FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
WATER TREATMENT DEVICE AND WATER TREATMENT METHOD;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED
AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Title of the Invention: WATER TREATMENT DEVICE AND WATER
TREATMENT METHOD
5
TECHNICAL FIELD
[0001]
The disclosure of the present application relates to
a water treatment device and a water treatment method.
10 BACKGROUND ART
[0002]
As a method for treating sewage water or wastewater
containing pollutants or contamination substances such as
organic substances, ammonia nitrogen and the like
15 (hereinafter, the water will be referred to as “water to be
treated”), a separation-membrane activated sludge method
(MBR: Membrane Bio Reactor) is used in which, using
microorganisms, the organic substances within the water to
be treated are degraded or resolved thereinto, and also,
20 liquid-solid separation is performed through a separation
membrane.
In a pretreatment stage of the separation-membrane
activated sludge method, air supply into activated sludge
(hereinafter, referred to as “auxiliary aeration”) is
25 performed in a bioreactor vessel or tank in which the
3
activated sludge is accumulated or stored in order to oxidize,
and/or to resolve pollutants or contamination substances
within water to be treated in the tank. At this time, an
‘aeration amount’ of the auxiliary aeration is controlled so
5 that dissolved oxygen concentration (DO: Dissolved Oxygen)
of the bioreactor tank achieves to be constant with respect
to a certain target value.
In a post-treatment stage of the separation-membrane
activated sludge method, the liquid-solid separation is
10 performed by membrane filtration in a membrane separation
vessel or tank. According to filtration treatment using a
separation membrane, clogging (fouling) is caused because of
pollutants or contamination substances which adhere on the
surface of the separation membrane and within its holes due
15 to continuous usage of the separation membrane. Therefore,
air is supplied from a lower portion of the separation
membrane below it (which means here the lower portion when
upward and downward positions are classified with respect to
the direction of gravity as their reference) (the air supply
20 is referred to as “membrane-face aeration”), so that the
fouling is curbed by peeling off fouling or adhered
substances on the surface of the separation membrane by means
of air bubbles in the water to be treated and by ascending
streams therein. Due to the progress of clogging in the
25 separation membrane, differential transmembrane pressure of
4
the separation membrane rises. Because of this, a membraneface aeration amount is controlled on the basis of the
differential transmembrane pressure.
[0003]
5 There is a disclosure in which a control method of an
auxiliary aeration amount and that of a membrane-face
aeration amount are proposed (for example, refer to Patent
Document 1). A membrane-face aeration amount is controlled
based on a target value of differential transmembrane
10 pressure after filtration has started, and on a prediction
value of differential transmembrane pressure which is
calculated on the basis of a measurement value in relation
to the clogging in a separation membrane. An auxiliary
aeration amount is controlled by a PI control so that the DO
15 of a bioreactor vessel or tank achieves a DO target value
which is given by operation personnel of a water treatment
device.
RELATED ART DOCUMENT
Patent Document
20 [0004]
[Patent Document 1] Japanese Patent Laid-Open No.
2017-18940
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
25 [0005]
5
The membrane-face aeration not only functions to
prevent the clogging in a filtration membrane, but also
functions to enhance biological treatment by supplying air
into water to be treated inside a membrane separation vessel
5 or tank. Therefore, in a case in which auxiliary aeration
is controlled based only on the DO of a bioreactor vessel or
tank as a manner in the related art, there has been a
possibility that, at a time when a membrane-face aeration
amount increases, the auxiliary aeration is supplied more
10 than it is required for by the bioreactor vessel or tank.
[0006]
The present disclosure in the application concerned
has been directed at disclosing technologies for solving
those problems as described above, an object of the
15 disclosure is to provide a water treatment device and a water
treatment method in both of which, by suitably controlling
an auxiliary aeration amount, its excessive aeration can be
curbed, while the quality of treated water is maintained in
a good condition.
20 Means for Solving the Problems
[0007]
A water treatment device disclosed in the disclosure
of the application concerned is a water treatment device
whose water treatment is carried out by performing liquid25 solid separation through a separation membrane on treated
6
water in which biological reactions are performed on water
to be treated; and the water treatment device comprises:
a membrane-face aeration supplying unit for performing
membrane-face aeration by supplying air on toward a membrane
5 face of the separation membrane across it;
an auxiliary aeration supplying unit, differing from
the membrane-face aeration supplying unit, for performing
aeration by supplying air for use in the biological
reactions; and
10 a control device for controlling an auxiliary aeration
amount being the amount of aeration supplied from the
auxiliary aeration supplying unit, in accordance with a
membrane-face aeration amount being the amount of aeration
supplied on toward the membrane face by the membrane-face
15 aeration supplying unit.
Effects of the Invention
[0008]
According to the water treatment device and a water
treatment method disclosed in the disclosure of the
20 application concerned, it is possible to provide a water
treatment device and a water treatment method in both of
which, by suitably controlling an auxiliary aeration amount,
its excessive aeration can be curbed, while the quality of
treated water is maintained in a good condition.
25 BRIEF DESCRIPTION OF DRAWINGS
7
[0009]
FIG. 1 is a configuration diagram of a water treatment
device according to Embodiments 1 through 5;
FIG. 2 is a configuration diagram of a water treatment
5 device according to Embodiment 2;
FIG. 3 is a configuration diagram of a water treatment
device according to Embodiment 3;
FIG. 4 is a configuration diagram of a water treatment
device according to Embodiment 4;
10 FIG. 5 is a configuration diagram of a water treatment
device according to Embodiment 5; and
FIG. 6 is a diagram showing an example of a hardware
configuration for executing signal processing of the water
treatment device according to Embodiments 1 through 5 each.
15 EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0010]
Embodiment 1.
The explanation will be made referring to FIG. 1 for
a water treatment device according to Embodiment 1. FIG. 1
20 is an overall configuration diagram illustrating the
entirety of water treatment devices each according to
Embodiments 1 through 5. In the figure, the solid lines
each with an arrow(s) indicate pipelines in each of which a
fluid flows thereinside, together with the directions of
25 those flows; and the broken lines each with an arrow indicate
8
signal lines each indicating flows of signals between
respective constituent elements constituting the water
treatment device of the embodiment, together with the
directions of those flows (the indications are also
5 applicable in FIG. 2 through FIG. 5 in a similar fashion as
will be explained below).
[0011]
In FIG. 1, water to be treated flows into a water
treatment vessel or tank 100 by way of a pipeline a. Within
10 the water treatment tank 100, purification treatment is
performed on the water to be treated through biological
reactions, so that treated water is obtained. Namely, within
the water treatment tank 100, produced are the treated water
that is cleaned or purified fluid in comparison with the
15 water to be treated, and solid matter or solid substances
including activated sludge.
In addition, in the water treatment tank 100, a
separation membrane 3 is placed, so that treated water
produced through the separation membrane 3 and solid
20 substances produced thereby are thus separated through
liquid-solid separation.
Moreover, to the separation membrane 3, a filtration
pump 4 is connected by way of a pipeline c, so that the
liquid-solid separation is performed by such a way that the
25 filtration pump 4 sucks through the separation membrane 3
9
solid substances of activated sludge or the like inside the
water treatment tank 100. A filtrate after the liquid-solid
separation has been performed is then emitted from the
filtration pump 4 by way of a pipeline d.
5 Furthermore, activated sludge by which liquid-solid
separation has been performed in a membrane separation vessel
or tank 2 is returned back into the water treatment tank 100
by way of a pipeline e; however, a surplus portion(s) of the
activated sludge is emitted to the exterior by way of a
10 pipeline f.
[0012]
Here, in the water treatment tank 100, a first airdiffusion unit 5 is placed, so that air supply (auxiliary
aeration) is performed from an auxiliary aeration supplying
15 unit 8 into the water treatment tank 100 by way of the first
air-diffusion unit 5. Air and activated sludge are mixed
with each other inside the water treatment tank 100, whereby
organic substances in the water to be treated and nitrogen
contents therein are oxidized and/or resolved into.
20 In addition, in the water treatment tank 100, a second
air-diffusion unit 6 is placed, so that air supply (membraneface aeration) is performed from a membrane-face aeration
supplying unit 10 through across the separation membrane 3
by way of the second air-diffusion unit 6.
25 And then, in order to curb the fouling which is caused
10
due to continuous usage of the separation membrane 3, air is
supplied from a lower portion of the separation membrane 3
below it, so that fouling or adhered substances on the
surface of the separation membrane 3 are peeled off by means
5 of air bubbles in the water treatment tank 100 and ascending
streams of the fluid therein.
Moreover, a control device 20 receives a pressure
measurement-value having been measured by a pressure
measurement unit 12 by way of a signal line 12a, and notifies
10 the value by transmitting it to the auxiliary aeration
supplying unit by way of a signal line 20a. The auxiliary
aeration supplying unit acts to change an auxiliary aeration
amount into the first air-diffusion unit 5 in accordance
with the pressure measurement-value. In this case, the
15 aforementioned pressure measurement-value varies by
receiving an influence of the amount of air supply (the
membrane-face aeration) supplied from the membrane-face
aeration supplying unit 10, and so, as a result, the control
device results in controlling an auxiliary aeration amount
20 in accordance with a membrane-face aeration amount.
[0013]
It should be noted that, in the control device
described above, a targeted auxiliary aeration-amount
setting unit may be provided for setting a targeted auxiliary
25 aeration amount in use for setting an auxiliary aeration
11
amount as a target being supplied into the auxiliary aeration
supplying unit. By providing the targeted auxiliary
aeration-amount setting unit, it becomes possible to supply
an auxiliary aeration amount into the first air-diffusion
5 unit 5 of the auxiliary aeration supplying unit more
accurately in accordance with a pressure measurement-value
of the pressure measurement unit, so that the water to be
treated can be made clean even more efficiently.
In addition, also through the membrane-face aeration,
10 activated sludge inside the water treatment tank 100 and air
are mixed with each other; and thus, the reactions proceed
by which organic substances included in the water to be
treated and nitrogen contents therein are oxidized and/or
resolved into.
15 [0014]
Embodiment 2.
Next, the explanation will be made referring to FIG.
2 for a water treatment device according to Embodiment 2.
FIG. 2 is an overall configuration diagram illustrating the
20 entirety of the water treatment device according to
Embodiment 2. Note that, the explanation will be simplified
for constituent elements of the water treatment device where
they are common to those in FIG. 1.
In FIG. 2, by using a bioreactor vessel or tank 1 in
25 which activated sludge is accumulated or stored, water to be
12
treated which flows in by way of the pipeline a is performed
through purification treatment by means of biological
reactions, and then, outflowed water on which the
purification treatment has been performed is subsequently
5 emitted into a pipeline b. The outflowed water having been
emitted from the bioreactor tank 1 flows into a membrane
separation vessel or tank 2 by way of the pipeline b. In
the membrane separation tank 2, the separation membrane 3 is
placed. The separation membrane 3 is connected to the
10 filtration pump 4 by way of the pipeline c, so that liquidsolid separation is performed by such a way that the
filtration pump 4 sucks activated sludge inside the membrane
separation tank 2 through the separation membrane 3. A
filtrate after the liquid-solid separation has been
15 performed is emitted from the filtration pump 4 by way of
the pipeline d.
In addition, activated sludge by which liquid-solid
separation has been performed in the membrane separation
tank 2 is returned back into the bioreactor tank 1 by way of
20 the pipeline e; however, a surplus portion(s) of the
activated sludge is emitted to the exterior by way of the
pipeline f.
[0015]
Here, in the bioreactor tank 1, the first air-diffusion
25 unit 5 is placed, so that air supply (auxiliary aeration) is
13
performed from the auxiliary aeration supplying unit 8 into
the bioreactor tank 1 by way of the first air-diffusion unit
5. Air and activated sludge are mixed with each other inside
the bioreactor tank 1, whereby organic substances in the
5 water to be treated and nitrogen contents therein are
oxidized and/or resolved into.
[0016]
Meanwhile, in the membrane separation tank 2, the
second air-diffusion unit 6 is placed, so that air supply
10 (membrane-face aeration) is performed from the membrane-face
aeration supplying unit 10 by way of its second air-diffusion
unit 6 through across the separation membrane 3 placed in
the membrane separation tank 2.
And then, in order to curb the fouling which is caused
15 due to continuous usage of the separation membrane 3, air is
supplied from a lower portion of the separation membrane 3
below it, so that fouling or adhered substances on the
surface of the separation membrane 3 are peeled off by means
of air bubbles in the water to be treated and ascending
20 streams therein.
[0017]
However in this case, also through the membrane-face
aeration, activated sludge inside the membrane separation
tank 2 and air are mixed with each other; and thus, similarly
25 to the case of the bioreactor tank 1, also inside the
14
membrane separation tank 2, the reactions proceed by which
organic substances in the water to be treated and nitrogen
contents therein are oxidized and/or resolved into.
[0018]
5 In addition, the targeted auxiliary aeration-amount
setting unit 7 calculates a target value of auxiliary
aeration amount supplied from the first air-diffusion unit
5, and transmits the target value of auxiliary aeration
amount to the aforementioned auxiliary aeration supplying
10 unit 8 by way of a signal line 7a. Through the auxiliary
aeration supplying unit 8, the amount of air in accordance
with the target value of auxiliary aeration amount calculated
by the targeted auxiliary aeration-amount setting unit 7 is
supplied into the first air-diffusion unit 5 by way of a
15 pipeline g.
[0019]
In addition, a targeted membrane-face aeration-amount
calculation unit 9 calculates a target value of membraneface aeration amount supplied from the second air-diffusion
20 unit 6, and transmits the target value of membrane-face
aeration amount to the membrane-face aeration supplying unit
10 by way of a signal line 9a. Through the membrane-face
aeration supplying unit 10, the amount of air in accordance
with the target value of membrane-face aeration amount
25 calculated by the targeted membrane-face aeration-amount
15
calculation unit 9 is supplied into the second air-diffusion
unit 6 by way of a pipeline h.
[0020]
In addition, in order to measure the DO (dissolved
5 oxygen concentration) within the bioreactor tank 1, a DO
measurement unit 11 is placed in the interior of the
bioreactor tank 1. The DO measurement unit 11 can be placed
at any place within the bioreactor tank 1; however, in order
to measure the DO at a time point when water to be treated
10 having been flowed into the bioreactor tank 1 ends the
treatment within the bioreactor tank 1, it is desirable that
the DO measurement unit 11 is placed at a position nearer to
the pipeline b.
[0021]
15 Moreover, the pressure measurement unit 12 is placed
on the pipeline c in use for measuring the pressure of fluid,
so that the pressure of fluid at a position of the pipeline
c (differential transmembrane pressure) is measured at a
time when the water to be treated goes through the filtration
20 by the filtration pump 4. Differential transmembrane
pressure measured by the pressure measurement unit 12 is
transmitted into the targeted membrane-face aeration-amount
calculation unit 9 by way of the signal line 12a.
[0022]
25 Furthermore, a targeted water quality setting unit 13
16
calculates a target value of the DO of the bioreactor tank
1 on the basis of a target value of membrane-face aeration
amount transmitted from the targeted membrane-face aerationamount calculation unit 9 by way of a signal line 9b. A
5 target value of the DO calculated by the targeted water
quality setting unit 13 is transmitted to the targeted
auxiliary aeration-amount setting unit 7 by way of a signal
line 13a. To the targeted auxiliary aeration-amount setting
unit 7, the DO having been measured by the DO measurement
10 unit 11 is transmitted by way of a signal line 11a, and a
target value of auxiliary aeration amount is calculated so
that the DO of the bioreactor tank 1 takes on a target value
of DO having been calculated by the targeted water quality
setting unit 13. Note that, in the embodiment, the control
15 device 20 controls by means of the aforementioned targeted
water quality setting unit 13 and the aforementioned targeted
auxiliary aeration-amount setting unit 7 an auxiliary
aeration amount supplied into the bioreactor tank 1 from the
auxiliary aeration supplying unit.
20 [0023]
Next, the explanation will be made for a calculation
method of a target value of membrane-face aeration amount by
the targeted membrane-face aeration-amount calculation unit
9 described above. By the targeted membrane-face aeration25 amount calculation unit 9, a target value of membrane-face
17
aeration amount is calculated on the basis of differential
transmembrane pressure having been measured by the pressure
measurement unit 12. Differential transmembrane pressure
measured by the aforementioned pressure measurement unit 12
5 is a determinant indicator for a progress degree of fouling
of the separation membrane 3, so that the more the fouling
of the separation membrane 3 proceeds, the higher the
differential transmembrane pressure increases. Meanwhile,
the separation membrane is washed by means of chemical
10 solution in a regular manner, and so, fouling of the
separation membrane is eliminated.
[0024]
Note that, a frequency to wash a separation membrane
by a chemical solution (hereinafter, the frequency may also
15 be referred to as a “frequency of chemical solution washing”
for brevity) is determined in every one of treatment sites
each for a time period between one week and six months in
view of the characteristics of the separation membrane and/or
an operational condition of a water treatment device. During
20 the time period, an appropriate membrane-face aeration
amount is supplied from the membrane-face aeration supplying
unit 10 in order not to observe a case in which differential
transmembrane pressure exceeds an upper-limit value
determined in every one of treatment sites (for example, 30
25 kPa) due to the separation membrane 3 rapidly causing its
18
fouling.
[0025]
Here, by the targeted membrane-face aeration-amount
calculation unit 9, a target value of membrane-face aeration
5 amount is determined in order not to observe a case in which
differential transmembrane pressure reaches the upper-limit
value within a time period to wash a separation membrane by
a chemical solution; and so, as far as such a case is not
observed, the target value of membrane-face aeration amount
10 may be determined by any scheme. For example, it is
conceivable to achieve by a scheme in which a target value
of membrane-face aeration amount is regulated so that
differential transmembrane pressure rises at a predetermined
speed, a scheme in which a target value of membrane-face
15 aeration amount is increased in proportional to differential
transmembrane pressure, or the like.
[0026]
Note that, because differential transmembrane pressure
measured by the pressure measurement unit 12 changes in
20 accordance with the continuation of filtration, a target
value of membrane-face aeration amount calculated by the
targeted membrane-face aeration-amount calculation unit 9 is
also a value which changes in accordance with the
continuation of the filtration.
25 [0027]
19
Next, the explanation will be made for a calculation
method of a target value of DO by the targeted water quality
setting unit 13. A target value of DO is determined in such
a manner that, on the basis of a target value of membrane5 face aeration amount calculate by the targeted membrane-face
aeration-amount calculation unit 9, a target value of DO
decreases when a target value of membrane-face aeration
amount increases, and the target value of DO increases when
the target value of membrane-face aeration amount decreases.
10 [0028]
As an example, a target value of DO is determined based
on Expression (1).
DO = A1/Qm  D1 • • • (1)
Here, DO designates a target value of DO of the bioreactor
15 tank 1; A1, D1, a positive constant; and Qm, a membrane-face
aeration amount of the membrane separation tank 2.
[0029]
By determining a target value of DO on the basis of
Expression (1) described above, a target value of DO is
20 determined in such a manner that, when a target value of
membrane-face aeration amount increases, a target value of
DO decreases, and that, when the target value of membraneface aeration amount decreases, the target value of DO
increases.
25 [0030]
20
In addition, the constants A1 and D1 of Expression (1)
are values each being set in advance so that, when a
membrane-face aeration amount Qm is supplied into the
membrane separation tank 2, a target value of DO, DO, is
5 calculated which is required to make water quality of treated
water (the quality of treated water) emitted from the
filtration pump 4 satisfy a management criterion, and so,
the constants are calculated by means of a stochastic
analysis of operating data of the past, or a simulation using
10 an activated sludge model or the like.
[0031]
Note that, as for the constant D1 of Expression (1),
it is desirable to set the value that becomes larger than a
lower-limit value to DO of the bioreactor tank 1 at each of
15 treatment sites, whereby the DO exceeds the lower-limit
value to the DO with reliability; and thus, a good quality
of treated water can be obtained.
[0032]
In addition, by the targeted auxiliary aeration-amount
20 setting unit 7, a target value of auxiliary aeration amount
is calculated by means of a PI control on the basis of the
difference between the DO having been measured by the DO
measurement unit 11 and a target value of DO having been
calculated by the targeted water quality setting unit 13.
25 According to this arrangement, a target value of auxiliary
21
aeration amount is determined so that the DO to be measured
by the DO measurement unit 11 takes on a target value of DO
having been calculated by the targeted water quality setting
unit 13.
5 [0033]
In general, there exists a positive correlation
between the DO and an auxiliary aeration amount, so that the
more the auxiliary aeration amount increases, the more the
amount of oxygen dissolving in the water to be treated within
10 the bioreactor tank 1 increases, whereby the DO increases.
Meanwhile, the less the auxiliary aeration amount becomes,
the less the DO takes on.
[0034]
In Expression (1) described above, when a membrane15 face aeration amount increases, a target value of DO
decreases, and thus, in accordance with this, a target value
of auxiliary aeration amount also results in being decreased.
In addition, biological treatment inside the membrane
separation tank 2 is accelerated because of the increase of
20 the membrane-face aeration amount, and thus, excessive
auxiliary aeration can be curbed, while an ultimate quality
of treated water is suppressed at a management criterion or
lower, even when an auxiliary aeration amount of the
bioreactor tank 1 is decreased.
25 [0035]
22
In addition, in Expression (1), when a membrane-face
aeration amount decreases, a target value of DO increases,
and thus, in accordance with this, a target value of
auxiliary aeration amount also results in being increased.
5 The biological treatment inside the membrane separation tank
2 is decelerated because of the decrease of the membraneface aeration amount, and thus, an ultimate quality of
treated water can be suppressed at a management criterion or
lower by increasing an auxiliary aeration amount of the
10 bioreactor tank 1.
[0036]
By taking the configuration described above, in
Embodiment 2, a target value of DO of the bioreactor tank 1
is decreased when a membrane-face aeration amount of the
15 membrane separation tank 2 increases, and the target value
of DO of the bioreactor tank 1 is increased when the
membrane-face aeration amount of the membrane separation
tank 2 decreases, whereby excessive auxiliary aeration can
be curbed, while the quality of treated water is maintained
20 in a good condition.
[0037]
Note that, in the manner described above, the
explanation has been made for a case in which the bioreactor
tank 1 and the membrane separation tank 2 are divided into
25 two tanks with respect to each other; however, it is not
23
necessarily limited to this. Similar effects can be achieved
even in a case in which, within one vessel or tank, there
coexist a biological reaction region for performing
purification treatment by means of biological reactions, and
5 a membrane separation region where the separation membrane
3 is placed.
[0038]
Embodiment 3.
The explanation will be made referring to FIG. 3 for
10 a water treatment device according to Embodiment 3. FIG. 3
is an overall configuration diagram illustrating the water
treatment device according to Embodiment 3.
[0039]
As shown in the figure, on the pipeline a, placed is
15 an inflow load measurement unit 14 for measuring an inflow
load of the water to be treated flowing into the bioreactor
tank 1. As for the inflow load measurement unit 14, one or
more measurement devices are usually provided among a fluid
flow-rate meter and a contamination-substance concentration
20 meter (an ammonia nitrogen concentration meter, a total
nitrogen concentration meter, a BOD meter, a COD meter and
the like). Note that, a fluid flow-rate meter may only be
placed in a case in which contamination-substance
concentration can be empirically predicted in advance. Here,
25 the abbreviation BOD stands for Biochemical Oxygen Demand,
24
and the abbreviation COD, Chemical Oxygen Demand.
[0040]
In addition, when both of a fluid flow-rate meter and
a contamination-substance concentration meter are provided,
5 it becomes possible to calculate the product between the
amount of flow of the water to be treated which is flowing
into the bioreactor tank 1 and contamination-substance
concentration as an inflow load. In addition, at a treatment
site where a fluid flow-rate meter is not included, it may
10 also be suitable for using the degree of opening of an inflow
channel or the like as an alternative to a fluid flow-rate
meter. Moreover, in order to take into consideration of an
influence by a season or the like, it may also be suitable
for including a water temperature meter, in addition to a
15 fluid flow-rate meter and/or a contamination-substance
concentration meter.
[0041]
Note that, in order to measure an inflow load by giving
consideration to the amount of activated sludge which is
20 returned back into the bioreactor tank 1 by way of the
pipeline e, the inflow load measurement unit 14 may be placed
at a position nearer to the pipeline a inside the bioreactor
tank or to the pipeline e thereinside. An inflow load having
been measured by the inflow load measurement unit 14 is
25 transmitted to the targeted water quality setting unit 13 by
25
way of a signal line 14a. Because other constituent items
and components are equivalent or similar to those in
Embodiment 2, the same reference numerals and symbols
designate the same items as, or the items corresponding to,
5 those; thus, their explanation is omitted.
[0042]
Next, the explanation will be made for a calculation
method of a target value of DO by the targeted water quality
setting unit 13. A target value of DO is calculated on the
10 basis of a target value of membrane-face aeration amount
calculated by the targeted membrane-face aeration-amount
calculation unit 9, and also on the basis of an inflow load
measured by the inflow load measurement unit 14. As an
example, a target value of DO is determined based on
15 Expression (2).
[0043]
DO = A2/Qm  B2 × Sin  D2 • • • (2)
Here, DO means a target value of DO of the bioreactor tank
1; A2, B2, D2, a positive constant; Qm, a membrane-face
20 aeration amount of the membrane separation tank 2; and Sin,
an inflow load measured by the inflow load measurement unit
14.
[0044]
In Expression (2), the constants A2, B2 and D2 are
25 values each being set in advance so that, when a membrane-
26
face aeration amount Qm is supplied into the membrane
separation tank 2, a target value of DO, DO, is calculated
which is required to make water quality of treated water
(the quality of treated water) emitted from the filtration
5 pump 4 satisfy a management criterion, and so, the constants
are calculated by means of a stochastic analysis of operating
data of the past, or a simulation using an activated sludge
model or the like.
[0045]
10 Note that, as for the constant D2 of Expression (2),
it is desirable to set the value that becomes larger than a
lower-limit value to DO of the bioreactor tank 1 at each of
treatment sites, whereby the DO exceeds the lower-limit
value to the DO with reliability; and thus, it is possible
15 to obtain a good quality of treated water.
[0046]
In addition, the difference from Embodiment 2 is a
point in which a computational expression proportional to an
inflow load ( B2 × Sin) is built in within the calculation
20 expression for a target value of DO. At a general townsewage treatment site, a constant pattern(s) can be observed
in the variation of an inflow load during one day at the
time of clear sky. As for the best known variation patterns,
there arise patterns which enable to observe the peaks of
25 inflow loads in the mornings and evenings.
27
[0047]
Here, because the width of the variation of an inflow
load is relatively small at the time of clear sky, there
arise many cases in Expression (2) in which a factor causing
5 the variation of a target value of the DO results in a target
value of membrane-face aeration amount (Qm). Therefore, in
the operations at the time of clear sky, a target value of
the DO of the bioreactor tank 1 decreases when a membraneface aeration amount of the membrane separation tank 2
10 increases, and a target value of DO of the bioreactor tank
1 increases when a membrane-face aeration amount of the
membrane separation tank 2 decreases.
[0048]
Meanwhile, at the time of rain, water to be treated is
15 diluted by the rain water, whereby an inflow load is sharply
decreased. For example, in general town-sewage, there may
also be a case in which, when ammonia nitrogen concentration
of an average water to be treated is in the degree of 20 to
30 mg-N/L at the time of clear sky, ammonia nitrogen
20 concentration of the water to be treated decreases down to
1 mg-N/L at the time of rain. As described above, when an
inflow load significantly decreases due to the rain, an
auxiliary aeration amount required for the bioreactor tank
results in also being decreased significantly in accordance
25 with the decrease of inflow load.
28
[0049]
As described in Embodiment 2, in a case in which a
target value of DO is calculated on the basis of Expression
(1), an auxiliary aeration amount increases when a membrane5 face aeration amount decreases without depending on a value
of an inflow load. However, as described in the embodiment,
a target value of DO is calculated on the basis of Expression
(2), whereby the contribution of an inflow load (Sin) in the
calculation of a target value of DO increases when the inflow
10 load sharply decreases at the time of rain, so that a target
value of the DO decreases (the calculation result is derived).
[0050]
According to this arrangement, there does not arise
such a case that a target value of the DO of a bioreactor
15 tank increases more than required, even when the membraneface aeration amount decreases. In addition, because of
this, it becomes possible to curb an excessive supply of the
auxiliary aeration by the bioreactor tank 1.
[0051]
20 By taking the configuration described above, in
Embodiment 3, a target value of DO of the bioreactor tank 1
is calculated based on a membrane-face aeration amount of
the membrane separation tank 2 and on an inflow load of the
water to be treated flowing into the bioreactor tank 1,
25 whereby excessive auxiliary aeration can be curbed, while
29
the quality of treated water is maintained in a good
condition.
[0052]
Embodiment 4.
5 The explanation will be made referring to FIG. 4 for
a water treatment device according to Embodiment 4. FIG. 4
is an overall configuration diagram illustrating the water
treatment device according to Embodiment 4.
[0053]
10 A concentration measurement device of a contaminationsubstance concentration measurement unit 15 for measuring
contamination-substance concentration within the bioreactor
tank 1 is placed in the interior of the bioreactor tank 1.
As for a placement position of the concentration measurement
15 device, it can be placed at any position in the bioreactor
tank 1; however, its main role is to measure the
contamination-substance concentration at a time point when
the water to be treated flowing into the bioreactor tank 1
ends the treatment inside the bioreactor tank 1, and so, it
20 is desirable to place the concentration measurement device
of the contamination-substance concentration measurement
unit 15 at a position further nearer to the pipeline b. In
addition, the concentration measurement device of the
contamination-substance concentration measurement unit 15
25 may be placed inside the pipeline b.
30
[0054]
Note that, the contamination-substance concentration
measurement unit 15 may be placed inside the membrane
separation tank 2; however, in order to measure the
5 contamination-substance concentration of the water to be
treated having been treated within the bioreactor tank 1 in
good accuracy to a further extent, it is desirable to place
the contamination-substance concentration measurement unit
15 within the bioreactor tank 1 or inside the pipeline b.
10 Here, a contamination-substance concentration meter(s) in
which the contamination-substance concentration measurement
unit 15 has is a measurement device for measuring the
contamination-substance concentration in the water to be
treated; and, as for the contamination-substance
15 concentration meter(s), the examples are measurement devices
such as an ammonia nitrogen concentration meter, a total
nitrogen concentration meter, a BOD meter, a COD meter and
the like. In the contamination-substance concentration
measurement unit 15, one or more measurement devices are
20 provided among those contamination-substance concentration
meters.
[0055]
Subsequently, the contamination-substance
concentration having been measured by the contamination25 substance concentration measurement unit 15 described above
31
is transmitted to the targeted auxiliary aeration-amount
setting unit 7 by way of a signal line 15a. By the targeted
auxiliary aeration-amount setting unit 7, a target value of
auxiliary aeration amount is calculated so that
5 contamination-substance concentration of the bioreactor tank
1 becomes a target value of contamination-substance
concentration having been calculated by the targeted water
quality setting unit 13.
Because other constituent items and components are
10 equivalent or similar to those in Embodiment 2, the same
reference numerals and symbols designate the same items as,
or the items corresponding to, those; thus, their explanation
is omitted.
[0056]
15 Next, the explanation will be made for a calculation
method of a target value of contamination-substance
concentration by the targeted water quality setting unit 13.
In what follows, the explanation will be made for a case in
which an ammonia nitrogen concentration meter is included as
20 the contamination-substance concentration measurement unit
15; however, the same also applies to a case in which another
measurement device is included. A target value of
contamination-substance concentration is calculated on the
basis of a target value of membrane-face aeration amount
25 calculated by the targeted membrane-face aeration-amount
32
calculation unit 9. As an example, a target value of
contamination-substance concentration is determined based on
Expression (3) given below.
[0057]
5 NH4 = A3 × Qm  D3 • • • (3)
Here, NH4 designates a target value of ammonia nitrogen
concentration of the bioreactor tank 1; A3, D3, a positive
constant; and Qm, a membrane-face aeration amount of the
membrane separation tank 2.
10 [0058]
The constants A3 and D3 of Expression (3) are values
each being set in advance so that, when a membrane-face
aeration amount Qm is supplied into the membrane separation
tank 2, a target value of ammonia nitrogen concentration,
15 NH4, inside the bioreactor tank 1 is calculated which is
required to make water quality of treated water (the quality
of treated water) emitted from the filtration pump 4 satisfy
a management criterion, and so, the constants are calculated
by means of a stochastic analysis of operating data of the
20 past, or a simulation using an activated sludge model or the
like.
[0059]
By the targeted auxiliary aeration-amount setting unit
7, a target value of auxiliary aeration amount is calculated
25 by means of a PID control on the basis of the difference
33
between ammonia nitrogen concentration having been measured
by the contamination-substance concentration measurement
unit 15, and a target value of ammonia nitrogen concentration
calculated by the targeted water quality setting unit 13.
5 According to this arrangement, a target value of auxiliary
aeration amount is determined so that ammonia nitrogen
concentration measured by the contamination-substance
concentration measurement unit 15 becomes a target value of
ammonia nitrogen concentration having been calculated by the
10 targeted water quality setting unit 13.
[0060]
The difference from Embodiment 2 is a point in which
a target value of ammonia nitrogen concentration
(contamination-substance concentration) inside the
15 bioreactor tank 1 is calculated in the targeted water quality
setting unit 13. By directly measuring contaminationsubstance concentration, an excessive auxiliary aeration
amount can be reduced, while the quality of treated water is
maintained at constant.
20 [0061]
One more difference from Embodiment 2 is a point in
which a target value of ammonia nitrogen concentration is
proportional with respect to a target value of membrane-face
aeration amount. In general, there exists a negative
25 correlation between ammonia nitrogen concentration and an
34
auxiliary aeration amount, so that the more an auxiliary
aeration amount increases, the less ammonia nitrogen
concentration within the bioreactor tank 1 becomes.
Meanwhile, the less an auxiliary aeration amount becomes,
5 the more ammonia nitrogen concentration within the
bioreactor tank 1 increases.
[0062]
In Expression (3) described above, biological
reactions are enhanced within the membrane separation tank
10 2 when its membrane-face aeration amount is increased; and
thus, a target value of ammonia nitrogen concentration within
the bioreactor tank 1 is set higher. According to this
arrangement, there results in achieving that a target value
of auxiliary aeration amount is to be decreased. In addition,
15 in Expression (3) described above, a target value of ammonia
nitrogen concentration within the bioreactor tank 1 is
decreased when the membrane-face aeration amount is
decreased; and thus, in accordance with this, there results
in achieving that a target value of auxiliary aeration amount
20 is to be increased. Because the membrane-face aeration
amount is decreased, biological treatment inside the
membrane separation tank 2 is decelerated; and thus, by
increasing an auxiliary aeration amount of the bioreactor
tank 1, an ultimate quality of treated water can be
25 suppressed at a management criterion or lower.
35
[0063]
By taking the configuration described above, in
Embodiment 4, a target value of contamination-substance
concentration of the bioreactor tank 1 is increased when a
5 membrane-face aeration amount of the membrane separation
tank 2 increases, and the target value of contaminationsubstance concentration of the bioreactor tank 1 is decreased
when the membrane-face aeration amount of the membrane
separation tank 2 decreases, whereby excessive auxiliary
10 aeration can be curbed, while the quality of treated water
is maintained in a good condition.
[0064]
Embodiment 5.
The explanation will be made referring to FIG. 5 for
15 a water treatment device according to Embodiment 5. FIG. 5
is an overall configuration diagram illustrating the water
treatment device according to Embodiment 5.
[0065]
On the pipeline a, placed is the inflow load
20 measurement unit 14 for measuring an inflow load of the water
to be treated flowing into the bioreactor tank 1, which
differs from Embodiments 2 and 4 described above. In the
inflow load measurement unit 14, one or more measurement
devices are provided among a fluid flow-rate meter and a
25 contamination-substance concentration meter (an ammonia
36
nitrogen concentration meter, a total nitrogen concentration
meter, a BOD meter, a COD meter and the like). In this case,
when a fluid flow-rate meter is only provided, it is a case
in which an inflow load is acquired when the contamination5 substance concentration in the water to be treated has been
known in advance; meanwhile, when a contamination-substance
concentration meter is only provided, it is a case in which
an inflow load is acquired when the amount of flow in the
water to be treated has been made apparent in advance. In
10 the case, when both of a fluid flow-rate meter and a
contamination-substance concentration meter are provided, it
becomes possible to calculate the product between the amount
of flow of the water to be treated which is flowing into the
bioreactor tank 1 and contamination-substance concentration
15 as an inflow load. In addition, the control device 20 of
Embodiment 5 does not include a targeted water quality
setting unit, differing from that in Embodiments 2 through
4 each.
[0066]
20 In addition, at a treatment site where a fluid flowrate meter is not included, it may also be suitable for using
the degree of opening of an inflow channel or the like as an
alternative to a fluid flow-rate meter. Moreover, in order
to take into consideration of an influence by a season or
25 the like, it may also be suitable for including a water
37
temperature meter, in addition to a fluid flow-rate meter
and/or a contamination-substance concentration meter. In
addition, in order to measure an inflow load by giving
consideration to the amount of activated sludge which is
5 returned back into the bioreactor tank 1 by way of the
pipeline e, the inflow load measurement unit 14 may be placed
at a position further nearer to the pipeline a inside the
bioreactor tank, or to the pipeline e thereinside. An inflow
load having been measured by the inflow load measurement
10 unit 14 is transmitted to the targeted auxiliary aerationamount setting unit 7 by way of the signal line 14a.
[0067]
A contamination-substance concentration meter of the
contamination-substance concentration measurement unit 15
15 for measuring the contamination-substance concentration
within the membrane separation tank 2 is placed in the
interior of the membrane separation tank 2. A placement
position of the contamination-substance concentration meter
can be at any position in the membrane separation tank 2.
20 In addition, the contamination-substance concentration meter
of the contamination-substance concentration measurement
unit 15 may be placed inside the pipeline c. A
contamination-substance concentration meter of the
contamination-substance concentration measurement unit 15
25 may be placed inside the pipeline b or the bioreactor tank
38
1; however, in order to measure the contamination-substance
concentration of water to be treated having been treated by
the bioreactor tank 1 and the membrane separation tank 2, it
is desirable to place the contamination-substance
5 concentration meter inside the membrane separation tank 2 or
the pipeline c. Note that, the contamination-substance
concentration meter described above is a measurement device
for measuring the contamination-substance concentration
within water to be treated, and so, by giving consideration
10 to a measurement object(s), required measurement accuracy
and the like, a plurality of measurement devices may also be
used among measurement devices such as an ammonia nitrogen
concentration meter, a total nitrogen concentration meter,
a BOD meter, a COD meter and the like.
15 [0068]
To the targeted auxiliary aeration-amount setting unit
7, transmitted are: an inflow load having been measured by
the inflow load measurement unit 14, by way of the signal
line 14a; contamination-substance concentration having been
20 measured by the contamination-substance concentration
measurement unit 15, by way of the signal line 15a; and a
target value of membrane-face aeration amount having been
calculated by the targeted membrane-face aeration-amount
calculation unit 9, by way of the signal line 9b,
25 respectively, so that a target value of auxiliary aeration
39
amount of the bioreactor tank 1 is calculated.
Because other constituent items and components are
approximately equivalent or similar to those in Embodiment
3, the same reference numerals and symbols designate the
5 same items as, or the items corresponding to, those; thus,
their explanation is omitted.
[0069]
Next, the explanation will be made for a calculation
method of a target value of auxiliary aeration amount by the
10 targeted auxiliary aeration-amount setting unit 7.
Hereinafter, the explanation will be made for a case in which
the contamination-substance concentration measurement unit
15 includes an ammonia nitrogen concentration meter as a
contamination-substance concentration meter; however, the
15 same also applies to a case in which another measurement
device is included. A target value of auxiliary aeration
amount is determined on the basis of a target value of
membrane-face aeration amount having been calculated by the
targeted membrane-face aeration-amount calculation unit 9.
20 As a specific example, a target value of auxiliary aeration
amount is determined based on Expression (4) given below.
Note that, as for the targeted water quality setting unit
among constituent elements of the control device explained
in Embodiments 2 through 4, a targeted water quality setting
25 unit is not shown in FIG. 5 that is the figure according to
40
Embodiment 5; however, as will be explained below, PI control
calculations are performed by means of a processor or the
like built-in in the targeted auxiliary aeration-amount
setting unit 7, so that substantially similar processing is
5 performed to a case in which there exists the targeted water
quality setting unit.
[0070]
Qa = A4 × Qm  B4 × Sin  C4 × [(NH4 − NH4) 
{ (NH4 − NH4)}/Ti]  D4 • • • (4)
10 Here, Qa designates a target value of auxiliary aeration
amount of the bioreactor tank 1; A4, a negative constant;
B4, C4, D4, a positive constant; Ti, a value indicating an
integration time (unit in second); Qm, a membrane-face
aeration amount of the membrane separation tank 2; NH4,
15 ammonia nitrogen concentration measured by the
contamination-substance concentration measurement unit 15;
and NH4, a target value of ammonia nitrogen concentration
inside the membrane separation tank 2. In addition, symbol
 represents a total sum of measurement values of (NH4 −
20 NH4) after the calculation of a targeted auxiliary aerationamount has been started in accordance with Expression (4).
For example, when consideration is given to a case in which
the calculation of a targeted auxiliary aeration-amount is
performed in every interval of one minute on the basis of
25 Expression (4), a value of the term  (NH4 − NH4) after one
41
hour takes on a combined total value of measurement values
of (NH4 − NH4) at sixty times in every one minute from a
time directly after the calculation of a targeted auxiliary
aeration-amount has been started in accordance with
5 Expression (4). In addition, the term (1/Ti) being a
reciprocal number of a value Ti is a constant related to the
term  (NH4 − NH4), and so, the value Ti is adjusted in a
range from one second to 3,600 seconds so that ammonia
nitrogen concentration NH4 measured by the contamination10 substance concentration measurement unit 15 takes on NH4.
[0071]
By Expression (4), a target value of auxiliary aeration
amount is calculated in accordance with a total sum of the
following four terms (a) through (d):
15 a term (a), a proportional control with respect to a target
value of membrane-face aeration amount;
a term (b), a proportional control with respect to an inflow
load;
a term (c), a PI control for controlling on ammonia nitrogen
20 concentration inside the membrane separation tank 2 to be a
target value; and
a term (d), a constant.
[0072]
In the term (a), a negative value is set for “A4” being
25 a proportionality constant. According to this arrangement,
42
a target value of auxiliary aeration amount decreases when
a target value of membrane-face aeration amount increases,
and the target value of auxiliary aeration amount increases
when a target value of membrane-face aeration amount
5 decreases.
[0073]
In the term (b), a control being proportional to an
inflow load is built in. When an inflow load significantly
decreases due to the rain or the like, the amount of air
10 required for the bioreactor tank 1 is also significantly
decreased. In such a time, there arises a case in which a
target value of auxiliary aeration amount is not necessarily
made being increased, even in a case in which a target value
of membrane-face aeration amount is decreased, if at all.
15 Therefore, by adding a computational expression of the term
(b), a target value of auxiliary aeration amount can be
lowered when an inflow load is predominantly lowered; and
thus, it becomes possible to curb an excessive supply of the
auxiliary aeration by the bioreactor tank 1.
20 [0074]
In the term (c), built in are the calculations for a
PI control which is based on the difference between ammonia
nitrogen concentration having been measured by the
contamination-substance concentration measurement unit 15
25 and a target value of ammonia nitrogen concentration.
43
According to this arrangement, the quality of treated water
can be maintained at constant, so that it becomes possible
to obtain a good quality of treated water with stability. A
target value of ammonia nitrogen concentration may be fixed
5 throughout a time period of water treatment, or altered in
accordance with times and/or seasons; however, the target
value is set at a value of management criterion in which
each of treatment sites defines, or lower.
[0075]
10 In the term (d), as for the constant D4, it is
desirable to set the value that becomes larger than a lowerlimit value to an auxiliary aeration amount of the bioreactor
tank 1 at each of treatment sites, whereby the auxiliary
aeration amount exceeds the lower-limit value with
15 reliability; and thus, it is possible to obtain a good
quality of treated water.
[0076]
In accordance with the four calculations of (a) through
(d) described above, a target value of auxiliary aeration
20 amount is calculated, whereby the target value of auxiliary
aeration amount is determined by giving consideration not
only to biological treatment which is proceeding inside the
membrane separation tank 2, but also to an inflow load into
the bioreactor tank 1 and/or to the quality of treated water;
25 and thus, in order to treat the amount of pollutants or

contamination substances of water to be treated flowing into
the bioreactor tank 1, it becomes possible to supply a
required amount of air without excess and without shortage.
Therefore, it becomes possible to curb excessive aeration
5 into the bioreactor tank 1.
[0077]
By taking the configuration described above, a target
value of auxiliary aeration amount is calculated on the basis
of a target value of membrane-face aeration amount in such
10 a manner that a target value of auxiliary aeration amount
decreases when the target value of membrane-face aeration
amount increases, and in such a manner that a target value
of auxiliary aeration amount increases when the target value
of membrane-face aeration amount decreases; and, in addition
15 to this, a target value of auxiliary aeration amount is
calculated on the basis of an inflow load flowing into the
bioreactor tank 1 and also on the basis of contaminationsubstance concentration inside the membrane separation tank
2, whereby excessive auxiliary aeration can be curbed, while
20 the quality of treated water is maintained in a good
condition.
[0078]
As explained above, in any one of the embodiments, an
auxiliary aeration amount by a bioreactor tank is determined
25 by taking into consideration of biological treatment which
45
is proceeding by means of membrane-face aeration by a
membrane separation tank; and thus, excessive aeration by
the bioreactor tank is curbed in a case in which a membraneface aeration amount increases by the membrane separation
5 tank. Meanwhile, in a case in which membrane-face aeration
by the membrane separation tank decreases, the amount of
aeration by the bioreactor tank increases in order to
compensate that biological treatment by the membrane
separation tank is curbed, so that the quality of treated
10 water is maintained in a good condition.
[0079]
It should be noted that shown in FIG. 6 is an example
of hardware 30 according to signal processing of a water
treatment device disclosed in the disclosure of the
15 application concerned. As shown in the figure, a processor
31 and a storage device 32 are included in the hardware 30
according to the signal processing of the water treatment
device. The storage device 32 is provided with a volatile
storage device of a random access memory (RAM) or the like,
20 and with a nonvolatile auxiliary storage device of a flash
memory or the like, which are not shown in the figure. In
addition, in place of the flash memory, an auxiliary storage
device of a hard disk may be provided with. The processor
31 executes a program(s) inputted from the storage device
25 32. In this case, the program(s) is inputted into the
46
processor 31 from the auxiliary storage device by way of the
volatile storage device. Moreover, the processor 31 may
output its data of a calculated result(s) or the like into
the volatile storage device of the storage device 32, or may
5 store the data into the auxiliary storage device by way of
the volatile storage device.
[0080]
Moreover, in the disclosure of the application
concerned, various exemplary embodiments and implementation
10 examples are described; however, various features, aspects
and functions described in one or a plurality of embodiments
are not necessarily limited to the applications of a specific
embodiment(s), but are applicable in an embodiment(s) solely
or in various combinations.
15 Therefore, limitless modification examples not being
exemplified can be presumed without departing from the scope
of the technologies disclosed in Description of the
disclosure of the application concerned. For example, there
arise cases which are included as a case in which at least
20 one constituent element is modified, added or eliminated,
and further a case in which at least one constituent element
is extracted and then combined with a constituent element(s)
of another embodiment.
Explanation of Numerals and Symbols
25 [0081]

Numeral “1” designates a bioreactor tank; “2,”
membrane separation tank; “3,” separation membrane; “5,”
first air-diffusion unit; “6,” second air-diffusion unit;
“7,” targeted auxiliary aeration-amount setting unit; “7a,”
5 “9a,” “9b,” “11a,” “12a,” “13a,” “14a,” “15a,” “20a,” signal
line; “8,” auxiliary aeration supplying unit; “9,” targeted
membrane-face aeration-amount calculation unit; “10,”
membrane-face aeration supplying unit; “11,” DO measurement
unit; “12,” pressure measurement unit; “13,” targeted water
10 quality setting unit; “14,” inflow load measurement unit;
“15,” contamination-substance concentration measurement
unit; “20,” control device; “30,” hardware; “31,” processor;
“32,” storage device; “100,” water treatment tank; and “a,”
“b,” “c,” “d,” “e,” “f,” “g,” “h,” pipeline.
15

We Claim :
1. A water treatment device whose water treatment is carried
5 out by performing liquid-solid separation through a
separation membrane on treated water in which a biological
reaction is performed on water to be treated, the water
treatment device, comprising:
a membrane-face aeration supplying unit for performing
10 membrane-face aeration by supplying air on toward a membrane
face of the separation membrane across it;
an auxiliary aeration supplying unit, differing from
the membrane-face aeration supplying unit, for performing
aeration by supplying air for use in the biological reaction;
15 and
a control device for controlling an auxiliary aeration
amount being an amount of aeration supplied from the
auxiliary aeration supplying unit, in accordance with a
membrane-face aeration amount being an amount of aeration
20 supplied on toward the membrane face by the membrane-face
aeration supplying unit.
2. The water treatment device as set forth in claim 1,
further comprising
25 a targeted auxiliary aeration-amount setting unit for
49
setting an auxiliary aeration-amount’s target value being a
target value of the auxiliary aeration amount, wherein
the targeted auxiliary aeration-amount setting unit
decreases the auxiliary aeration-amount’s target value when
5 the membrane-face aeration amount increases, and increases
the auxiliary aeration-amount’s target value when the
membrane-face aeration amount decreases.
3. The water treatment device as set forth in claim 1 or
10 claim 2, further comprising:
a bioreactor tank for performing the biological
reaction thereinside;
a water-quality measurement unit for acquiring a
water-quality measurement value by measuring water quality
15 of the water to be treated; and
a targeted water quality setting unit for setting a
bioreactor tank’s water-quality target value being a target
value of water quality in the bioreactor tank, wherein
the control device controls the auxiliary aeration
20 amount by the auxiliary aeration supplying unit, on a basis
of the bioreactor tank’s water-quality target value at which
the targeted water quality setting unit sets, and on a basis
of said water-quality measurement value at which the waterquality measurement unit acquires.
25
50
4. The water treatment device as set forth in claim 3,
further comprising a membrane separation tank for placing
the separation membrane thereinside, differing from the
bioreactor tank.
5
5. The water treatment device as set forth in claim 3 or
claim 4, wherein
the water-quality measurement unit is configured to
acquire said water-quality measurement value at which
10 dissolved oxygen concentration within the water to be treated
is defined to be its water quality; and
the targeted water quality setting unit is configured
to set the bioreactor tank’s water-quality target value at
which the dissolved oxygen concentration in the bioreactor
15 tank is defined to be its water quality.
6. A water treatment method whose water treatment is
performed through a separation membrane with respect to
treated water in which a biological reaction is performed on
20 water to be treated, the water treatment method, comprising:
a membrane-face aeration supplying process-step of
performing membrane-face aeration by supplying air on toward
a membrane face of the separation membrane across it;
an auxiliary aeration supplying process-step of
25 performing aeration, differing from the membrane-face
51
aeration supplying process-step, by supplying air for use in
the biological reaction; and
a control process-step of controlling an auxiliary
aeration amount being an amount of aeration supplied at the
5 auxiliary aeration supplying process-step, in accordance
with a membrane-face aeration amount being an amount of
aeration supplied on toward the membrane face at the
membrane-face aeration supplying process-step.