Description
MEMBRANE CARTRIDGE
Technical Field
The present invention relates to a membrane cartridge
used in a submerged membrane separator.
Background Art
Conventionally, as the membrane cartridge of this
type, for example as shown in FIG. 27, a filtration
membrane 3 is arranged on the surface of a filtration
plate 2 having a square flat plate shape and the
peripheral portion of the filtration membrane 3 is welded
over the entire periphery of the surface of the
filtration plate 2. The welded portion 12 is formed in a
position slightly inward from a peripheral edge 3a of the
filtration membrane 3. A range from the welded portion 12
of the filtration membrane 3 to the peripheral edge 3a is
an un-joined portion 13 that is not welded.

A water intake nozzle 5 for sucking treated water
obtained by membrane filtration is provided at the upper
end of the filtration plate 2. A membrane cartridge 4
having the configuration as mentioned above is described
in, for example, Japanese Patent No. 3010979. The
membrane cartridge 4 has, in addition to the welded
portion 12, intermittent welded portions formed by
intermittently welding the peripheral edge 3a of the
filtration membrane 3.

FIG. 2 8 shows a submerged membrane separator 6
including the membrane cartridge 4. This submerged

membrane separator 6 is submerged in a treatment tank
filled with activated sludge and separates activated
sludge and treated water. A plurality of the membrane
cartridges 4 are detachably stored in a box-type casing 7
opened at the top and the bottom in a state in which the
membrane cartridges 4 are arrayed in parallel at
predetermined intervals. An air diffuser 8 is provided
below the membrane cartridges 4.
A water collecting pipe 10 for collecting the treated
water is provided on one side of an upper opening 9 of
the casing 7. The water collecting pipe 10 and water
intake nozzles 5 of the membrane cartridges 4 are
connected via connection pipes 11.
Consequently, during filtration operation, the inner
sides of the membrane cartridges 4 are decompressed while
air diffusion is performed from the air diffuser 8,
whereby sludge or the like in liquid to be treated is
caught by filtration membranes 3 of the membrane
cartridges 4. Permeate permeating through the filtration
membranes 3 and flowing into the inner sides of the
cartridges 4 is discharged as treated water 14 to the
water collecting pipe 10 from the water intake nozzles 5
through the connection pipes 11
In this case, upflow is caused between the membrane
cartridges 4 by air bubbles of the air diffused from the
air diffuser 8. The matter adhering to the membrane
surface of the membrane cartridges 4 is removed by this
upflow.
In some case, for example, when properties of the
liquid to be treated are deteriorated, the sludge clogs
in spaces between the membrane cartridges 4 and the

membrane surfaces of the membrane cartridges 4 are
blocked. When such blocking of the membrane surfaces
occurs, after stopping the air diffusion by the air
diffuser 8, stopping the filtration operation is stopped,
and draining the liquid to be treated in the treatment
tank, as shown in FIG. 29, an operator jets high-pressure
cleaning liquid 15 to the spaces between the membrane
cartridges 4 from the upper opening 9 of the casing 7.
According to the jetting of the cleaning liquid 15, the
sludge clogging the spaces between the membrane
cartridges 4 is smashed and removed and the membrane
surfaces of the membrane cartridges 4 are cleaned.
Disclosure of the Invention
Problems to be Solved by the Invention

However, in the conventional form, when the high-
pressure cleaning liquid 15 is jetted to the spaces
between the membrane cartridges 4 from the upper opening
9 of the casing 7 as shown in FIG. 28 and FIG. 29, the
cleaning liquid 15 directly hits against the upper end
edge of the filtration membrane 3 as shown in FIG. 3 0A.
Therefore, unfortunately, the un-joined portion 13 of the
upper end edge of the filtration membrane 3 is turned up
and, as shown in FIG. 30B, the upper end edge of the
filtration membrane 3 peels from the filtration plate 2.
Such a problem occurs as long as the filtration membrane
3 has the un-joined portion 13 even when the peripheral
edge of the filtration membrane 3 is intermittently
welded.
It is an object of the present invention to provide a
membrane cartridge in which a filtration membrane can be
prevented from being peeled by cleaning liquid when the
cleaning liquid is jetted to clean the membrane cartridge.

Means for Solving the Problems
In order to attain the object, a first invention is a
membrane cartridge used in a submerged membrane separator,
wherein
the peripheral portion of a filtration membrane is
joined to the surface of a filtration plate, and
a portion higher than the surface of the filtration
plate corresponding to the peripheral edge of the
filtration membrane is formed on the surface of the
filtration plate further on the outer side than the
peripheral edge of the filtration membrane.
Consequently, a plurality of the membrane cartridges
are provided to be arrayed at predetermined intervals in
a casing of the submerged membrane separator. When
cleaning liquid is jetted to clean the membrane
cartridges, the cleaning liquid is jetted from the side
of one side of the filtration plate to spaces between the
membrane cartridges. In this case, since the portion
higher than the surface of the filtration plate
corresponding to the peripheral edge of the filtration
membrane functions as a screen (a wall) immediately
before the peripheral portion of the filtration membrane,
it is possible to prevent the cleaning liquid from
directly hitting against the peripheral portion of the
filtration membrane. Consequently, it is possible to
prevent the peripheral portion of the filtration membrane
from peeling from the filtration plate.
A second invention is the membrane cartridge, wherein
a projecting portion higher than the surface of the
filtration plate corresponding to the peripheral edge of
the filtration membrane is formed on the surface of the

filtration plate further on the outer side than the
peripheral edge of the filtration membrane.
Consequently, when the cleaning liquid is jetted to
clean the membrane cartridges, the cleaning liquid is
jetted to the spaces between the membrane cartridges from
the side of one side of the filtration plate. In this
case, the cleaning liquid hits against the projecting
portion immediately before the peripheral portion of the
filtration membrane. It is possible to prevent the
cleaning liquid from directly hitting against the
peripheral portion of the filtration membrane.
Consequently, it is possible to prevent the peripheral
portion of the filtration membrane from peeling from the
filtration plate.

A third invention is the membrane cartridge, wherein
a projecting portion is continuously formed on the
surface of the filtration plate.

A fourth invention is the membrane cartridge, wherein
projecting portions are intermittently (discontinuously)
formed on the surface of the filtration plate.
A fifth invention is the membrane cartridge, wherein
a recess is formed on the surface of the filtration plate,
and the peripheral edge of the filtration membrane is
located in the recess.
Consequently, when the cleaning liquid is jetted to
clean the membrane cartridges, the cleaning liquid is
jetted to the spaces between the membrane cartridges from
the side of one. side of the filtration plate. In this
case, since the peripheral edge of the filtration
membrane enters the inside of the recess, it is possible

to prevent the cleaning liquid from directly hitting
against the peripheral portion of the filtration membrane.
Consequently, it is possible to prevent the peripheral
portion of the filtration membrane from peeling from the
filtration plate.

A sixth invention is a flat membrane cartridge used
in a submerged membrane separator, wherein
a filtration membrane is provided on the surface of a
filtration plate,
an inclined surface is formed on the filtration
plate,
the inclined surface is inclined in a direction in
which the thickness of the filtration plate decreases
further in an outer side direction, and
the peripheral portion of the filtration membrane is
joined to the inclined surface.
Consequently, a plurality of the membrane cartridges
are provided to be arrayed at predetermined intervals in
a casing of the submerged membrane separator. When
cleaning liquid is jetted to clean the membrane
cartridges, the cleaning liquid is jetted to spaces
between the membrane cartridges from the side of one side
of the filtration plate. In this case, since the cleaning
liquid hits against one side of the peripheral portion of
the filtration membrane joined to the inclined surface of
the filtration plate, the surface of the peripheral
portion of the filtration membrane is subjected to a flow
of the cleaning liquid and pressed against the inclined
surface of the filtration plate. Consequently, it is
possible to prevent the peripheral portion of the
filtration membrane from peeling from the filtration
plate.

Advantages of the Invention
As explained, according to the present invention, the
portion higher than the surface of the filtration plate
corresponding to the peripheral edge of the filtration
membrane functions as the screen (the wall) immediately
before the peripheral portion of the filtration membrane.
Therefore, it is possible to prevent the cleaning liquid
from directly hitting against the peripheral portion of
the filtration membrane. Consequently, it is possible to
prevent the peripheral portion of the filtration membrane
from peeling from the filtration plate.
Brief Description of the Drawings
FIG. 1 is a schematic 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 supporting member are removed and a
membrane cartridge is pulled out from a casing of the
submerged membrane separator in the first embodiment;
FIG. 3 is a disassembled 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. 5 is an X-X arrow view in FIG. 4;
FIG. 6 is a sectional perspective view of projecting
portions of the membrane cartridge of the submerged
membrane separator in the first embodiment,-
FIG. 7 is a perspective view showing a method of
jetting cleaning liquid on and cleaning membrane
cartridges of the submerged membrane separator in the
first embodiment;

FIG. 8A is a disassembled perspective view of the
supporting member of the submerged membrane separator in
the first embodiment;
FIG. 8B is a perspective view of the membrane
cartridges restrained by the supporting member of the
submerged membrane separator in the first embodiment;
FIG. 9A is an enlarged perspective view of a mating
portion of a slit of the supporting member of the
submerged membrane separator and a slit of a supporting
plate of the membrane cartridges in the first embodiment
and shows a state in which air diffusion is stopped;
FIG. 9B is an enlarged perspective view of the mating
portion of the slit of the supporting member of the
submerged membrane separator and the slit of the
supporting plate of the membrane cartridges in the first
embodiment and shows a state in which air diffusion is
performed;
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 the submerged membrane
separator in the first embodiment;
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 the submerged membrane
separator in the first embodiment and shows a state in
which the side cover and the supporting member is removed
from the casing;
FIG. 12A is an X-X arrow view in FIG. 10;
FIG. 12B is an X-X arrow view in FIG. 11;
FIG. 13 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a second embodiment of the present
invention;

FIG. 14 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a third embodiment of the present invention;
FIG. 15 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a fourth embodiment of the present
invention;
FIG. 16 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a fifth embodiment of the present invention;
FIG. 17 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a sixth embodiment of the present invention;
FIG. 18A is an enlarged view of a peripheral portion
of a membrane cartridge of a submerged membrane separator
in a seventh embodiment of the present invention;
FIG. 18B is an enlarged view of a peripheral portion
of a membrane cartridge of a submerged membrane separator
in an eighth embodiment of the present invention;
FIG. 18C is an enlarged view of a peripheral portion
of a membrane cartridge of a submerged membrane separator
in a ninth embodiment of the present invention;
FIG. 19 is a sectional perspective view of projecting
portions of a membrane cartridge of a submerged membrane
separator in a tenth embodiment of the present invention;
FIG. 20 is a sectional view of recesses of a membrane
cartridge of a submerged membrane separator in an
eleventh embodiment of the present invention;
FIG. 21 is a sectional view of recesses of a membrane
cartridge of a submerged membrane separator in a twelfth
embodiment of the present invention;
FIG. 22 is a sectional view of a peripheral portion
of a membrane cartridge of a submerged membrane separator
in a thirteenth embodiment of the present invention;

FIG. 23 is a perspective view of a membrane cartridge
of a submerged membrane separator in a fourteenth
embodiment of the present invention;
FIG. 24 is a disassembled perspective view showing
the configuration of the submerged membrane separator in
the fourteenth embodiment;
FIG. 25A is a longitudinal sectional view of the
membrane cartridge of the submerged membrane separator in
the fourteenth embodiment and shows the membrane
cartridge in which a filtration membrane is divided into
upper and lower two portions;
FIG. 25B is a longitudinal sectional view of the
membrane cartridge of the submerged membrane separator in
the fourteenth embodiment and shows the membrane
cartridge in which the filtration membrane is not
divided;
FIG. 26 is a perspective view of a membrane cartridge
of a submerged membrane separator in a fifteenth
embodiment of the present invention;
FIG. 27A is a front view of a membrane cartridge
provided in a submerged membrane separator in a prior
art;
FIG. 27B is an enlarged view in an X portion in FIG.
2 7A;
FIG. 28 is a partially cutout perspective view of the
submerged membrane separator including membrane
cartridges in the prior art;
FIG. 29 is a perspective view showing a method of
jetting cleaning liquid on and cleaning the membrane
cartridges of the submerged membrane separator in the
prior art;
FIG. 30A shows a state in which the cleaning liquid
directly hits against the edge of a filtration membrane
when the cleaning liquid is jetted on the membrane

cartridge of the submerged membrane separator in the
prior art; and
FIG. 30B shows a state in which the edge of the
filtration membrane peels from a filtration plate when
the cleaning liquid is jetted on the membrane cartridge
of the submerged membrane separator in the prior art.
Best Mode for Carrying Out the Invention
A first embodiment in the present invention is
explained below with reference to FIGS. 1 to 12.
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 filled
with activated sludge and separates activated sludge and
treated water. The submerged membrane separator 31
includes a box-type casing 33 for membranes opened at the
top and the bottom, a plurality of flat membrane
cartridges 34 arrayed in parallel to one another in this
casing 33, and an air diffuser 36 provided below these
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 3 8 that cover both front and rear ends of
the frame body 37, and a pair of left and right side
covers 39a and 39b detachably attached to both sides of
the frame body 37.
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 four corners of both the frames 41
and 42.

[0027]
Side openings 45a and 45b through which the membrane
cartridges 34 can be removed and inserted in a width
direction A (left-right direction) are formed on both the
left and right sides of the frame body 37. One side cover
39a is attached to the frame body 37 by a plurality of
bolts 46 and closes one side opening 45a. Similarly, the
other side cover 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 one side cover
3 9a is removed from the frame body 37, one side opening
45a is opened. Similarly, when the other side cover 39b
is removed from the frame body 37, the other side opening
45b is opened.
Each of the membrane cartridges 34 is formed in a
rectangular shape long in the up-down direction and
includes a filtration plate 49, filtration membranes 50
attached to both the front and rear sides of the
filtration plate 49, and a plurality of supporting
portions 51a and 51b. A pair of upper and lower
supporting portions 51a and 51b are provided on both the
sides of the filtration plate 49 in the width direction A
and project to the outer side. Recesses 52 having a
square shape are formed in the supporting portions 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 in 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 the front and rear sides of the filtration plate

49. The permeate channels are covered with the filtration
membranes 50.

As shown in FIGS. 1 to 3, a pair of left and right
water collecting pipes 55 that collect 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.
[0031]
As shown in FIGS. 4 to 6, peripheral portions of the
filtration membranes 50 are welded to the filtration
plate 4 9 by ultrasound or the like, whereby the
filtration membranes 50 are joined to the filtration
plate 49. Melting allowances 58 are respectively
projected and formed on both the front and rear sides of
the filtration plate 49. These melting allowances 58 melt,
whereby the peripheral portions of the filtration
membranes 50 are welded to the filtration plate 49.
Welded portions 59 of the filtration membranes 50 and the
filtration plate 49 are formed over the entire periphery
along the peripheral portions of the filtration membranes
50. A method of joining the filtration membranes 50 and
the filtration plate 49 is not limited to the welding and
may be fusion-bonding or bonding by an adhesive.
[0032]
A projecting portion 60 that surrounds the outer side
of the peripheral portion of the filtration membrane 50
is formed on each of both the front and rear surfaces of
the filtration plate 49. The projecting portion 60 is
equivalent to a portion higher than the surface of the
filtration plate 49 corresponding to the peripheral edge
of the filtration membrane 50. The projecting portion 60

is formed in a square frame shape by a projecting portion
60a on one side, a projecting portion 60b on the other
side, an upper projecting portion 60c, and a lower
projecting portion 60d.

The projecting portion 60a on one side is formed
along the outer side of left or right one side of the
filtration membrane 50. The projecting portion 60b on the
other side is formed along the outer side of the other
left or right side of the filtration membrane 50. The
upper projecting portion 60c is continuously formed along
the outer side of the upper side of the filtration
membrane 50. The lower projecting portion 60d is
continuously formed along the outer side of the lower
side of the filtration membrane 50.

The projecting portion 60 has a triangular section
and includes inclined surfaces 61 that further incline in
a projecting direction from the surface of the filtration
plate 49 in places closer to the peripheral edge of the
filtration membrane 50 from the peripheral edge of the
filtration plate 49. Height h from the surface of the
filtration plate 49 to the distal end of the projecting
portion 60 is set larger than height t (thickness) of the
peripheral portions of the filtration membrane 50 (i.e.,
height h ≥ thickness t).
The filtration plate 49 may have a solid structure
filled inside, may be a hollow structure having a hollow
in the inside, or may be a frame body. The filtration
plate 49 only has to have in a flat shape in a state in
which the filtration membrane 50 is arranged.
As shown in FIGS. 2 and 3, a pair of left and right
supporting members 63a and 63b are provided in upper and

lower two places in the inside of the casing 33 for
membranes. As shown in FIGS. 8 and 9, these supporting
members 63a and 63b support the supporting portions 51a
and 51b of the membrane cartridges 34 while allowing
movement in an up-down direction B. The supporting
members 63a and 63b have horizontal frames 64 and
supporting members 65 provided in the horizontal frames
64.
As shown in FIGS. 8 to 12, the horizontal frames 64
are angle-shaped members having vertical plate portions
64a and horizontal plate portions 64b. Both ends of the
horizontal frames 64 are detachably coupled between the
front and rear vertical frames 43a and 43b by bolts 66
and nuts 67.
A material of the supporting members 65 is an elastic
material such as rubber. Grooves 68 are formed over the
entire length on the outer surfaces of the supporting
members 65. A plurality of front and rear V-shaped slits
6 9 are formed on the inner surfaces of the supporting
members 65. The horizontal plate portions 64b of the
horizontal frames 64 are inserted into the grooves 68 of
the supporting members 65, whereby the supporting members
65 are attached to the horizontal frames 64.

As shown in FIGS. 9, 10, and 12A, the recesses 52 of
the supporting portions 51a and 51b of the membrane
cartridge 34 are inserted into the slits 69 of the
supporting member 65. In this state, the membrane
cartridges 34 are supported by the supporting members 63a
and 63b and a space S in a thickness direction C between
the membrane cartridges 34 is maintained at a
predetermined space by the supporting members 63a and 63b.
The recesses 52 of the supporting portions 51a and 51b

are fit in the slits 69 of the supporting member 65
without backlashing in a width direction A (left-right
direction), an up-down direction B, and an arrangement
direction C (front-rear direction).
As shown in FIG. 3 and FIGS. 10 to 12, upper guiding
members 7 0 and lower guiding members 71 are provided in
the inside of the casing 33 for membranes. The upper
guiding members 70 and the lower guiding members 71 are
members for guiding the membrane cartridge 34 in the
width direction A (left-right direction) and regulating
an amount of movement of the membrane cartridge 34
supported by the supporting members 63a and 63b in the
up-down direction B to a predetermined allowable movement
amount a. A pair of left and right upper guiding members
70 are provided in the upper frame 42 of the frame body
37 and a pair of left and right lower guiding members 71
are provided in the bottom frame 41.
A plurality of front and rear guide grooves 72 are
formed in each of the upper and lower guiding members 70
and 71. The upper end of the membrane cartridge 34 can be
inserted into and removed from the guide grooves 72 of
the upper guiding members 70 from the width direction A
(left-right direction). The lower end of the membrane
cartridge 34 can be inserted into and removed from the
guide grooves 72 of the lower guiding members 71 from the
width direction A (left-right direction).
Height H1 between upper inner surfaces 70a of the
guide grooves 72 of the upper guiding members 70 and
lower inner surfaces 71a of the guide grooves 72 of the
lower guiding members 71 is set slightly higher than
height H2 of the membrane cartridge 34. A difference

between the height H1 and the height H2 is equivalent to
the allowable movement amount a (i.e., H1-H2=α).
Actions in the configuration are explained below.
(1) As shown in FIG. 1, during filtration operation,
the inner side of the membrane cartridges 34 is
decompressed while air diffusion is performed from the
air diffuser 36, whereby sludge or the like in liquid to
be treated 74 is caught by the filtration membranes 50 of
the membrane cartridges 34. Permeate permeating through
the filtration membranes 50 and flowing into the inner
side of the membrane cartridges 34 is collected as
treated water 79 in the water collecting pipe 55 from the
water intake nozzles 53 through the connection pipes 56.

In this case, as shown in FIG. 9B, upflow 77 is
generated between the membrane cartridges 34 by air
bubbles of the air diffused from the air diffuser 36. The
matter adhering to the membrane surfaces of the membrane
cartridges 34 is removed by the upflow 77.

As shown in FIGS. 3 and 4, since the water intake
nozzles 53 are provided at the upper ends on both the
sides of the filtration plate 49, the upflow 77 smoothly
flows without hitting against the connection pipes 56.
Therefore, the matter adhering to the membrane surfaces
of the membrane cartridges 34 is sufficiently removed.
Since the upflow 77 does not hit against 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.
(2) When the membrane cartridge 34 is removed in
maintenance or the like, after the air diffusion by the

air diffuser 36 is stopped, the filtration operation is
stopped, and the liquid to be treated in the treatment
tank 32 is discharged, as shown in FIGS. 2 and 11, the
bolts 46 are unscrewed to remove one side cover 39a from
the frame body 3 7 and open one side opening 45a.
Subsequently, the bolts 66 are unscrewed to remove
the supporting members 63a on one of the left and right
from the frame body 37. Consequently, as shown in FIGS.
11 and 12B, the supporting portions 51a on one of the
left and right of the membrane cartridge 34 disengage
from the slits 69 of the supporting members 63a on one of
the left and right. Thereafter, as indicated by imaginary
lines of FIGS. 2 and 11, the membrane cartridge 34 can be
pulled out from the inside of the casing 33 for membranes
in the width direction A of the membrane cartridge 34
through one side opening 4 5a and taken out to the outer
side of the casing 33. At this point, the recesses 52 of
the supporting portions 51b on the other of the left and
right of the membrane cartridge 34 disengage from the
slits 69 of the supporting members 63b on the other of
the left and right. The membrane cartridge 34 is pulled
out in the width direction A while being guided by the
upper and lower guide 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 horizontal direction. As shown in FIG. 1,
it is possible to suppress the height of the space 73
above the casing 33 low. Even when sludge clogs 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 11, 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 guide grooves 72. The
recesses 52 of the supporting portions 51b on the other
of the left and right of the membrane cartridge 34 are
inserted into the slits 69 of the supporting members 63b
on the other of the left and right.
Subsequently, as shown in FIG. 8B, the bolts 66 are
screwed to attach the supporting members 63a on one of
the left and right to the vertical frames 43a on one of
the left and right of the frame body 37. Consequently, as
shown in FIGS. 10 and 12A, the recesses 52 of the
supporting portions 51a on one of the left and right of
the membrane cartridges 34 are inserted into the slits 69
of the supporting members 63a on one of the left and
right.
Thereafter, the bolts 46 are screwed to attach one
side cover 39a to the frame body 37 as shown in FIGS. 10
and 12A to close one side opening 45a. Consequently, the
membrane cartridge 34 is housed in the inside of the
casing 33 and supported by the supporting members 63a and
63b.
As explained above, one side opening 4 5a of the
casing 33 for membranes is closed by one side cover 39a
and the other side opening 45b is closed by the other
side cover 39b. Therefore, during filtration operation,
it is possible to prevent air bubbles of the air diffused
from the air diffuser 36 from escaping to the outside of
the casing 33 through the side openings 45a and 45b.

[0053]
(4) When properties of the liquid to be treated are
deteriorated and sludge clogs between the membrane
cartridges 34, an operator jets high-pressure cleaning
liquid 75 from an injection nozzle 76 of a cleaning
device (not shown) to clean the membrane cartridges 34.
In this case, after the air diffusion by the air diffuser
36 is stopped, the filtration operation is stopped, and
the liquid to be treated in the treatment tank 32 is
discharged, as shown in FIG. 2, the bolts 46 are
unscrewed to remove one side cover 3 9a from the frame
body 3 7 and open one side opening 4 5a.
Subsequently, as shown in FIG. 7, the injection
nozzle 76 is opposed to one side opening 45a and the
high-pressure cleaning liquid 75 is jetted from the
injection nozzle 76 to the membrane cartridges 34.
Consequently, the high-pressure cleaning liquid 75 is
jetted to spaces between the membrane cartridges 34 from
one side through one side opening 45a, the sludge
clogging between the membrane cartridges 34 is smashed
and removed, and the membrane surfaces of the membrane
cartridges 34 are cleaned.
In this case, as shown in FIGS. 5 and 6, the cleaning
liquid 75 hits against the projecting portion 60a on one
side immediately before left or right one side edge of
the filtration membrane 50 and the direction of the
cleaning liquid 75 is bent by the projecting portion 60a
on one side. Therefore, it is possible to prevent the
cleaning liquid 75 from directly hitting against left or
right one side edge of the filtration membrane 50.
Consequently, it is possible to prevent left or right one
side edge of the filtration membrane 50 from peeling from
the filtration plate 49.

[0056]
A type of the cleaning liquid 75 is not specifically
limited. For example, water, hot water, activated sludge,
acid solution, or alkaline solution is used.
In the first embodiment, as shown in FIG. 2, one side
cover 3 9a and one supporting member 63a are removed from
the frame body 3 7 to open one side opening 45a and remove
the membrane cartridge 34 from and insert the membrane
cartridge 34 into the casing 33 from one side opening 45a.
However, as shown in FIG. 3, the other side cover 3 9b and
the other supporting 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
from the other side opening 45b.

In the first embodiment, as shown in FIG. 3, the pair
of left and right water intake nozzles 53 are provided in
the membrane cartridge 34 and the pair of left and right
water collecting pipes 55 are provided in the frame body
37. However, only the left or right water intake nozzle
53 may be provided and only the left or right water
collecting pipe 55 may be provided.
In the first embodiment, as shown in FIG. 2, one side
cover 3 9a is removed from the frame body 3 7 to open one
side opening 45a and jet the cleaning liquid 75 from one
side opening 4 5a to the spaces between the membrane
cartridges 34. However, as shown in FIG. 3, the other
side cover 3 9b may be removed from the frame body 3 7 to
open the other side opening 45b and jet the cleaning
liquid 75 from the other side opening 45b to the spaces
between the membrane cartridges 34. In this case, since
the cleaning liquid 75 hits against the projecting
portions 60b on the other side of the membrane cartridges

34, it is possible to prevent the cleaning liquid 75 from
directly hitting against the left or right other side
edges of the filtration membranes 50. Alternatively, the
cleaning liquid 75 may be jetted from the upper opening
40 of the casing 33 to the spaces between the membrane
cartridges 34. In this case, since the cleaning liquid 75
hits against the projecting portions 60c above the
membrane cartridges 34, it is possible to prevent the
cleaning liquid 75 from directly hitting against the
upper edges of the filtration membranes 50.

Next, a second embodiment in the present invention is
explained.
As shown in FIG. 13, the section of the projecting
portions 60 of the membrane cartridge 34 is formed in a
semicircular shape. Consequently, as in the first
embodiment, when an operator jets the high-pressure
cleaning liquid 75 from the injection nozzle 76 of the
cleaning device and cleans the membrane cartridge 34, the
cleaning liquid 75 hits against the projecting portion
60a on one side immediately before left or right one side
edge of the filtration membrane 50 and the direction of
the cleaning liquid 75 is bent by the projecting portion
60a on one side. Therefore, it is possible to prevent the
cleaning liquid 75 from directly hitting against left or
right one side edge of the filtration membrane 50.

Next, a third embodiment in the present invention is
explained.
As shown in FIG. 14, the section of the projecting
portions 60 of the membrane cartridge 34 is formed in a
square shape. Consequently, as in the first embodiment,
when an operator jets the high-pressure cleaning liquid

75 from the injection nozzle 76 of the cleaning device
and cleans the membrane cartridge 34, the cleaning liquid
75 hits against the projecting portion 60a on one side
immediately before left or right one side edge of the
filtration membrane 50 and the direction of the cleaning
liquid 75 is bent by the projecting portion 60a on one
side. Therefore, it is possible to prevent the cleaning
liquid 75 from directly hitting against left or right one
side edge of the filtration membrane 50.
Next, a fourth embodiment in the present invention is
explained.

As shown in FIG. 15, the section of the projecting
portions 60 of the membrane cartridge 34 is formed in a
square shape. The outer peripheral edges of the
projecting portions 60 are extended to the outer edge of
the filtration plate 49.
Next, a fifth embodiment in the present invention is
explained.
As shown in FIG. 16, the section of the projecting
portions 60 of the membrane cartridge 34 is formed in a
triangular shape.
Next, a sixth embodiment in the present invention is
explained.
As shown in FIG. 17, the projecting portions 60 of
the membrane cartridge 34 have a section of a regular
triangular shape. The projecting portions 60 include
inclined surfaces 80 that further incline in a projecting
direction from the surface of the filtration plate 49 in
places closer to the outer peripheral edge of the

filtration plate 49 from the filtration membranes 50. The
peripheral portions of the filtration membranes 50 are
joined to the inclined surfaces 80.

In the first to sixth embodiments, the continuous
linear projecting portions 60 are provided in the
filtration plate 49. However, the projecting portions 60
are not limited to the linear shape and may be a wavy-
shape. A plurality of the projecting portions 60 may be
provided to be superimposed on inner and outer sides
(e.g., may be provided double on inner and outer sides)
in the filtration plate 49.
Next, a seventh embodiment in the present invention
is explained.
As shown in FIG. 18A, the projecting portions 60 are
intermittently (discontinuously) provided at
predetermined spaces 81. These projecting portions 60 are
provided double on inner and outer sides. The projecting
portions 60 on an inner side 82 are disposed in positions
corresponding to the spaces 81 of the projecting portions
60 on an outer side 83.

Consequently, the cleaning liquid 75 hits against the
projecting portions 60 on the outer side 83 immediately
before left or right one side edge of the filtration
membrane 50. The cleaning liquid 75 passing through the
spaces 81 of the projecting portions 60 on the outer side
83 hits against the projecting portion 60 on the inner
side 82 immediately before left or right one side edge of
the filtration membrane 50. Consequently, the direction
of the cleaning liquid 75 is bent. Therefore, it is
possible to prevent the cleaning liquid 75 from directly
hitting against left or right one side edge of the

filtration membrane 50 and prevent left or right one side
edge of the filtration membrane 50 from peeling from the
filtration plate 49. In the seventh embodiment, the
projecting portions 60 are provided double on the inner
and outer side. However, the projecting portions 60 may
be provided triple or more.
Next, an eighth embodiment in the present invention
is explained.
As shown in FIG. 18B, the projecting portions 60 are
intermittently (discontinuously) provided at the
predetermined spaces 81. These projecting portions 60
incline at a predetermined angle (5 with respect to the
outer edge side of the filtration plate 49 to overlap
when viewed from the jetting direction of the cleaning
liquid 75.
Consequently, the cleaning liquid 75 hits against the
projecting portions 60 immediately before left or right
one side edge of the filtration membrane 50. Consequently,
the direction of the cleaning liquid 75 is bent.
Therefore, it is possible to prevent the cleaning liquid
75 from directly hitting left or right one side edge of
the filtration membrane 50 and prevent left or right one
side edge of the filtration membrane 50 from peeling from
the filtration plate 49. In the seventh and eighth
embodiments, when viewed from a direction parallel to the
jetting direction of the cleaning liquid 75, i.e., the
membrane surface direction of the filtration membrane 50
and substantially perpendicular to the peripheral edge
side of the filtration membrane 50, it is sufficient that
there is no space between the projecting portions 60. The
projecting portions 60 do not have to overlap.

Next, a ninth embodiment in the present invention is
explained.
As shown in FIG. 18C, the projecting portions 60 are
intermittently (discontinuously) provided at the
predetermined spaces 81. In this case, the cleaning
liquid 75 that collides against the projecting portions
60 adjacent to each other obstructs a flow of the
cleaning liquid 75 about to pass through the space 81 and
weakens the flow. On the basis of such an action, the
spaces 81 only have to be set to size for preventing the
filtration membrane 50 from peeling even if the cleaning
liquid 75 passes through the spaces 81. For example, a
proportion of the spaces 81 in a formation area of the
projecting portions 60 is set to be equal to or smaller
than 50%.
In the seventh to ninth embodiments, the projecting
portions 6 0 are formed in a belt shape. However, the
projecting portions 60 are not limited to the belt shape
and may be formed in, for example, a circular shape.
[0080]
Next, a tenth embodiment in the present invention is
explained with reference to FIG. 19.
Melting allowances 58 having a square frame shape are
formed to be projected on both the front and rear sides
of the filtration plate 49. These melting allowances 58
melt, whereby the peripheral edge portions of the
filtration membranes 50 are welded to the filtration
plate 49. Outer side portions of the melting allowances
58 further extend to the outer side than the peripheral
edge portions of the filtration membranes 50. Extending
portions of the melting allowances 58 are also used as
the projecting portions 60. Consequently, the peripheral

edge portions of the filtration membranes 50 are joined
to the projecting portions 60 over the entire periphery.

As explained, since the extending portions of the
melting allowances 58 are also used as the projecting
portions 60, labor and time for forming the projecting
portions 60 separately from the melting allowances 58 are
saved.
In the embodiments, the projecting portion 60a on one
side, the projecting portion 60b on the other side, the
upper projecting portion 60c, and the lower projecting
portion 60d are provided in the four places of the
filtration plate 49 of the membrane cartridge 34. However,
at least the projecting portion on any one of the sides
between these projecting portions 60a to 60d on the four
sides may be provided. In this case, the cleaning liquid
75 only has to be jetted from the side of the provided
projecting portion on at least one side.

In the embodiments, the projecting portions 60 are
formed on the filtration plate 49. However, in an
eleventh embodiment in the present invention, as shown in
FIG. 20, recesses 85 are formed on both the front and
rear sides of the filtration plate 49 instead of the
projecting portions 60. The recesses 85 have a square
sectional shape. The peripheral edges of the filtration
membranes 50 enter the bottoms in the recesses 85. Outer
side edges 88 of the recesses 85 are equivalent to the
portions higher than the surfaces of the filtration plate
49 corresponding to the peripheral edges of the
filtration membranes 50. Depth d of the recesses 85 is
set to be equal to or larger than thickness t of the
filtration membranes 50 (i.e., depth d > thickness t).

Consequently, when the high-pressure cleaning liquid
75 is jetted from the injection nozzle 76 to left or
right one side edge of the membrane cartridge 34 to clean
the membrane cartridge 34, since the peripheral edges of
the filtration membranes 50 enter (fall to) the bottoms
in the recesses 85, it is possible to prevent the
cleaning liquid 75 from directly hitting against left or
right one side edges of the filtration membranes 50.
Consequently, it is possible to prevent left or right one
side edge of the filtration membrane 50 from peeling from
the filtration plate 49.
Next, a twelfth embodiment in the present invention
is explained with reference to FIG. 21. The recesses 85
have a triangular sectional shape that inclines deeper on
sides closer to the outer edge of the filtration plate 49.
The peripheral edges of the filtration membranes 50 fall
into the recesses 85 along inclined surfaces. The outer
side edges 88 of the recesses 85 are equivalent to the
portions higher than the surfaces of the filtration plate
49 corresponding to the peripheral edges of the
filtration membranes 50.
Consequently, when the high-pressure cleaning liquid
75 is jetted from the injection nozzle 76 to left or
right one side edge of the membrane cartridge 34 to clean
the membrane cartridge 34, since the peripheral edges of
the filtration membranes 50 enter and are located on
(fall to) the bottoms in the recesses 85, it is possible
to prevent the cleaning liquid 75 from directly hitting
against left or right one side edges of the filtration
membranes 50. Consequently, it is possible to prevent
left or right one side edge of the filtration membrane 50
from peeling from the filtration plate 49.

In the eleventh and twelfth embodiments, a recess 85a
on one side, a recess 85b on the other side, an upper
recess 85c, and a lower recess 85d are provided in four
places of the filtration plate 4 9 of the membrane
cartridge 34. However, at least the projecting portion on
any one of the sides between these recesses 85a to 85d on
the four sides may be provided. In this case, the
cleaning liquid 75 only has to be jetted from the side of
the provided recess on at least one side.
Next, a thirteenth embodiment in the present
invention is explained with reference to FIG. 22.
The filtration plate 49 includes a filtration plate
main body portion 49a and a peripheral portion 49b formed
in the periphery of the filtration plate main body
portion 49a. The thickness of the peripheral portion 49b
is smaller than the thickness of the filtration plate
main body portion 49a. The filtration membranes 50 are
provided on both front and rear surfaces of the
filtration plate main body portion 49a. A step portion 86
is formed over the entire circumference between the
filtration plate main body portion 49a and the peripheral
portion 49b. Inclined surfaces 87 are formed in the step
portion 86. The inclined surfaces 87 is inclined in a
direction in which the thickness of the filtration plate
49 decreases further in an outer side direction. The
peripheral portions of the filtration membranes 50 are
bent and welded to the inclined surfaces 87. A method of
joining the filtration membranes 50 and the filtration
plate 49 is not limited to the welding and may be fusion-
bonding or bonding by an adhesive.

Consequently, when the high-pressure cleaning liquid
75 is jetted from the injection nozzle 76 to left or

right one side edge of the membrane cartridge 34 to clean
the membrane cartridge 34, the cleaning liquid 75 hits
against left or right one sides of the peripheral edge
portions of the filtration membranes 50 joined to the
inclined surfaces 87 of the filtration plate 49.
Therefore, left or right one sides of the peripheral
portions of the filtration membranes 50 are subjected to
a flow of the cleaning liquid 75 and pressed against the
inclined surfaces 87. Consequently, it is possible to
prevent the peripheral portions of the filtration
membranes 50 from peeling from the filtration plate 49.

In the thirteenth embodiment, the inclined surfaces
87 are formed on the four sides in the peripheral portion
of the filtration plate 49 of the membrane cartridge 34.
However, it is also possible that the inclined surface 87
is formed on at least one of the sides of the filtration
plate 49 and at least one of the sides of the peripheral
portion of the filtration membrane 50 is bent and welded
to the inclined surface 87. In this case, the cleaning
liquid 75 only has to be jetted from the side of one side
on which the inclined surface 87 is formed.

Next, a fourteenth embodiment in the present
invention is explained with reference to FIGS. 23 to 25.
The filtration membrane 50 of the membrane cartridge
34 is divided into upper and lower two portions 91 and 92.
A boundary section where the upper portion 91 and the
lower portion 92 are adjacent to each other is welded to
the filtration plate 49. Consequently, a welded portion
93 is formed over the entire width of the filtration
membrane 50 in the boundary section 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 left or right one side
of the filtration plate 49 and at the upper end of the
upper portion 91. The lower water intake nozzle 53b is
provided on left or right one side of the filtration
plate 49 and at the upper end of the lower portion 92.
A pair of upper and lower water collecting piles 55a
and 55b that collect treated water sucked from the water
intake nozzles 53a and 53b are provided on one side of
the frame body 37 of the casing 33. The upper water
collecting pipe 55a and the upper water intake nozzle 53a
are connected via the connection pipe 56 and the lower
water collecting pipe 55b and the lower water intake
nozzle 53b are connected via the connection pipe 56.
Both the side covers 39a and 39b are respectively
divided vertically 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 37 by the bolts 46.
Consequently, during filtration operation, the inner
side of the membrane cartridges 34 is decompressed while
air diffusion is performed from an air diffuser 36,
whereby sludge or the like in the liquid to be treated is
caught by the filtration membranes 50 of the membrane
cartridge 34. Permeate permeating through the filtration
membranes 50 and flowing into the inner side of the
membrane cartridges 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, the upflow 77 is generated between the
membrane cartridges 34 by air bubbles of the air diffused
from the air diffuser 36. The matter adhering to the
membrane surface of the membrane cartridges 34 is removed
by the upflow 77.

The upper water intake nozzle 53a is provided at the
upper end of the upper portion 91 and the lower water
intake nozzles 53b is provided at the upper end of the
lower portion 92. Therefore, it is possible to surely
collect treated water from the entire area in the
portions 91 and 92 and prevent air pocket from occurring
in the portions 91 and 92.
When the upflow 77 flows along the filtration
membrane 50, the filtration membrane 50 vibrates in the
thickness direction with respect to the filtration plate
49 because of the force of the upflow 77. As shown in FIG.
25A, the height L of the filtration membrane 50 is
divided short into upper and lower half heights (=L/2) by
the portions 91 and 92. Therefore, as shown in FIG. 25B,
width Wl of vibration of the filtration membrane 50
vibrating in the thickness direction in each of the
portions 91 and 92 is small compared with width W2 of
vibration of the filtration membrane 50, in which the
portions 91 and 92 are not formed as shown in FIG. 25B,
vibrating in the thickness direction (W1