wastewater treatment apparatus according to one
embodiment is shown generally at 100 and includes a cylindrical wastewater
treatment tank
102. The wastewater treatment tank 102 includes a tank wall 104, a tank lid
105, and a tank
floor 106 defining a treatment chamber shown generally at 108; a tank inlet
110; and a tank
outlet 112. Each of the tank inlet 110 and the tank outlet 112 is in fluid
communication with
the treatment chamber 108.
The wastewater treatment tank 102 further includes a chamber divider 114 which
extends from the tank floor 106 to the tank lid 105 and from a first side 115
of the tank wall
104 to a second side 117 of the tank wall 104. The chamber divider 114 divides
the treatment
chamber 108 into an anaerobic treatment chamber shown generally at 116 and a
clarifying
chamber shown generally at 118. That is, on a first side 120 of the chamber
divider 114, the
tank wall 104, the tank floor 106, and the chamber divider 114 together form a
container
defining the anaerobic treatment chamber 116, and on a second side 122 of the
chamber
divider 114, the tank wall 104, the tank floor 106, and the chamber divider
114 together form a
container defining the clarifying chamber 118.
Referring now to FIGS. 2 to 5, the wastewater treatment tank 102 also includes
a
reactor wall 124 and a reactor screen 126 which together form a reactor
container 127 defining
an aerobic treatment chamber shown generally at 128. The reactor wall 124 has
a cylindrical
shape in the embodiment shown; however, other shapes may be used.
Additionally, it is to be
understood that the term "screen" as used herein includes the terms "mesh" and
"sieve". The
reactor screen 126 is located at a bottom, shown generally at 130, of the
aerobic treatment
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chamber 128 and thus forms a floor of the aerobic treatment chamber 128. The
reactor wall
124, the reactor screen 126, and, consequently, the aerobic treatment chamber
128 are all
disposed within the clarifying chamber 118. The reactor screen 126 is
supported a distance
132 above the tank floor 106 by support legs 134, 136, and 138, and 140. The
reactor screen
126 includes one or more screen openings, such as screen opening 142, and thus
allows fluid
to pass between the bottom 130 of the aerobic treatment chamber 128 and the
clarifying
chamber 118. That is, the bottom 130 of the aerobic treatment chamber 128 is
in fluid
communication with the clarifying chamber 118 through the reactor screen 126.
Each of the tank wall 104, the tank floor 106, the chamber divider 114, the
reactor wall
124, and the reactor screen 126 may be made of any suitable material, such as,
for example,
fiberglass, metal, or concrete.
Referring again to FIGS. 1 to 4, the wastewater treatment tank 102 further
includes an
inter-tank conduit 144 extending through the chamber divider 114 between the
anaerobic
treatment chamber 116 and the aerobic treatment chamber 128. The inter-tank
conduit 144
allows fluid to pass between the anaerobic treatment chamber 116 and the
aerobic treatment
chamber 128. That is, the anaerobic treatment chamber 116 is in fluid
communication with the
aerobic treatment chamber 128 through the inter-tank conduit 144. The inter-
tank conduit 144
includes a first portion 146 inside the anaerobic treatment chamber 116 and a
second portion
148 inside the aerobic treatment chamber 128. The second portion 148 includes
an end cap
149 which seals its end, thus preventing fluid from passing through said end.
However, the
second portion 148 also includes one or more conduit openings, such as conduit
opening 150,
through which fluid can pass from the inter-tank conduit 144 to the aerobic
treatment chamber
128.
Referring now to FIG. 5, the wastewater treatment tank 102 also includes an
air supply
apparatus 152 positioned below the reactor screen 126 and thus below the
bottom 130 of the
aerobic treatment chamber 128. The air supply apparatus 152 is operable to
provide air to the
aerobic treatment chamber 128, as will be described further below. The air
supply apparatus
152 includes one or more branch arms, such as branch arm 154. Each of the one
or more
branch arms includes one or more air outlets, such as air outlet 156 of branch
arm 154, located
on an underside of the respective branch arm (i.e., on a side of the branch
arm that faces down
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towards the tank floor 106). The air supply apparatus 152 further includes an
air inlet 158 to
which an external source of air, such as, for example, a compressor, can be
connected using,
for example, an air conduit.
Referring now to FIG. 4, the aerobic treatment chamber 128 may have within it
one or
more media carriers, such as media carrier 160. As will be described further
below, each of the
one or more media carriers provides a surface for a biofilm of microorganisms
to grow. The
one or more media carriers may be made of any suitable material, such as, for
example, high
density polyethylene or other polymers. The one or more media carriers may
have any suitable
shape. For example, the media carrier 160 may have a cross-disk shape as shown
in FIGS. 6
.. and 7. Furthermore, each of the one or more media carriers is sized such
that it cannot pass
through any of the one or more screen openings of the reactor screen 126 or
any of the one or
more conduit openings of the inter-tank conduit 144. Thus, the reactor screen
126 prevents the
one or more media carriers from entering the clarifying chamber 118 and the
inter-tank
conduit 144 prevents the one or more media carriers from entering the
anaerobic treatment
chamber 116; that is, the reactor screen 126 and the inter-tank conduit 144
prevent the one or
more media carriers from leaving the aerobic treatment chamber 128.
The embodiment of FIGS. 1 to 5 is an example only, and alternative embodiments
may
vary. For example, alternative embodiments may include a separate treatment
tank, with its
own tank wall and tank floor, for each of the anaerobic treatment chamber 116
and the
clarifying chamber 118. Furthermore, in alternative embodiments, the
wastewater treatment
tank 102 may have a non-cylindrical shape. For example, the wastewater
treatment tank 102
may have a cubic shape, or may include a spherical or oval shell instead of
the tank wall 104
and the tank floor 106. Alternative embodiments may also include additional
chambers.
Referring now to FIGS. 1, 2, and 8, in operation, untreated wastewater enters
the
wastewater treatment tank 102 through the tank inlet 110, as shown at block
200. The
untreated wastewater may include both liquid and solid waste. The wastewater
first enters
anaerobic treatment chamber 116, where, at block 202, it is subjected to
anaerobic treatment.
Most of the solid waste is removed from the wastewater during this step,
settling on the tank
floor 106 in the anaerobic treatment chamber 116.
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Next, at block 204, the wastewater moves through the inter-tank conduit 144
into the
aerobic treatment chamber 128. In the aerobic treatment chamber 128, the
wastewater is
subjected to aerobic treatment, as shown at block 206. An external source of
air (not shown)
provides air to the air supply 152 through the air inlet 158. The air leaves
the air supply
.. through the air outlets of the branch arms. Because the air supply
apparatus 152 is positioned
directly below the reactor screen 126 and the bottom 130 of the aerobic
treatment chamber
128, when the air leaves the air outlets, it moves upward through the screen
openings of the
screen 126 into the aerobic treatment chamber 128. Minimal¨if any¨air enters
the clarifying
chamber 118.
Once in the aerobic treatment chamber 128, the air causes the one or more
media
carriers within to circulate and also aerates the wastewater within. Aeration
oxidizes the
wastewater and stimulates and promotes the growth of aerobic microorganisms,
such as, for
example, aerobic bacteria. The media carriers provide a surface for the
aerobic
microorganisms to grow and form biofilms. The aerobic microorganisms enhance
the aerobic
treatment of the wastewater. The reactor wall 124, reactor screen 126, and
media carriers can
thus be considered to form a media reactor or a moving bed biofilm reactor.
After aerobic treatment, at block 208, the wastewater moves through the
reactor screen
126 into the clarifying chamber 118. In the clarifying chamber 118, solid
particles remaining
in the wastewater are allowed to settle out, as shown at block 210. At block
212, the treated
wastewater leaves the wastewater treatment tank 102 through the tank outlet
112.
Although specific embodiments have been described and illustrated, such
embodiments should be considered illustrative only and not as limiting the
invention as
construed according to the accompanying claims.
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