Description
Title of Invention: MEMBRANE CARTRIDGE
Technical Field
[0001]
The present invention relates to a membrane cartridge
constituting a submerged membrane separator used for,
e.g., solid-liquid separation of activated sludge or the
like.
Background Art
[0002]
In the related art, e.g., in a membrane bioreactor
system, a submerged membrane separator is submerged in a
reaction tank where activated sludge treatment is
performed on sewage or the like. In such a membrane
separator, multiple membrane cartridges of an organic
flat-membrane type are arranged in parallel at
predetermined intervals in the main-unit casing.
[0003]
As shown in FIGS. 9 and 10, a membrane cartridge 10
includes a rectangular filtration plate 11 extended in
vertical direction A and filtration membranes 12 provided
on both surfaces of the filtration plate 11.
Further, channel grooves 13 are formed on both
surfaces of the filtration plate 11. A permeated liquid
having passed through the filtration membranes 12 flows
through the channel grooves 13. The channel grooves 13
are extended in the vertical direction A (longitudinal
direction) and are arranged in parallel in width
direction B of the filtration plate 11.
[0004]
On the upper end of the filtration plate 11, a liquid
collection part 14 for collecting the permeated liquid in
the channel grooves 13 is formed. The liquid collection
part 14 penetrates both filtration plate surfaces of the
filtration plate 11 and the upper ends of the channel
grooves 13 communicate with the liquid collection part 14.
Moreover, the channel grooves 13 and the liquid
collection part 14 constitute a permeated liquid channel
17. On the upper edge of the filtration plate 11, a
permeated liquid outlet nozzle 15 is provided through
which the permeated liquid collected in the liquid
collection part 14 is discharged out of the membrane
cartridge 10.
[0005]
With this configuration, when the membrane cartridge
10 is used for solid-liquid separation, a suction
pressure (negative pressure) is applied to the permeated
liquid outlet nozzle 15 by using a suction pump, so that
the suction pressure is applied to the permeated liquid
channel 17 (i.e., the channel grooves 13 and the liquid
collection part 14) through the permeated liquid outlet
nozzle 15 and a tank liquid mixture 18 (liquid to be
treated) is filtered through the filtration membranes 12.
At this point, the filtered liquid having passed through
the filtration membranes 12 flows into the liquid
collection part 14 through the channel grooves 13 and the
liquid collected in the liquid collection part 14 is
discharged out of the membrane cartridge 10 from the
liquid collection part 14 through the permeated liquid
outlet nozzle 15.
[0006]
For example, the published unexamined patent
application of patent literature 1 describes the membrane
cartridge 10 in which the channel grooves 13 and the
liquid collection part 14 are formed thus on the
filtration plate 11.
[0007]
When a suction pressure is applied to the permeated
liquid channel 17 of the membrane cartridge 10, a
pressure loss to the permeated liquid outlet nozzle 15
increases toward the lower part of the membrane cartridge
10. FIG. 11 shows suction pressure distribution on the
surface of the filtration plate 11. In FIG. 11, constant-
pressure lines 19a to 19e each indicate positions having
equal pressures. The constant-pressure lines 19a to 19e
indicate lower pressures toward the lower part of the
filtration plate 11. In the pressure distribution, the
constant-pressure lines 19a to 19e are extended downward
directly under the permeated liquid outlet nozzle 15 and
the suction pressure decreases away from the permeated
liquid outlet nozzle 15. Further, in the pressure
distribution in the width direction B, the suction
pressure decreases away from beneath the permeated liquid
outlet nozzle 15 in the width direction B.
Citation List
Patent Literature
[0008]
Patent literature 1: Japanese Patent Laid-Open No. 8-
281264
Summary of Invention
Technical Problem
[0009]
In the related art, however, as shown in FIG. 11, a
pressure difference (pressure distribution, pressure
variations) in the width direction B of the filtration
plate surface increases toward the lower part of the,
filtration plate 11. Thus disadvantageously, efficient
collection of the permeated liquid becomes more difficult
toward lower parts 20 on both sides of the filtration
plate 11, so that it is difficult to effectively use the
overall surface of the filtration membrane 12 at the same
time.
[0010]
Further, as shown in FIG. 12, one membrane surface of
the membrane cartridge 10 may be blocked by, e.g., a
deposit 24 of a solid matter formed between the membranes
of the adjacent membrane cartridges 10. In this case,
filtering is not performed at the blockage of the
membrane surface, so that an effective filtration
membrane area for obtaining the permeated liquid on one
surface of the membrane cartridge 10 is smaller than that
of the other surface of the membrane cartridge 10. As a
result, an amount of the permeated liquid from the one
surface of the membrane cartridge 10 is smaller than that
from the other surface of the membrane cartridge 10. In
this way, if a blockage occurs on one membrane surface of
the membrane cartridge 10, an amount of the permeated
liquid from the front side of the membrane cartridge 10
may be different from that from the back side of the
membrane cartridge 10.
[0011]
An object of the present invention is to provide a
membrane cartridge which can effectively use filtration
membranes by efficiently collecting a permeated liquid,
and reduce a difference in the amount of permeated liquid
between the front and back sides of the membrane
cartridge, the difference being caused by, e.g., a
blockage on a membrane surface.
Solution to Problem
[0012]
In order to attain the object, a first invention is a
membrane cartridge constituting a submerged membrane
separator, the membrane cartridge including:
a filtration membrane provided at least on one
surface of a filtration plate;
a channel groove pattern formed on the surface of the
filtration plate covered with the filtration membrane,
the channel groove pattern allowing the passage of a
permeated liquid having passed through the filtration
membrane; and
a permeated liquid outlet provided on the
circumferential edge of the filtration plate, the
permeated liquid outlet collecting and taking out the
permeated liquid having passed through the channel groove
pattern,
wherein the channel groove pattern includes multiple
channel grooves,
the filtration plate includes a pressure difference
reduction groove crossing an area where the channel
groove pattern is formed,
the area where the channel groove pattern is formed
is divided into multiple water collection areas by the
pressure difference reduction groove,
the pressure difference reduction groove communicates
with the permeated liquid outlet through the channel
grooves, and
the pressure difference reduction groove has a larger
channel cross-sectional area than the channel groove.
[0013]
With this configuration, in solid-liquid separation
performed by a membrane cartridge on a liquid to be
treated, a suction pressure is applied to the inside of
the membrane cartridge through the permeated liquid
outlet, so that the liquid to be treated is filtered
through the filtration membranes, and the permeated
liquid having passed through the filtration membranes
flows through the channel grooves and the pressure
difference reduction groove and is collected out of the
membrane cartridge from the permeated liquid outlet.
[0014]
At this point of time, the permeated liquid flowing
through the channel grooves of the water collection area
farther from the permeated liquid outlet than the
pressure difference reduction groove is collected to the
pressure difference reduction groove from the channel
grooves before reaching the permeated liquid outlet. The
channel cross-sectional area of the pressure difference
reduction groove is larger than that of the channel
groove and the pressure difference "reduction groove
crosses the area where the channel groove pattern is
formed, so that the flow velocity of the permeated liquid
in the pressure difference reduction groove is lower than
the flow velocity of the permeated liquid in the channel
grooves.
[0015]
With this configuration, variations in suction
pressure in the water collection area closer to the
permeated liquid outlet than the pressure difference
reduction groove are averaged and reduced in the
longitudinal direction of the pressure difference
reduction groove. Thus suction pressures in the water
collection area farther from the permeated liquid outlet
than the pressure difference reduction groove are
averaged in the longitudinal direction of the pressure
difference reduction groove, so that the permeated liquid
can be effectively obtained by using the overall membrane
surface.
[0016]
According to a second invention, the filtration plate
has a shape whose length and width are different,
the permeated liquid outlet is provided on or near
the upper end of the filtration plate when the filtration
plate is placed upright such that the longitudinal
direction of the filtration plate is oriented in the
vertical direction, and
the pressure difference reduction groove is provided
from one side to the other side of the filtration plate.
[0017]
With this configuration, the overall surface of the
vertically oriented filtration membrane is effectively-
used by suppressing variations in suction pressure in the
width direction of the filtration plate surface. Since
the pressure difference reduction groove is provided from
one side to the other side of the filtration p'late,
variations in suction pressure in the water collection
area closer to the permeated liquid outlet than the
pressure difference reduction groove are averaged in the
width direction of the filtration plate surface by the
pressure difference reduction groove. Thus suction
pressures in the water collection area farther from the
permeated liquid outlet than the pressure difference
reduction groove are averaged in the width direction of
the filtration plate surface, so that the overall surface
of the filtration membrane can be effectively used.
[0018]
According to a third invention, the channel grooves
are linearly formed and arranged in parallel.
[0019]
With this configuration, the channel resistance
decreases when the permeated liquid flows into the
channel grooves.
[0020]
According to a fourth invention, the channel groove
pattern includes multiple communication grooves
connecting the adjacent channel grooves.
[0021]
With this configuration, the permeated liquid flows
to the permeated liquid outlet through the channel
grooves and the communication grooves, and is collected
out of the membrane cartridge from the permeated liquid
outlet. At this point, the permeated liquid having passed
through the filtration membrane in the water collection
area farther from the permeated liquid outlet than the
pressure difference reduction groove is collected to the
pressure difference reduction groove before reaching the
permeated liquid outlet.
[0022]
According to a fifth invention, the communication
groove and the channel groove cross each other like a
letter T.
[0023]
With this configuration, at an intersection where the
communication groove and the channel groove cross each
other, the filtration membrane is supported by the two
corners of cells surrounded by the communication grooves
and the channel grooves and one side edge of the channel
groove (i.e., supported by two points and one linear
portion) . Thus an area for supporting the filtration
membrane is larger than in the case where the
communication groove and the channel groove cross each
other like a letter X. It is therefore possible to
suppress extension of the filtration membrane and prevent
the filtration membrane from coming into the channel
grooves or the communication grooves and reducing the
effective channel cross-sectional areas of these grooves.
[0024]
According to a sixth invention, the filtration
membrane, the channel groove pattern, and the pressure
difference reduction groove are provided on each surface
of the filtration plate, and
the pressure difference reduction groove includes
communication holes communicating with both sides of the
filtration plate.
[0025]
With this configuration, a difference in suction
pressure between the front and back sides of the
filtration plate is reduced through the communication
holes, thereby suppressing an imbalance in filtering on
the front and back sides of the filtration plate.
[0026]
For example, in the case where a deposit occurs on
one surface of the membrane cartridge, the permeated
liquid cannot be obtained from the blocked area of the
membrane surface. Thus on the one surface of the membrane
cartridge, an effective filtration membrane area for
obtaining the permeated liquid is smaller than an
effective filtration membrane area for obtaining the
permeated liquid on the other surface of the membrane
cartridge. Consequently, the mean value of suction
pressures on the filtration membrane surface on the one
surface is larger than the mean value of suction
pressures on the filtration membrane surface on the other
surface.
[0027]
Therefore, the permeated liquid having passed through
the filtration membrane on the other surface partially
flows through the channel grooves on the other surface,
flows into the pressure difference reduction groove on
the one surface from the pressure difference reduction
groove on the other surface through the communication
holes, flows through the channel grooves on the one
surface with the permeated liquid having passed through
the filtration membrane on the one surface, and is
collected out of the membrane cartridge from the
permeated liquid outlet.
[0028]
When the membrane surface is blocked thus, the
communication holes act as bypass channels through which
the permeated liquid on the unblocked side partially
flows to the blocked side by using a suction pressure on
the blocked side of the membrane cartridge, and then the
permeated liquid is taken out from the permeated liquid
outlet. Thus even when an effective filtration membrane
area on one surface of the membrane cartridge is reduced
by a blockage on the membrane surface, it is possible to
reduce a difference in the amount of permeated liquid
between the front and back sides of the membrane
cartridge.
Advantageous Effects of Invention
[0029]
As has been discussed, according to the present
invention, filtration membranes can be effectively used
by efficiently collecting a permeated liquid. Further, it
is possible to reduce a difference in the amount of
permeated liquid between the front and back sides of a
membrane cartridge, the difference being caused by, e.g.,
a blockage on a membrane surface.
Brief Description of Drawings
[0030]
[FIG. 1] FIG. 1 is a partially cut perspective view of a
membrane separator including membrane cartridges
according to a first embodiment of the present invention.
[FIG. 2] FIG. 2 is a partially cut front view of the
membrane cartridge.
[FIG. 3] FIG. 3 is an enlarged view showing an
intersection of a channel groove and a communication
groove in a channel groove pattern of the membrane
cartridge.
[FIG. 4] FIG. 4 is a front view showing the filtration
plate of the membrane cartridge.
[FIG. 5] FIG. 5 is a partially cut front view of a
membrane cartridge according to a second embodiment of
the present invention.
[FIG. 6] FIG. 6 is a longitudinal sectional view showing
the sides of the two membrane cartridges.
[FIG. 7] FIG. 7 is a longitudinal sectional view showing
the sides of the two membrane cartridges with a blockage
occurring between the membrane surfaces.
[FIG. 8A] FIG. 8A is a front view showing the filtration
plate of a membrane cartridge according to a third
embodiment of the present invention.
[FIG. 8B] FIG. 8B is a front view showing the filtration
plate of a membrane cartridge according to a fourth
embodiment of the present invention.
[FIG. 8C] FIG. 8C is a front view showing the filtration
plate of a membrane cartridge according to a fifth -
embodiment of the present invention.
[FIG. 8D] FIG. 8D is a front view showing the filtration
plate of a membrane cartridge according to a sixth
embodiment of the present invention.
[FIG. 9] FIG. 9 is a partially cut front view of a
membrane cartridge according to the related art.
[FIG. 10] FIG. 10 is a longitudinal sectional view
showing the sides of the two membrane cartridges.
[FIG. 11] FIG. 11 is a front view showing the filtration
plate of the membrane cartridge.
[FIG. 12] FIG. 12 is longitudinal sectional view showing
the sides of the two membrane cartridges with a blockage
occurring between the membrane surfaces.
Description of Embodiments
[0031]
Referring to FIGS. 1 to 4, a first embodiment of the
present invention will be described below.
[0032]
As shown in FIG. 1, a submerged membrane separator 31
is provided in a reaction tank in which activated sludge
treatment is performed on sewage or the like. The
membrane separator 31 includes: a square main-unit casing
33 whose upper and lower ends are opened; multiple
membrane cartridges 34 of an organic flat-membrane type
which are provided in the main-unit casing 33; and an air
diffuser 3 5 provided below the membrane cartridges 34.
[0033]
The adjacent membrane cartridges 34 having opposed
membrane surfaces are arranged in parallel at
predetermined intervals. Although the membrane cartridges
34 are spaced at the predetermined intervals, the
membrane cartridges 34 may be contacted with each other
at least on the side edges of the membrane cartridges 34.
In this case, one side of the main-unit casing 33 may be
opened or the main-unit casing 33 may be eliminated.
[0034]
As shown in FIG. 2, the membrane cartridge 34
includes: a filtration plate 36 shaped like a rectangle
extended in vertical direction A (an example of a shape
whose length and width are different), and filtration
membranes 37 attached to both surfaces of the filtration
plate 36. The periphery of the filtration membrane 37 is
fixed to the filtration plate 36 by, e.g., welding or
bonding.
[0035]
On each surface of the filtration plate. 36, a channel
groove pattern 3 8 and first and second header grooves 43
and 44 are formed. The first and second header grooves 43
and 44 average suction pressures in width direction B of
the filtration plate surface. A permeated liquid having
passed through the filtration membrane 3 7 flows through
the channel groove pattern 38.
[0036]
The channel groove pattern 38 and the header grooves
43 and 44 are covered with the filtration membrane 37. On
the upper end of the filtration plate 36, a permeated
liquid outlet nozzle 3 9 (an example of a permeated liquid
outlet) is provided that collects the permeated liquid in
the channel groove pattern 38 and discharges the
permeated liquid out of the membrane cartridge 34.
[0037]
The channel groove pattern 38 is formed by multiple
linear channel grooves 38a that are arranged in parallel
and inclined with respect to the vertical direction, and
multiple communication grooves 38b connecting the
adjacent channel grooves 38a. As shown in FIGS. 2 and 3,
by forming the channel groove pattern 38, multiple
rectangular cells 40 surrounded by the channel grooves
38a and the communication grooves 38b are formed on both
surfaces of the filtration plate 36. The channel groove
38a and the communication groove 38b cross each other
like a letter T, and the channel cross-sectional area of
the channel groove 38a is equal to that of the
communication groove 38b.
[0038]
The first and second header grooves 43 and 44 are
linear grooves that are parallel to the upper and lower
end sides of the filtration plate 36 and are extended in
the width direction B of the filtration plate 36. The
header grooves 43 and 44 are formed from one side to the
other side of the filtration plate 36. Further, the
second header groove 44 (an example of a pressure
difference reduction groove) is formed so as to cross the
area of the channel groove pattern 38 in the width
direction B. The area of the channel groove pattern 38 is
divided into an upper water collection area 46 and a
lower water collection area 47 by the second header
groove 44.
[0039]
The permeated liquid outlet nozzle 39 includes a
nozzle body 39a protruding upward from the upper end of
the filtration plate 36, and a hole 39b formed on the
nozzle body 39a. One end of the hole 39b is opened on the
end of the nozzle body 39a and the other end of the hole
39b communicates with the first header groove 43. With
this configuration, the permeated liquid outlet nozzle 39
and the second header groove 44 communicate with each
other through the first header groove 43 and the channel
grooves 38a and the communication grooves 38b in the
upper water collection area 46. The channel grooves 38a
in the lower water collection area 47 communicate with
the second header groove 44.
[0040]
Width W1 of the first and second header grooves 43
and 44 is larger than width W2 of the channel groove 38a.
The first and second header grooves 43 and 44 have the
same depth as the channel groove 38a. Thus the channel
cross-sectional areas of the header grooves 43 and 44 are
larger than that of the channel groove 38a. The first
header groove 43 has the same channel cross-sectional
area as the second header groove 44.
[0041]
As shown in FIG. 1, above one side of the main-unit
casing 33, a water collecting pipe 50 is provided that
collects the permeated liquid sucked from the permeated
liquid outlet nozzles 39 of the membrane cartridges 34.
The permeated liquid outlet nozzle 39 and the water
collecting pipe 50 are connected to each other via a
connecting pipe 51.
[0042]
To the water collecting pipe 50, a delivery pipe 52
for delivering the permeated liquid out of the tank is
connected. On the delivery pipe 52, a suction pump is
provided that generates a suction force (negative
pressure) in the membrane cartridge 34 to suck the
permeated liquid. Without using a suction pump, a suction
pressure may be generated by using the hydraulic head
pressure of a liquid to be treated 53 in a reaction tank
32 as a filtering pressure.
[0043]
The effect of the configuration will be described
below.
[0044]
In a filtering operation, the suction pump is driven
to draw the permeated liquid through the permeated liquid
outlet nozzle 39 while air is diffused from the air
diffuser 35. Thus a suction pressure is applied to the
header grooves 43 and 44, the channel grooves 38a, and
the communication grooves 38b through the permeated
liquid outlet nozzle 39, reducing a pressure in the
membrane cartridge 34. As a result, solid matters such as
sludge in the liquid to be treated 53 are captured by the
filtration membrane 37 and removed from the surface of
the filtration membrane 37 by air diffusion. At this
point, the permeated liquid having passed through the
filtration membrane 37 flows through the first and second
header grooves 43 and 44, the channel grooves 38a, and
the communication grooves 38b, is collected out of the
membrane cartridge 34 from the permeated liquid outlet
nozzle 39, is collected to the water collecting pipe 50
through the connecting pipe 51, and is delivered out of
the tank from the water collecting pipe 50 through the
delivery pipe 52.
[0045]
At this point, the permeated liquid flowing through
the channel grooves 38a and the communication grooves 38b
of the lower water collection area 47 (that is, the water
collection area farther from the permeated liquid outlet
nozzle 39 than the second header groove 44) is collected
to the second header groove 44 from the channel grooves
38a before reaching the permeated liquid outlet nozzle 39.
The channel cross-sectional area of the second header
groove 44 is larger than that of the channel groove 38a
and the second header groove 44 crosses the area of the
channel groove pattern 38 in the width direction B, so
that the flow velocity of the permeated liquid in the
second header groove 44 is lower than the flow velocity
of the permeated liquid in the channel grooves 38a.
[0046]
With this configuration, variations in suction
pressure in the upper water collection area 46 (that is,
the water collection area closer to the permeated liquid
outlet nozzle 39 than the second header groove 44) are
averaged and reduced in the longitudinal direction of the
second header groove 44 (i.e., in the width direction B
of the filtration plate surface). Thus suction pressures
in the lower water collection area 47 are averaged in the
longitudinal direction of the header groove 44 (i.e., in
the width direction B of the filtration plate surface),
so that the permeated liquid can be effectively obtained
by using the overall membrane surface.
[0047]
FIG. 4 shows the distribution of suction pressures
generated on the surface of the filtration plate 36. The
suction pressures are averaged thus in the width
direction B of the surface of the filtration plate 36, so
that constant-pressure lines 54 in the lower water
collection area 47 become more flattened than in the
membrane cartridge of the related art. Therefore, in the
lower water collection area 47, a difference (variations)
in suction pressure in the width direction B of the
surface of the filtration plate 36 can be reduced and the
permeated liquid can be efficiently collected from lower
parts 55 on both side edges of the filtration plate 36 in
the width direction B, leading to effective use of the
overall surface of the filtration membrane 37, whereas a
permeated liquid is hard to effectively obtain from the
filtration membrane in the related art.
[0048]
The permeated liquid collected to the second header
groove 44 and. the permeated liquid having passed through -:
the filtration membrane 37 in the upper water collection
area 46 flow through the channel grooves 38a and the
communication grooves 38b of the upper water collection
area 46, are collected to the first header groove 43, and
flow into the hole 39b of the permeated liquid outlet
nozzle 39 from the first header groove 43.
[0049]
Since the channel grooves 38a are linearly formed in
the upper and lower water collection areas 4 6 and 47, the
permeated liquid smoothly flows through the channel
grooves 38a and the channel resistance is reduced.
[0050]
As shown in FIG. 3, at an intersection 58 where the
channel groove 38a and the communication groove 38b cross
like a letter T, the filtration membrane 37 is supported
by corners 59a and 59b of the two adjacent cells 40 and
one side edge 59c of the channel groove 38a (i.e.,
supported by two points and one linear portion).
Therefore, when a suction pressure is applied to the
inside of the membrane cartridge 34, the filtration
membrane 37 can be more sufficiently supported at the
intersection 58 than in the case where, for example, the
channel groove and the communication groove cross like a
letter X and the filtration membrane is supported only by
the corners of multiple cells (supported by multiple
points). It is thus possible to prevent the filtration
membrane 37 at the intersection 58 from coming into the
channel groove 38a and reducing the effective channel
cross-sectional area of the channel groove 38a.
[0051]
Referring to FIGS. 5 to 7, a second embodiment of the
present invention will be described below.
[0052]
In a second header groove 44, multiple communication
holes 63 (two communication holes in FIG. 5) are formed
that communicate with both sides of a filtration plate 36.
As shown in FIG. 6, one end of the communication hole 63
is opened in the second header groove 44 on one of the
front and back sides of the filtration plate 3 6 and the
other end of the communication hole 63 is opened in the
second header groove 44 on the other side of the
filtration plate 36.
[0053]
The effect of the configuration will be described
below.
[0054]
A difference in suction pressure between the front
and back sides of the filtration plate 36 is reduced
through the communication holes 63, thereby suppressing
an imbalance in filtering on the front and back sides of
the filtration plate 36.
[0055]
For example, as shown in FIG. 7, in the case where a
deposit 64 occurs on a filtration membrane 37 on one
surface S1 of a membrane cartridge 34 and blocks the
membrane surface in an upper water collection area 4 6 on
the one surface S1 of the membrane cartridge 34, a
permeated liquid cannot be obtained from the blocked area
of the membrane surface. Thus on the one surface S1 of
the membrane cartridge 34, an effective filtration
membrane area for obtaining the permeated liquid is
smaller than that on the other surface S2 of the membrane
cartridge 34. Consequently, the mean value of suction
pressures on the membrane surface of the filtration
membrane 37 on the one surface S1 is larger than that on
the other surface S2.
[0056]
Therefore, a part of the permeated liquid having
passed through the filtration membrane 37 on the other
surface S2 flows through channel grooves 38a on the other
surface S2, flows into the second header groove 44 on the
one surface S1 from the second header groove 44 on the
other surface S2 through the communication holes 63,
flows through the channel grooves 38a on the one surface
S1 with the permeated liquid having passed through the
filtration membrane 37 on the one surface S1, and is
collected out of the membrane cartridge 34 from a
permeated liquid outlet nozzle 39.
[0057]
When the membrane surface is blocked thus, the
communication holes 63 act as bypass channels through
which a part of the permeated liquid on the unblocked
side (S2) flows to the blocked side (S1) by using a
suction pressure on the blocked side (S1) of the membrane
cartridge 34, and then the permeated liquid is taken out
from the permeated liquid outlet nozzle 39. Thus even
when the effective filtration membrane area of one of the
front and back sides of the membrane cartridge 34 is
reduced by a blockage on the membrane surface, it is
possible to reduce a difference in the amount of
permeated liquid between the front and back sides of the
membrane cartridge 34.
[0058]
As shown in FIG. 5, the two communication holes 63
are formed in the second embodiment. At least three
communication holes or only one communication hole may be
formed.
[0059]
Referring to FIGS. 8A to 8D, the following will
describe third to sixth embodiments of the present
invention.
[0060]
In the first embodiment, as shown in FIG. 2, the
second header groove 44 crossing the area of the channel
groove pattern 38 in the width direction B is formed in
parallel with the upper and lower end sides of the
filtration plate 36, whereas in the third embodiment, as
shown in FIG. 8A, a second header groove 44 crossing the
area of a channel groove pattern 38 in width direction B
is inclined with respect to the upper and lower end sides
of a filtration plate 36.
[0061]
In the first embodiment, as shown in FIG. 2, the
channel groove pattern 38 of the upper water collection
area 46 and the channel groove pattern 38 of the lower
water collection area 47 are identical to each other,
whereas in the fourth embodiment, as shown in FIG. 8B, a
channel groove pattern 38 of an upper water collection
area 46 and a channel groove pattern 66 of a lower water
collection area 47 may be different from each other. The
channel groove pattern 66 is formed by multiple channel
grooves 66a and multiple communication grooves 66b.
[0062]
In the channel groove pattern 38 of the upper water
collection area 46, channel grooves 38a are inclined to
one side with respect to the vertical direction and are
directed to a permeated liquid outlet nozzle 39. The
channel grooves 66a of the channel groove pattern 66 in
the lower water collection area 47 are inclined with
respect to the vertical direction, in the opposite
direction from the channel grooves 38a (to the other
side).
[0063]
In the first embodiment, as shown in FIG. 2, the two
upper and lower header grooves 43 and 44 and the two
upper and lower water collection areas 46 and 47 are
provided on the filtration plate surface of the
filtration plate 36, whereas in the fifth embodiment, as
shown in FIG. 8C, three header grooves 43, 44, and 6 8 and
three water collection areas 46, 47, and 69-may be
vertically provided on the filtration plate surface of a
filtration plate 36. In the sixth embodiment, as shown in
FIG. 8D, four header grooves 43, 44, 68, and 70 and four
water collection areas 46, 47, 69, and 71 may be
vertically provided on the filtration plate surface of a
filtration plate 36. With this configuration, the header
grooves 44, 68, and 70 act as pressure difference
reduction grooves, so that suction pressures are averaged
in width direction B of the filtration plate surface by
the header grooves 43, 44, 68, and 70. Five or more
header grooves may be formed and five or more water
collection areas may be formed.
[0064]
In the third to sixth embodiments, communication
holes 63 may be formed in the header grooves of the
membrane cartridge 34 as in the second embodiment.
[0065]
In the foregoing embodiments, the filtration membrane
37, the channel groove patterns 38 and 66, and the header
grooves 43, 44, 68, and 70 are provided on each of the
surfaces of the filtration plate 36. The filtration
membrane, the channel groove patterns, and the header
grooves may be provided only on one of the filtration
plate surfaces. Further, the header grooves 43, 44, 68,
and 70 may penetrate both filtration plate surfaces of
the filtration plate 36. The depths of the header grooves
43, 44, 68, and 70 are not particularly limited as long
as the capacities of the header grooves are large enough
to act as headers.
[0066]
In the foregoing embodiments, a spacer (e.g., a
nonwoven fabric or sponge) may be disposed between the
filtration plate 3 6 and the filtration membrane 37 to
prevent the filtration membrane 37 from closely
contacting with the filtration plate 36.
[0067]
In the foregoing embodiments, the permeated liquid
outlet nozzle 39 is provided on the upper end of the
filtration plate 36. The permeated liquid outlet nozzle
39 may be provided near the upper end of the filtration
plate 36, e.g., on the upper part of the side edge of the
filtration plate 36.
[0068]
In the foregoing embodiments, the membrane cartridges
34 are disposed in the membrane separator 31 such that
the long sides of the membrane cartridges 34 are extended
in the vertical direction A. The membrane cartridges 34
may be disposed in the membrane separator 31 with the
long sides extended in the width direction B.
WE CLAIM
[Claim 1]
A membrane cartridge constituting a submerged
membrane separator, the membrane cartridge comprising:
a filtration membrane provided at least on one
surface of a filtration plate;
a channel groove pattern formed on the surface of the
filtration plate covered with the filtration membrane,
the channel groove pattern allowing passage of a
permeated liquid having passed through the filtration
membrane; and
a permeated liquid outlet provided on a
circumferential edge of the filtration plate, the
permeated liquid outlet collecting and taking out the
permeated liquid having passed through the channel groove
pattern,
wherein the channel groove pattern comprises multiple
channel grooves,
the filtration plate comprises a pressure difference
reduction groove crossing an area where the channel
groove pattern is formed,
the area where the channel groove pattern is formed
is divided into multiple water collection areas by the
pressure difference reduction groove,
the pressure difference reduction groove communicates
with the permeated liquid outlet through the channel
grooves, and
the pressure difference reduction groove has a larger
channel cross-sectional area than the channel groove.
[Claim 2]
The membrane cartridge according to claim 1, wherein
the filtration plate has a shape whose length and width
are different,
the permeated liquid outlet is provided on or near an
upper end of the filtration plate when the filtration
plate is placed upright such that a longitudinal
direction of the filtration plate is oriented in a
vertical direction, and
the pressure difference reduction groove is provided
from one side to the other side of the filtration plate.
[Claim 3]
The membrane cartridge according to one of claims 1
and 2, wherein the channel grooves are linearly formed
and arranged in parallel.
[Claim 4]
The membrane cartridge according to one of claims 1
to 3, wherein the channel groove pattern comprises -
multiple communication grooves connecting the adjacent
channel grooves.
[Claim 5]
The membrane cartridge according to claim 4, wherein
the communication groove and the channel groove cross
each other like a letter T.
[Claim 6]
The membrane cartridge according to one of claims 1
to 5, wherein the filtration membrane, the channel groove
pattern, and the pressure difference reduction groove are
provided on each filtration plate surface of the
filtration plate, and
the pressure difference reduction groove comprises
communication holes communicating with both sides of the
filtration plate.

A channel groove pattern 38 allowing the passage of a
permeated liquid having passed through a filtration
membrane 37 is provided on one filtration plate surface
of a filtration plate 36, and a permeated liquid outlet
nozzle 39 is provided on the filtration plate 36. The
channel groove pattern 38 includes multiple channel
grooves 38a, and a header groove 44 for averaging suction
pressures is formed on the filtration plate 36. An area
where the channel groove pattern 38 is formed is divided
into upper and lower water collection areas 46 and 47 by
the header groove 44. The permeated liquid outlet nozzle
39 and the header groove 44 communicate with each other
through the channel grooves 38a of the water collection
area 46, and the channel cross-sectional area of the
header groove 44 is larger than that of the channel
groove 38a.