Technical Field
The present invention relates to a water treatment device, and
particularly relates to a water treatment device used when treating water using
a biological treatment.
5
Background Art
There is known a water treatment device that cleans waste water that
includes contaminants, such as sewage and plant waste water, using a
membrane bioreactor. This water treatment device includes a biological
10 treatment tank, an air diffuser, and a filtration membrane. The biological
treatment tank stores activated sludge that contains microorganisms and waste
water that flows into the tank. The air diffuser aerates the biological treatment
tank by supplying an oxygen containing gas to the activated sludge. The
aeration of the biological treatment tank causes the microorganisms to
15 decompose the contaminants in the waste water, breed, and proliferate. The
filtration membrane filters a suspension of the treated water and the activated
sludge in the biological treatment tank, separating the treated water from the
activated sludge. When the activated sludge is aerated, the filtration membrane
is cleaned by an upflow generated by rising bubbles, preventing clogging (refer
20 to Patent Documents 1 to 3).
There is known a two-phase high-load activated sludge system that
separates microbiota in activated sludge into two phases, and treats water using
the two phases. This two-phase high-load activated sludge system includes a
first aeration tank and a second aeration tank. The first aeration tank treats
25 untreated waste water using non-agglomerative bacteria only. The second
aeration tank further treats the waste water treated by the first aeration tank
using activated sludge having excellent protozoa and metazoa that feed upon
the non-agglomerative bacteria. Such a two-phase high-load activated sludge
system is capable of treating untreated waste water with high efficiency,
30 making it possible to reduce the size of the tanks and decrease excess sludge.
Citation List
Patent Literature
Patent Document 1 : Japanese Unexamined Patent Application
35 Publication No. 20 1 1 - 177608A
Patent Document 2: Japanese Unexamined Patent Application
Publication No. 2009-6 1349A
Patent Document 3: International Publication No. W0/2008/038436
5 Summary of Invention
Technical Problem
Such a water treatment device should preferably adequately treat
contaminants in the waste water, and adequately aerate the activated sludge in
the biological treatment tank. The filtration membrane that filters the activated
10 sludge in the biological treatment tank should preferably be adequately
cleaned. Such a water treatment device may need to aerate a greater volume of
air than that required by the microorganisms in order to adequately clean a
membrane surface of the filtration membrane, requiring an increase in power
for aeration. Such a water treatment device should preferably decrease the
15 aeration power required to adequately treat the waste water. The two-phase
high-load activated sludge system should preferably adequately treat the waste
water using non-agglomerative bacteria.
It is an object of the present invention to provide a water treatment
device that adequately aerates a stored liquid in the biological treatment tank.
20 It is another object of the present invention to provide a water treatment
device that decreases a power for aerating the biological treatment tank.
It is yet another object of the present invention to provide a water
treatment device that adequately cleans a filtration membrane that filters an
activated sludge in the biological treatment tank.
2 5 It is yet another object of the present invention to provide a water
treatment device that adequately treats waste water using non-agglomerative
bacteria.
Solution to Problem
3 0 A water treatment device according to the present invention includes a
biological treatment tank configured to store a stored liquid containing
organisms that decompose contaminants, a circulation pump configured to
generate a circulating liquid flow in which the stored liquid is extracted to
outside the tank and circulated back into the tank, a gas-liquid two-phase flow
35 generation device configured to use the circulating liquid flow to suction a gas
containing oxygen and thus generate a gas-liquid two-phase flow in which the
gas is dispersed in the circulating liquid flow, and a nozzle configured to inject
the gas-liquid two-phase flow into a region in which the stored liquid is stored.
Such a gas-liquid two-phase flow is generated by such a gas-liquid twophase
flow generation device, causing dispersed air bubbles to be finely
5 formed. With the air bubbles being fine, such a water treatment device is
capable of increasing an oxygen dissolving efficiency, and supplying enough
oxygen to decompose contaminants, even with a small volume of air compared
to a conventional air diffuser. Such a water treatment device further injects the
gas-liquid two-phase flow into the biological treatment tank, making it possible
10 to circulate the stored liquid throughout the biological treatment tank with high
efficiency. By circulating the stored liquid throughout the biological treatment
tank, such a water treatment device is' capable of adequately agitating the stored
liquid, and thus adequately aerating the stored liquid. As a result, such a water
treatment device is capable of adequately treating the stored liquid.
15 The water treatment device further includes a circulating liquid pipe that
supplies a circulating liquid to a pump by extracting the stored liquid from a
bottom portion of the biological treatment tank.
The stored liquid stored in the bottom portion of the biological treatment
tank has less air bubbles. By generating the circulating liquid from the stored
20 liquid having less air bubbles, such a water treatment device is capable of
decreasing the air bubbles mixed into the circulating liquid. With the decrease
in the air bubbles mixed into the circulating liquid, such a water treatment
device is capable of adequately generating a circulating liquid flow using the
pump, and adequately generating a gas-liquid two-phase flow using the gas-
25 liquid two-phase flow generation device.
The water treatment device further includes a separation membrane
immersed in the stored liquid. At this time, the separation membrane generates
treated water by filtering the stored liquid. The nozzle injects the gas-liquid
two-phase flow toward the separation membrane.
3 0 By injecting the gas-liquid two-phase flow from the nozzle toward the
separation membrane, such a water treatment device is capable of more
adequately cleaning the separation membrane compared to a conventional water
treatment device in which air bubbles in the gas-liquid two-phase flow are
supplied from below the separation membrane and the separation membrane is
cleaned by an upflow generated by rising air bubbles. As a result, such a water
treatment device is capable of adequately filtering the stored liquid, and thus
adequately generating treated water.
The region in which the stored liquid is stored includes an upflow
5 portion in which the separation membrane is disposed, and a downflow portion
disposed side-by-side with the upflow portion in a horizontal direction. That is,
the separation membrane is disposed so that a line segment obtained by
orthogonally projecting the downflow portion onto a vertical line includes a
line segment obtained by orthogonally projecting the separation membrane onto
10 the vertical line. The circulating liquid pipe extracts the stored liquid from the
downflow portion.
By generating an upflow in which the stored liquid ascends in the
upflow portion, such a water treatment device is capable of generating a
downflow in which the stored liquid descends in the downflow portion. With
15 the upflow and the downflow thus generated, such a water treatment device is
capable of adequately circulating the stored liquid throughout the biological
treatment tank, and adequately aerating the stored liquid.
The nozzle is formed from a plurality of nozzles which inject the gasliquid
two-phase flow into a plurality of different regions of the separation
20 membrane. Such a water treatment device is capable of more uniformly
injecting the gas-liquid two-phase flow into the separation membrane in its
entirety, and thus more adequately cleaning the separation membrane even
when the separation membrane is relatively large, compared to other water
treatment devices that inject a liquid-gas two-phase flow into one nozzle.
Each of the nozzles preferably injects the gas-liquid two-phase flow
upward. Such a water treatment device is capable of adequately generating an
upflow, and thus more adequately cleaning the separation membrane.
The gas-liquid two-phase flow generation device is disposed above the
membrane separation tank. Such a water treatment device allows the gas-liquid
30 two-phase flow generation device to be disposed aboveground when the
membrane separation tank is buried underground, making it possible to easily
maintain the gas-liquid two-phase flow generation device.
The water treatment device further includes a pipe that supplies the gasliquid
two-phase flow from the gas-liquid two-phase flow generation device to
the nozzle, and a gas-liquid agitation device that agitates the fluid that flows
through the pipe. By thus preventing air bubbles dispersed in the gas-liquid
two-phase flow from coarsening, such a water treatment device is capable of
adequately generating an upflow of the stored liquid and the air bubbles, and
5 thus more adequately cleaning the separation membrane.
The pipe is disposed so as to extend through a liquid surface of the
stored liquid. Such a water treatment device can be more easily manufactured
compared to other water treatment devices in which the pipe extends through a
hole formed in a side wall of the membrane separation tank.
The biological treatment tank includes a membrane separation tank
configured to form a region in which the separation membrane is disposed, and
a biological oxidation tank configured to supply the stored liquid to the
membrane separation tank. At this time, the water treatment device of the
present invention further includes a biological oxidation tank gas-liquid two-
15 phase flow generation device and a biological oxidation tank nozzle. The
biological oxidation tank gas-liquid two-phase flow generation device extracts
the stored liquid from the membrane separation tank and uses the circulating
liquid flow that circulates the stored liquid to the biological oxidation tank to
suction a gas containing oxygen, thereby generating a gas-liquid two-phase
20 flow in which the gas containing oxygen is dispersed in the stored liquid. The
biological oxidation tank nozzle supplies the gas-liquid two-phase flow
generated by the biological oxidation tank gas-liquid two-phase flow
generation device to the biological oxidation tank.
When a load of the contaminants, specifically a biological oxygen
25 demand (BOD) and chemical oxygen demand (COD), is high, decomposition of
the contaminants by aeration of the membrane separation tank alone becomes
difficult. As such, with the biological. oxidation tank arranged in a preceding
stage, such a water treatment device makes it possible to facilitate the
decomposition of contaminants. The water treatment device further increases
30 the oxygen dissolving efficiency of the biological oxidation tank by generating
finer air bubbles using the biological oxidation tank gas-liquid two-phase flow
generation device, and supplies enough oxygen to decompose the contaminants,
even with a small volume of air compared to a conventional air diffuser.
The biological treatment tank further includes a dispersed bacteria
35 treatment tank configured to store a dispersed bacteria mixture in which nonagglomerative
bacteria that decompose contaminants are dispersed, and an
activated sludge treatment tank configured to store an activated sludge mixture
in which activated sludge that decomposes the dispersed bacteria is suspended.
At this time, the dispersed bacteria mixture is supplied to the activated sludge
5 mixture. The circulating liquid is generated by being extracted from the
dispersed bacteria mixture. The nozzle injects the gas-liquid two-phase flow
into a region in which the dispersed bacteria mixture is stored.
The air bubbles dispersed in the dispersed bacteria mixture are finely
formed, making it possible for such a water treatment device to dissolve the
10 oxygen in the dispersed bacteria mixture with high efficiency, and supply
enough oxygen to the non-agglomerative bacteria, even with a small volume of
air compared to a conventional air diffuser. Further, by injecting the gas-liquid
two-phase flow into the dispersed bacteria treatment tank, such a water
treatment device is capable of adequately agitating the dispersed bacteria
15 mixture, adequately cleaning a surface of a carrier that carries nonagglomerative
bacteria, and thus adequately treating the waste water.
The water treatment device further includes an activated sludge
treatment tank nozzle that injects the gas-liquid two-phase flow into a region in
which the activated sludge mixture is stored.
2 0 By injecting the gas-liquid two-phase flow injected into the activated
sludge mixture, such a water treatment device is capable of adequately aerating
the activated sludge mixture, and thus adequately treating the waste water.
Advantageous Effects of Invention
2 5 The water treatment device of the present invention injects the gasliquid
two-phase flow into the stored liquid, making it possible to circulate the
stored liquid in the tank with high efficiency, adequately aerate the stored
liquid, and adequately treat the stored liquid.
30 Brief Description of Drawings
Fig. 1 is a schematic configuration diagram illustrating an embodiment
of a water treatment device.
Fig. 2 is a cross-sectional view illustrating a gas-liquid two-phase flow
generation device.
Fig. 3 is a schematic configuration diagram illustrating another
embodiment of the water treatment device.
Fig. 4 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
5 Fig. 5 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
Fig. 6 is a cross-sectional view illustrating a gas-liquid two-phase flow
pipe.
Fig. 7 is a schematic configuration diagram illustrating yet another
10 embodiment of the water treatment device.
Fig. 8 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
Fig. 9 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
15 Fig. 10 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
Fig. 11 is a schematic configuration diagram illustrating yet another
embodiment of the water treatment device.
20 Description of Embodiments
An embodiment of a water treatment device is described below, with
reference to the drawings. A water treatment device 1 includes a membrane
separation tank 2 and a separation membrane 3, as illustrated in FIG. 1. The
membrane separation tank 2 is formed into a vessel, and forms a storage space
25 in an interior thereof. The membrane separation tank 2 stores a stored liquid 5
that contains waste water and activated sludge supplied from outside in the
storage space. The activated sludge contains an aerobic microbe group. The
stored liquid 5 is aerated by a gas containing oxygen, causing the aerobic
microbe group to decompose contaminants in the waste water, breed, and
30 proliferate. Examples of the contaminants include organic matter, and a volume
of contaminants in the waste water corresponds to a biological oxygen demand
(BOD) and a chemical oxygen demand (COD) in the waste water. The storage
space includes an upflow portion 61, a first downflow portion 62, and a second
downflow portion 63. The upflow portion 61 is substantially disposed in a
35 center of the storage space. The first downflow portion 62 is disposed side-byside
with the upflow portion 61 in a horizontal direction, along one portion of a
side wall of the membrane separation tank 2, between the upflow portion 61
and the side wall. The second downflow portion 63 is disposed side-by-side
with the upflow portion 61 in a horizontal direction, along one portion of the
side wall of the membrane separation tank 2 opposite to the one portion along
the first downflow portion 62, that is, disposed between the upflow portion 61
and the side wall so that the upflow portion 61 is disposed between the first
downflow portion 62 and the second downflow portion 63.
The separation membrane 3 is disposed in the upflow portion 61 of the
storage space of the membrane separation tank 2 so as to be immersed in the
stored liquid 5. The separation membrane 3 is further disposed so that a
separation membrane projection line segment obtained by orthogonally
projecting the separation membrane 3 onto a vertical line is included in a line
segment obtained by orthogonally projecting the first downflow portion 62 onto
the vertical line, and the separation membrane projection line segment is
included in a line segment obtained by orthogonally projecting the second
downflow portion 63 onto the vertical line. The separation membrane 3 is
formed by a plurality of modules. Each of the modules is formed by bundling a
plurality of hollow fibers. Each of the plurality of hollow fibers is formed by a
filtration membrane. The separation membrane 3 generates treated water by
filtering the stored liquid 5 using the filtration membrane. A concentration of
the contaminants contained in the treated water is less than the concentration of
the contaminants contained in the waste water, and the concentration of the
aerobic microbe group contained in the treated water is less than the
concentration of the aerobic microbe group contained in the stored liquid 5.
The water treatment device 1 further includes a circulating liquid pipe 6,
a circulation pump 7, and a gas-liquid two-phase flow generation device 8. The
circulating liquid pipe 6 forms a flow path by connecting one end of the
circulating liquid pipe 6 to a bottom portion of the second downflow portion 63
of the storage space of the membrane separation tank 2 and the other end to the
circulation pump 7. The circulating liquid pipe 6 extracts the stored liquid 5
from the bottom portion of the second downflow portion 63 of the membrane
separation tank 2, and supplies the extracted circulating liquid to the circulation
pump 7. The circulation pump 7 is disposed outside the membrane separation
tank 2. The circulation pump 7 takes in the circulating liquid from the
membrane separation tank 2 via the circulating liquid pipe 6 using power
externally supplied, generating a flow of the circulating liquid. The gas-liquid
two-phase flow generation device 8 is disposed outside the membrane
separation tank 2. The gas-liquid two-phase flow generation device 8 generates
a gas-liquid two-phase flow using the flow generated by the circulation pump
7. In the gas-liquid two-phase flow, air is dispersed in the circulating liquid.
The water treatment device 1 further includes a gas-liquid two-phase
5 flow pipe 11 and a nozzle 12. The gas-liquid two-phase flow pipe 11 is
disposed so as to extend through a hole formed in a section near a bottom
portion of the first downflow portion 62 of the side wall of the membrane
separation tank 2, connected to the gas-liquid two-phase flow generation device
8 on one end, and disposed in the bottom portion of the first downflow portion
'10 62 of the storage space of the membrane separation tank 2 on the other end.
The gas-liquid two-phase flow pipe 11 forms a flow path in which the gasliquid
two-phase flow generated by the gas-liquid two-phase flow generation
device 8 flows. The nozzle 12 is disposed in the bottom portion of the first
downflow portion 62 of the storage space of the membrane separation tank 2,
15 with a tip end facing a bottom portion of the upflow portion 61. The nozzle 12
is connected to an end of the gas-liquid two-phase flow pipe 11, the end being
disposed in the storage space of the membrane separation tank 2. The gasliquid
two-phase flow is thus supplied from the gas-liquid two-phase flow pipe
11, causing the nozzle 12 to inject the gas-liquid two-phase flow toward the
20 bottom portion of the upflow portion 61 of the storage space of the membrane
separation tank 2,
FIG. 2 illustrates the gas-liquid two-phase flow generation device 8.
The gas-liquid two-phase flow generation device 8 includes a flow intake pipe
15, an orifice 16, and an air suction pipe 17. The flow intake pipe 15 forms a
25 flow path in which the circulating liquid flow generated by the circulation
pump 7 flows. The orifice 16 is formed midway on the flow intake pipe 15, and
forms a flow path in which the flow generated by the circulation pump 7 flows.
A cross-sectional area of the flow path formed by the orifice 16 is less than a
cross-sectional area of the flow path formed by the flow intake pipe 15. The air
30 suction pipe 17 forms a flow path in which air flows by disposing one end of
the air suction pipe 17 in the atmosphere and connecting the other end to a
downstream side of the orifice 16 of the flow intake pipe 15.
The gas-liquid two-phase flow generation device 8 generates negative
pressure on the downstream side of the orifice 16 when the circulating liquid
35 flows in the flow intake pipe 15. The occurrence of the negative pressure on the
downstream side of the orifice 16 causes the gas-liquid two-phase flow
generation device 18 to suction air from the atmosphere via the air suction pipe
17 into the flow intake pipe 15. The suctioning of the air into the flow intake
pipe 15 via the air suction pipe 17 causes the gas-liquid two-phase flow
generation device 8 to disperse the air in the circulating liquid, and generate a
5 gas-liquid two-phase flow of the circulating liquid having the air dispersed
therein. Air bubbles of the air dispersed in the gas-liquid two-phase flow are
relatively fine. Such a gas-liquid two-phase flow generation device 8 is known,
and examples are used in, for example, technologies disclosed in Japanese
Patent No. 3854481 and Japanese Patent No. 3486399.
10 The water treatment device 1 operates when waste water is externally
supplied to the membrane separation tank 2 and the stored liquid 5 is stored in
the storage space of the membrane separation tank 2. The separation membrane
3 generates treated water by filtering the stored liquid 5 when immersed in the
stored liquid 5. The circulation pump 7 takes in the stored liquid 5 from the
15 bottom portion of the second downflow portion 63 of the membrane separation
tank 2 via the circulating liquid pipe 6 when the stored liquid 5 is stored in the
storage space of the membrane separation tank 2, and thus generates a flow of
the circulating liquid taken in the circulation pump 7. The gas-liquid two-phase
flow generation device 8 suctions air from the atmosphere and generates a gas-
20 liquid two-phase flow in which air bubbles of the air are dispersed in the
circulating liquid, using the flow generated by the circulation pump 7. The gasliquid
two-phase flow is supplied to the nozzle 12 via the gas-liquid two-phase
flow pipe 11. The supply of the gas-liquid two-phase flow from the gas-liquid
two-phase flow pipe 11 causes the nozzle 12 to inject the gas-liquid two-phase
25 flow toward the bottom portion of the upflow portion 61 of the membrane
separation tank 2.
When the gas-liquid two-phase flow is supplied to the bottom portion of
the upflow portion 61 of the membrane separation tank 2, the air bubbles of the
air dispersed in the gas-liquid two-phase flow cause the stored liquid 5 to
30 ascend by buoyancy, generating an upflow of the storage liquid 5 in the upflow
portion 61 of the storage space of the membrane separation tank 2. The upflow
generates a downflow in which the stored liquid 5 flows downward in the first
downflow portion 62 and the second downflow portion 63 of the storage space
of the membrane separation tank 2. The upflow and the downflow aerate the
35 stored liquid 5 by the air dispersed in the gas-liquid two-phase flow.
Furthermore, the water treatment device 1, with a flow rate of the
upflow and the downflow accelerated by the injection of the gas-liquid twophase
flow into the membrane separation tank 2, is capable of adequately
forming a circulating liquid flow in which the stored liquid 5 flows throughout
5 the membrane separation tank 2, and adequately agitating the stored liquid 5.
The water treatment device 1, with the stored liquid 5 adequately agitated, is
capable of prolonging the period in whicli the air bubbles of the air are
dispersed in the stored liquid 5, and thus adequately aerating the stored liquid
10 The stored liquid 5, being aerated, causes the aerobic microbe group
contained in the stored liquid 5 to decompose the contaminants contained in the
waste water, breed, and proliferate. The air bubbles dispersed in the gas-liquid
two-phase flow, with the gas-liquid two-phase flow having been generated by
the gas-liquid two-phase flow generation device 8, are relatively small. The
15 water treatment device 1, with the small size of the air bubbles of the gas-liquid
two-phase, is capable of increasing a contact surface area between the stored
liquid 5 and the air, and dissolving the oxygen in the stored liquid 5 with high
efficiency. The aerobic microbe group, with oxygen thus dissolved in the stored
liquid 5 at a high concentration, can breed and proliferate with high efficiency.
20 The water treatment device 1, with the highly efficient breeding and
proliferation of the aerobic microbe group, is capable of adequately treating the
waste water.
Furthermore, the water treatment device 1, because the nozzle 12 injects
the gas-liquid two-phase flow toward the bottom portion of the upflow portion
25 61 of the membrane separation tank 2, is capable of introducing the upflow to
the upflow portion 61 at a higher speed compared to other water treatment
devices that gently supply air to the bottom portion of the upflow portion 61
using an air diffuser pipe or the like. The upflow flows through the upflow
portion 61, thereby flowing near the separation membrane 3. The upflow flows
30 near the separation membrane 3 along with the air bubbles, thereby cleaning a
surface of the separation membrane 3 that comes into contact with the stored
liquid 5. The high speed of the upflow that flows near the separation membrane
3 makes it possible for the water treatment device 1 to more adequately clean
the separation membrane 3. Adequate cleaning prevents the separation
35 membrane 3 from being clogged and allows the separation membrane 3 to
adequately filter the stored liquid 5. As a result, the water treatment device 1 is
capable of adequately treating the stored liquid 5.
A portion of the air bubbles mixed into the upflow is released from a
liquid surface of the stored liquid 5 into the environment. The upflow thus
5 having a reduced amount of air bubbles causes a downflow of the stored liquid
5 generated in the first downflow portion 62 and the second downflow portion
63 of the storage space of the membrane separation tank 2, and a portion of the
air bubbles mixed into the downflow rises, making it possible for such a water
treatment device 1 to decrease the air bubbles contained in the stored liquid
10 disposed in the bottom portion of the first downflow portion 62 and the bottom
portion of tlie second downflow portion 63 of the stored liquid 5. The
circulating liquid pipe 6 extracts the stored liquid 5 from the bottom portion of
the second downflow portion 63, making it possible to decrease the amount of
air bubbles mixed into the circulating liquid supplied to the circulation pump 7.
15 As a result, with less air bubbles being mixed into the circulating liquid
supplied via the circulating liquid pipe 6, the circulation pump 7 is capable of
adequately generating a flow of the circulating liquid. Furthermore, with less
air bubbles being mixed into the circulating liquid generated by the circulation
pump 7, the gas-liquid two-phase flow generation device 8 is capable of
20 adequately dispersing air into the circulating liquid and adequately generating a
gas-liquid two-phase flow.
The water treatment device 1, with the downflow generated in the first
downflow portion 62 and the second downflow portion 63, does not need to
provide space for the downflow of the downward-flowing stored liquid 5
25 between the gaps of the plurality of modules that form the separation
membrane 3, and is therefore capable of more closely disposing the plurality of
modules, allowing compact formation of the separation membrane 3, The
separation membrane 3 requires removal from the storage space of the
membrane separation tank 2 for maintenance each predetermined period. The
30 water treatment device 1, with the separation membrane 3 thus compactly
formed, allows the separation membrane 3 to be handled in a smaller space,
making it possible to maintain the separation membrane 3 more easily.
Furthermore, the water treatment device 1, with the separation membrane 3
compactly formed, potentially allows the storage space of the membrane
35 separation tank 2 to be formed smaller in size.
FIG. 3 illustrates another embodiment of the water treatment device. In
the water treatment device 21, the water treatment device 1 of the
aforementioned embodiment further includes another gas-liquid two-phase flow
generation device 22, another gas-liquid two-phase flow pipe 23, and another
5 nozzle 24. The gas-liquid two-phase flow generation device 22 is formed in the
same way as the gas-liquid two-phase flow generation device 8. That is, the
gas-liquid two-phase flow generation device 22 generates a gas-liquid twophase
flow using the flow generated by the circulation pump 7. The gas-liquid
two-phase flow pipe 23 is disposed so as to extend through another hole formed
10 in a section near the bottom portion of the second downflow portion 63 of the
side wall of the membrane separation tank 2. That is, the hole is formed in a
region opposite to the region in which the hole through which the gas-liquid
two-phase flow pipe 11 extends is formed. The gas-liquid two-phase flow pipe
23 is connected to the gas-liquid two-phase flow generation device 22 on one
15 end, and disposed in the storage space of the membrane separation tank 2 on
the other end. The gas-liquid two-phase flow pipe 23 forms a flow path in
which the gas-liquid two-phase flow generated by the gas-liquid two-phase
flow generation device 22 flows. The nozzle 24 is disposed in the second
downflow portion 63 of the storage space of the membrane separation tank 2,
20 with a tip end facing the bottom portion of the upflow portion 61 of the storage
space of the membrane separation tank 2, that is, with the tip end facing the
separation membrane 3. At this time, the region of the separation membrane 3
to which the tip end of the nozzle 24 is directed differs from the region of the
separation membrane 3 to which the tip end of the nozzle 12 is directed. The
25 nozzle 24, with the gas-liquid two-phase flow supplied from the gas-liquid twophase
flow pipe 23, injects the gas-liquid two-phase flow toward the bottom
portion of the upflow portion 61 of the storage space of the membrane
separation tank 2.
In the water treatment device 21, the gas-liquid two-phase flow is
30 injected from the nozzle 12, while the gas-liquid two-phase flow is injected
from the nozzle 24. The gas-liquid two-phase flow injected from the nozzle 12
and the gas-liquid two-phase flow injected from the nozzle 24 aerate the stored
liquid 5 by the air bubbles of the air dispersed in the gas-liquid two-phase flow.
The air bubbles of the air dispersed in the gas-liquid two-phase flow
35 cause the stored liquid 5 to ascend by buoyancy, and tlius the gas-liquid twophase
flow injected from the nozzle 12 and the gas-liquid two-phase flow
injected from the nozzle 24 generate an upflow of the stored liquid 5 in the
upflow portion 61 of the storage space of the membrane separation tank 2.
Such an upflow flows near the separation membrane 3, thereby cleaning the
separation membrane 3. Such an upflow flows through a more extensive range
5 compared to the upflow generated by the gas-liquid two-phase flow injected
from the one nozzle 12. As a result, the water treatment device 21, by injecting
the gas-liquid two-phase flow from a plurality of nozzles, makes it possible to
more uniformly cause the upflow to act on the surface of the separation
membrane 3, more uniformly clean the surface of the separation membrane 3,
10 and more adequately prevent the clogging of the separation membrane 3
compared to the water treatment device 1 of the aforementioned embodiment,
even when the separation membrane 3 is a sufficient size for the one nozzle 12.
FIG. 4 illustrates yet another embodiment of the water treatment device.
In a water treatment device 5 1, the nozzle 12 of the water treatment device 1 of
15 the aforementioned embodiment is replaced with a plurality of nozzles 33. The
plurality of nozzles 33 are disposed in the bottom portion of the upflow portion
61 of the storage space of the membrane separation tank 2. The plurality of
nozzles 33 are disposed so that the tip ends thereof face upward and toward a
plurality of different regions of the separation membrane 3. With the gas-liquid
20 two-phase flow supplied from the gas-liquid two-phase flow pipe 32, the
plurality of nozzles 33 inject the gas-liquid two-phase flow upward, that is,
toward the separation membrane 3.
The circulating liquid injected upward by the plurality of nozzles 33 in
addition to the buoyancy of the air bubbles of the air dispersed in the gas-liquid
25 two-phase flow cause the stored liquid 5 to ascend, and thus the gas-liquid twophase
flow injected from the nozzle 33 generates an upflow of the stored liquid
5 in the upflow portion 61 of the membrane separation tank 2. The upflow
generates a downflow in which the stored liquid 5 flows downward in the first
downflow portion 62 and the second downflow portion 63 of the storage space
30 of the membrane separation tank 2. The upflow and the downflow aerate the
stored liquid 5 by the air dispersed in the gas-liquid two-phase flow.
Such an upflow flows near the separation membrane 3, thereby cleaning
the separation membrane 3. Furthermore, such an upflow, with the gas-liquid
two-phase flow injected from the plurality of nozzles 33, flows through a more
35 extensive range compared to the upflow generated by the gas-liquid two-phase
flow injected from the one nozzle 12. As a result, the water treatment device 3 1
is capable of more uniformly causing the upflow to act on the surface of the
separation membrane 3, more uniformly cleaning the surface of the separation
membrane 3, and more adequately cleaning the separation membrane 3
compared to the water treatment device 1 of the aforementioned embodiment,
5 even when the separation membrane 3 is a sufficient size for the one nozzle 12.
Such an upflow, with the gas-liquid two-phase flow injected from the
plurality of nozzles 33, flows upward at a higher speed compared to an upflow
generated by injecting a gas-liquid two-phase flow in another direction that is
not parallel with the upward direction. As a result, the water treatment device
10 31 is capable of more adequately cleaning the separation membrane 3. The
water treatment device 3 1, with the upflow flowing at a higher speed, is
capable of adequately cleaning even a separation membrane 3 having the
plurality of modules disposed more closely. The separation membrane 3, with
the plurality of modules closely disposed, is compactly formed, resulting in
15 easy handling. This configuration enables the separation membrane 3 of the
water treatment device 3 1 to be more easily maintained. Furthermore, the water
treatment device 31, with the separation membrane 3 compactly formed,
potentially allows the storage space of the membrane separation tank 2 to be
formed smaller in size.
FIG. 5 illustrates yet another embodiment of the water treatment device.
In the water treatment device 31, the gas-liquid two-phase flow pipe 11 of the
water treatment device 51 of the aforementioned embodiment is replaced with
another gas-liquid two-phase flow pipe 32. The gas-liquid two-phase flow pipe
32 is disposed so as to extend through a liquid surface 34 of the stored liquid 5,
25 connected to the gas-liquid two-phase flow generation device 8 on one end, and
connected to the plurality of nozzles 33 on the other end. The gas-liquid twophase
flow pipe 32 forms a flow path in which the gas-liquid two-phase flow
generated by the gas-liquid two-phase flow generation device 8 flows.
Furthermore, the water treatment device 31, with the gas-liquid two-
30 phase flow pipe 32 disposed in the storage space of the membrane separation
tank 2 on one end via the liquid surface 34, does not require formation of a hole
through which the gas-liquid two-phase flow pipe 32 extends in the membrane
separation tank 2. As a result, the water treatment device 31 can be easily
manufactured and, in particular, can be easily manufactured by modification
35 even from an existing water treatment device in which the membrane
separation tank is buried. For example, when the water treatment device 1 is
modified into the water treatment device 21, a hole through which the gasliquid
two-phase flow pipe 32 extends needs to be newly formed in the
membrane separation tank 2. Modification of the water treatment device 1 into
the water treatment device 31 does not require formation of a new hole in the
5 membrane separation tank 2, and is therefore easier compared to modification
of the water treatment device 1 into the water treatment device 21.
At this time, the gas-liquid two-phase flow generation device 8 is
disposed above the membrane separation tank 2. The gas-liquid two-phase flow
generation device 8, being disposed above the membrane separation tank 2,
10 makes it possible to more easily secure space for air to be taken in by the air
suction pipe 17, and more easily secure space utilized for maintenance of the
gas-liquid two-phase flow generation device 8.
FIG. 6 further illustrates the gas-liquid two-phase flow pipe 32. The gasliquid
two-phase flow pipe 32 includes a line mixer 19. The line mixer 19 is
15 formed from a plurality of elements. Each of the plurality of elements is formed
into a twisted strip shape. Each of the plurality of elements is disposed in the
flow path formed by the gas-liquid two-phase flow pipe 32, and is secured to
the gas-liquid two-phase flow pipe 32. When the gas-liquid two-phase flow
flows in the gas-liquid two-phase flow pipe 32, the line mixer 19 agitates the
20 gas-liquid two-phase flow by swirling the gas-liquid two-phase flow using the
flow of the gas-liquid two-phase flow. The line mixer 19 thus agitates the gasliquid
two-phase flow, thereby preventing the air bubbles of the air dispersed in
the gas-liquid two-phase flow from coarsening, even when the gas-liquid twophase
flow pipe 32 is relatively long.
2 5 Such a water treatment device 31, by preventing the air bubbles of the
air dispersed in the gas-liquid two-phase flow from coarsening, makes it
possible to more reliably supply fine air bubbles to the stored liquid 5 and thus
more adequately aerate the stored liquid 5 compared to other water treatment
devices in which the line mixer 19 is not provided to the gas-liquid two-phase
30 flow pipe 32. It should be noted that the line mixer 19 may be replaced with
another gas-liquid agitation device that agitates the gas-liquid two-phase flow
that flows through the gas-liquid two-phase flow pipe 32. In this case as well,
the water treatment device 3 1 is capable of preventing the air bubbles dispersed
in the gas-liquid two-phase flow from coarsening, more adequately aerating the
35 stored liquid 5, and more adequately cleaning the separation membrane 3.
It should be noted that the gas-liquid two-phase flow pipe 11 of the
aforementioned embodiment may include the line mixer 19 in the same way as
the gas-liquid two-phase flow pipe 32. The water treatment device that includes
the line mixer 19 is capable of preventing the air bubbles dispersed in the gas-
5 liquid two-phase flow from coarsening, more adequately aerating the stored
liquid 5, and more adequately cleaning the separation membrane 3, in the same
manner as the water treatment device 3 1. Furthermore, the line mixer 19 may
be omitted when the gas-liquid two-phase flow flows through the gas-liquid
two-phase flow pipe 32, thereby making the amount of coarsened air bubbles
10 sufficiently small. The water treatment device that omits the line mixer 19 as
well, in the same manner as the water treatment device 31 of the
aforementioned embodiment, is capable of more adequately aerating the stored
liquid 5, and more adequately cleaning the separation membrane 3.
FIG. 7 illustrates yet another embodiment of the water treatment device.
15 In the water treatment device 41, the water treatment device 1 of the
aforementioned embodiment further includes a biological oxidation tank 42.
The biological oxidation tank 42 is formed into a vessel, and forms a storage
space in an interior thereof. The biological oxidation tank 42 stores a stored
liquid 46 that contains waste water and activated sludge supplied from outside
20 in the storage space. The biological oxidation tank 42 is disposed so as to be
adjacent to the membrane separation tank 2, and a barrier 47 that causes the
stored liquid 46 to flow over the membrane separation tank 2 is formed
between the biological oxidation tank 42 and the membrane separation tank 2.
The storage space of the biological oxidation tank 42 includes an upflow
25 portion 64, and a downflow portion 65. The upflow portion 64 is disposed
substantially in a center of the storage space. The downflow portion 65 is
disposed along one side wall of the biological oxidation tank 42, between the
upflow portion 64 and the side wall.
The water treatment device 41 further includes a gas-liquid two-phase
30 flow generation device 43, a gas-liquid two-phase flow pipe 44, and a nozzle
45. The gas-liquid two-phase flow generation device 43 is formed in the same
way as the gas-liquid two-phase flow generation device 8. That is, the gasliquid
two-phase flow generation device 43 generates a gas-liquid two-phase
flow using the flow generated by the circulation pump 7. The gas-liquid two-
35 phase flow pipe 44 is disposed so as to extend through another hole formed in
the biological oxidation tank 42, connected to the gas-liquid two-phase flow
generation device 43 on one end, and disposed in the storage space of the
biological oxidation tank 42 on the other end. The gas-liquid two-phase flow
pipe 44 forms a flow path in which the gas-liquid two-phase flow generated by
the gas-liquid two-phase flow generation device 43 flows. The gas-liquid two-
5 phase flow pipe 44 may further include a line mixer on the flow path in the
same way as the gas-liquid two-phase flow pipe 32 of the aforementioned
embodiment. The nozzle 45 is disposed in a bottom portion of the downflow
portion 65 of the storage space of the biological oxidation tank 42. The nozzle
45, with the gas-liquid two-phase flow being supplied from the gas-liquid two-
10 pliase flow pipe 44, injects the gas-liquid two-phase flow into a bottom portion
of the upflow portion 64 of the storage space of the biological oxidation tank
42.
Such a water treatment device 41 as well, in the same manner as the
water treatment device 1 of the aforementioned embodiment, generates treated
water by the filtering of the stored liquid 5 stored in the membrane separation
tank 2 by the separation membrane 3, and adequately cleans the separation
membrane 3 by the injection of the gas-liquid two-phase flow generated by the
gas-liquid two-phase flow generation device 8 toward the separation membrane
3.
The nozzle 45, with the gas-liquid two-phase flow being supplied from
the gas-liquid two-phase flow pipe 44, injects the gas-liquid two-phase flow
toward the bottom portion of the upflow portion 64 of the biological oxidation
tank 42. When the gas-liquid two-phase flow is supplied to the bottom portion
of the upflow portion 64 of the biological oxidation tank 42, the air bubbles of
the air dispersed in the gas-liquid two-phase flow cause the stored liquid 46 to
ascend by buoyancy, generating an upflow of the stored liquid 46 in the upflow
portion 64 of the storage space of the biological oxidation tank 42. The upflow
generates a downflow in which the stored liquid 46 flows downward in the
downflow portion 62 of the storage space of the biological oxidation tank 42.
The upflow and the downflow aerate the stored liquid 46 stored in the
biological oxidation tank 42 by the air dispersed in the gas-liquid two-phase
flow injected from the nozzle 45. The aeration of the stored liquid 46 causes
the aerobic microbe group contained in the stored liquid 46 to decompose the
organic matter contained in the stored liquid 46, breed, and proliferate. The air
bubbles dispersed in the gas-liquid two-phase flow, with the gas-liquid twophase
flow being generated by the gas-liquid two-phase flow generation device
43, are relatively small. The water treatment device 41, with the small size of
the air bubbles of the gas-liquid two-phase flow, is capable of increasing a
contact surface area between the stored liquid 46 and the air, and dissolving the
oxygen in the stored liquid 46 with high efficiency. The aerobic microbe group,
5 with the oxygen thus dissolved in the stored liquid 46 at a high concentration,
can breed and proliferate with high efficiency.
Furthermore, the biological oxidation tank 42 supplies the stored liquid
46 to the membrane separation tank 2 by causing the stored liquid 46 to
overflow.
Such a water treatment device 41, with the gas-liquid two-phase flow
supplied to the stored liquid 46 stored in the biological oxidation tank 42, is
capable of sufficiently aerating the stored liquid 5, even if aeration of the
stored liquid 5 is insufficient by the gas-liquid two-phase flow injected toward
the separation membrane 3 alone.
15 An existing water treatment device includes the membrane separation
tank in which the separation membrane is disposed and the biological oxidation
tank that supplies the stored liquid by overflow to the membrane separation
tank. The existing water treatment device generally further includes a
circulation pipe and an aeration device that is separate from the circulation
20 pipe. The circulation pile supplies the stored liquid from the membrane
separation tank to the biological oxidation tank and, the aeration device aerates
the stored liquid of the biological oxidation tank. Such a water treatment device
41 no longer needs to include the aeration device, and therefore can be more
easily manufactured compared to the existing water treatment device. Such a
25 water treatment device 41 can be easily manufactured from the existing water
treatment device by a modification of adding the gas-liquid two-phase flow
generation device to an area midway on the circulation pipe.
It should be noted that the separation membrane 3 may be replaced with
another separation membrane that includes a filtration membrane formed into
30 flat membrane. The water treatment device that includes such a separation
membrane as well, in the same manner as the water treatment device of the
aforementioned embodiment, is capable of more adequately cleaning the
separation membrane.
FIG. 8 illustrates yet another embodiment of the water treatment device.
A water treatment device 71 includes a dispersed bacteria treatment tank 72, an
activated sludge treatment tank 73, and a screen 74. The dispersed bacteria
treatment tank 72 forms a storage space and stores a dispersed bacteria mixture
5 in the storage space. The dispersed bacteria mixture contains waste water
supplied from outside, and non-agglomerative bacteria are dispersed therein
without forming a floc. The non-agglomerative bacteria are formed from
bacteria and use oxygen dissolved in the dispersed bacteria mixture to
decompose the organic matter dissolved in the dispersed bacteria mixture and
10 proliferate. The storage space is filled with a plurality of microorganism
immobilizing carriers. Each of the microorganism immobilizing carriers is
formed from a porous substance, and is substantially formed into a spherical
shape. The microorganism immobilizing carriers hold the non-agglomerative
bacteria. Such microorganism immobilizing carriers are known and examples
15 include "Kuragel" (registered trademark) manufactured by Kuraray Co., Ltd.
The activated sludge treatment tank 73 forms a storage space, and stores
an activated sludge mixture in the storage space. The activated sludge mixture
contains dispersed bacteria treated water and activated sludge supplied by the
screen 74. The activated sludge includes non-agglomerative bacteria and
20 microorganisms, and forms a floc in the activated sludge mixture. The
microorganisms are protozoa and metazoa relatively larger than the nonagglomerative
bacteria. The protozoa and the metazoa use the oxygen dissolved
in the activated sludge mixture to decompose the organic matter and nonagglomerative
bacteria dissolved in the activated sludge mixture and
25 proliferate.
The screen 74 is formed from a perforated metal obtained by forming a
plurality of holes in a metal plate, and is disposed so that the perforated metal
is interposed between the storage space of the dispersed bacteria treatment tank
72 and the storage space of the activated sludge treatment tank 73. Each of the
30 plurality of holes has a diameter that is less than a diameter of the
microorganism immobilizing carriers. The screen 74 supplies the dispersed
bacteria treated water of the dispersed bacteria mixture, the treated water
having passed through the perforated metal, to the activated sludge treatment
tank 73 at a predetermined flow rate. It should be noted that the screen 74 may
35 be replaced with another screen capable of filtering the dispersed bacteria
mixture and separating the mixture into a plurality of microorganism
immobilizing carriers and dispersed bacteria treated water. Examples of the
screen include a wire mesh in which a plurality of gaps, which does not allow
passage of the microorganism immobilizing carriers therethrough, are formed.
The water treatment device 71 further includes a circulating liquid pipe
5 75, a circulation pump 76, and a gas-liquid two-phase flow generation device
77. The circulating liquid pipe 75 is disposed so as to extend through a liquid
surface of the dispersed bacteria mixture stored in the dispersed bacteria
treatment tank 72, and forms a flow path by connecting one end of the
circulating liquid pipe 75 to a bottom portion of the storage space of the
10 dispersed bacteria treatment tank 72 and the other end of the circulating liquid
pipe 75 to the circulation pump 76. The circulating liquid pipe 75 extracts the
dispersed bacteria mixture from the bottom portion of the dispersed bacteria
treatment tank 72, and supplies the extracted circulating liquid to the
circulation pump 76. The circulation pump 76 takes in the circulating liquid
15 from the dispersed bacteria treatment tank 72 via the circulating liquid pipe 75
using power externally supplied, and generates a flow of the circulating liquid.
The gas-liquid two-phase flow generation device 77 is disposed outside the
dispersed bacteria treatment tank 72. The gas-liquid two-phase flow generation
device 77 generates a gas-liquid two-phase flow using the flow generated by
20 the circulation pump 76. In the gas-liquid two-phase flow, air is dispersed in
the circulating liquid.
The water treatment device 71 further includes a gas-liquid two-phase
flow pipe 78 and a nozzle 79. The gas-liquid two-phase flow pipe 78 is
disposed so as to extend through a hole formed in a section near a bottom
25 portion of a side wall of the dispersed bacteria treatment tank 72. The gasliquid
two-phase flow pipe 78 supplies the gas-liquid two-phase flow generated
by the gas-liquid two-phase flow generation device 77 to the nozzle 79. The
nozzle 79 is disposed in a bottom portion of the storage space of the dispersed
bacteria treatment tank 72. The nozzle 79, with the gas-liquid two-phase flow
30 supplied from the gas-liquid two-phase flow pipe 78, injects the gas-liquid twophase
flow toward the bottom portion of the storage space of the dispersed
bacteria treatment tank 72.
The water treatment device 71 further includes a blower 81 and an air
diffusing pipe 82. The blower 81 supplies air to the air diffusing pipe 82 using
35 externally supplied power. The air diffusing pipe 82 is disposed in a bottom
portion of the storage space of the activated sludge treatment tank 73. With the
air being supplied from the blower 81, the air diffusing pipe 82 supplies air
bubbles of the air to the activated sludge mixture stored in the activated sludge
treatment tank 73, and aerates the activated sludge mixture.
The water treatment device 71 operates when waste water is externally
5 supplied to the dispersed bacteria treatment tank 72. The circulation pump 76
takes in the dispersed bacteria mixture from the bottom of the dispersed
bacteria treatment tank 72 via the circulating liquid pipe 75, and thus generates
a flow of the circulating liquid taken in the circulation pump 76. The gas-liquid
two-phase flow generation device 77 suctions air from the atmosphere and
10 generates a gas-liquid two-phase flow in which air bubbles of the air are
dispersed in the circulating liquid, using the flow generated by the circulation
pump 76. The gas-liquid two-phase flow is supplied to the nozzle 79 via the
gas-liquid two-phase flow pipe 78. The nozzle 79, with the gas-liquid twophase
flow supplied from the gas-liquid two-phase flow pipe 78, injects the
15 gas-liquid two-phase flow toward the bottom portion of the dispersed bacteria
treatment tank 72, and aerates the dispersed bacteria mixture.
The dispersed bacteria mixture is agitated by the aeration, and the
oxygen is dissolved. The dispersed bacteria mixture, being agitated, is mixed
with the waste water externally supplied. The oxygen is dissolved in the
20 dispersed bacteria mixture, and thus the non-agglomerative bacteria dispersed
in the dispersed bacteria mixture and the non-agglomerative bacteria held in the
microorganism immobilizing carriers use the oxygen to decompose the organic
matter contained in the dispersed bacteria mixture, and proliferate.
When a load of the entered waste water becomes low, a biofilm may
25 form on a surface of each of the microorganism immobilizing carriers
immersed in the dispersed bacteria mixture. When the biofilm is formed on the
surfaces of the microorganism immobilizing carriers, the non-agglomerative
bacteria may no longer be able to adequately decompose the organic matter
contained in the dispersed bacteria mixture. The dispersed bacteria mixture is
30 then agitated, causing the microorganism immobilizing carriers immersed in
the dispersed bacteria mixture to flow through the storage space of the
dispersed bacteria treatment tank 72. The flow of the plurality of
microorganism immobilizing carriers causes the surfaces of the dispersed
bacteria mixture to be cleaned. The plurality of microorganism immobilizing
35 carriers, with the gas-liquid two-phase flow being further injected at high speed
from the nozzle 79, can be more adequately cleaned. The plurality of
microorganism immobilizing carriers, with the surfaces thereof being
adequately cleaned, can adequately hold the non-agglomerative bacteria. The
non-agglomerative bacteria adequately held by the plurality of microorganism
immobilizing carriers can adequately decompose the contaminants contained in
5 the dispersed bacteria mixture.
The screen 74 filters the dispersed bacteria mixture and separates the
mixture into the plurality of microorganism immobilizing carriers and the
dispersed bacteria treated water. The screen 74 returns the microorganism
immobilizing carriers to the dispersed bacteria treatment tank 72, and supplies
10 the dispersed bacteria treated water to the activated sludge treatment tank 73 at
a predetermined flow rate.
When the activated sludge treatment tank 73 stores the activated sludge
mixture, the blower 81 supplies air to the air diffusing pipe 82. The air
diffusing pipe 82, with the air being supplied from the blower 81, supplies air
15 bubbles of the air to the activated sludge mixture stored in the activated sludge
treatment tank 73, and aerates the activated sludge mixture.
The activated sludge mixture is agitated by the aeration, and the oxygen
is dissolved. The activated sludge mixture, being agitated, is mixed with the
dispersed bacteria treated water supplied from the dispersed bacteria treatment
20 tank 72. The agitation of the activated sludge mixture causes the floc
suspended in the activated sludge mixture to flow. The oxygen is dissolved in
the activated sludge mixture, and thus the activated sludge contained in the
activated sludge mixture uses the oxygen to decompose the organic matter
contained in the activated sludge mixture and proliferate. Furthermore, the
25 microorganisms contained in the activated sludge use the oxygen dissolved in
the activated sludge mixture to decompose the non-agglomerative bacteria
contained in the activated sludge mixture.
The activated sludge mixture is discharged to equipment in a following
stage at a predetermined flow rate. Examples of the equipment of the following
30 stage include a sedimentation tank and a membrane separation tank.
The sedimentation tank stores the activated sludge mixture, thereby
depositing solid content of the activated sludge mixture and separating the
activated sludge mixture into treated water and excess sludge. The
sedimentation tank drains the treated water to an outside area at a
predetermined flow rate. The sedimentation tank further returns the excess
sludge to the activated sludge treatment tank 73 at a predetermined flow rate,
and discharges the excess sludge to an outside area at a predetermined flow
rate.
5 The membrane separation tank includes a separation membrane. The
separation membrane filters the activated sludge mixture, separating the
activated sludge mixture into excess sludge and treated water. The membrane
separation tank drains the treated water to an outside area at a predetermined
flow rate. The membrane separation tank further returns the excess sludge to
10 the activated sludge treatment tank 73 at a predetermined flow rate, and
discharges the excess sludge to an outside area at a predetermined flow rate.
The non-agglomerative bacteria can decompose organic matter other
than the microorganisms with higher efficiency compared to the protozoa and
the metazoa. As a result, the dispersed bacteria treatment tank 72 is capable of
15 decomposing the organic matter with higher efficiency compared to the
activated sludge treatment tank 73. The water treatment device 71 further
injects the gas-liquid two-phase flow into the dispersed bacteria mixture,
making it possible to dissolve the oxygen in the dispersed bacteria mixture with
high efficiency. The non-agglomerative bacteria, with the oxygen being
20 dissolved in the dispersed bacteria mixture with high efficiency, can decompose
the organic matter with higher efficiency. As a result, the water treatment
device 71 is capable of decomposing the organic matter with higher efficiency
compared to other water treatment devices that supply air from the bottom
portion of the dispersed bacteria treatment tank 72 using an air diffusing pipe
25 or the like.
The dispersed bacteria treated water drained from the dispersed bacteria
treatment tank 72 contains non-agglomerative bacteria, The non-agglomerative
bacteria are dispersed in the dispersed bacteria treated water, making the nonagglomerative
bacteria less likely to settle as solid content even if stored as is
30 in the sedimentation tank. According to such an operation, the nonagglomerative
bacteria form protozoa, metazoa, and a floc in the activated
sludge mixture drained from the activated sludge treatment tank 73.
Furthermore, the protozoa and the metazoa feed upon the non-agglomerative
bacteria. As a result, when the activated sludge mixture is separated into the
35 excess sludge and the treated water, the water treatment device 71 is capable of
decreasing a concentration of the non-agglomerative bacteria contained in the
treated water with higher efficiency. That is, according to such an operation,
the water treatment device 71 is capable of more adequately treating the waste
water compared to the water treatment device of a comparison example in
which the waste water is treated by only the dispersed bacteria treatment tank
5 72 that does not include the activated sludge treatment tank 73.
It should be noted that when the water treatment device 71 does not
require renioval of the non-agglomerative bacteria from the dispersed bacteria
treated water separated by the screen 74, the activated sludge treatment tank 73
may be omitted. In such a water treatment device as well, the non-
10 agglomerative bacteria decompose the organic matter with higher efficiency,
thereby making it possible to adequately treat the waste water.
FIG. 9 illustrates yet another embodiment of the water treatment device.
In a water treatment device 91, the blower 81 and the air diffusing pipe 82 of
the water treatment device 71 of the aforementioned embodiment are replaced
15 with a flow rate adjustment valve 95, a gas-liquid two-phase flow generation
device 92, a gas-liquid two-phase flow pipe 93, and an activated sludge
treatment tank nozzle 94. The flow rate adjustment valve 95 is provided
midway on the flow path that supplies flow from the circulation pump 76 to the
gas-liquid two-phase flow generation device 92. The flow rate adjustment valve
20 95 adjusts a flow rate of the flow supplied from the circulation pump 76 to the
gas-liquid two-phase flow generation device 77, and a flow rate of the flow
supplied from the circulation pump 76 to the gas-liquid two-phase flow
generation device 92. The gas-liquid two-phase flow generation device 92
generates a gas-liquid two-phase flow using the flow generated by the
25 circulation pump 76 in the same way as the gas-liquid two-phase flow
generation device 77. The gas-liquid two-phase flow pipe 93 is disposed so as
to extend through a hole formed in a section near the bottom portion of the side
wall of the activated sludge treatment tank 73. The gas-liquid two-phase flow
pipe 93 supplies the gas-liquid two-phase flow generated by the gas-liquid two-
30 phase flow generation device 92 to the activated sludge treatment tank nozzle
94. The activated sludge treatment tank nozzle 94 is disposed in the bottom
portion of the storage space of the activated sludge treatment tank 73. The
activated sludge treatment tank nozzle 94, with the gas-liquid two-phase flow
being supplied from the gas-liquid two-phase flow pipe 93, injects the gas-
35 liquid two-phase flow toward the bottom portion of the storage space of the
activated sludge treatment tank 73.
The water treatment device 91 injects the gas-liquid two-phase flow into
the storage space of the dispersed bacteria treatment tank 72 at high speed,
making it possible to more adequately decompose the organic matter in the
waste water and more adequately treat the waste water, in the same manner as
5 the water treatment device 71 of the aforementioned embodiment.
Furthermore, the water treatment device 91 injects the gas-liquid two-phase
flow into the storage space of the activated sludge treatment tank 73 at high
speed as well, making it possible to more adequately aerate the activated sludge
mixture stored in the activated sludge treatment tank 73 and adequately agitate
10 the activated sludge mixture. The water treatment device 91 more adequately
agitates and aerates the activated sludge mixture, making it possible to treat the
waste water with higher efficiency compared to the water treatment device 71
of the aforementioned embodiment.
The water treatment device 91 does not need to include the blower 81.
15 As a result, the water treatment device 91 can be more easily manufactured and
maintained with less labor compared to the water treatment device 71 of the
aforementioned embodiment.
Furthermore, in the water treatment device 91, the gas-liquid two-phase
flow generation device 92, the gas-liquid two-phase flow pipe 93, and the
20 activated sludge treatment tank nozzle 94 are capable of supplying the
dispersed bacteria mixture stored in the dispersed bacteria treatment tank 72 to
the activated sludge treatment tank 73 at a predetermined flow rate. With the
dispersed bacteria mixture being supplied to the activated sludge treatment tank
73 at a predetermined flow rate, the water treatment device 91 does not need to
25 include the screen 74 and can therefore be more easily manufactured compared
to the water treatment device 71 of the aforementioned embodiment.
FIG. 10 illustrates yet another embodiment of the water treatment
device. In a water treatment device 10 1, the gas-liquid two-phase flow pipe 78
and the gas-liquid two-phase flow pipe 93 of the water treatment device 91 of
30 the aforementioned embodiment are replaced with another gas-liquid two-phase
flow pipe 102 and another gas-liquid two-phase flow pipe 103, respectively.
The gas-liquid two-phase flow pipe 102 is disposed so as to not extend through
the side wall of the dispersed bacteria treatment tank 72, and to extend through
the liquid surface of the dispersed bacteria mixture stored in the dispersed
35 bacteria treatment tank 72. The gas-liquid two-phase flow pipe 102 supplies the
gas-liquid two-phase flow generated by the gas-liquid two-phase flow
generation device 77 to the nozzle 79. The gas-liquid two-phase flow pipe 103
is disposed so as to not extend through the side wall of the activated sludge
treatment tank 73, and to extend through the liquid surface of the activated
sludge mixture stored in the activated sludge treatment tank 73. The gas-liquid
5 two-phase flow pipe 103 supplies the gas-liquid two-phase flow generated by
the gas-liquid two-phase flow generation device 92 to the activated sludge
treatment tank nozzle 94.
The water treatment device 101 injects the gas-liquid two-phase flow
into the storage space of the dispersed bacteria treatment tank 72 at high speed,
10 making it possible to more adequately decompose the organic matter in the
waste water; and injects the gas-liquid two-phase flow into the storage space of
the activated sludge treatment tank 73 at high speed, making it possible to more
adequately aerate the activated sludge mixture stored in the activated sludge
treatment tank 73, in the same manner as the water treatment device 91 of the
15 aforementioned embodiment. The water treatment device 10 1 does not require
formation of a hole through which the gas-liquid two-phase flow pipe 102
extends in the side wall of the dispersed bacteria treatment tank 72, and
therefore can be more easily manufactured compared to the water treatment
device 91 of the aforementioned embodiment. The water treatment device 101
20 does not require formation of a hole through which the gas-liquid two-phase
flow pipe 103 extends in the side wall of the activated sludge treatment tank
73, and therefore can be more easily manufactured compared to the water
treatment device 91 of the aforementioned embodiment.
FIG. 11 illustrates yet another embodiment of the water treatment
25 device. In a water treatment device 11 1, the gas-liquid two-phase flow pipe 103
of the water treatment device 101 of the aforementioned embodiment is
replaced with another gas-liquid two-phase flow pipe 112, and a flow rate
adjustment valve 113 is further included. The gas-liquid two-phase flow pipe
112 supplies the gas-liquid two-phase flow generated by the gas-liquid two-
30 phase flow generation device 77 to the activated sludge treatment tank nozzle
94. The flow rate adjustment valve 113 is provided midway on the gas-liquid
two-phase flow pipe 112. The flow rate adjustment valve 113 adjusts a flow
rate of the gas-liquid two-phase flow that flows through the gas-liquid twophase
flow pipe 102, and a flow rate of the gas-liquid two-phase flow that
35 flows through the gas-liquid two-phase flow pipe 112.
The water treatment device 11 1 injects the gas-liquid two-phase flow
into the storage space of the dispersed bacteria treatment tank 72 at high speed,
making it possible to more adequately decompose the organic matter in the
waste water; and injects the gas-liquid two-phase flow into the storage space of
5 the activated sludge treatment tank 73 at high speed, making it possible to more
adequately aerate the activated sludge mixture stored in the activated sludge
treatment tank 73, in the same manner as the water treatment device 101 of the
aforementioned embodiment. The water treatment device 11 1 does not need to
include the gas-liquid two-phase flow generation device 92. As a result, the
10 water treatment device 11 1 can be more easily manufactured compared to the
water treatment device 10 1 of the aforementioned embodiment.
It should be noted that the plurality of microorganism immobilizing
carriers may be replaced with other carriers capable of holding nonagglomerative
bacteria. Examples of the carriers include a plurality of sheet-
15 shaped carriers each disposed along a plurality of flat surfaces that are parallel
to each other. In the dispersed bacteria treatment tank filled with such carriers
as well, in the same manner as the dispersed bacteria treatment tank 72 of the
aforementioned embodiment, the non-agglomerative bacteria decompose the
organic matter with higher efficiency, making it possible to adequately treat the
20 waste water.
It should be noted that the activated sludge tank 73 may further include
a separation membrane immersed in the activated sludge mixture. The
separation membrane filters the activated sludge mixture, separating the
activated sludge mixture into excess sludge and treated water, in the same
25 manner as the separation membrane 3 of the aforementioned embodiment. The
treated water is drained to an outside area at a predetermined flow rate. At this
time, the nozzle 94 injects the gas-liquid two-phase flow toward the bottom
portion of the separation membrane. In the activated sludge tank that includes
such a separation membrane, the nozzle 94 injects the gas-liquid two-phase
30 flow toward the bottom portion of the separation member, making it possible to
adequately clean the separation membrane and adequately filter the activated
sludge mixture with the separation membrane, in the same manner as the
membrane separation tank 2 of the aforementioned embodiment.
Reference Signs List
1 : Water treatment device
2: Membrane separation tank
5 3 : Separation membrane
5: Stored liquid
6: Circulating liquid pipe
7: Circulation pump
8: Gas-liquid two-phase flow generation device
10 11: Gas-liquid two-phase flow pipe
12: Nozzle
15: Flow intake pipe
16: Orifice
17: Air suction pipe
1 5 19: Line mixer
2 1 : Water treatment device
22: Gas-liquid two-phase flow generation device
23: Gas-liquid two-phase flow pipe
24: Nozzle
20 5 1 : Water treatment device
3 1 : Water treatment device
32: Gas-liquid two-phase flow pipe
33: Plurality of nozzles
34: Liquid surface
25 41: Water treatment device
42: Biological oxidation tank
43: Gas-liquid two-phase flow generation device
44: Gas-liquid two-phase flow pipe
45: Nozzle
30 46: Stored liquid
7 1 : Water treatment device
72: Dispersed bacteria treatment tank
73: Activated sludge treatment tank
75: Circulating liquid pipe
35 76: Circulation pump
77: Gas-liquid two-phase flow generation device
78: Gas-liquid two-phase flow pipe
79: Nozzle
91 : Water treatment device
92: Gas-liquid two-phase flow generation device
93: Gas-liquid two-phase flow pipe
94: Activated sludge treatment tank nozzle
5 101 : Water treatment device
102: Gas-liquid two-phase flow pipe
103: Gas-liquid two-phase flow pipe
1 1 1 : Water treatment device
11 2: Gas-liquid two-phase flow pipe

Claims:
1. A water treatment device, comprising:
a biological treatment tank configured to store a stored liquid
containing organisms that decompose contaminants;
a pump configured to generate a circulating liquid flow formed of
a circulating liquid extracted from the stored liquid;
a gas-liquid two-phase flow generation device configured to use
the circulating liquid flow to suction a gas containing oxygen and thus
generate a gas-liquid two-phase flow of the circulating liquid having the
gas dispersed therein; and
a nozzle for injecting the gas-liquid two-phase flow into a region
that stores the stored liquid.
15 2. The water treatment device according to claim 1, further comprising a
circulating liquid pipe configured to supply the circulating liquid to the
pump by extracting the stored liquid from a bottom portion of the
biological treatment tank.
20 3. The water treatment device according to claim 2, further comprising a
separation membrane immersed in the stored liquid;
the separation membrane generating treated water by filtering the
stored liquid; and
the nozzle injecting the gas-liquid two-phase flow toward the
2 5 separation membrane.
4. The water treatment device according to claim 3, wherein the region
includes:
an upflow portion having the separation membrane disposed
therein; and
a downflow portion disposed side-by-side with the upflow portion
in a horizontal direction;
the circulating liquid pipe extracting the stored liquid from the
downflow portion.
3 5
5. The water treatment device according to claim 4, wherein the nozzle is
formed by a plurality of nozzles that inject the gas-liquid two-phase
flow into a plurality of different regions of the separation membrane.
6. The water treatment device according to claim 5, wherein each of the
nozzles injects the gas-liquid two-phase flow upward.
7. The water treatment device according to claim 6, wherein the gas-liquid
5 two-phase flow generation device is disposed above the biological
treatment tank.
8. The water treatment device according to claim 7, further comprising:
a pipe that supplies the gas-liquid two-phase flow from the gasliquid
two-phase flow generation device to the nozzle; and
a gas-liquid agitation device that agitates a fluid and a gas that
flow through the pipe.
9. The water treatment device according to claim 8, wherein the pipe is
15 disposed so as to extend through a liquid surface of the stored liquid.
10. The water treatment device according to claim 9, wherein the biological
treatment tank includes:
a membrane separation tank that forms a region having the
separation membrane disposed therein; and
a biological oxidation tank configured to supply the stored liquid
to the membrane separation tank;
the biological oxidation tank including a biological oxidation
tank nozzle configured to inject the gas-liquid two-phase flow into a
region that stores the stored liquid.
I I. The water treatment device according to claim 1, wherein the biological
treatment tank includes:
a dispersed bacteria treatment tank configured to store a dispersed
bacteria mixture having non-agglomerative bacteria that decompose
dispersed contaminants; and
an activated sludge treatment tank configured to store an
activated sludge mixture having suspended activated sludge that
decomposes the dispersed bacteria;
the dispersed bacteria mixture being supplied to the activated
sludge mixture;
the circulating liquid being extracted from the dispersed bacteria
mixture; and
the nozzle injecting the gas-liquid two-phase flow into a region
that stores the dispersed bacteria mixture.
12. The water treatment device according to claim 11, further comprising an
5 activated sludge treatment tank nozzle configured to inject the gas-liquid
two-phase flow into a region that stores the activated sludge mixture.