FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
OXIDATION DEVICE, WATER TREATMENT DEVICE, WATER TREATMENT
METHOD, OZONE WATER GENERATION METHOD, AND CLEANING 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.

DESCRIPTION
TECHNICAL FIELD
[0001] The present disclosure relates 5 to an oxidation
device for performing treatment on oxidizable substances in
treatment target water, a water treatment device including
the oxidation device, a water treatment method using the
oxidation device, an ozone water generation method for
generating ozone water on the basis of treatment target water
treated by the water treatment method, and a cleaning method
using the ozone water.

BACKGROUND ART
[0002] In water cleaning treatment, waste water treatment,
and the like, water treatment technology using ozone is
widely applied. This water treatment technology is also used,
for example, in the case of decomposing impurities such as
organic substances contained in waste water by directly
supplying ozone gas to waste water to be treated, or in the
case of generating ozone water as a cleaning agent for a
filtration membrane to which impurities are adhered in
membrane separation technology for filtering impurities in
waste water by the filtration membrane to obtain clean water
(see, for example, Patent Document 1).
Both of the above cases are equal in using ozone
(dissolved ozone) dissolved in water for decomposing organic
substances in waste water or organic substances adhered to a
filtration membrane, and thus it is important to stably keep
the dissolved ozone present 5 in water.
[0003] However, ozone can react with substances other than
organic substances to be removed, and thus can be consumed.
In particular, ozone readily reacts with oxidizable inorganic
substances such as iron, manganese, and nitrous acid, and
these substances act as inhibitors against the purpose of
stably ensuring the dissolved ozone concentration. Therefore,
in order to prevent ozone from being consumed through
reaction between ozone and oxidizable inorganic substances in
water, disclosed is technology of blowing air into water
before supplying ozone to the water, so as to aerate the
water, thereby oxidizing and removing oxidizable substances
(see, for example, Patent Document 2).
CITATION LIST
PATENT DOCUMENT
[0004] Patent Document 1: Japanese Laid-Open Patent
Publication No. 2004-105876 (paragraphs [0008] to [0012], FIG.
4) (paragraph [0067])
Patent Document 2: Japanese Laid-Open Patent
Publication No. 11-253940

SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0005] In the above conventional water treatment
technology, in the case of using water such 5 as underground
water that has comparatively stable water quality so that
variation in the oxidizable substance concentration is small,
an oxidizable substance removing effect is obtained to a
certain extent even if air is redundantly supplied. However,
in the case of using water such as sewage water or industrial
waste water that has unstable water quality so that variation
in the oxidizable substance concentration is great,
excess/deficiency of air supply can occur.
[0006] In the case where air is deficient, supplied ozone
is consumed by oxidizable substances remaining in water, and
therefore the dissolved ozone concentration cannot be
increased. In this case, there is a problem that organic
substances remain in discharged water or the cleaning effect
of generated ozone water is reduced.
Meanwhile, in the case of supplying air to water
more than necessary, there is a problem that an excess amount
of carbonate ions is dissolved in the water. In particular,
in the case of cleaning a filtration membrane by using ozone
water, in order to enhance the cleaning effect, it is
necessary that hydroxyl radicals (OH radicals) which are
generated through self-decomposition of ozone and are lower
in reactivity with organic substances than ozone, are
contained at a high concentration in ozone water. It is
known that a carbonate ion acts as a radical scavenger, and
excess air supply can reduce the filtration 5 membrane cleaning
effect of the ozone water.
From the above, technology that enables oxidizable
substances to be sufficiently removed from water without
supplying excess air to water, is required.
[0007] The present disclosure has been made to solve the
above problem, and an object of the present disclosure is to
provide an oxidation device capable of supplying, without
excess/deficiency, an oxidation material containing an
oxidizing substance to treatment target water, and a water
treatment device including the oxidation device, provide a
water treatment method using the oxidation device, provide an
ozone water generation method for generating ozone water
having a high cleaning effect on the basis of treatment
target water treated by the water treatment method, and
provide a cleaning method using the ozone water.

SOLUTION TO THE PROBLEMS
[0008] An oxidation device according to the present
disclosure is an oxidation device for oxidizing oxidizable
substances contained in treatment target water by causing an
oxidation material containing an oxidizing substance to be in
contact with the treatment target water, the oxidation device
including: an oxidation unit for causing the oxidation
material to be in contact with the treatment target water; a
measurement unit for performing water quality 5 measurement for
the treatment target water; and a control unit which controls
the oxidation unit, determines oxidation progress of the
oxidizable substances in the treatment target water on the
basis of a first change amount obtained from change over time
in a measurement value obtained through water quality
measurement for the treatment target water by the measurement
unit, and determines to continue or stop supply of the
oxidation material to the treatment target water.
[0009] A water treatment device according to the present
disclosure includes: the oxidation device configured as
described above; a filtration unit for filtering organic
substances in raw water to generate filtered water; a first
transfer unit for transferring the filtered water as the
treatment target water to the oxidation unit; an ozone water
generation unit for generating ozone water by supplying ozone
gas to the treatment target water for which supply of the
oxidation material has been determined to be stopped; and a
second transfer unit for transferring the ozone water to the
filtration unit.
[0010] A water treatment method according to the present
disclosure is a water treatment method for oxidizing
oxidizable substances contained in treatment target water by
causing an oxidation material containing an oxidizing
substance to be in contact with the treatment target water,
the water treatment method including: determining 5 oxidation
progress of the oxidizable substances in the treatment target
water on the basis of a first change amount obtained from
change over time in a measurement value obtained through
water quality measurement for the treatment target water, and
determining to continue or stop supply of the oxidation
material to the treatment target water.
[0011] An ozone water generation method according to the
present disclosure includes generating ozone water by
supplying ozone gas to the treatment target water for which
supply of the oxidation material has been determined to be
stopped in the water treatment method configured as described
above.
[0012] A cleaning method according to the present
disclosure includes cleaning a cleaning target part using the
ozone water generated by the ozone water generation method
configured as described above.

EFFECT OF THE INVENTION
[0013] In the oxidation device and the water treatment
method according to the present disclosure, an oxidation
material containing an oxidizing substance can be supplied
without excess/deficiency, to treatment target water, whereby
it is possible to obtain treatment target water in which
dissolution of carbonate ions is reduced and oxidizable
substances are sufficiently 5 removed.
The water treatment device according to the present
disclosure includes the oxidation device configured as
described above, and the ozone water generation unit for
generating ozone water on the basis of treatment target water
treated by the oxidation device. Therefore, the filtration
unit can be cleaned using ozone water having a high cleaning
effect.
In the ozone water generation method according to
the present disclosure, ozone water is generated on the basis
of treatment target water in which dissolution of carbonate
ions is reduced and oxidizable substances are sufficiently
removed, whereby ozone water having a high cleaning effect
can be obtained.
In the cleaning method according to the present
disclosure, a cleaning target part is cleaned using ozone
water having a high cleaning effect. Therefore, an effect of
removing dirt in the cleaning target part can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS
[0014] [FIG. 1] FIG. 1 is a block diagram showing the
schematic configuration of an oxidation device and a water
treatment device according to embodiment 1.
[FIG. 2] FIG. 2 is a flowchart showing a treatment
method for treatment target water in the oxidation device
according 5 to embodiment 1.
[FIG. 3] FIG. 3 is a result of water quality
measurement for treatment target water obtained by the
oxidation device according to embodiment 1.
[FIG. 4] FIG. 4 is a flowchart showing a treatment
method for treatment target water in the oxidation device
according to embodiment 1.
[FIG. 5] FIG. 5 is a result of water quality
measurement for treatment target water obtained by the
oxidation device according to embodiment 1.
[FIG. 6] FIG. 6 is a flowchart showing a treatment
method for treatment target water in the oxidation device
according to embodiment 1.
[FIG. 7] FIG. 7 is a result of water quality
measurement for treatment target water obtained by the
oxidation device according to embodiment 1.
[FIG. 8] FIG. 8 is a result of water quality
measurement for treatment target water obtained by the
oxidation device according to embodiment 1.
[FIG. 9] FIG. 9 is a block diagram showing the
schematic configuration of a water treatment device according
to embodiment 2.
[FIG. 10] FIG. 10 is a diagram showing the
schematic configuration of an outside air contact device
according to embodiment 2.
[FIG. 11] FIG. 11 is a block diagram 5 showing the
schematic configuration of an oxidation device and a water
treatment device according to embodiment 3.
[FIG. 12] FIG. 12 is a flowchart showing a
treatment method for treatment target water in the oxidation
10 device according to embodiment 3.
[FIG. 13] FIG. 13 is a flowchart showing a
treatment method for treatment target water in the oxidation
device according to embodiment 3.
[FIG. 14] FIG. 14 is a block diagram showing the
schematic configuration of a water treatment device according
to embodiment 4.
[FIG. 15] FIG. 15 is a flowchart showing a
treatment method for treatment target water in the water
treatment device according to embodiment 4.

DESCRIPTION OF EMBODIMENTS
[0015] Embodiment 1
Hereinafter, an oxidation device, a water treatment
device, a water treatment method, an ozone water generation
method, and a cleaning method according to the present
embodiment 1 will be described with reference to the drawings.
FIG. 1 is a diagram showing the schematic
configuration of a water treatment device 100 including an
oxidation device 50 according to embodiment 1.
[0016] As shown in FIG. 1, the water treatment 5 device 100
according to the present embodiment includes: a filtration
unit 1 for filtering organic substances and the like in raw
water X which is a filtration target, to generate filtered
water; a first transfer unit 10 for transferring filtered
water Y obtained by the filtration unit 1, as treatment
target water, to the oxidation device 50 at the subsequent
stage; the oxidation device 50 for oxidizing oxidizable
substances such as iron, manganese, and nitrous acid
contained in the filtered water Y; an ozone water generation
unit 60 for supplying ozone gas to the filtered water Y to
generate ozone water O; and a second transfer unit 20 for
transferring the generated ozone water O to the filtration
unit 1.
[0017] The filtration unit 1 includes a filtration
membrane 2 for filtering the raw water X, a filtration water
tank 3 storing the filtration membrane 2, and a raw water
pipe 4 for supplying the raw water X to the filtration water
tank 3. The raw water X is stored in the filtration water
tank 3, and the filtration membrane 2 is immersed in the raw
water X. Here, the raw water X is not particularly limited,
and may be, for example, natural water taken from a river, a
lake, the sea, or the like, or may be waste water such as
sewage or industrial waste water.
[0018] The first transfer unit 10 includes a filtration
pipe 15 connected to the filtration membrane 5 2, switch valves
11A, 11B provided to the filtration pipe 15, and a filtration
pump 12. In addition to the filtration pipe 15, a cleaning
water pipe 22 is connected to the switch valve 11A. In
addition to the filtration pipe 15, a cleaning water pipe 16
is connected to the switch valve 11B. Further, the cleaning
water pipe 16 is connected to the oxidation device 50. It is
noted that the flow path of the filtered water Y can be
changed through operations of the switch valve 11A and the
switch valve 11B, and this will be described later.
By driving the filtration pump 12 of the first
transfer unit 10, the filtered water Y is sucked from the
filtration unit 1. The sucked filtered water Y as treatment
target water is transferred to the oxidation device 50 via
the switch valve 11A and the switch valve 11B.
[0019] The oxidation device 50 includes an oxidation unit
54 for causing pretreatment gas P as an oxidation material
containing an oxidizing substance such as oxygen to be in
contact with the filtered water Y, a control unit 55 for
controlling the oxidation unit 54, and a water quality
measurement device 56 as a measurement unit for performing
water quality measurement for the filtered water Y.
As the water quality measurement device 56, for
example, any one of a pH meter, a dissolved oxygen
concentration (DO) meter, or a standard oxidation reduction
potential (ORP) meter is used or some of 5 them are used in
combination.
[0020] The oxidation unit 54 includes a treatment water
tank 51 for storing the filtered water Y transferred by the
first transfer unit 10, a pretreatment gas supply device 52
for sending pretreatment gas P, and a pretreatment gas supply
pipe 53 for jetting the pretreatment gas P sent from the
pretreatment gas supply device 52, into the filtered water Y
stored in the treatment water tank 51. The control unit 55
receives a water quality measurement result obtained by the
water quality measurement device 56, and performs calculation
described later on the basis of the result, to perform output
control for the pretreatment gas P.
[0021] It is noted that the control unit 55 may be any
device, such as a programmable logic controller (PLC), a C
language controller, or a general-purpose personal computer,
that can receive a signal from the water quality measurement
device 56 and perform a predetermined calculation described
later on the basis thereof. Alternatively, for example, an
operation manager acting as the control unit may perform
operation in accordance with a predetermined calculation
described later.
[0022] The ozone water generation unit 60 includes an
ozone generator 61 for generating ozone gas, and an ozone gas
supply pipe 62 for supplying the generated ozone gas into the
filtered water Y stored in the treatment water 5 tank 51. When
the ozone gas is supplied into the filtered water Y, ozone is
dissolved into the filtered water Y. Hereinafter, the
filtered water Y having ozone dissolved therein is referred
to as ozone water O.
[0023] The second transfer unit 20 includes a transfer
pump 21 and the cleaning water pipe 22 provided so that ozone
water O is sucked from a lower part of the treatment water
tank 51 via the transfer pump 21. The cleaning water pipe 22
is connected to the switch valve 11A and is configured to be
able to transfer the ozone water O to the filtration unit 1
via the filtration pipe 15 by the switch valve 11A being
operated to change the flow path.
[0024] Next, a series of operations of the water treatment
device 100 including the oxidation device 50 according to the
present embodiment 1 configured as described above, will be
described.
The series of operation processes performed by the
water treatment device 100 include a membrane filtration
process, a pretreatment process, an ozone water generation
process, and a cleaning process. Through these processes,
the water treatment device 100 filters waste water or the
like by the filtration membrane, removes oxidizable inorganic
substances such as iron from a part of the filtered water,
generates ozone water on the basis of the filtered water from
which oxidizable inorganic substances have 5 been removed, and
cleans the filtration membrane by the generated ozone water.
[0025] First, the membrane filtration process will be
described.
In the membrane filtration process, in the
filtration unit 1, raw water X is fed to the filtration water
tank 3, the raw water X is filtered by the filtration
membrane 2, and the filtered water is transferred by the
first transfer unit.
[0026] The raw water X such as waste water supplied from
the raw water pipe 4 is stored in the filtration water tank 3
once, and then the filtration pump 12 is driven so that the
raw water X flows from the primary side to the secondary side
of the filtration membrane 2 and thus is filtered. The
filtered water Y obtained through the filtration is
discharged to a treatment facility (not shown) at the
subsequent stage through the filtration pipe 15 by the first
transfer unit 10, or in the case where the water level of the
treatment water tank 51 in the oxidation device 50 is not at
a predetermined position, the filtered water Y is transferred
to the treatment water tank 51 by operation of the switch
valve 11B.
In the case of performing treatment using activated
sludge mainly containing microorganisms in the filtration
unit 1 (in the case of operating as a membrane bioreactor),
activated sludge may be stored in the filtration 5 water tank 3
and the raw water X may be introduced there. In addition,
filtration may be performed continuously or intermittently.
In addition, even if reverse cleaning is performed to cause
the filtered water Y to flow as cleaning water from the
secondary side to the primary side of the filtration membrane
2 at an interval during filtration, this does not prevent the
effects of the present invention from being obtained.
[0027] Next, the pretreatment process will be described.
In the pretreatment process, in the oxidation
device 50, a pretreatment gas supply step and a water quality
confirmation step are performed at the same time or
alternately, whereby the pretreatment gas P is supplied in
accordance with oxidation progress of oxidizable inorganic
substances contained in the filtered water Y, to remove
oxidizable inorganic substances in the filtered water Y.
Thus, oxidizable substances which hamper generation of ozone
water in the ozone water generation process described later
can be removed by the pretreatment gas P.
[0028] In the pretreatment gas supply step performed in
the pretreatment process, the pretreatment gas P is supplied
from the pretreatment gas supply device 52 through the
pretreatment gas supply pipe 53 to the filtered water Y
stored in the treatment water tank 51. Thus, the oxidizing
substance contained in the pretreatment gas P and oxidizable
substances in the filtered water Y react 5 with each other,
whereby the oxidizable substances are oxidized.
As the pretreatment gas P, for example, gas
containing an oxidizing substance, such as air, oxygen gas,
or mixture gas of nitrogen and oxygen, can be used.
Therefore, as the pretreatment gas supply device 52, for
example, a blower, a cylinder filled with oxygen gas, a gas
cylinder filled with mixture gas of oxygen and nitrogen, an
oxygen gas generation device, or the like can be used.
[0029] In addition, in the water quality confirmation step
15 performed in the pretreatment process, the control unit 55
determines oxidation progress of oxidizable substances in the
filtered water Y on the basis of a result of water quality
measurement for the filtered water Y obtained through water
quality measurement by the water quality measurement device
56, and on the basis of this determination result, determines
to continue or stop supply of the pretreatment gas P to the
filtered water Y.
That is, in the case where the control unit 55 has
determined that oxidation of oxidizable substances in the
filtered water Y is all completed, the control unit 55
determines to stop supply of the pretreatment gas P from the
pretreatment gas supply device 52 and thus finishes the
pretreatment process. In the case where the control unit 55
has determined that oxidation of oxidizable substances in the
filtered water Y is not completed, the 5 control unit 55
determines to continue supply of the pretreatment gas P from
the pretreatment gas supply device 52. The details of
processing for performing this determination by the control
unit 55 will be described later.
[0030] Next, the ozone water generation process will be
described.
In the ozone water generation process, generation
of ozone water O is performed after the pretreatment process
is completed. That is, the ozone generator 61 starts to
generate ozone gas, and the generated ozone gas is supplied
through the ozone gas supply pipe 62 into the filtered water
Y in the treatment water tank 51. The ozone gas is supplied
into the filtered water Y during a predetermined period, and
when the ozone concentration in the filtered water Y has
reached a target concentration, supply of the ozone gas is
stopped and thus the ozone water generation process is
completed.
As an ozone gas supply method, for example, the
ozone gas may be supplied from a lower part of the treatment
water tank 51 by using an air diffuser formed from ceramic,
fluororesin, stainless steel, or the like, or may be supplied
while the filtered water Y and the ozone gas are mixed by an
ejector or the like.
[0031] Next, the cleaning process will be described.
In the cleaning process, in 5 the case where the
filtration performance of the filtration membrane 2 is
considered to be reduced in the membrane filtration process,
the membrane filtration process is stopped and cleaning of
the filtration membrane 2 by ozone water O is started. That
is, the switch valve 11A is operated to switch the flow path
so that the ozone water O in the treatment water tank 51
flows from the cleaning water pipe 22 to the filtration pipe
Then, the transfer pump 21 is driven to transfer the
ozone water O in the treatment water tank 51 to the
filtration membrane 2 so that the ozone water O flows from
the secondary side to the primary side of the filtration
membrane 2. In this way, by performing reverse cleaning so
that the ozone water O flows from the secondary side to the
primary side of the filtration membrane 2, clogging of the
filtration membrane is eliminated and organic substances
adhered to the filtration membrane are decomposed by ozone so
as to be removed.
After the cleaning process is completed, the
membrane filtration process is restarted.
Thus, the membrane filtration process, the
pretreatment process, the ozone water generation process, and
the cleaning process which are a series of operations of the
filtration device 100, have been described.
[0032] Next, the reason why the control unit 55 performs
the pretreatment gas supply step and 5 the water quality
confirmation step at the same time or alternately to supply
the pretreatment gas P in accordance with oxidation progress
of oxidizable substances in the filtered water Y in the above
pretreatment process, and the details of this process, will
be described.
[0033] The water quality of the filtered water Y, i.e.,
the concentration of oxidizable substances contained in the
filtered water Y is not always constant, but greatly varies
in accordance with mainly the water quality of the filtered
water Y. Therefore, if the supply amount of the pretreatment
gas P to the filtered water Y is fixed, oxidizable substances
are not sufficiently removed or the pretreatment gas P is
excessively supplied, leading to inefficiency. That is, by
supplying necessary and sufficient pretreatment gas P while
recognizing the oxidation completion point of oxidizable
substances in the filtered water Y at each time, it is
possible to avoid ineffective consumption of ozone during
generation of ozone water O so as to efficiently generate
ozone water O, and also keep the cleaning performance of
ozone water O stably at high level.
Through earnest studies, it has been found that the
oxidation completion point of oxidizable substances in the
filtered water Y can be confirmed by water quality
measurement for the filtered water Y. That is, in the
pretreatment process, as described below, 5 by performing the
"pretreatment gas supply step" and the "water quality
confirmation step" at the same time or alternately, it
becomes possible to oxidize oxidizable substances contained
in the filtered water Y by the pretreatment gas P without
excess/deficiency.
[0034] In the water quality confirmation step, as
described above, the control unit 55 determines oxidation
progress of oxidizable substances in the filtered water Y on
the basis of a result of water quality measurement for the
filtered water Y. That is, the control unit 55 calculates a
water quality change amount as a first change amount in a
predetermined period, which is obtained from change over time
in the water quality measurement value, and determines
oxidation progress of oxidizable substances on the basis of
the water quality change amount.
As described above, as the water quality
measurement device 56, any one of a pH meter, a dissolved
oxygen concentration (DO) meter, or a standard oxidation
reduction potential (ORP) meter is used or some of them is
used in combination. Then, the control unit 55 performs the
above determination on the basis of the water quality change
amount obtained from change over time in the pH value, the
dissolved oxygen concentration (DO) value, or the standard
oxidation reduction potential (ORP) value.
[0035] Hereinafter, the pretreatment 5 process of the
control unit 55 will be described, assuming that the DO meter
or the ORP meter is provided as the water quality measurement
device 56, and the pretreatment gas supply step and the water
quality confirmation step are performed at the same time,
i.e., while the pretreatment gas P is always supplied to the
filtered water Y, water quality confirmation for the filtered
water Y is performed.
FIG. 2 is a flowchart showing the treatment method
in the case where the control unit 55 performs the
pretreatment process on the basis of at least one of the DO
value or the ORP value measured while the pretreatment gas P
is always being supplied, according to embodiment 1.
FIG. 3 is a graph showing change over time in the
DO value or the ORP value obtained by the water quality
measurement device 56 measuring the filtered water Y while
the pretreatment gas P is being supplied, according to
embodiment 1.
[0036] When the pretreatment process is started (step S1),
first, the control unit 55 starts the pretreatment gas supply
step to supply the pretreatment gas P into the filtered water
Y (step S2).
Next, the control unit 55 starts the water quality
confirmation step for determining oxidation progress of
oxidizable substances in the filtered water Y (step S3).
[0037] In the water quality confirmation 5 step (step S3),
the control unit 55 performs water quality measurement for at
least one of the DO value or the ORP value of the filtered
water Y by the water quality measurement device 56, and
records the measurement value thereof (step S3a).
Next, the control unit 55 performs water quality
measurement again after elapse of a time L1, and records the
measurement value thereof again (step S3b).
Next, using the measurement values obtained in step
S3a and step S3b as a first measurement value α and a second
measurement value β, respectively, the control unit 55
calculates the first change amount obtained from change over
time in the measurement value, i.e., an absolute value ΔP of
the slope of a line connecting the measurement value α and
the measurement value β, in accordance with the following
Expression (1), and records the calculated value (step S3c).
ΔP = |α - β|/T ... Expression (1)
[0038] Next, if the number of recorded values of ΔP is
less than two (step S3d, No), the control unit 55 returns to
step 3a to newly acquire the first measurement value α and
the second measurement value β, calculate the absolute value
ΔP of the slope therebetween, and record the calculated value.
Thus, when the number of recorded values of ΔP has become two
or more, the control unit 55 compares the magnitudes of a
first slope Pt1 and a second slope Pt2, using the previously
acquired absolute value ΔP of the slope 5 as the first slope
Pt1, and the newly acquired absolute value ΔP of the slope as
the second slope Pt2.
As a result of the comparison, if the second slope
Pt2 is greater than the first slope Pt1 (step S3d, Yes), the
control unit 55 determines that oxidation of oxidizable
substances in the filtered water Y is completed, and
determines to stop supply of the pretreatment gas P to the
filtered water Y. In this case, after completing the water
quality confirmation step S3, the control unit 55 completes
the pretreatment gas supply step, to stop supply of the
pretreatment gas P (step S4), and thus finishes the
pretreatment process (step S5).
It is noted that, as a result of the comparison, if
the second slope Pt2 is equal to or smaller than the first
slope Pt1 (step S3d, No), the control unit 55 returns to step
S3a to continue the water quality confirmation step.
It is noted that the above time L1 is favorably 10
to 600 seconds.
[0039] Hereinafter, the reason why oxidation progress of
oxidizable substances in the filtered water Y can be
determined by the processing in the water quality
confirmation step S3 shown in FIG. 2, will be described.
As shown in FIG. 3, in the case where the
pretreatment gas P containing oxygen continues to be supplied
to the filtered water Y so that oxidizable 5 substances in the
filtered water Y continue to be oxidized, even though the
pretreatment gas P continues to be supplied, the oxidizing
substance contained in the pretreatment gas P is consumed by
oxidizable substances, whereby the DO value or the ORP value
in the filtered water Y is prevented from sharply increasing.
The period from t0 to t9 shown in FIG. 3 is a period during
which oxidizable substances remain in the filtered water Y,
and it is found that the DO value or the ORP value increases
at a gradual and almost constant slope even while the
pretreatment gas P is being supplied.
[0040] On the other hand, when oxidation of oxidizable
substances is completed, the increase speed of the DO value
or the ORP value becomes great. The period from t9 to t10
shown in FIG. 3 is a period in which oxidation of oxidizable
substances has been completed, and it is found that the DO
value or the ORP value sharply increases as the pretreatment
gas P is supplied.
Therefore, as described above, by calculating the
change amount of the DO value or the ORP value obtained from
change over time in the water quality measurement value,
continuously comparing this, and detecting increase in the
increase speed of the measurement value, it becomes possible
to determine oxidation progress of oxidizable substances and
find the oxidation completion point.
[0041] As described above, in the case 5 where there are
characteristics in which the slope of the measurement value
changes between before and after completion of oxidation of
oxidizable substances, it is possible to accurately find the
oxidation completion point of oxidizable substances by
performing determination using the slope of the measurement
value as the first change amount of the measurement value.
In the present embodiment, when a magnitude
relationship is compared between a first slope ΔPt1 which is
the absolute value of the slope of a line connecting a first
measurement value and a second measurement value respectively
measured at a first time point t7 and a second time point t8
in FIG. 3, and a second slope ΔPt2 which is the absolute
value of the slope of a line connecting a third measurement
value and a fourth measurement value respectively measured at
a first time point t9 and a second time point t10, it is
determined that oxidation of oxidizable substances is
completed, and thus supply of the pretreatment gas P is
stopped.
[0042] In the above water quality confirmation step S3
(S3a, S3b, S3c, S3d), the example in which the control unit
55 calculates the first slope Pt1 and the second slope Pt2 on
the basis of at least four measurement values obtained at
four time points (e.g., t7, t8, t9, t10), has been shown.
However, without limitation thereto, the control unit 55 may
calculate the first slope Pt1 and the second 5 slope Pt2 on the
basis of at least three measurement values obtained at three
time points (e.g., t8, t9, t10). In this case, the slope of
a line connecting the first measurement value at the first
time point t8 and the second measurement value at the second
time point t9 is used as the first slope Pt1, and the slope
of a line connecting the second measurement value at the
second time point t9 and the third measurement value at the
third time point t10 is used as the second slope Pt2, to
perform the above determination.
[0043] In the above water quality confirmation step S3,
whether or not the second slope Pt2 is greater than the first
slope Pt1 (first slope Pt1 < second slope Pt2) is determined
in the oxidation progress determination step S3d. However,
without limitation to this determination method, for example,
whether or not a value obtained by dividing the second slope
Pt2 by the first slope Pt1 is equal to or greater than a
predetermined first value R1 ((second slope Pt2/first slope
Pt1) ≥ R1) may be determined. In this case, if, for example,
a predetermined value greater than 1 is set as the first
value R1, a margin can be provided for the determination,
whereby the pretreatment process is prevented from being
unintentionally stopped due to error of the measurement value
or the like, and thus operation of the pretreatment process
can be stabilized.
[0044] Thus, the operation in the case 5 of performing the
pretreatment process on the basis of at least one of the DO
value or the ORP value measured while the pretreatment gas P
is always being supplied, has been described.
Hereinafter, operation in the case of providing a
pH meter as the water quality measurement device 56 and
performing the pretreatment process on the basis of a pH
value measured while the pretreatment gas P is always being
supplied, will be described.
[0045] FIG. 4 is a flowchart showing the treatment method
in the case where the control unit 55 performs the
pretreatment process on the basis of the pH value measured
while the pretreatment gas P is always being supplied,
according to embodiment 1.
FIG. 5 is a graph showing change over time in the
pH value obtained by the water quality measurement device 56
measuring the filtered water Y while the pretreatment gas P
is being supplied, according to embodiment 1.
As shown in FIG. 4, in the case of measuring the pH
value, only the oxidation progress determination step (step
S3d1) in the water quality confirmation step (step S31) is
different. The other steps are the same as those in FIG. 2,
and description thereof is omitted.
[0046] In the case of using a pH meter as the water
quality measurement device, as shown in the oxidation
progress determination step S3d1 in FIG. 5 4, as a result of
comparison of the slope ΔP, if the second slope Pt2 which is
the newly acquired absolute value of the slope is smaller
than the first slope Pt1 which is the previously acquired
absolute value of the slope (step S3d1, Yes), the control
unit 55 determines that oxidation of oxidizable substances in
the filtered water Y is completed, and determines to stop
supply of the pretreatment gas P to the filtered water Y. In
this case, after completing the water quality confirmation
step, the control unit 55 completes the pretreatment gas
supply step, to stop supply of the pretreatment gas P (step
S4), and thus finishes the pretreatment process (step S5).
[0047] Hereinafter, the reason why oxidation progress of
oxidizable substances in the filtered water Y can be
determined by the processing in the water quality
confirmation step shown in FIG. 4, will be described.
As shown in FIG. 5, in the case where the
pretreatment gas P containing oxygen continues to be supplied
to the filtered water Y, for example, when oxidizable
substances such as ferrous ions are contained in the filtered
water Y, these substances continue to be oxidized so that
hydroxide ions continue to be consumed through formation of
iron hydroxide, and thus reduction in pH is recognized. The
period from t0 to t7 shown in FIG. 5 is a period during which
oxidizable substances remain in the filtered water Y, and it
is found that the pH value reduces with 5 an almost constant
slope.
[0048] On the other hand, when oxidation of oxidizable
substances is completed, formation of hydroxide is stopped,
so that reduction of the pH value becomes gradual. The
period from t7 to t8 shown in FIG. 5 is a period in which
oxidation of oxidizable substances is completed, and it is
found that reduction in the pH value has become gradual.
Therefore, as described above, by calculating the
change amount of the pH value obtained from change over time
in the water quality measurement value, continuously
comparing this, and detecting decrease in the reduction speed
of the pH value, it becomes possible to determine oxidation
progress of oxidizable substances and find the oxidation
completion point.
[0049] As described above, in the case where there are
characteristics in which the slope of the measurement value
changes between before and after completion of oxidation of
oxidizable substances, it is possible to accurately find the
oxidation completion point of oxidizable substances by
performing determination using the slope of the measurement
value as the change amount of the measurement value.
In the present embodiment, when a magnitude
relationship is compared between a first slope ΔPt1 which is
the absolute value of the slope of a line connecting a first
measurement value and a second measurement 5 value respectively
measured at a first time point t5 and a second time point t6
in FIG. 5, and a second slope ΔPt2 which is the absolute
value of the slope of a line connecting a third measurement
value and a fourth measurement value respectively measured at
a third time point t7 and a fourth time point t8, it is
determined that oxidation of oxidizable substances is
completed, and thus supply of the pretreatment gas P is
stopped.
[0050] In the above water quality confirmation step S31
(S3a, S3b, S3c, S3d1), the example in which the control unit
55 calculates the first slope Pt1 and the second slope Pt2 on
the basis of at least four measurement values obtained at
four time points (e.g., t5, t6, t7, t8), has been shown.
However, without limitation thereto, the control unit 55 may
calculate the first slope Pt1 and the second slope Pt2 on the
basis of at least three measurement values obtained at three
time points (e.g., t6, t7, t8). In this case, the slope of a
line connecting the first measurement value at the first time
point t6 and the second measurement value at the second time
point t7 is used as the first slope Pt1, and the slope of a
line connecting the second measurement value at the second
time point t7 and the third measurement value at the third
time point t8 is used as the second slope Pt2, to perform the
above determination.
[0051] In the above water quality confirmation 5 step S31,
whether or not the second slope Pt2 is smaller than the first
slope Pt1 (first slope Pt1 > second slope Pt2) is determined
in the oxidation progress determination step S3d1. However,
without limitation to this determination method, for example,
whether or not a value obtained by dividing the second slope
Pt2 by the first slope Pt1 is equal to or smaller than a
predetermined second value R2 ((second slope Pt2/first slope
Pt1) ≤ R2) may be determined. In this case, for example, if
a predetermined value smaller than 1 is set as the first
value R1, a margin can be provided for the determination,
whereby the pretreatment process is prevented from being
unintentionally stopped due to error of the measurement value
or the like, and thus operation of the pretreatment process
can be stabilized.
[0052] Thus, the pretreatment process by the control unit
55 in the case of performing the pretreatment gas supply step
and the water quality confirmation step at the same time,
i.e., in the case of performing water quality measurement for
the filtered water Y while always supplying the pretreatment
gas P into the filtered water Y, has been described.
Hereinafter, the case of performing the
pretreatment gas supply step and the water quality
confirmation step alternately, i.e., the case of
intermittently supplying the pretreatment gas P to the
filtered water Y with a predetermined interruption 5 period
provided, and performing water quality measurement for the
filtered water Y in the interruption period at the interval
in supply of the pretreatment gas P, will be described.
[0053] In the above-described case of performing the
pretreatment gas supply step and the water quality
confirmation step at the same time, the control unit 55 uses
a determination method different between the case of
measuring at least one of the DO value or the ORP value and
the case of measuring the pH value. In the below-described
case of performing the pretreatment gas supply step and the
water quality confirmation step alternately, the same
determination method is used in any of the cases where the
measurement value to be acquired is the DO value, the ORP
value, or the pH value.
[0054] FIG. 6 is a flowchart showing the treatment method
in the case where the control unit 55 performs the
pretreatment process on the basis of the DO value, the ORP
value, or the pH value measured in the interruption period at
the interval in supply of the pretreatment gas P, according
to embodiment 1.
FIG. 7 is a graph showing change over time in the
DO value or the ORP value obtained by the water quality
measurement device 56 measuring the filtered water Y in the
interruption period at the interval in supply of the
pretreatment gas P, according 5 to embodiment 1.
FIG. 8 is a graph showing change over time in the
pH value obtained by the water quality measurement device 56
measuring the filtered water Y in the interruption period at
the interval in supply of the pretreatment gas P, according
to embodiment 1.
[0055] When the pretreatment process is started (step S1),
first, the control unit 55 starts the pretreatment gas supply
step to supply the pretreatment gas P into the filtered water
Y (step S2).
Next, when a predetermined supply time L2 has
elapsed, the control unit 55 interrupts supply of the
pretreatment gas P (step S2a), and in the interruption period
during which supply of the pretreatment gas is interrupted,
the control unit 55 starts the water quality confirmation
step for determining oxidation progress of oxidizable
substances in the filtered water Y (step S32). It is noted
that L2 is favorably 10 to 600 seconds.
[0056] In this water quality confirmation step S32, the
control unit 55 performs water quality measurement for at
least one of the DO value, the ORP value, or the pH value of
the filtered water Y by the water quality measurement device
, and records the measurement value thereof (step S3a).
Next, the control unit 55 further performs water
quality measurement again after elapse of a time L3 therefrom,
and records the measurement value thereof 5 (step S3b).
Next, the control unit 55 uses the measurement
values obtained in step S3a and step S3b as a first
measurement value α and a second measurement value β,
respectively, and compares the ratio therebetween, i.e., a
value obtained by dividing the second measurement value β by
the first measurement value α, with a predetermined third
value R3 (step S3d2).
It is noted that L3 is favorably 10 to 600 seconds
and the third value R3 is favorably 0.5 to 1.2.
[0057] As a result of the comparison, if the measurement
value ratio obtained by dividing the second measurement value
β by the first measurement value α is equal to or greater
than the third value R3 (step S3d2, Yes), the control unit 55
determines that oxidation of oxidizable substances in the
filtered water Y is completed, and determines to stop supply
of the pretreatment gas P to the filtered water Y. In this
case, after completing the water quality confirmation step
S32, the control unit 55 completes the pretreatment gas
supply step, to stop supply of the pretreatment gas P (step
S4), and thus finishes the pretreatment process (step S5).
On the other hand, as a result of the comparison,
if the value of second slope β/first slope α is smaller than
R3 (step S3d2), the control unit 55 returns to step S2 to
restart the pretreatment gas supply step, and performs the
water quality confirmation step S32 again in 5 the interruption
period of supply of the pretreatment gas P.
[0058] Hereinafter, the reason why oxidation progress of
oxidizable substances in the filtered water Y can be
determined by the processing in the water quality
confirmation step S32 shown in FIG. 6, will be described.
In FIG. 7, periods during which the DO value or the
ORP value increases (e.g., t0 to t1, t2 to t3, t4 to t5, ...)
are periods during which the pretreatment gas P is supplied
into the filtered water Y. In addition, periods during which
the DO value or the ORP value decreases (e.g., t1 to t2, t3
to t4, t5 to t6, ...) are interruption periods during which
supply of the pretreatment gas P is interrupted.
In FIG. 8, periods (t0 to t1, t2 to t3, t4 to
t5, ...) are periods during which the pretreatment gas P is
supplied into the filtered water Y. In addition, periods (t1
to t2, t3 to t4, t5 to t6, ...) are interruption periods
during which supply of the pretreatment gas P is interrupted.
In FIG. 7, the increase speed of the DO value or
the ORP value during a period in which the pretreatment gas P
is supplied is greater than that shown in FIG. 3, but the
increase speed of the measurement value varies depending on
the condition of supply of the pretreatment gas P, and the
like.
[0059] As shown in FIG. 7, when supply of the pretreatment
gas P is interrupted, during the interruption 5 period, the
oxidizing substance in the filtered water Y such as oxygen
supplied from the pretreatment gas P is consumed by
oxidizable substances, so that the pH value, the DO value, or
the ORP value gradually reduces. Therefore, in the case
where the oxidizing substance remains in the filtered water
and oxidation has not been completed, the second measurement
value β after elapse of the predetermined time L2 is
sufficiently reduced relative to the first measurement value
α acquired immediately after supply of the pretreatment gas
is stopped.
On the other hand, when oxidation of oxidizable
substances has sufficiently progressed, the reduction width
of the second measurement value β relative to the first
measurement value α becomes small or the second measurement
value β becomes equal to or greater than the first
measurement value α. Such a fact has been found through
earnest studies.
[0060] Therefore, by comparing the ratio between the first
measurement value α and the second measurement value β, i.e.,
the measurement value ratio obtained by dividing the second
measurement value β by the first measurement value α with the
predetermined third value R3 every time the water quality
confirmation step is performed in the interruption period of
supply of the pretreatment gas P, it is possible to determine
oxidation progress of oxidizable substances 5 and find the
oxidation completion point.
[0061] As described above, in the interruption period of
supply of the pretreatment gas P, in the case where there are
characteristics in which the measurement value ratio changes
between before and after completion of oxidation of
oxidizable substances, it is possible to accurately find the
oxidation completion point of oxidizable substances by
performing determination using the measurement value ratio as
the first change amount of the measurement value.
In the present embodiment, when a magnitude
relationship is compared between the third value R3 and the
measurement value ratio obtained by dividing the second
measurement value β measured at the second time point t18 in
FIG. 7 by the first measurement value α measured at the first
time point t17, it is determined that oxidation of oxidizable
substances is completed, and thus supply of the pretreatment
gas P is stopped.
[0062] As described above, also in the interruption period
of supply of the pretreatment gas P, there are
characteristics in which the slope of the measurement value
in the interruption period changes between before and after
completion of oxidation of oxidizable substances. Therefore,
also in the interruption period of supply of the pretreatment
gas P, determination may be performed using the slope of the
measurement value in the interruption period 5 as the first
change amount of the measurement value.
In this case, for example, a magnitude relationship
is compared between the first slope ΔPt1 which is the
absolute value of the slope of a line connecting a first
measurement value and a second measurement value respectively
measured at the first time point t15 and the second time
point t16 in FIG. 7, and the second slope ΔPt2 which is the
absolute value of the slope of a line connecting a third
measurement value and a fourth measurement value respectively
measured at the third time point t17 and the fourth time
point t18.
[0063] In the oxidation device and the water treatment
method according to the present embodiment configured as
described above, the control unit determines oxidation
progress of oxidizable substances in the treatment target
water on the basis of the first change amount obtained from
change over time in the measurement value obtained through
water quality measurement for the treatment target water by
the water quality measurement device, and determines to
continue or stop supply of the pretreatment gas to the
treatment target water. Thus, the oxidation completion point
of oxidizable substances contained in the treatment target
water can be found, and the supply amount of the pretreatment
gas to be supplied into the treatment target water can be
adjusted in accordance with oxidation progress 5 of oxidizable
substances. Therefore, it becomes possible to supply the
pretreatment gas without excess/deficiency even in the case
where the water quality of the treatment target water is not
stable. Thus, it is possible to obtain treatment target
water in which dissolution of carbonate ions due to excess
supply of the pretreatment gas is reduced and oxidizable
substances are sufficiently removed.
[0064] The water treatment device configured as described
above includes the filtration unit for filtering organic
substances in raw water to generate filtered water, the first
transfer unit for transferring the filtered water to the
treatment water tank, the ozone water generation unit for
supplying ozone gas to the filtered water for which supply of
the pretreatment gas has been determined to be stopped, to
generate ozone water, and the second transfer unit for
transferring the ozone water to the filtration unit. Thus,
the filtration membrane for filtering organic substances can
be cleaned using ozone water having a high cleaning effect,
which is generated on the basis of filtered water in which
dissolution of carbonate ions is reduced and oxidizable
substances are sufficiently removed. Thus, clogging of the
filtration membrane and the like are effectively prevented
and the water treatment device can be stably operated.
In addition, since the ozone water is generated
using the filtered water, the cost can be reduced 5 as compared
to the case of generating ozone water using tap water or the
like.
[0065] In the ozone water generation method configured as
described above, ozone water is generated by supplying ozone
gas to the treatment target water for which supply of the
pretreatment gas has been determined to be stopped. Thus,
ozone water is generated on the basis of the treatment target
water in which dissolution of carbonate ions is reduced and
oxidizable substances are sufficiently removed. Therefore,
ineffective consumption of ozone by oxidizable substances can
be minimized and ozone water having a high cleaning effect
can be obtained.
[0066] In the cleaning method configured as described
above, the filtration membrane can be cleaned using the ozone
water generated as described above. Since the filtration
membrane is cleaned using the ozone water having a high
cleaning effect as described above, a high sterilizing effect,
a high deodorizing effect, and the like for the filtration
membrane are obtained.
It is noted that a cleaning target part to be
cleaned using the ozone water generated as described above is not limited to such a filtration membrane used for water cleaning treatment, waste water treatment, or the like. For example, the cleaning target part may be food, a medical apparatus, or the like, and a high cleaning effect can be
similarly obtained also for such cleaning target parts.
[0067] The control unit uses the slope of the measurement
value as the first change amount obtained from change over
time in the measurement value obtained through water quality
measurement for the filtered water.
Therefore, in the case where the measurement target
has characteristics in which the slope of the measurement
value changes before and after completion of oxidation of
oxidizable substances, it is possible to accurately find the
oxidation completion point of oxidizable substances by
performing determination using the above slope of the
measurement value as the first change amount of the
measurement value.
[0068] The control unit uses the relationship between the
first slope of a line connecting a first measurement value
and a second measurement value and the second slope of a line
connecting a third measurement value and a fourth measurement
value, as the first change amount. By thus performing
determination using the relationship between two slopes that
change over time, the oxidation completion point of
oxidizable substances can be found more accurately.
The control unit may use the relationship between
the first slope of a line connecting a first measurement
value and a second measurement value and the second slope of
a line connecting a second measurement 5 value and a third
measurement value, as the first change amount. In this case,
measurement for a fourth measurement value is not needed, and
thus the oxidation completion point for oxidizable substances
can be found quickly.
[0069] In the configuration in which the pretreatment gas
is continuously supplied to the filtered water, in the case
of measuring the DO value or the ORP value of filtered water,
the control unit determines to stop supply of the
pretreatment gas to the filtered water when the absolute
value of the second slope becomes greater than the absolute
value of the first slope. In the case of using, as a
measurement target, the DO value or the ORP value of which
the increase speed becomes great when oxidation of oxidizable
substances in the filtered water is completed, it is possible
to accurately find the oxidation completion point of
oxidizable substances by detecting the time point at which
the second slope becomes great as described above.
When a value obtained by dividing the second slope
by the first slope becomes equal to or greater than the
predetermined first value, the control unit may determine to
stop supply of the pretreatment gas to the filtered water.
In this case, the pretreatment process is prevented from
being unintentionally stopped due to error of the measurement
value or the like, and thus operation of the pretreatment
process can 5 be stabilized.
[0070] In the configuration in which the first substances
are continuously supplied to the treatment target water, in
the case of measuring the pH value of the filtered water, the
control unit determines to stop supply of the pretreatment
gas to the filtered water when the second slope becomes
smaller than the first slope. In the case of using, as a
measurement target, the pH value for which the reduction
speed of the measurement value becomes small when oxidation
of oxidizable substances in the filtered water is completed,
it is possible to accurately find the oxidation completion
point of oxidizable substances by detecting the time point at
which the second slope becomes small as described above.
When a value obtained by dividing the second slope
by the first slope becomes equal to or smaller than the
predetermined second value, the control unit may determine to
stop supply of the pretreatment gas to the filtered water.
In this case, the pretreatment process is prevented from
being unintentionally stopped due to error of the measurement
value or the like, and thus operation of the pretreatment
process can be stabilized.
[0071] In the configuration in which the pretreatment gas
is intermittently supplied to the filtered water with a
predetermined interruption period provided, the control unit
uses the ratio of two measurement values immediately after
the interruption period and after elapse 5 of a predetermined
time, as the first change amount obtained from change over
time in the measurement value obtained through water quality
measurement for the filtered water.
Therefore, in the interruption period of the
pretreatment gas, in the case where the measurement target
has characteristics in which the ratio of the two measurement
values respectively measured changes between before and after
completion of oxidation of oxidizable substances, it is
possible to accurately find the oxidation completion point of
oxidizable substances by performing determination using the
ratio of the two measurement values as the first change
amount of the measurement value.
[0072] In the interruption period, when the measurement
value ratio obtained by dividing the second measurement value
by the first measurement value becomes equal to or greater
than the predetermined third value, the control unit
determines to stop supply of the pretreatment gas to the
filtered water.
In the case of using the DO value, the ORP value,
or the ph value as the measurement target, when oxidation of
oxidizable substances in the filtered water is completed, in
the interruption period, the measurement value ratio obtained
by dividing the second measurement value by the first
measurement value becomes small. Therefore, it is possible
to more accurately find the oxidation completion 5 point of
oxidizable substances by performing such determination as
described above.
[0073] The control unit performs supply of the oxidizing
substance to the filtered water by jetting the pretreatment
gas which is gas containing the oxidizing substance as an
oxidation material into the filtered water. Thus, handling
is easy as compared to the case of using a liquid or the like
containing an oxidizing substance.
[0074] In the above description, the case where the
control unit 55 uses the amount of change over time in the pH
value, the dissolved oxygen concentration (DO) value, or the
standard oxidation reduction potential (ORP) value, as the
first change amount of the measurement value, has been shown,
but the first change amount of the measurement value is not
limited thereto. As the first change amount of the
measurement value, a water quality other than the pH value,
the DO value, and the ORP value may be measured as long as
characteristics in which the measurement value changes over
time between before and after completion of oxidation of
oxidizable substances in the filtered water Y are obtained.
[0075] In the above description, the case where the
oxidation unit 54 includes the treatment water tank 51, the
pretreatment gas supply device 52, and the pretreatment gas
supply pipe 53, has been shown. However, without limitation
to this configuration, the oxidation unit 5 54 may have any
configuration that can supply an oxidation material to the
filtered water Y and oxidize oxidizable substances contained
in the filtered water.
In the above description, the case where the ozone
water generation unit 60 includes only the ozone generator 61
and the ozone gas supply pipe 62, has been shown. However,
without limitation to this configuration, the ozone water
generation unit 60 may include an ozone water generation tank
dedicated for generating ozone water O, for example.
In addition, the ozone water generation unit 60 may
be provided in the oxidation device 50.
[0076] In the case of using the slope of the measurement
value as the first change amount, the control unit is not
limited to a configuration of calculating the absolute value
ΔP of the slope of a line connecting the measurement value α
and the measurement value β as shown in the above Expression
(1). The control unit may use the slope that is not an
absolute value, of a line connecting the measurement value α
and the measurement value β, to detect change over time in
the slope of the measurement value, and determine oxidation
progress.
[0077] The oxidation material containing an oxidizing
substance, to be supplied into the filtered water, is not
limited to gas such as the pretreatment gas P, but may be
liquid oxygen, 5 for example.
[0078] In the above description, the oxidation device 50
performs the pretreatment process for removing oxidizable
substances, for the filtered water Y filtered by the
filtration unit 1. However, the oxidation device is not
limited thereto.
For example, the oxidation device may be configured
to remove oxidizable substances in the raw water X stored in
the filtration water tank 3 of the filtration unit 1. In
this case, the water quality measurement device 56 and the
pretreatment gas supply device 52 may be provided to the
filtration water tank 3. Then, the control unit 55
determines oxidation progress of oxidizable substances in the
raw water X on the basis of the first change amount obtained
through water quality measurement for the raw water X as
treatment target water obtained by the water quality
measurement device 56, and thereby determines to continue or
stop supply of the pretreatment gas P to the raw water X. In
this case, the ozone water generation unit 60 directly
supplies ozone gas to the raw water X in the filtration water
tank 3, thereby decomposing impurities such as organic
substances contained in the raw water X.
[0079] Embodiment 2
Hereinafter, the present embodiment 2 will be
described, focusing on differences from the above embodiment
1, with reference to the drawings. The same 5 parts as those
in the above embodiment 1 are denoted by the same reference
characters, and description thereof is omitted.
FIG. 9 is a diagram showing the schematic
configuration of a water treatment device 200 according to
10 embodiment 2.
FIG. 10 is a diagram showing an example of the
schematic configuration of an outside air contact device 270
according to embodiment 2.
The water treatment device 200 shown in FIG. 9 is
the same as the water treatment device 100 shown in FIG. 1
except that the outside air contact device 270 is provided to
the cleaning water pipe 16.
[0080] When the filtered water Y is transferred to the
treatment water tank 51 via the cleaning water pipe 16, the
outside air contact device 270 causes the filtered water Y
and outside air to be in contact with each other, thereby
oxidizing a part of oxidizable substances in the filtered
water Y. This makes it possible to shorten the execution
period of the pretreatment process and reduce the usage
amount of the pretreatment gas P in the oxidation device 50.
As shown in FIG. 10, as the outside air contact
device 270, a water tank 71 that opens to the outside air
(atmosphere) is used. In the outside air contact device 270,
for example, an ejector can also be used, and the outside air
is sucked by a negative pressure caused 5 when the filtered
water Y flows down through the ejector, whereby the filtered
water Y can be mixed with the outside air. In this case, it
is possible to oxidize oxidizable substances by the filtered
water Y contacting with the outside air when the filtered
water Y flows down through the water tank.
[0081] The oxidation device and the water treatment method
according to the present embodiment configured as described
above provide the same effects as in embodiment 1 and can
obtain filtered water in which dissolution of carbonate ions
in the filtered water is reduced and oxidizable substances
are sufficiently removed.
Further, since the outside air contact device for
assisting the pretreatment process in the oxidation device is
provided, it becomes possible to shorten the execution period
of the pretreatment process and reduce the usage amount of
the pretreatment gas in the pretreatment process. Thus, the
oxidation device and the water treatment device that require
low cost and have a high treatment speed can be provided.
[0082] Embodiment 3
Hereinafter, the present embodiment 3 will be
described, focusing on differences from the above embodiments
1 and 2, with reference to the drawings. The same parts as
those in the above embodiments 1 and 2 are denoted by the
same reference characters, and description thereof is omitted.
FIG. 11 is a diagram showing 5 the schematic
configuration of a water treatment device 300 including an
oxidation device 350 according to embodiment 3.
FIG. 12 is a flowchart showing the treatment method
in the case where a control unit 355 performs the
pretreatment process on the basis of at least one of the DO
value or the ORP value measured while a circulation process
is being performed, according to embodiment 3.
FIG. 13 is a flowchart showing the treatment method
in the case where the control unit 355 performs the
pretreatment process on the basis of the pH value measured
while the circulation process is being performed, according
to embodiment 3.
[0083] The oxidation device 350 shown in FIG. 11 is
configured such that the pretreatment gas supply device 52
and the pretreatment gas supply pipe 53 are removed from the
oxidation unit 54 of the oxidation device 50 shown in FIG. 9
in embodiment 2, a switch valve 323 is provided to the
cleaning water pipe 22, and the cleaning water pipe 16 and
the switch valve 323 are connected via a circulation pipe 317
at a stage preceding the outside air contact device 270.
In the oxidation device 350 according to the
present embodiment, an oxidation unit 354 for causing an
oxidation material containing an oxidizing substance to be in
contact with the filtered water Y includes the outside air
contact device 270, the switch valve 323, 5 the circulation
pipe 317, and the transfer pump 21. In addition, the control
unit 355 receives a water quality measurement result obtained
by the water quality measurement device 56, performs
calculation described later on the basis of this result, and
performs drive control for the transfer pump 21.
[0084] In the case of this oxidation device 350, the
pretreatment process can be executed as shown in the
flowcharts in FIG. 12 and FIG. 13. FIG. 12 and FIG. 13 are
different from FIG. 2 and FIG. 4 in that the pretreatment gas
supply step S2 is replaced with a circulation step S302.
In the circulation step S302 shown in FIG. 12 and
FIG. 13, the control unit 355 drives the transfer pump 21 to
suck the filtered water Y stored in the treatment water tank
51 so as to return the filtered water Y to the primary side
of the outside air contact device 270 via the switch valve
323 and the circulation pipe 317. Then, the filtered water Y
is passed through the outside air contact device 270 to the
secondary side, so as to circulate into the treatment water
tank 51.
[0085] During execution of the circulation step S302, the
transfer pump 21 is always driven to repeatedly circulate the
filtered water Y. That is, in the present embodiment, the
filtered water Y is transferred so that, instead of the
pretreatment gas P, the outside air supplied from the outside
air contact device 270 is repeatedly brought 5 into contact
with the filtered water Y, and the filtered water Y is
exposed to the outside air as an oxidation material, whereby
oxidizable substances contained in the filtered water Y are
oxidized. If the control unit 355 determines that oxidation
of oxidizable substances in the filtered water Y is completed,
the control unit 355 determines to stop circulation of the
filtered water Y to the outside air contact device 270, and
stops transfer of the filtered water Y to the outside air
contact device 270 (step S304). On the other hand, if the
control unit 355 determines that oxidation of oxidizable
substances in the filtered water Y is not completed, the
control unit 355 determines to continue circulation of the
filtered water Y to the outside air contact device 270, and
continues to transfer the filtered water Y to the outside air
contact device 270.
[0086] The water quality confirmation step S3 can be
performed in the same manner as the water quality
confirmation step S3 described in embodiment 1. In the case
of using a DO meter or an ORP meter as the water quality
measurement device 56, the pretreatment process can be
performed in accordance with the flowchart in FIG. 12. In
the case of using a pH meter as the water quality measurement
device 56, the flowchart in FIG. 13 can be employed. In
addition, as in embodiment 1, it is also possible to perform
the circulation step and the water quality 5 confirmation step
alternately. In this case, the process may be performed such
that start, interruption, and finish of the pretreatment gas
supply step shown in FIG. 6 are replaced with start,
interruption, and finish of the circulation step.
[0087] The oxidation device and the water treatment method
according to the present embodiment configured as described
above provide the same effects as in embodiment 1, and the
control unit determines oxidation progress of oxidizable
substances in the filtered water on the basis of the first
change amount obtained from change over time in the
measurement value obtained through water quality measurement
for the filtered water by the water quality measurement
device, and determines to continue or stop transfer of the
filtered water to the outside air contact device. Thus, the
circulation amount of the filtered water to be circulated to
the outside air contact device can be adjusted in accordance
with oxidation progress of oxidizable substances. Thus, it
is possible to obtain filtered water in which dissolution of
carbonate ions in the filtered water is reduced and
oxidizable substances are sufficiently removed.
[0088] Further, the outside air contact device is provided
as the oxidation unit for causing the oxidation material
containing an oxidizing substance to be in contact with the
filtered water Y, and the transfer pump is driven to
circulate the filtered water to the outside 5 air contact
device so that the filtered water is exposed to the outside
air. Thus, it becomes possible to supply an oxidation
material without excess/deficiency, to the filtered water Y,
with a simple device configuration as in the outside air
contact device. Thus, the oxidation device and the water
treatment device can be provided at low cost.
[0089] Embodiment 4
Hereinafter, the present embodiment 4 will be
described, focusing on differences from the above embodiment
1, with reference to the drawings. The same parts as those
in the above embodiment 1 are denoted by the same reference
characters, and description thereof is omitted.
FIG. 14 is a diagram showing the schematic
configuration of a water treatment device 500 according to
embodiment 4.
FIG. 15 is a flowchart showing the treatment method
for a control unit 555 to remove carbonate ions in the
filtered water Y, according to embodiment 4.
In the present embodiment, the control unit 555
performs a decarbonation process for removing carbonate ions
in the filtered water Y after the pretreatment process is
finished, before the ozone water generation process is
started. The process by the control unit 555 is the same as
that shown in embodiment 1 except that the decarbonation
process 5 is performed.
[0090] As shown in FIG. 14, the water treatment device 500
is obtained by adding a decarbonation unit 570 to the water
treatment device 100 shown in FIG. 1.
[0091] Here, the reason why the decarbonation process for
removing carbonate ions is performed for the filtered water Y
for which the pretreatment process has been completed, will
be described.
In the case where the concentration of oxidizable
substances contained in the filtered water is high, it takes
time to oxidize the oxidizable substances, so that the period
for performing the pretreatment process is comparatively long,
and the supply amount of the pretreatment gas or the amount
of outside air supplied by the outside air contact device
also increases. Therefore, in particular, in the case of
using air as the pretreatment gas and in the case of
performing oxidation using outside air by the outside air
contact device, the amount of dissolution of carbon dioxide
gas contained in the air and the outside air into the
filtered water also increases.
[0092] Carbonate ions in water act as a radical scavenger
and consume OH radicals which are generated through selfdecomposition
of ozone and have a high capability of
decomposing organic substances. Therefore, presence of
carbonate ions in high concentration might not be preferable
in terms of keeping the cleaning effect 5 of ozone water at
high level.
Through earnest studies, it has been found that, by
executing the "decarbonation process" for removing carbonate
ions in the filtered water by a predetermined method after
the pretreatment process is completed, it is possible to keep
the cleaning effect of ozone water at high level irrespective
of the method and the time period for performing the
pretreatment process. In addition, it has been found that,
in removal of carbonate ions, it is possible to clearly
recognize completion of removal of carbonate ions by
monitoring a certain water quality while performing operation
for removing carbonate ions.
[0093] Hereinafter, the details of the decarbonation
process will be described. The decarbonation process can be
executed in accordance with the flowchart shown in FIG. 15.
After the pretreatment process is completed, the
control unit 555 starts the decarbonation process (step S510),
and thus starts a decarbonation treatment (step S511).
Here, in the decarbonation treatment, the
decarbonation unit 570 is driven to perform a decarbonation
operation for removing carbonate ions from the filtered water.
The decarbonation unit 570 may be formed from one or a
plurality of devices selected from a "decarbonation gas
supply device" for supplying the filtered water Y with
decarbonation gas having a carbon dioxide 5 gas content volume
ratio of 100 ppm or smaller, such as oxygen gas, nitrogen gas,
or mixture gas of oxygen and nitrogen, a "heating device"
capable of heating the filtered water Y, an "ultrasonic
oscillation device" capable of applying ultrasonic waves to
the filtered water Y, and the like. Therefore, in the
decarbonation treatment, for example, in the case of using
the decarbonation gas supply device as the decarbonation unit
570, decarbonation gas is supplied through a decarbonation
gas supply pipe 572 to the filtered water Y stored in the
15 treatment water tank 51, in the case of using the heating
device, heating is started, and in the case of using the
ultrasonic oscillation device, application of ultrasonic
waves is started.
[0094] Next, the control unit 555 starts a water quality
confirmation step for determining removal progress of
carbonate ions in the filtered water Y being subjected to the
decarbonation treatment (step S512).
In the water quality confirmation step, the control
unit 555 performs water quality measurement for the filtered
water Y by the water quality measurement device 56, and
records the water quality measurement result as an
intermediate treatment measurement value (step S512a). The
water quality to be measured is favorably pH.
Next, after elapse of time L4, the control unit 555
performs water quality measurement again 5 and records the
water quality measurement result as an intermediate treatment
measurement value again (step S512b).
[0095] Next, using the intermediate treatment measurement
values obtained in step S512a and step S512b as a first
intermediate treatment measurement value α and a second
intermediate treatment measurement value β, respectively, the
control unit 555 compares a second change amount obtained
from change over time in the intermediate treatment
measurement value, i.e., a value obtained by dividing the
second intermediate treatment measurement value β by the
first intermediate treatment measurement value α, with a
predetermined fourth value R4 (step S512c).
[0096] As a result of the comparison, if the value
obtained by dividing the second intermediate treatment
measurement value β by the first intermediate treatment
measurement value α is equal to or smaller than the fourth
value R4 (step S512c, Yes), the control unit 555 determines
that removal of carbonate ions in the filtered water Y is
completed, and determines to stop the decarbonation treatment
for the filtered water Y. In this case, after the water
quality confirmation step is completed, the control unit 55
completes the decarbonation treatment and stops the
decarbonation treatment (step S513), and then finishes the
decarbonation process (step S514).
On the other hand, as a result 5 of the comparison,
if the value obtained by dividing the second intermediate
treatment measurement value β by the first intermediate
treatment measurement value α is greater than the fourth
value R4 (step S512c, No), the control unit 555 returns to
step S512a to continue the water quality confirmation step.
It is noted that the fourth value R4 is favorably
1.0 to 1.5.
[0097] After the decarbonation process is completed, the
control unit 555 performs the ozone water generation process
and the cleaning process as in embodiment 1.
[0098] Hereinafter, the reason why removal progress of
carbonate ions in the filtered water Y can be determined
through the processing in the water quality confirmation step
S512 shown in FIG. 15, will be described.
Although not shown, in the case of performing
decarbonation for the filtered water by supply of
decarbonation gas, heating, or ultrasonic waves, carbonate
ions in the liquid phase are released as gas to the gas phase,
so that the pH of the filtered water increases. However,
when carbonate ions are sufficiently released from the
filtered water, change in each water quality becomes gradual.
Therefore, it is possible to clearly confirm the
decarbonation completion point by monitoring the pH value as
described above.
[0099] In the above description, the 5 "decarbonation gas
supply device", the "heating device", and the "ultrasonic
oscillation device" have been shown as the decarbonation unit
570, but another device may be used.
As the decarbonation unit 570, a pH adjustment
device for adding an acidic chemical as a pH adjustment agent
to the filtered water Y so that the filtered water Y has a
desired pH value, may be used.
The state of carbonate ions changes depending on
the pH, and generally in an acidic region, most part thereof
is released as carbon dioxide gas to the gas phase. Using
this property, it is possible to remove carbonate ions from
the filtered water by adding an acidic chemical such as
hydrochloric acid or sulfuric acid to the filtered water Y so
as to adjust the pH to an acidic state. In this case, the
water quality confirmation step does not necessarily need to
be performed as shown in the water quality confirmation step
S512 in FIG. 15, and the control unit 555 may control a
decarbonation device 571 (pH adjustment device) so that the
pH value obtained by the water quality measurement device 56
becomes a predetermined target pH value, to add an acidic
chemical to the filtered water Y.
[0100] The target pH value is favorably 4 to 6.5. If the
target pH value is excessively low, an acidic chemical is
added even when carbonate ions are no longer present, and
this is inefficient. In addition, in the subsequent 5 cleaning
process, self-decomposition of ozone is significantly
inhibited and thus there is a possibility that generation of
OH radicals is hampered, leading to reduction in the cleaning
effect. On the other hand, if the target pH value is high,
the carbonate ions cannot be sufficiently turned into carbon
dioxide gas, and thus the decarbonation effect cannot be
obtained.
[0101] It is noted that whether or not to perform the
decarbonation process for the filtered water Y after the
pretreatment process is completed may be determined at each
time by, for example, measuring M alkalinity or directly
measuring the sodium bicarbonate ion concentration by ion
chromatography, and estimating the carbonate ion
concentration. Alternatively, the decarbonation process may
be performed in the case of exceeding a reference value
optionally set, within a range in which the cumulative period
of supply of the pretreatment gas in the pretreatment process
or the cumulative period of execution of the circulation step
does not exceed 60 minutes.
[0102] In the oxidation device and the water treatment
method according to the present embodiment configured as
described above, the control unit determines removal progress
of carbonate ions in the filtered water on the basis of the
second change amount obtained from change over time in the
measurement value obtained through water quality 5 measurement
for the filtered water by the water quality measurement
device, and determines to continue or stop removal of
carbonate ions from the filtered water. Thus, it is possible
to find the removal completion point of carbonate ions
contained in the filtered water, and adjust the operation
quantity of decarbonation operation to be performed for the
filtered water in accordance with removal progress.
Therefore, filtered water from which carbonate ions are
sufficiently removed can be obtained irrespective of the
execution period of the pretreatment process or the supply
amount of the oxidation material.
[0103] In the ozone water generation method configured as
described above, ozone gas is supplied to the filtered water
for which the decarbonation process has been determined to be
stopped, thereby generating ozone water. Thus, since ozone
water can be generated on the basis of the filtered water
from which carbonate ions are removed, ozone water having a
higher cleaning effect can be obtained.
[0104] In the cleaning method configured as described
above, a cleaning target part can be cleaned using the ozone
water generated as described above. Thus, since a cleaning
target part is cleaned using ozone water having a higher
cleaning effect, the effect of removing dirt in the cleaning
target part can be further improved.
[0105] Although the disclosure is described 5 above in terms
of various exemplary embodiments and implementations, it
should be understood that the various features, aspects, and
functionality described in one or more of the individual
embodiments are not limited in their applicability to the
particular embodiment with which they are described, but
instead can be applied, alone or in various combinations to
one or more of the embodiments of the disclosure.
It is therefore understood that numerous
modifications which have not been exemplified can be devised
without departing from the scope of the present disclosure.
For example, at least one of the constituent components may
be modified, added, or eliminated. At least one of the
constituent components mentioned in at least one of the
preferred embodiments may be selected and combined with the
constituent components mentioned in another preferred
embodiment.

DESCRIPTION OF THE REFERENCE CHARACTERS
[0106] 1 filtration unit
25 2 filtration membrane (cleaning target part)
10 first transfer unit
20 second transfer unit
50, 350 oxidation device
54 oxidation unit
55, 355, 5 555 control unit
56 water quality measurement device (measurement
unit)
570 decarbonation unit
60 ozone water generation unit
10 270 outside air contact device
100, 200, 300, 500 water treatment device
We Claim :
[1] An oxidation device for oxidizing oxidizable
substances contained in treatment target water by causing an
oxidation material containing an oxidizing substance to be in
contact with the treatment target water, the 5 oxidation device
comprising:
an oxidation unit for causing the oxidation
material to be in contact with the treatment target water;
a measurement unit for performing water quality
measurement for the treatment target water; and
a control unit which controls the oxidation unit,
determines oxidation progress of the oxidizable substances in
the treatment target water on the basis of a first change
amount obtained from change over time in a measurement value
obtained through water quality measurement for the treatment
target water by the measurement unit, and determines to
continue or stop supply of the oxidation material to the
treatment target water.
[2] A water treatment device comprising:
the oxidation device according to claim 1;
a filtration unit for filtering organic substances
in raw water to generate filtered water;
a first transfer unit for transferring the filtered
water as the treatment target water to the oxidation unit;
an ozone water generation unit for generating ozone
water by supplying ozone gas to the treatment target water
for which supply of the oxidation material has been
determined to be stopped; and
a second transfer unit for transferring 5 the ozone
water to the filtration unit.
[3] The water treatment device according to claim 2,
wherein
the first transfer unit includes a first outside
air contact device for exposing the filtered water to outside
air.
[4] A water treatment method for oxidizing oxidizable
substances contained in treatment target water by causing an
oxidation material containing an oxidizing substance to be in
contact with the treatment target water, the water treatment
method comprising:
determining oxidation progress of the oxidizable
substances in the treatment target water on the basis of a
first change amount obtained from change over time in a
measurement value obtained through water quality measurement
for the treatment target water, and determining to continue
or stop supply of the oxidation material to the treatment
target water.
[5] The water treatment method according to claim 4,
Wherein a slope of the measurement value is used as the
first change amount.
[6] The water treatment method according to claim 4,
Wherein a ratio of the measurement value is used as the
first change amount.
[7] The water treatment method according to claim 5,
wherein
the measurement value measured at a first time
point is defined as a first measurement value, and the
measurement value measured at a second time point after the
first time point is defined as a second measurement value,
the measurement value measured at a third time
point after the second time point is defined as a third
measurement value, and the measurement value measured at a
fourth time point after the third time point is defined as a
fourth measurement value, and
a relationship between a first slope of a line
connecting the first measurement value and the second
measurement value, and a second slope of a line connecting
the third measurement value and the fourth measurement value
or a line connecting the second measurement value and the
third measurement value, is used.
[8] The water treatment method according 5 to claim 7,
wherein
the measurement value is at least one of a
dissolved oxygen concentration value or a standard oxidation
reduction potential value of the treatment target water, and
the oxidation material is continuously supplied to the
treatment target water, and
supply of the oxidation material to the treatment
target water is determined to be stopped, when an absolute
value of the second slope becomes greater than an absolute
value of the first slope or a value obtained by dividing the
absolute value of the second slope by the absolute value of
the first slope becomes equal to or greater than a
predetermined first value.
[9] The water treatment method according to claim 7, wherein the measurement value is a pH value of the treatment target water, and the oxidation material is continuously supplied to the treatment target water, and
supply of the oxidation material to the treatment
target water is determined to be stopped, when an absolute value of the second slope becomes smaller than an absolute value of the first slope or a value obtained by dividing the absolute value of the second slope by the absolute value of the first slope becomes equal to 5 or smaller than a predetermined second value.
[10] The water treatment method according to claim 6, wherein
the oxidation material is intermittently supplied
to the treatment target water with a predetermined
interruption period provided,
the ratio of the measurement value in the
interruption period is used as the first change amount, the measurement value measured at a first time point is defined as a first measurement value, and the measurement value measured at a second time point after the
first time point is defined as a second measurement value,
and supply of the oxidation material to the treatment target water is determined to be stopped, when the ratio of the measurement value obtained by dividing the second
measurement value by the first measurement value becomes equal to or greater than a predetermined third value.
[11] The water treatment method according to any one of claims 4 to 7 and 10, wherein
the measurement value is at least one of a
dissolved oxygen concentration value, a standard oxidation reduction potential value, or a pH value 5 of the treatment target water.
[12] The water treatment method according to any one of
claims 4 to 11, wherein
supply of the oxidation material to the treatment
target water is performed by jetting gas containing the oxidizing substance, as the oxidation material, into the
treatment target water.
[13] The water treatment method according to any one of
claims 4 to 11, wherein
supply of the oxidation material to the treatment
target water is performed by transferring the treatment
target water so that the treatment target water is exposed to
outside air as the oxidation material.
[14] The water treatment method according to any one of
claims 4 to 13, wherein
removal of carbonate ions in the treatment target
water is performed for the treatment target water for which
supply of the oxidation material has been determined to be
stopped.
[15] The water treatment method according to claim 14,
wherein
removal progress of the carbonate ions in the
treatment target water is determined on the basis of a second
change amount obtained from change over time in an
intermediate treatment measurement value obtained through
water quality measurement for the treatment target water for
which the removal of the carbonate ions has been performed,
and thus the removal of the carbonate ions in the treatment
target water is determined to be continued or stopped.
[16] The water treatment method according to claim 15,
wherein
the intermediate treatment measurement value is a
pH value of the treatment target water, and
a ratio of the intermediate treatment measurement
value is used as the second change amount.
[17] The water treatment method according to any one of
claims 14 to 16, wherein
the removal of the carbonate ions in the treatment
target water is performed using at least one of jetting of
decarbonation gas into
the treatment target water, or application of ultrasonic
vibration to the treatment target water
[18] The water 5 treatment method
wherein
the removal of
target water is performed by adding
made of an acidic chemical to
that the treatment target water
[19] An ozone water generation method
generating ozone water
treatment target water
material has been determined to be stopped in
treatment method according to any one of claims
[20] A cleaning method comprising cleaning
target part using the
water generation method