Description
SUBMERGED MEMBRANE SEPARATOR
Technical Field

The present invention relates to a submerged membrane
separator to be submerged and arranged in, for example, a
liquid to be treated such as an activated sludge mixture
in a treatment tank
Background Art
Conventionally, as a submerged membrane separator 1
of this type, there has been a submerged membrane
separator that is submerged in a treatment tank and
separates activated sludge and treated water as shown in
FIG 21 The submerged membrane separator 1 includes a
box-type casing 2 opened at the top and the bottom, a
plurality of membrane cartridges 3 arrayed in parallel to
one another in the casing 2, and an air diffuser 4
provided below the membrane cartridges 3.
The membrane cartridges 3 have filtration plates 12
and filtration membranes 13 attached to both sides of the
filtration membranes 12 The air diffuser 4 is configured
to diffuse air from a diffusion pipe A pressing plate 5
for preventing lifting of the membrane cartridges 3 is
attached to the upper part of the casing 2
Consequently, during a filtration operation, the
inner sides of the membrane cartridges 3 are
depressurized while air is diffused from the air diffuser
4 Therefore, sludge or the like in a liquid to be
treated is caught by the filtration membranes 13 of the

membrane cartridges 3 Permeate permeating through the
filtration membranes 13 and flowing into the inner sides
of the cartridges 3 is collected as treated water 19 in a
water collecting pipe 16 from water intake nozzles 14
through connection pipes 15
In this case, upflow 17 is caused among the membrane
cartridges 3 by bubbles of the air diffused from the air
diffuser 4 Matters adhering to the membrane surfaces of
the membrane cartridges 3 are removed by this upflow 17
At this point, an upward force acts on the membrane
cartridges 3 due to the upflow 17 However, the membrane
cartridges 3 can be prevented from being lifted owing to
the pressing plate 5
However, since there is a space between the upper end
of the membrane cartridge 3 and the pressing plate 5,
unfortunately, the upper end of the membrane cartridge 3
is brought into contact with the pressing plate 5 by the
upflow 17, the membrane cartridge 3 minutely vibrates,
and the upper end of the membrane cartridge 3 repeatedly
comes into contact with the pressing plate 5 and is worn

As a measure against the problem, as shown in FIG 22,
a pressing plate 6 is formed by a tabular supporting
portion 7 and a comb-like pressing portion 8 of an
elastic material bonded to the tabular supporting portion
7 The tabular supporting portion 7 is fixed to the upper
end surface of the casing 2 by a bolt 9 and a nut 10 The
comb-like pressing portion 8 has a plurality of
protrusions 8a The protrusions 8a are pressed into
spaces between the membrane cartridges 3

Consequently, the membrane cartridges 3 are pressed
from above by the pressing plate 6 and are immovably

secured Therefore, it is possible to prevent vibrations
of the membrane cartridges 3
The submerged membrane separator including the
pressing plate as explained is described in, for example,
Japanese Patent Application Laid-Open No H10-137556
Disclosure of the Invention
Problems to be Solved by the Invention

However, in the conventional form described above, as
shown in FIG 22, the vibrations of the membrane
cartridges 3 are prevented by the pressing plate 6
Therefore, unfortunately, it is difficult to improve a
cleaning effect for the membrane surfaces of the membrane
cartridges 3 by the upflow 17

The membrane cartridges 3 are forcibly pressed by the
pressing plate 6 against a force to cause vibrations
Therefore, when the force to cause vibrations becomes
excessively large, it is likely that the filtration
plates 12 of the membrane cartridges 3 break
It is an object of the present invention to provide a
submerged membrane separator that can reduce the abrasion
of membrane cartridges and improve a cleaning effect for
the membrane surfaces of the membrane cartridges by
upflow
Means for Solving the Problems
In order to attain the object, a first invention is a
submerged membrane separator including a casing opened
at the top, a plurality of flat membrane cartridges
arrayed at intervals in the casing, and an air diffuser

provided below the membrane cartridges, wherein the
membrane cartridges are movably held in the up-down
direction in the casing while having a space in the up-
down direction, and a lifting suppressing member for
restricting a lifting amount of the membrane cartridges
during a filtration operation to be smaller than the
space in the up-down direction is provided in the casing

Consequently, during the filtration operation, upflow
is generated among the membrane cartridges by bubbles of
air diffused from the air diffuser Matters adhering to
the membrane surfaces of the membrane cartridges are
removed by this upflow At this point, an upward force
acts on the membrane cartridges due to the upflow and the
membrane cartridges are lifted with the upward force

In this case, the lifting amount of the membrane
cartridges is restricted by the lifting suppressing
member to be smaller than the space in the up-down
direction Consequently, the membrane cartridges actively
vibrate while being kept in a state in which the membrane
cartridges are lifted within the range of the space in
the up-down direction Therefore, a cleaning effect for
the membrane surfaces of the membrane cartridges is
improved Further, a contact portion between the membrane
cartridges and a member fixed on the casing side is
reduced, so that the abrasion of the membrane cartridges
is reduced
A second invention is the submerged membrane
separator, wherein the membrane cartridges are movably
held in the array direction of the membrane cartridges in
the casing

A third invention is the submerged membrane separator,
wherein the lifting suppressing member restricts the
lifting amount of the membrane cartridges in the side
portion of the membrane cartridges
A fourth invention is the submerged membrane
separator, wherein the lifting suppressing member
restricts the lifting amount of the membrane cartridges
in the lower side portion of the membrane cartridges

A fifth invention is the submerged membrane separator,
wherein the lifting suppressing member restricts the
lifting amount of the membrane cartridges in the upper
side portion of the membrane cartridges
A sixth invention is the submerged membrane separator,
wherein the lifting suppressing member holds spaces
between the membrane cartridges

A seventh invention is the submerged membrane
separator, wherein a portion of the lifting suppressing
member that comes into contact with the membrane
cartridges is an elastic member
Consequently, when an upward force acts on the
membrane cartridges due to the upflow, the portion of the
elastic member of the lifting suppressing member is
elastically deformed and the membrane cartridges are
lifted In this case, the lifting amount of the membrane
cartridges is restricted to be smaller than the space in
the up-down direction owing to the lifting suppressing
member

An eighth invention is the submerged membrane
separator, wherein a fitting portion is provided in the

side portion of the membrane cartridges, and the lifting
suppressing member fits in the fitting portion
lca&24f
A ninth invention is the submerged membrane separator,
wherein an engaging portion is provided in the side
portion of the membrane cartridges, and the engaging
portion engages with the lifting suppressing member from
below during a filtration operation.
[9025>
A tenth invention is the submerged membrane separator,
wherein the lifting suppressing member is attached to the
frame body of the casing
An eleventh invention is the submerged membrane
separator, wherein the lifting suppressing member is
attached to a side panel that surrounds both sides of the
membrane cartridges
Advantages of the Invention
As described above, according to the present
invention, during the filtration operation, upflow is
generated among the membrane cartridges by bubbles of air
diffused from the air diffuser, an upward force acts on
the membrane cartridges due to the upflow, and the
membrane cartridges are lifted
In this case, the lifting amount of the membrane
cartridges is restricted to be smaller than the space in
the up-down direction by the lifting suppressing member
Therefore, the membrane cartridges actively vibrate while
being kept in a state in which the membrane cartridges
are lifted within the range of the space in the up-down
direction Consequently, the cleaning effect for the
membrane surfaces of the membrane cartridges is improved

The contact portion between the membrane cartridges and
the member fixed on the casing side is reduced, so that
the abrasion of the membrane cartridges is reduced
When an upward force acts on the membrane cartridges
due to the upflow, the portion of the elastic member of
the lifting suppressing member is elastically deformed
and the membrane cartridges are lifted In this case, the
lifting amount of the membrane cartridges is restricted
to be smaller than the space in the up-down direction
owing to the lifting suppressing member
Brief Description of the Drawings
FIG 1 is a longitudinal sectional view showing the
configuration of a submerged membrane separator in a
first embodiment of the present invention,
FIG 2 is a perspective view showing a state .in which
a side cover and a lifting suppressing member are removed
and a membrane cartridge is pulled out from the casing of
the submerged membrane separator in the first embodiment,
FIG 3 is an exploded perspective view showing the
configuration of the submerged membrane separator in the
first embodiment,
FIG 4 is a front view of the membrane cartridge of
the submerged membrane separator in the first embodiment,
FIG 5A is an exploded perspective view of the
lifting suppressing member of the submerged membrane
separator in the first embodiment,
FIG 5B is a perspective view of the membrane
cartridges restricted from being lifted by the lifting
suppressing member of the submerged membrane separator in
the first embodiment,
FIG 6A is an enlarged perspective view of the mating
portion of slits of the lifting suppressing member and

the recesses of side plates of the membrane cartridges of
the submerged membrane separator in the first embodiment,
and shows a state in which air diffusion is stopped,
FIG 6B is an enlarged perspective view of the mating
portion of slits of the lifting suppressing member and
the recesses of side plates of the membrane cartridges of
the submerged membrane separator in the first embodiment,
and shows a state in which air diffusion is performed,
FIG 7 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of the submerged membrane
separator in the first embodiment,
FIG 8 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of the submerged membrane
separator in the first embodiment, and shows a state in
which the side cover and the lifting suppressing member
are removed from the casing,
FIG 9A is a view taken along arrows X-X in FIG 7,
FIG 9B is a view taken along arrows X-X in FIG 8,
FIG 10 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of a submerged membrane
separator in a second embodiment of the present invention,
and shows a state in which a side cover and a lifting
suppressing member are removed from the casing,
FIG 11 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of a submerged membrane
separator in a third embodiment of the present invention,
FIG 12A is a perspective view of the lower part of
the membrane cartridges and the lifting suppressing
member of a submerged membrane separator in a fourth
embodiment of the present invention, and shows a state in
which air diffusion is stopped,

FIG 12B is a perspective view of the lower part of
the membrane cartridges and the lifting suppressing
member of the submerged membrane separator in the fourth
embodiment, and shows a state in which air diffusion is
performed,
FIG 13 is a view taken along arrows X-X in FIG 12A,
FIG 14 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of a submerged membrane
separator in a fifth embodiment of the present invention,
FIG 15A is a perspective view of a state in which
the space maintaining member of the submerged membrane
separator is removed from the membrane cartridges in the
fifth embodiment,-
FIG 15B is a perspective view of a state in which
the space maintaining member of the submerged membrane
separator is attached to the membrane cartridges in the
fifth embodiment,
FIG 16 is a longitudinal sectional view of left or
right one side of the casing and left or right one side
of the membrane cartridge of a submerged membrane
separator in a sixth embodiment of the present invention,
FIG 17 is a perspective view of the membrane
cartridge of a submerged membrane separator in a seventh
embodiment of the present invention,
FIG 18 is an exploded perspective view showing the
configuration of the submerged membrane separator in the
seventh embodiment,
FIG 19A is a longitudinal sectional view of the
membrane cartridge of the submerged membrane separator in
the seventh embodiment, and shows a filtration membrane
divided into upper and lower portions,
FIG 19B is a longitudinal sectional view of the
membrane cartridge of the submerged membrane separator in

the seventh embodiment, and shows the filtration membrane
not divided,
FIG 2 0 is a perspective view of the membrane
cartridge of a submerged membrane separator in an eighth
embodiment of the present invention,
FIG 21 is a partially cut-out perspective view of a
submerged membrane separator in a prior art,
FIG 22A is a front view of the pressing plate of the
submerged membrane separator in the prior art, and
FIG 22B is a view taken along arrows X-X in FIG 22A.
Best Mode for Carrying Out the Invention
[-©■es-rr
A first embodiment in the present invention is
explained below with reference to FIGS 1 to 9
As shown in FIG 1, reference numeral 31 denotes a
submerged membrane separator This submerged membrane
separator 31 is submerged in a treatment tank 32 and
separates raw water containing activated sludge and
treated water The submerged membrane separator 31
includes a box-type casing 3 3 for membranes opened at the
top and the bottom, a plurality of flat membrane
cartridges 34 arrayed in parallel and opposed to one
another in the casing 33 for membranes, and an air
diffuser 36 provided below these membrane cartridges 34
The air diffuser 36 is an example of a flow
generating device The air diffuser 36 diffuses air from
a plurality of diffusing holes formed in an air diffusion
pipe to thereby generate upflow 77 along the membrane
surfaces of the membrane cartridges 34
As shown in FIGS 2 and 3, the casing 33 for
membranes includes a frame body 37, a pair of front and
rear end covers 38 for covering both front and rear ends

of the frame body 37, and a pair of left and right side
panels 39a and 39b detachably attached to both sides of
the frame body 3 7
[003-4+
The frame body 3 7 includes a bottom frame 41 having a
square frame shape, an upper frame 42 having a square
frame shape, and a plurality of vertical frames 43a and
43b coupled between the four corners of both the frames
41 and 4 2
[&03Dfr
Side openings 45a and 45b through which the membrane
cartridge 34 can be removed and inserted in a width
direction A (left-right direction) are formed on both
left and right sides of the frame body 3 7 The one side
panel 39a is attached to the frame body 37 by a plurality
of bolts 46 and closes the one side opening 45a.
Similarly, the other side panel 39b is attached to the
frame body 37 by a plurality of bolts 46 and closes the
other side opening 45b. When the bolts 46 are unscrewed
and the one side panel 3 9a is removed from the frame body
37, the one side opening 45a is opened Similarly, when
the other side panel 3 9b is removed from the frame body
37, the other side opening 45b is opened
As shown in FIG 4, each of the membrane cartridges
34 includes a flat filtration plate 49 formed in a
rectangular shape in the up-down direction, filtration
membranes 50 attached to both front and rear sides of the
filtration plate 49, and a plurality of side plates 51a
and 51b (an example of side portions) The peripheral
edges of the filtration membranes 50 are welded to the
filtration plate 49 by ultrasound or the like, whereby
the filtration membranes 50 are attached to the
filtration plate 49 The upper and lower side plates 51a
and 51b are provided in pairs on both sides of the

filtration plate 49 in the width direction A, and project
to the outer side Recesses 52 having a square shape (an
example of fitting portions) are formed in the side
plates 51a and 51b
Water intake nozzles 53 (an example of water intake
portions) for sucking treated water obtained by the
filtration membranes 50 are provided at upper ends on
both sides orthogonal to the width direction A of the
filtration plate 49 Permeate channels (not shown) that
communicate with the water intake nozzles 53 are
respectively formed on both front and rear sides of the
filtration plate 49 The permeate channels are covered
with the filtration membranes 50
[0038]
As shown in FIGS 1 to 3, a pair of left and right
water collecting pipes 55 for collecting treated water
sucked from the water intake nozzles 53 of the membrane
cartridges 34 are provided in the front-rear direction on
the outer sides on the left and right of the upper frame
42 of the frame body 37 The water collecting pipes 55
and the water intake nozzles 53 are connected via
connection pipes 56 having flexibility
[0-0-3-9}
As shown in FIG 3 and FIGS 7 to 9, upper guiding
members 70 and lower guiding members 71 for guiding the
membrane cartridges 34 in the width direction A (left-
right direction) are provided in the inside of the casing
3 3 for membranes The left and right upper guiding
members 70 are provided in pairs in the upper frame 42 of
the frame body 3 7 The left and right lower guiding
members 71 are provided in pairs in the bottom frame 41
[004 0] ■
A plurality of front and rear guiding grooves 72 are
formed in each of the upper and lower guiding members 70

and 71 The upper ends of the membrane cartridges 34 are
freely inserted into and removed from the guiding grooves
72 of the upper guiding member 70 from the width
direction A (left-right direction) The lower ends of the
membrane cartridges 34 are freely inserted into and
removed from the guiding grooves 72 of the lower guiding
member 71 from the width direction A (left-right
direction)
[(W44t
As shown in FIG 7, a height HI between an upper
inner surface 7 0a of the guiding groove 72 of the upper
guiding member 70 and a lower inner surface 71a of the
guiding groove 72 of the lower guiding member 71 is set
larger than a height H2 of the membrane cartridge 34
Consequently, the membrane cartridge 34 has a space a
(I e , a=Hl-H2) in the up-down direction and is held in
the inside of the casing 33 so as to move in an up-down
direction B
As shown in FIG. 9, a width D of each of the guiding
grooves 72 is set larger than a thickness T of the
membrane cartridge 34 Consequently, the membrane
cartridge 34 has a space (3 (l e , P=D-T) in an array
direction C (front-rear direction) and is held in the
inside of the casing 33 so as to move in the array
direction C
As shown in FIGS 2 and 3, left and right lifting
suppressing members 63a and 63b are provided in pairs in
upper and lower places in the casing 3 3 for membranes As
shown in FIGS 5 and 6, these lifting suppressing members
63a and 63b restrict a lifting amount of the membrane
cartridges 34 during a filtration operation to be smaller
than the space a in the up-down direction (I e , 0 <
lifting amount < space a) The lifting suppressing

members 63a and 63b include horizontal frames 64 and
suppressing bodies 65 provided in the horizontal frames
64
[004^-
As shown in FIGS 5 to 9, the horizontal frames 64
are angle-shaped members having vertical plate portions
64a and horizontal plate portions 64b Both ends of the
horizontal frame 64 are detachably coupled between the
front and rear vertical frames 43a and 43b by bolts 66
and nuts 6 7
[ft©*5?
The suppressing bodies 65 are portions that come into
contact with the side plates 51a and 51b of the membrane
cartridges 34 The material of the suppressing bodies 65
is an elastic body such as rubber Grooves 68 are formed
over the entire length on the outer surfaces of the
suppressing bodies 65 A plurality of front and rear V-
shaped slits 69 are formed on the inner surfaces of the
suppressing bodies 65 The horizontal plate portions 64b
of the horizontal frames 64 are inserted into the grooves
68 of the suppressing bodies 65, whereby the suppressing
bodies 65 are attached to the horizontal frames 64
KUJ4-60
As shown m_FIGS 6, 7, and 9A, the slits 69 of the
suppressing bodies 65 fit in the recesses 52 of the side
plates 51a and 51b of the membrane cartridges 34 In this
state, the membrane cartridges 34 are supported by the
lifting suppressing members 63a and 63b, and a space S in
the array direction C between the membrane cartridges 34
is maintained at a predetermined space The recesses 52
and the slits 69 are fit without backlashing in the width
direction A (left-right direction), the up-down direction
B, and the array direction C (front-rear direction)
[•Q047i
Actions in the configuration are explained below

(1) During a filtration operation, as shown in FIG 1,
the inner sides of the membrane cartridges 34 are
depressurized while air is diffused from the air diffuser
36, whereby sludge or the like in a liquid to be treated
47 is caught by the filtration membranes 50 of the
membrane cartridges 34 Permeate permeating through the
filtration membranes 5~0 and flowing into the inner sides
of the membrane cartridges 34 is collected as treated
water 48 in the water collecting pipe 55 from the water
intake nozzles 53 through the connection pipes 56
[.004*3
In this case, as shown in FIG 6B, the upflow 77 is
generated among the membrane cartridges 34 by bubbles of
the air diffused from the air diffuser 36 Matters
adhering to the membrane surface deposits of the membrane
cartridges 34 (sludge, etc ) are removed by the upflow 77
As shown in FIG 3, since the water intake nozzles 53
are provided at the upper ends on both sides of the
filtration plate 49, the upflow 77 smoothly flows without
hitting the connection pipes 56 Therefore, matters
adhering to the membrane surfaces of the membrane
cartridges 34 are sufficiently removed Since the upflow
77 does not hit the connection pipes 56, vibration of the
connection pipes 56 is reduced and it is possible to
prevent a crack from occurring around the water intake
nozzles 53 During the filtration operation, an upward
force acts on the membrane cartridges 34 due to the
upflow 77 and buoyancy The suppressing bodies 65 (a
portion of the elastic body) of the lifting suppressing
members 63a and 63b are elastically deformed by this
upward force As indicated by a virtual line in FIG 7,
the membrane cartridge 34 lifts upward from the lower

inner surface 71a of the guiding groove 72 of the lower
guiding member 71
In this case, the lifting amount of the membrane
cartridges 34 is restricted by the lifting suppressing
members 63a and 63b to be smaller than the space a in the
up-down direction B For example, if the space a is 6 mm,
the lifting amount of the membrane cartridges 34 is
restricted to 3 mm The space a and the lifting amount of
the membrane cartridges 34 are not limited to the
numerical values
[0*521
Consequently, the membrane cartridges 34 vibrate
actively and minutely while being kept in a state in
which the membrane cartridges 34 are lifted within the
range of the space a in the up-down direction B
Therefore, a cleaning effect for the membrane surfaces of
the membrane cartridges 34 is improved Further, a
contact portion between the membrane cartridges 34 and
the upper guiding members 70 fixed to the casing 33 is
reduced and a contact portion between the membrane
cartridges 34 and the lower guiding members 71 fixed to
the casing 33 is reduced Therefore, the abrasion of the
membrane cartridges 34 is reduced
The minute vibration of the membrane cartridges 34
occurs in the width direction A (left-right direction) ,
the up-down direction B, and the array direction C
(front-rear direction)
(2) When the membrane cartridge 3 4 is removed in
maintenance or the like, the air diffusion by the air
diffuser 36 is stopped, the filtration operation is
stopped, and the liquid to be treated 47 in the treatment
tank 32 is discharged In this case, the upward force

does not act on the membrane cartridge 34, the
suppressing bodies 65 of the lifting suppressing members
63a and 63b are subjected to own weight 78 of the
membrane cartridge 34 and are elastically deformed, and
the membrane cartridge 34 sinks with the own weight 78
As indicated by a solid line in FIG 7, the lower end of
the membrane cartridge 34 comes into contact with and is
supported by the lower inner surface 71a of the guiding
groove 72 of the lower guiding member 71 The space a in
the up-down direction B is formed between the upper end
of the membrane cartridge 34 and the upper inner surface
7 0a of the guiding groove 72 of the upper guiding member
70.
[0055]
Thereafter, as shown in FIGS 2 and 8, the bolts 46
are unscrewed to remove the one side panel 3 9a from the
frame body 37 and open the one side opening 45a
[0056]
Subsequently, the bolts 66 are unscrewed to remove
the left or right one lifting suppressing member 63a from
the frame body 3 7 Consequently, as shown in FIGS. 8 and
9B, the left or right one side plate 51a of the membrane
cartridge 34 disengages from the slit 69 of the left or
right one space suppressing member 63a Thereafter, as
indicated by virtual lines in FIGS 2 and 8, the membrane
cartridge 34 can be pulled out from the inside of the
casing 33 in the width direction A of the membrane
cartridge 34 through the one side opening 45a, and taken
out to the outer side of the casing 33 At this point,
the recesses 52 of the left or right other side plate 51b
of the membrane cartridge 34 disengage from the slits 69
of the left or right other lifting suppressing member 63b
The membrane cartridge 34 is pulled out in the width
direction A while being guided by the upper and lower
guiding grooves 72

Consequently, it is possible to easily pull out the
membrane cartridge 34 from the inside of the casing 33 in the left-right lateral direction As shown in FIG 1, it
is possible to keep the height of a space 73 above the
casing 33 low Further, even if sludge clogs spaces
between the sides of the membrane cartridges 34 opposed
to each other, it is possible to easily pull out the
membrane cartridges 34 from the inside of the casing 33
(3) When the membrane cartridge 34 is attached, as
shown in FIGS 2 and 8, the membrane cartridge 34 is
inserted from the outer side of the casing 33 in the
width direction A of the membrane cartridge 34 through
one side opening 45a At this point, the membrane
cartridge 34 is inserted in the width direction A while
being guided by the upper and lower guiding grooves 72
The recesses 52 of the left or right other side plate 51b
of the membrane cartridge 34 fit in the slits 69 of the
left or right other lifting suppressing member 63b
[0059]
Subsequently, as shown in FIG 5B, the bolts 66 are
screwed to attach the left or right one lifting
suppressing member 63a to the vertical frame 43a on one
of the left and right of the frame body 3 7 Consequently,
as shown in FIGS 7 and 9A, the recess 52 of the left or
right one side plate 51a of the membrane cartridge 34
fits into the slit 69 of the left or right one lifting
suppressing member 63a
[9-eis-oi—
Thereafter, the bolts 46 are screwed to attach the
one side panel 3 9a to the frame body 3 7 to close the one
side opening 45a Consequently, the membrane cartridge 34
is housed and held in the inside of the casing 33

Since the one side opening 45a of the casing 33 for
membranes is closed by the one side panel 39a and the
other side opening 45b is closed by the other side panel
39b, during the filtration operation, it is possible to
prevent bubbles of the air diffused from the air diffuser
36 from being released to the outside of the casing 33
through the side openings 45a and 45b
In the first embodiment, as shown in FIG. 2, the one
side panel 39a and one lifting suppressing member 63a are
removed from the frame body 3 7 to open the one side
opening 4 5a and remove the membrane cartridge 3 4 from and
insert the membrane cartridge 34 into the casing 33
through the one side opening 45a However, as shown in
FIG 3, the other side panel 39b and the other lifting
suppressing member 63b may be removed from the frame body
3 7 to remove the membrane cartridge 3 4 from and insert
the membrane cartridge 34 into the casing 33 through the
other side opening 4 5b
In the first embodiment, as shown in FIG. 3, the left
and right water intake nozzles 53 are provided in pairs
in the membrane cartridge 34 and the left and right water
collecting pipes 55 are provided in pairs in the frame
body 3 7 However, only one of the left and right water
intake nozzles 53 may be provided and only one of the
left and right water collecting pipes 55 may be provided
In the first embodiment, the suppressing bodies 65 of
the lifting suppressing members 63a and 63b have the
slits 69 However, in a second embodiment of the present
invention, as shown in FIG 10, suppressing bodies 65 do
not have slits 69 The suppressing bodies 65 fit in
recesses 52 of side plates 51a and 51b of membrane
cartridges 34

[00&44
In the first embodiment and the second embodiment,
the left and right side plates 51a and 51b are provided
in pairs in the upper and lower places of the membrane
cartridge 34 However, the side plates 51a and 51b may be
provided in a plurality of places or only one place other
than the upper and lower places In the first embodiment
and the second embodiment, the left and right lifting
suppressing members 63a and 63b are provided in pairs in
the upper and lower places in the inside of the casing 33
However, the lifting suppressing members 63a and 63b may
be provided in a plurality of places or only one place
other than the upper and lower places
[0^6-5-T
Next, a third embodiment in the present invention is
explained with reference to FIG 11
[006-61
A membrane cartridge 34 has a plurality of engaging
plates 80a and 80b (an example of engaging portions) The
upper and lower engaging plates 8 0a and 8 0b are provided
in pairs on both sides in the width direction A of a
filtration plate 49 and project to the outer side
One of the left and right engaging plates 80a engages
with a suppressing body 65 of one of left and right
lifting suppressing members 63a from below Similarly,
the other one of the left and right engaging plates 80b
engages with the suppressing body 65 of the other one of
left and right lifting suppressing members 63b from below
Consequently, during a filtration operation, an
upward force acts on the membrane cartridge 34 with
upflow 77 and buoyancy, and the engaging plates 80a and
80b press upward the suppressing bodies 65 (a portion of
an elastic body) of the lifting suppressing members 63a

and 63b, whereby the suppressing bodies 65 of the lifting
suppressing members 63a and 63b are elastically deformed
As indicated by a virtual line in FIG 11, the membrane
cartridge 34 is lifted upward from a lower inner surface
71a of a guiding groove 72 of a lower guiding member 71
In this case, the lifting amount of the membrane
cartridge 34 is restricted by the lifting suppressing
members 63a and 63b to be smaller than a space a in an
up-down direction B Consequently, the membrane cartridge
34 vibrates actively and minutely while being kept in a
state in which the membrane cartridge 34 is lifted within
the range of the space a in the up-down direction B.
Therefore, a cleaning effect for the membrane surface of
the membrane cartridge 34 is improved Further, a contact
portion between the membrane cartridge 34 and an upper
guiding member 70 fixed to a casing 33 is reduced and a
contact portion between the membrane cartridge 34 and the
lower guiding member 71 fixed to the casing 33 is reduced
Therefore, the abrasion of the membrane cartridge 34 is
reduced
When air diffusion by an air diffuser 36 is stopped,
the filtration operation is stopped, and a liquid to be
treated 47 in a treatment tank 32 is discharged, an
upward force does not act on the membrane cartridge 34
and the membrane cartridge 34 sinks with own weight 78
As indicated by a solid line in FIG 11, the lower end of
the membrane cartridge 34 comes into contact with and are
supported by the lower inner surface 71a of the guiding
groove 72 of the lower guiding member 71 The space a in the up-down direction B is formed between the upper end
of the membrane cartridge 34 and an upper inner surface
70a of the guiding groove 72 of the upper guiding member
70

In the third embodiment, the left and right engaging
plates 80a and 80b are provided in pairs in the upper and
lower places of the membrane cartridge 34 However, the
engaging plates 80a and 80b may be provided in a
plurality of places or only one place other than the
upper and lower places In the third embodiment, the left
and right lifting suppressing members 63a and 63b are
provided in pairs in the upper and lower places in the
inside of the casing 33 However, the lifting suppressing
members 63a and 63b may be provided in a plurality of
places or only one place other than the upper and lower
places
In the first to third embodiments, the lifting
suppressing members 63a and 63b are provided in a frame
body 37 However, one of the left and right lifting
suppressing members 63a may be provided on the inner
surface of one side panel 39a and the other one of the
left and right lifting suppressing members 63b may be
provided on the inner surface of the other side panel 39b
In the first to third embodiments, even in a state in
which the filtration operation is stopped, the membrane
cartridges 34 are set in contact with the lifting
suppressing members 63a and 63b However, when the
filtration operation is stopped, the membrane cartridges
34 may be separated from the lifting suppressing members
63a and 63b without being in contact with the lifting
suppressing members 63a and 63b, and when the filtration
operation is carried out, the membrane cartridges 34 may
be set in contact with the lifting suppressing members
63a and 63b

Next, a fourth embodiment in the present invention is
explained with reference to FIGS 12 and 13
A membrane cartridge 34 has a plurality of lower
engaging projecting portions 82 (an example of engaging
portions) These lower engaging projecting portions 82
are provided on both sides of the lower side of a
filtration plate 49 and project in an array direction C
In a bottom frame 41 of a frame body 37, a pair of
left and right lifting suppressing members 84 for
restricting a lifting amount with respect to the lower
side of the membrane cartridge 34 are provided Each of
the lifting suppressing members 84 includes a bottom
plate portion 85, a plurality of vertical plate portions
86 erected upward from the bottom plate portion 85, and
projecting portions 87 to be engaged projecting in the
array direction C from the upper ends of the vertical
plate portions 86.
The lower engaging projecting portion 82 is removably
msertable into a width direction A between the vertical
plate portions 86 opposed to each other in the array
direction C The filtration plate 49 is removably
msertable into the width direction A between the
projecting portions 87 to be engaged opposed to each
other in the array direction C The lower engaging
projecting portion 82 engages with the projecting portion
87 to be engaged from below As in the first embodiment,
the upper ends of the membrane cartridges 34 are inserted
into grooves 72 of upper guiding members 70 Further, as
in the first embodiment, the membrane cartridges 34 are
held in the inside of a casing 33 in a state in which the
membrane cartridges 34 have a space a in an up-down
direction B

J>e-THT
A vertical space from the bottom plate portion 85 to
the projecting portions 87 to be engaged is larger than
the vertical thickness of the lower engaging projecting
portions 82 A space y is formed between the projecting
portions 8 7 to be engaged and the lower engaging
projecting portions 82 This space y is set smaller than
the space a
[0079]
Actions in the configuration are explained below
[■QS-S-e*]
During a filtration operation, as shown in FIG. 12B,
an upward force acts on the membrane cartridges 34 due to
upflow 77 and buoyancy As indicated by a virtual line in
FIG 13, the membrane cartridges 34 are lifted upward and
the lower engaging projecting portions 82 engage with the
projecting portions 87 to be engaged of the lifting
suppressing member 84
In this case, the lifting amount of the membrane
cartridges 34 is restricted by the lifting suppressing
member 84 to an amount equivalent to the space y smaller
than the space a in the up-down direction B Consequently,
the membrane cartridges 34 vibrate actively and minutely
while being kept in a state in which the membrane
cartridges 34 are lifted within the range of the space a
Therefore, a cleaning effect for the membrane surfaces of
the membrane cartridges 34 is improved A contact portion
between the membrane cartridges 34 and the upper guiding
member 70 fixed to a casing 33 is reduced and the
abrasion of the membrane cartridges 34 is reduced
When air diffusion by an air diffuser 36 is stopped,
the filtration operation is stopped, and a liquid to be
treated 47 in a treatment tank 32 is discharged, an

upward force does not act on the membrane cartridges 34
As indicated by a solid line in FIG 13, the membrane
cartridges 34 sink with own weight 78, the lower ends of
the membrane cartridges 34 are supported by the bottom
plate portion 85 of the lifting suppressing member 84,
and the space a in the up-down direction B is formed
between the upper ends of the membrane cartridges 34 and
upper inner surfaces 7 0a of the guiding grooves 72 of the
upper guiding member 7 0
Next, a fifth embodiment in the present invention is
explained with reference to FIGS 14 and 15
Lifting suppressing members 88 restrict a lifting
amount with respect to the upper side of a membrane
cartridge 34 Like the upper guiding member 70 in the
first embodiment, the lifting suppressing members 88 have
a comb-tooth structure including a plurality of guide
grooves 72 The left and right lifting suppressing
members 88 are provided in pairs in an upper frame 42
A space S among the membrane cartridges 34 is kept at
a predetermined space by space maintaining members 89
Like the suppressing bodies 65 in the first embodiment,
the space maintaining members 89 have a plurality of
front and rear V-shaped slits 69
[£-6-8-67
The slits 69 of the space maintaining members 89 fit
in recesses 52 of side plates 51a and 51b of the membrane
cartridges 34 Consequently, the space S in the array
direction C among the membrane cartridges 34 is
maintained at the predetermined space
During a filtration operation, an upward force acts
on the membrane cartridges 34 with upflow 77 and buoyancy

The membrane cartridges 34 are lifted upward The upper
ends of the membrane cartridges 34 come into contact with
upper inner surfaces 70a of the guiding grooves 72 of the
lifting suppressing member 88 A space is formed between
the lower ends of the membrane cartridges 34 and lower
inner surfaces 71a of the guiding grooves 72 of a lower
guiding member 71
In this case, the lifting amount of the membrane
cartridges 34 is restricted to an amount equivalent to a
space a in an up-down direction B. Consequently, the
membrane cartridges 34 vibrate actively and minutely
while being kept in a state in which the membrane
cartridges 34 are lifted Therefore, a cleaning effect
for the membrane surfaces of the membrane cartridges 34
is improved
When air diffusion by an air diffuser 36 is stopped,
the filtration operation is stopped, and a liquid to be
treated in a treatment tank 32 is discharged, an upward
force does not act on the membrane cartridges 34 As
shown in FIG 14, the membrane cartridges 34 sink with
own weight 78, the lower ends of the membrane cartridges
34 come into contact with and are supported by the lower
inner surfaces 71a of the guiding grooves 72 of the lower
guiding member 71, and the space a in the up-down
direction B is formed between the upper ends of the
membrane cartridges 34 and the upper inner surfaces 70a
of the guiding grooves 72 of the lifting suppressing
member 8 8
Next, a sixth embodiment in the present invention is
explained with reference to FIG 16
[UUbir]

The sixth embodiment is a modification of the first
embodiment Left and right side plates 51a and 51b of a
membrane cartridge 34 are provided in a pair in positions
lower than the center of gravity G of the membrane
cartridge 34 Similarly, left and right lifting
suppressing members 63a and 63b are also provided in a
pair in positions lower than a center of gravity G of the
membrane cartridge 34
Consequently, during a filtration operation, the
membrane cartridge 34 minutely vibrates while being kept
in a state in which the membrane cartridge 34 is lifted
within the range of a space a in an up-down direction B
by upflow 77 generated when air diffusion is performed
from an air diffuser 36 At this point, since the side
plates 51a and 51b of the membrane cartridge 34 and the
lifting suppressing members 63a and 63b are respectively
provided in the positions lower than the center of
gravity G of the membrane cartridge 34, the vibration of
the membrane cartridge 34 is facilitated
^093]-
In the sixth embodiment, the side plates 51a and 51b
of the membrane cartridge 34 and the lifting suppressing
members 63a and 63b are respectively provided in the
positions lower than the center of gravity G of the
membrane cartridge 34 However, the side plates 51a and
51b of the membrane cartridge 34 and the lifting
suppressing members 63a and 63b may be provided in
positions at the same height as the center of gravity G
of the membrane cartridge 34
Next, a seventh embodiment in the present invention
is explained with reference to FIGS 17 to 19
A filtration membrane 50 of a membrane cartridge 34
is divided into upper and lower portions 91 and 92 A

boundary portion where the upper portion 91 and the lower
portion 92 are adjacent to each other is welded to a
filtration plate 49 Consequently, a welded portion 93 is
formed over the entire width of the filtration membrane
50 in the boundary portion in the vertical center of the
filtration membrane 50
Two water intake nozzles 53a and 53b for sucking
treated water obtained by the membrane filtration 50 are
provided in the filtration plate 49 The upper water
intake nozzle 53a is provided on one of the left and
right sides of the filtration plate 49 and at the upper
end of the upper portion 91 The lower water intake
nozzle 53b is provided on one of the left and right sides
of the filtration plate 49 and at the upper end of the
lower portion 92
[ooocy
Upper and lower water collecting pipes 55a and 55b
for collecting treated water sucked from the water intake
nozzles 53a and 53b are provided in a pair on one side of
a frame body 3 7 of a casing 3 3 The upper water
collecting pipe 55a and the upper water intake nozzle 53a
are connected via a connection pipe 56 and the lower
water collecting pipe 55b and the lower water intake
nozzle 53b are connected via 0the connection pipe 56
Both side covers 39a and 39b are respectively divided
into two as an upper side cover body 97 and a lower side
cover body 98 The upper and lower side cover bodies 97
and 98 are respectively detachably attached to the frame
body 3 7 by bolts 4 6
E-O-OS-81
Consequently, during a filtration operation, the
inner side of the membrane cartridge 34 is depressurized
while air diffusion is performed from an air diffuser 36,

whereby sludge or the like in a liquid to be treated 47
is caught by the filtration membrane 5 0 of the membrane
cartridge 34 Permeate permeating through the filtration
membrane 50 and flowing into the inner side of the
membrane cartridge 34 is collected in the water
collecting pipes 55a and 55b from the water intake
nozzles 53a and 53b through the connection pipes 56
In this case, upflow 77 is generated among the
membrane cartridges 34 by bubbles of air diffused from
the air diffuser 36 Matters adhering to the membrane
surfaces of the membrane cartridges 34 are removed by the
upflow 77
[