Note: Descriptions are shown in the official language in which they were submitted.
CA 02278915 1999-07-26
190P4CA
WASTE WATER TREATMENT APPARATUS AND METHOD
The present invention relates to a waste water treatment apparatus and method
employing
aerobic and anaerobic treatments for the purification of waste water.
It has previously been proposed to purify waste water by firstly subjecting
the waste water
to anaerobic treatment and, subsequently, to aerobic treatment.
It has now been found that improved results can be obtained by firstly
effecting an aerobic
treatment of the waste water, and by subsequently effecting an anaerobic
treatment of the
thus-treated waste water.
More particularly, according to the present invention there is provided a
waste water
treatment apparatus comprising a first chamber, the first chamber being an
aerobic chamber
having upper and lower portions, an aeration air inlet communicating with the
lower portion
of the first chamber, a second chamber, the second chamber comprising an
anaerobic
chamber, a waste water inlet communicating with the first chamber, a first
outlet from the
upper portion of the first chamber, the outlet communicating with the second
chamber, a
third chamber, a second outlet from the second chamber communicating with the
third
chamber, and a third outlet from the third chamber.
The present invention also provides a method of treating waste water, which
comprises
discharging the waste water and aerating air into a first chamber, effecting
aerobic treatment
in the first chamber discharging the treated liquid from the first chamber
into a second
chamber, effecting aerobic treatment in the second chamber, recycling solids
from the second
chamber to the first chamber, and discharging the liquid from the second
chamber to a third
chamber.
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The invention will be more readily understood from the following description
of an
embodiment thereof given, by way of example, with reference to the
accompanying
drawings, in which:-
Figure 1 shows a view in side elevation of a waste water treatment apparatus
embodying the
presentinvention;
Figure 2 shows a plan view of the apparatus of Figure 1;
Figure 3 shows a view in vertical cross-section through a first chamber
forming. part of the
apparatus of Figure 1, with the top of the chamber removed;
Figure 4 shows a plan view of the chamber of Figure 3;
Figures S and 6 show views taken in vertical cross-section along the lines 5-5
and 6-6 of
Figure 4;
Figure 7 shows a view in vertical cross-section through a second chamber
forming part of
the apparatus of Figure 1 with the cover of the second chamber removed;
Figure 8 shows a plan view of the second chamber, with the cover removed;
Figures 9 and 10 show views taken in vertical cross-section along the lines 9-
9 and 10-10 of
Figure 8;
Figure 11 shows a view in perspective of the cover of the first and second
chambers;
Figure 12 shows a broken-away view illustrating means for securing the cover
of Figure 11;
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Figures 13 and 14 show views in side elevation and elevation, respectively, of
an air intake;
Figure 15 shows a view in side elevation of a disinfection unit; and
Figure 16 shows a view in end elevation of the disinfection unit of Figure 15.
In Figures 1 and 2, there are shown a first tank 10 and a second tank 11,
which form parts
of a waste water treatment apparatus embodying the present invention and
indicated
generally by reference numeral 12, the first and second tanks 10 and 11 being
sunk into
ground indicated generally by reference numeral 14.
The second tank 11 is equipped with a removable housing 16 containing air
pumps and
electronic equipment (not shown) and connected to an air supply outlet 18 and
an air intake
20.
As shown in Figure 3, the first tank 10 contains three chambers, namely a
first chamber 22,
a second chamber 24 and a third chamber. The first and second chambers 22 and
24 are
separated by a baffle 28 and an outlet 30 from an upper portion of the first
chamber 22
communicates with an upper portion of the second chamber 24.
A bottom portion of the first chamber 22 contains an air diffusing particulate
material 32,
which in the present embodiment comprises sand, and aeration air inlet pipes
34 extend
downwardly through the first chamber 22 into the particulate material 32, at
which they are
provided with air outlet openings 36 for discharging air through the sand into
the remainder
of the first chamber 22.
In the second chamber 24, a U-shaped piping 38, which extends downwardly
through the
second chamber 24, is provided at a lower portion of the second chamber 24
with a venturi
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outlet 40, this piping 3 8 being connected through a ball valve 42 to an air
supply line 44 and
by a return pipe 45 to the first chamber 22.
A second outlet 46, from the second chamber 24, communicates through a baffle
48,
separating the second and third chambers 24 and 26, with the third chamber 26,
which in turn
is provided with a third outlet 50.
The third outlet 50 communicates with the second tank 11, which is divided by
baffles 52
and 54 into a fourth chamber 56, a fifth chamber 58 and a sixth chamber 60.
The outlet 50
communicates with an inlet 62 to the fourth chamber 56, and the baffle 52
terminates above
the bottom of the second tank 11 so as to provide a fourth outlet 63 from the
fourth chamber
56, communicating with the fifth chamber 58.
Air inlet pipes 64 and 65 extend downwardly through the fourth and fifth
chambers 56 and
58 to openings 61 in particulate material 66 in the bottom of the tank and, in
the first
embodiment, the particulate material 66 is sand. This particulate material 66
serves to
diffuse air supplied through the pipes 64 and 65 into the fourth and fifth
chambers 56 and 58
for effecting aerobic digestion of waste in the fourth and fifth chambers 56
and 58.
The fourth and fifth chambers 56 and 58 also contain bacteria growth media 68
and 70,
which are each formed by a plurality of corrugated plates arranged side by
side, with the
corrugations extending in alternate diagonal directions. The fifth chamber 58
is also provided
with a U-shaped piping 67 provided, at the bottom of the fifth chamber 58,
with a venturi
outlet and also connected to a return pipe 71 extending to the fourth chamber
56.
An outlet 72 from the fifth chamber 58 to the sixth chamber 60 is provided in
an upper
portion of the baffle 54, and a further baffle 74 extends downwardly from past
this opening.
As can be seen in Figure 7, the baffle 54 is formed by upper and lower
vertical sections 76
and 77 connected by an inclined intermediate section 78, and the baffle 74 is
formed with
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a vertical upper section 80 and a lower section 82 which is inclined towards
the baffle 54,
but which is spaced from the baffle 74. By this means, solids within the fifth
chamber 58
are deflected downwardly, past the outlet opening 72 by the baffle 74 to the
lower section
77 of the baffle 54, while liquid is able to flow past the lower edge of the
baffle 74 to the
outlet opening 72.
The sixth chamber 60 has an outlet opening 84 which communicates with a
disinfection unit
indicated generally by reference numeral 86 in Figure 15.
The first and second chambers 22 and 24 are each provided with a cover,
indicated generally
by reference numeral 88in Figure 11. The cover has a lower portion 90 and a
lid 92, which
is held down onto the lower portion by a cable 94, provided with a turnbuckle
96, the cable
94 being engaged with retainer hooks 98 secured to the lower portion 90, one
of the retainer
hooks 98 being shown in Figure 12.
The air inlet 20, which is shown in Figures 13 and 14, is provided with a
louvre 100, as
shown in Figure 14.
The disinfection unit 86, as shown in Figures 15 and 16, comprises a housing
102 of
triangular cross-section, which has a bottom 104. Within the housing 102, an
ultraviolet
radiation source 106 extends substantially the entire length of the housing
102, along an
upper portion of the housing 102.
An inlet 108 for the liquid being treated communicates with the interior of
the housing, and
the bottom of the housing is provided with raised portions in the form of a
plurality of
parallel raised ribs 110.
In operation of the above-described apparatus, waste water is supplied into
the first chamber
22 and is subjected in the first chamber 22 to aeration produced by discharge
of air into the
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particulate diffusing material 32. From the first chamber 22, the liquid
passes through the
first outlet 32 into the second chamber 24, where it is subjected to anaerobic
treatment. Solid
material, which tends to fall to the bottom of the second chamber 22, is
extracted by a venturi
effect through the venturi outlet 40, by passing air through the U-shaped
piping 38, and the
solid material thus extracted is recycled through a sludge return pipe 112 to
the first chamber
22.
From the second chamber 24, the thus-treated liquid passes into the third
chamber 26 and,
in turn, to the second tank 11 and, more particularly, to the fourth chamber
56. In the fourth
and fifth chambers 56 and 58, the liquid is again subjected to aeration
through the pipes 64
and 65 and to aerobic digestion by bacteria growing on the bacteria growth
media 68 and 70.
From the fifth chamber 58, solids are returned through the return pipe 71 to
the fourth
chamber 56.
The liquid then flows through the outlet 72 into the sixth chamber 60 and,
from the sixth
chamber 60, into the disinfection unit 86.
As the liquid flows across the bottom of the disinfection unit 86, the raised
portions or ribs
110 cause the liquid to be swirled about, so that the liquid is thoroughly
exposed to
ultraviolet radiation and, thus is effectively purified by this radiation.
As will be apparent to those skilled in the art, various modifications may be
made to the
above-described embodiment within the scope of the appended claims.
