FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
WATER TREATMENT APPARATUS AND WATER TREATMENT METHOD
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TECHNICAL FIELD
5 [0001] The present disclosure relates to a water treatment
apparatus and a water treatment method.
BACKGROUND ART
[0002] One of general methods for treating urban sewage,
10 organic waste water, and nitrogen-containing waste water is
an activated sludge process. The activated sludge process is
a method in which microorganisms (activated sludge) having a
purification function are stored in a biological reaction
tank and then are mixed and contacted with the waste water
15 while being aerated, whereby contaminants in the waste water
are oxidized and decomposed. In order to sufficiently clean
out the contaminants, it is necessary to supply an
appropriate amount of air to the biological reaction tank.
[0003] In addition, for disinfection, sterilization,
20 deodorization, and the like of secondary treated water
treated through the activated sludge process as described
above and water that has undergone flocculation sedimentation
or rapid sand filtration in water treatment, ozone gas is
supplied to treatment target water, thereby performing
25 treatment of oxidizing and decomposing contaminants such as
3
organic substances and viruses in the water. Also here, in
order to sufficiently clean out the contaminants, it is
necessary to supply an appropriate amount of ozone gas to the
treatment target water.
5 [0004] Further, as a method for treating phosphoruscontaining
waste water, there is a flocculation sedimentation
method. In this method, a flocculant is reacted with
phosphoric acid in treatment target water, whereby phosphorus
is settled as a metal salt or a calcium salt and thus
10 phosphorus is cleaned out from the water. The supply amount
of the flocculant varies in accordance with the concentration
of phosphorus contained in the treatment target water.
Therefore, it is necessary to supply an appropriate amount of
the flocculant to the treatment target water.
15 [0005] All of the water treatment methods shown above are
the same in that the treatment target water is purified by
supplying a treatment agent such as air, ozone gas, or a
flocculant to a water treatment tank into which the treatment
target water flows, and therefore it is necessary to
20 immediately control the supply amount of the treatment agent
in response to variation in a load value. For example,
Patent Document 1 discloses that, in a water treatment system
using activated sludge, a setting value for the nitrification
rate in an aerobic tank is determined from an organic
25 substance concentration and a nitrogen concentration in raw
4
water, and on the basis of an ammonia nitrogen concentration
and a nitrate nitrogen concentration in the aerobic tank, a
calculated value of the nitrification rate in the aerobic
tank is compared with the setting value of the nitrification
5 rate, thereby performing aeration control.
[0006] In addition, for example, Patent Document 2
discloses that, in water treatment equipment using ozone, an
ozone generator and an ozone dissolver are incorporated into
an ozone aeration tank, all the generated ozone is dissolved
10 into treatment target water, and ozone treatment is performed,
thus reducing construction cost and operation cost for the
ozone generator.
[0007] In addition, for example, Patent Document 3
discloses that, in a water treatment system, an aeration
15 amount and a flocculant injection amount for a biological
treatment tank are controlled on the basis of the flow rate
and the phosphorus component concentration of treatment
target water, and the phosphorus component concentration of
flow-out water.
20
CITATION LIST
PATENT DOCUMENT
[0008] Patent Document 1: Japanese Laid-Open Patent
Publication No. 2014-184396
25 Patent Document 2: Japanese Laid-Open Patent
5
Publication No. 2011-5406
Patent Document 3: Japanese Laid-Open Patent
Publication No. 2010-269276
5 SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0009] For example, in Patent Document 1, aeration control
is performed on the basis of the present values of the
organic substance concentration and the nitrogen
10 concentration of flow-in water. However, it takes time for
activated sludge to increase in its purification function
through aeration, and therefore, the control based on the
present value of the flow-in water quality might cause water
quality deterioration due to insufficiency of the aeration
15 amount in a case of high load. In addition, in a case of low
load, a necessary aeration amount is reduced, but control for
the aeration amount does not catch up with reduction of the
load value, and thus energy loss might occur due to excessive
aeration.
20 [0010] In Patent Document 2, the output of the ozone
generator is changed in response to variation in the load
value at the present. Therefore, in a case of high load, the
flow-out water quality might be deteriorated due to
insufficiency of the supply amount of ozone gas, and in a
25 case of low load, energy loss might occur due to excess
6
supply of ozone gas.
[0011] In Patent Document 3, the flocculant is supplied in
response to variations in the flow rate and the phosphorus
component concentration of flow-in water at the present, as
5 in Patent Document 1. Therefore, in a case where the load
value is increased, water quality might be deteriorated due
to insufficiency of supply of the flocculant, and in a case
of low load, cost might increase due to excessive supply of
the flocculant.
10 [0012] As described above, in any of the conventional
technologies, in a case of using control of supplying a
treatment agent in response to variation in the load value at
the present, the supply amount of the treatment agent is
increased or decreased after the variation in the load value
15 is detected. Therefore, there is a problem that, in a case
of high load, the flow-out water quality might be
deteriorated due to insufficiency of the supply amount of the
treatment agent, and in a case of low load, cost might
increase due to excessive supply of the treatment agent.
20 [0013] The present disclosure has been made to solve the
above problem, and an object of the present disclosure is to
provide a water treatment apparatus and a water treatment
method that can suppress variation in the water quality of
treated water obtained through water treatment on treatment
25 target water and reduce operation cost.
7
SOLUTION TO THE PROBLEMS
[0014] A water treatment apparatus according to the
present disclosure is a water treatment apparatus for
5 performing water treatment by supplying a treatment agent to
treatment target water flowing into a water treatment tank,
the water treatment apparatus including: a load measurement
unit which measures, as a first load value, a load value of
the treatment target water flowing into the water treatment
10 tank at a first time point; a prediction unit which predicts,
as a second load value, a load value of the treatment target
water flowing into the water treatment tank at a second time
point after the first time point, on the basis of the first
load value measured by the load measurement unit; and a
15 supply unit which supplies the treatment agent in a supply
amount corresponding to the second load value predicted by
the prediction unit, to the treatment target water in the
water treatment tank, at a third time point between the first
time point and the second time point.
20 A water treatment method according to the present
disclosure is a water treatment method for performing water
treatment by supplying a treatment agent to treatment target
water, the water treatment method including: a first step of
measuring, as a first load value, a load value of the
25 treatment target water at a first time point; a second step
8
of predicting, as a second load value, a load value of the
treatment target water at a second time point after the first
time point, on the basis of the first load value measured in
the first step; and a third step of supplying the treatment
5 agent in a supply amount corresponding to the second load
value predicted in the second step, to the treatment target
water, at a third time point between the first time point and
the second time point.
10 EFFECT OF THE INVENTION
[0015] The water treatment apparatus and the water
treatment method according to the present disclosure can
suppress variation in the water quality of treated water
obtained through water treatment on treatment target water
15 and reduce operation cost.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] [FIG. 1] FIG. 1 is a diagram showing the
configuration of a water treatment apparatus according to
20 embodiment 1.
[FIG. 2] FIG. 2 is a flowchart showing a water
treatment method in the water treatment apparatus shown in
FIG. 1.
[FIG. 3] FIG. 3 is a graph showing temporal
25 changes in a load value and an aeration amount in the water
9
treatment apparatus according to embodiment 1 and in a
comparative example.
[FIG. 4] FIG. 4 is a graph showing temporal
changes in the ammonia nitrogen concentration of treated
5 water in the water treatment apparatus according to
embodiment 1.
[FIG. 5] FIG. 5 is a graph showing temporal
changes in a load value and an aeration amount in the water
treatment apparatus according to embodiment 1 and in a
10 comparative example.
[FIG. 6] FIG. 6 is a graph showing temporal
changes in the ammonia nitrogen concentration of treated
water in the water treatment apparatus according to
embodiment 1.
15 [FIG. 7] FIG. 7 is a diagram showing the
configuration of a water treatment apparatus according to
embodiment 2.
[FIG. 8] FIG. 8 is a diagram showing the
configuration of a water treatment apparatus according to
20 embodiment 3.
[FIG. 9] FIG. 9 is a diagram showing the
configuration of a water treatment apparatus according to
embodiment 4.
25 DESCRIPTION OF EMBODIMENTS
1 0
[0017] The present disclosure relates to a water treatment
apparatus and a water treatment method for performing water
treatment through purification treatment for contaminants
contained in treatment target water such as urban sewage,
5 organic waste water, nitrogen-containing waste water, sewage
secondary treated water, or phosphorus-containing waste water.
[0018] Embodiment 1
FIG. 1 is a diagram showing the configuration of a
water treatment apparatus according to embodiment 1. In FIG.
10 1, the water treatment apparatus includes: a water treatment
tank 1; a first calculation unit 91, a first supply unit 41,
and a first aeration unit 31, a second calculation unit 92, a
second supply unit 42, and a second aeration unit 32, and a
third calculation unit 93, a third supply unit 43, and a
15 third aeration unit 33, as supply units; a load measurement
unit 5; a recording unit 6; a prediction unit 7; and a
sedimentation tank 2. The first calculation unit 91, the
first supply unit 41, and the first aeration unit 31 form one
supply unit.
20 [0019] In addition, the second calculation unit 92, the
second supply unit 42, and the second aeration unit 32 form
one supply unit. In addition, the third calculation unit 93,
the third supply unit 43, and the third aeration unit 33 form
one supply unit. In the present embodiment, three supply
25 units are provided as an example. However, depending on the
1 1
size of the water treatment tank 1, the treatment amount for
treatment target water, and the like, a case of providing one
supply unit, a case of providing two supply units, and a case
of providing four or more supply units, are also conceivable.
5 The number of the supply units is the same also in the
subsequent embodiments, and the description thereof is
omitted as appropriate.
[0020] Treatment target water flows from the outside into
the water treatment tank 1 via a pipe 101. In the water
10 treatment tank 1, activated sludge is stored and purification
treatment is performed on the treatment target water through
biological reaction with the activated sludge. The treatment
target water treated in the water treatment tank 1
(hereinafter, the treatment target water treated in the water
15 treatment tank 1 is referred to as "treated water") is
discharged to the sedimentation tank 2 via a pipe 102. In
the sedimentation tank 2, activated sludge contained in the
treated water discharged from the water treatment tank 1 via
the pipe 102 is settled. The supernatant water after the
20 sedimentation treatment in the sedimentation tank 2 is
discharged via a pipe 103. In addition, the activated sludge
separated through the sedimentation treatment in the
sedimentation tank 2 is returned to the water treatment tank
1 via a pipe 104. Meanwhile, excess activated sludge in the
25 sedimentation tank 2 is discharged to the outside via a pipe
1 2
105.
[0021] The aeration units 31 to 33 are provided so as to
be arranged in the direction in which the treatment target
water flows downstream in the water treatment tank 1. The
5 aeration units 31 to 33 supply treatment agents in a gas
state sent via pipes 411, 421, 431 from the supply units 41
to 43, into the water treatment tank 1.
[0022] The load measurement unit 5 is mounted to the pipe
101 and measures a load value of the treatment target water
10 flowing into the water treatment tank 1. The recording unit
6 receives the load value measured by the load measurement
unit 5 via a signal line 51, and records the load value
together with a time. The prediction unit 7 receives a past
load value and a time of the load value recorded in the
15 recording unit 6, via a signal line 61, and further receives
a first load value of treatment target water at the present
as a first time point measured by the load measurement unit 5,
and the time thereof, via a signal line 52 from the load
measurement unit 5. Then, the prediction unit 7 predicts, as
20 a second load value, a load value of treatment target water
that flows into the water treatment tank 1 at a second time
point after the present (first time point).
[0023] The calculation units 91 to 93 receive the second
load value of treatment target water predicted by the
25 prediction unit 7 via a signal line 71, and calculate the
1 3
supply amounts of the treatment agents corresponding to the
second load value. In the present embodiment 1, air is used
as the treatment agents, and therefore the supply amounts may
be referred to as aeration amounts. Then, the calculation
5 units 91 to 93 cause the supply units 41 to 43 to supply, to
the respective aeration units 31 to 33, the treatment agents
in the supply amounts calculated correspondingly for the
second load value of the treatment target water, at a third
time point between the first time point and the second time
10 point.
[0024] At this time, the supply amounts of the treatment
agents calculated by the calculation units 91 to 93 are sent
to the supply units 41 to 43 via signal lines 911, 921, 931.
In addition, the treatment agents supplied from the supply
15 units 41 to 43 are supplied to the aeration units 31 to 33,
and the treatment agents are supplied into the water
treatment tank 1. Thus, the water treatment apparatus of the
present embodiment 1 is configured such that, in the water
treatment tank 1, the treatment target water flowing in via
20 the pipe 101 is mixed and stirred with the activated sludge
while being aerated by the aeration units 31 to 33 with air
which is the treatment agents supplied from the supply units
41 to 43, so that contaminants in the water are biologically
oxidized and decomposed, whereby purification treatment is
25 performed.
1 4
[0025] Next, a specific example and the details of each
part will be described. First, a specific example of the
load measurement unit 5 will be described. The load
measurement unit 5 measures a load value of treatment target
5 water flowing into the water treatment tank 1, and,
specifically, includes at least one measurement device of a
flowmeter or a contaminant concentration meter (an ammonia
nitrogen concentration meter, a total nitrogen concentration
meter, a biochemical oxygen demand (BOD) meter, a chemical
10 oxygen demand (COD) meter, etc.) for the treatment target
water. The load measurement unit 5 measures the load value
continuously or intermittently at predetermined time
intervals. All the load values are associated with times at
which the load values are measured.
15 [0026] The load measurement unit 5 may include both of the
flowmeter and the contaminant concentration meter described
above. In this case, the product of the flow rate and the
contaminant concentration of the treatment target water
flowing into the water treatment tank 1 may be calculated as
20 the load value. Thus, the load measurement unit 5 measures
the load value of the treatment target water substantially
flowing into the water treatment tank 1. As an alternative
for the flowmeter, the opening degree of a weir of an inflow
ditch may be used instead of the flow rate. Further, for
25 considering the influence of the temperature depending on the
1 5
seasons or the like, a water temperature meter may be
provided in addition to the flowmeter and the contaminant
concentration meter. Here, a case of not providing a water
temperature meter will be described.
5 [0027] In FIG. 1, an example in which the load measurement
unit 5 is connected to the pipe 101 is shown. However, the
load measurement unit 5 may be provided on the upstream side
in the water treatment tank 1. Thus, it is possible to
consider the load value including the influence of activated
10 sludge returned via the pipe 104. Further, the influence of
a time lag until actually flowing into the water treatment
tank 1 after passing through the pipe 101 can be eliminated,
whereby more accurate control can be performed. This also
applies in the subsequent embodiments, and the description
15 thereof is omitted as appropriate.
[0028] Next, a specific example of the prediction unit 7
will be described. The prediction unit 7 predicts the second
load value of treatment target water for a predetermined
period later (second time point), on the basis of a past load
20 value and the first load value at the present (first time
point) measured by the load measurement unit 5. Regarding
the predetermined period later (second time point) for which
the prediction unit 7 performs prediction, an optimum value
thereof differs in accordance with a load variation pattern
25 of the treatment target water flowing into the water
1 6
treatment apparatus. It is generally known that, in a case
of urban sewage in sunny weather, or the like, the load value
varies periodically. Therefore, it is desirable that the
predetermined period is set within a range not exceeding the
5 cycle of the load value, and the prediction is performed for
approximately thirty minutes to six hours later. Such
prediction makes it possible to operate the water treatment
apparatus in prospect of variation in the load value.
[0029] In the prediction for the second load value of
10 treatment target water at the second time point by the
prediction unit 7, the second load value of treatment target
water for the predetermined period later as the second time
point after the first time point is predicted from the first
load value of treatment target water at the present which is
15 the first time point, on the basis of data of the past load
values accumulated. Specific examples of the prediction
method include a neural network, deep learning, reinforcement
learning, machine learning, and local approximation. As data
for learning, data of the past load values recorded in the
20 recording unit 6 is used. The load value may be predicted in
association with water quality data other than load value
data, or data that can be acquired from the outside.
[0030] For example, in water treatment by the activated
sludge process, it is general that the aeration amount to be
25 supplied to the water treatment tank 1 is also increased or
1 7
decreased along with increase or decrease of the load value.
Therefore, if data of the past load values and time-series
data of the past aeration amounts are learned in association
with each other, it becomes possible to accurately predict
5 load value variation that requires great increase or decrease
of the aeration amount among load value variation patterns.
In addition, if data of the past load values and time-series
data of a rain cloud radar or a rainfall amount are learned
in association with each other, it becomes possible to
10 accurately predict variation in the inflow amount of
treatment target water or the water quality of treatment
target water due to rainfall.
[0031] Next, a specific example of the calculation units
91 to 93 will be described. The calculation units 91 to 93
15 have calculation formulas for calculating the aeration
amounts of the treatment agents to be supplied from the
aeration units 31 to 33 at the third time point between the
first time point and the second time point, using the first
load value of treatment target water at the present as the
20 first time point, measured by the load measurement unit 5, or
the second load value of treatment target water for the
predetermined period later as the second time point after the
first time point, predicted by the prediction unit 7.
[0032] Specifically, the calculation units 91 to 93 have
25 coefficients set in advance for the aeration units 31 to 33
1 8
respectively connected thereto, and each calculate the sum of
the following (A) and (B).
(A) A supply amount obtained by multiplying the
load value of treatment target water flowing into the water
5 treatment tank 1 measured by the load measurement unit 5, by
the coefficient set in advance for each aeration unit 31 to
33
(B) Constant
The above coefficients are values set in advance so
10 as to obtain, through the above calculation, optimum aeration
amounts for the aeration amounts to quickly follow variation
in the load value flowing into the water treatment tank 1,
and these values can be set in accordance with the positions
or the number of the aeration units 31 to 33.
15 [0033] For example, in a case where the load measurement
unit 5 is provided with the flowmeter and the ammonia
nitrogen concentration meter as the contaminant concentration
meter, the first calculation unit 91 calculates a setting
value G1 [Nm3/hr] for the aeration amount to be supplied from
20 the first aeration unit 31, by the following Expression (1).
G1 = k11•SIN٬N•QIN + k13 ... (1)
SIN٬N: the ammonia nitrogen concentration [mg/L] of
treatment target water flowing into the water treatment tank
1
25 QIN: the flow rate [m3/hr] of treatment target
1 9
water flowing into the water treatment tank 1
k11, k13: constant
[0034] Similarly as in the above case, the calculation
units 92, 93 calculate setting values G2, G3 [Nm3/hr] for the
5 aeration amounts to be supplied from the aeration units 32,
33, by the following Expressions (2), (3), respectively.
G2 = k21•SIN٬N•QIN + k23 ... (2)
k21, k23: constant
G3 = k31•SIN٬N•QIN + k33 ... (3)
10 k31, k33: constant
[0035] In the above Expressions (1) to (3), the
coefficients k11, k21, k31 set in advance correspondingly for
the aeration units 31 to 33 are values set in advance so as
to obtain, through the above calculation, optimum aeration
15 amounts for the aeration amounts to quickly follow variation
in the load value for flowing into the water treatment tank 1,
as described above. The coefficients k11, k21, k31 are not
necessarily all equal to each other, and may be set to
different values in accordance with the positions of the
20 aeration units 31 to 33. In addition, even after the
coefficients k11, k21, k31 are set once, it is possible to
set optimum values again as appropriate in accordance with
season change, change of a target water quality of the
treated water, and the like.
25 [0036] As described above, the calculation units 91 to 93
2 0
calculate the aeration amounts to be supplied from the
aeration units 31 to 33 at the third time point between the
first time point and the second time point, on the basis of
the aeration amount calculation formulas provided in the
5 calculation units 91 to 93 and the second load value of
treatment target water at the second time point predicted by
the prediction unit 7. In the aeration amount calculation
formulas provided in the calculation units 91 to 93, the
first load value at the present (first time point) is denoted
10 by "SIN٬N, QIN". With respect to this, the above calculation
formulas are for calculating optimum aeration amounts.
However, in the calculation units 91 to 93, the second load
value "S’IN٬N, Q’IN" of treatment target water at the second
time point, instead of the first load value "SIN٬N, QIN" of
15 treatment target water at the present, is inputted in the
above calculation formulas, thereby calculating the aeration
amounts corresponding to the second load value of treatment
target water.
[0037] Specific description will be given on the basis of
20 Expressions (1) to (3) shown above. In Expressions (1) to
(3) shown above, the first load value "SIN٬N, QIN" of
treatment target water at the present is inputted, whereby
optimum aeration amounts for the first load value at the
present are calculated. However, in the calculation units 91
25 to 93, the second load value "S’IN٬N, Q’IN" of treatment
2 1
target water predicted for the second time point is inputted,
to calculate target aeration amounts (at the third time
point) for the respective aeration units 31 to 33.
[0038] The setting values G1 to G3 for the aeration
5 amounts at the third time point calculated as described above
are respectively transmitted to the supply units 41 to 43 via
the signal lines 911 to 931. The supply units 41 to 43
supply air in the aeration amounts set respectively, via the
pipes 411 to 431 and the aeration units 31 to 33, into the
10 water treatment tank 1.
[0039] As described above, after the first load value of
treatment target water at the present is measured by the load
measurement unit 5, the second load value of treatment target
water for the predetermined period later is calculated by the
15 prediction unit 7, the supply amounts of the treatment agents
at the third time point are calculated by the calculation
units 91 to 93, the aeration amounts are controlled in the
supply units 41 to 43, and air is moved through the pipes 411
to 431, whereby the target aeration amounts are supplied from
20 the aeration units 31 to 33 to the water treatment tank 1.
At this time, until the aeration amounts at the third time
point calculated by the calculation units 91 to 93 are
actually supplied from the aeration units 31 to 33 after the
first load value of treatment target water at the present is
25 measured by the load measurement unit 5, there is a time lag
2 2
including a calculation time for the second load value of
treatment target water, a calculation time for the aeration
amount at the third time point, a control time for the
aeration units 31 to 33, a movement time of air in the pipes,
5 and the like. Therefore, it is necessary to set the
predetermined period used for prediction of the second load
value of treatment target water in the prediction unit 7 so
that the time lag becomes shorter than the predetermined
period. Thus, the aeration amounts can be controlled in
10 advance before the load value actually reaches the predicted
value.
[0040] Next, a water treatment method for the water
treatment apparatus of embodiment 1 configured as described
above will be described with reference to FIG. 2. First,
15 treatment target water flows into the water treatment tank 1
via the pipe 101. At this time, the load measurement unit 5
measures the first load value of the treatment target water
at the present (first time point) (step ST1 in FIG. 2). In
addition, the first load value is recorded in the recording
20 unit 6 together with the measurement time thereof (step ST5
in FIG. 2). Next, the prediction unit 7 predicts the second
load value of the treatment target water at the second time
point after the present (first time point), using the first
load value measured by the load measurement unit 5, the past
25 load value recorded in the recording unit 6, and the like
2 3
(step ST2 in FIG. 2). Next, the calculation units 91 to 93
calculate the supply amounts of the treatment agents on the
basis of the second load value of the treatment target water
(step ST3 in FIG. 2). Next, the calculation units 91 to 93
5 supply the treatment agents in the above-calculated supply
amounts, to the water treatment tank 1 via the supply units
41 to 43 and the aeration units 31 to 33, at the third time
point between the first time point and the second time point
(step ST4 in FIG. 2).
10 [0041] Next, the effects of the water treatment method of
embodiment 1 performed as described above will be described
with reference to FIG. 3 to FIG. 6. FIG. 3 and FIG. 4 show a
case where, at a predetermined period later from the present,
the second load value of the treatment target water is
15 predicted to become greater than the first load value of the
treatment target water at the present. FIG. 5 and FIG. 6
show a case where, at the predetermined period later from the
present, the second load value of the treatment target water
is predicted to become smaller than the first load value of
20 the treatment target water at the present. FIG. 3 and FIG. 5
are graphs showing temporal changes in the aeration amount
and the load value. FIG. 4 and FIG. 6 are graphs showing
temporal changes in the ammonia nitrogen concentration of the
treated water that has flowed out, i.e., the treated water
25 that has undergone the water treatment in the water treatment
2 4
tank 1.
[0042] In FIG. 3 to FIG. 6, T1 denotes the present and is
defined as the first time point. T2 is the second time point
T2 which is the predetermined period later from the first
5 time point T1. In addition, T3 is the third time point
between the first time point T1 and the second time point T2.
In FIG. 3, F1 is a graph indicating the actual value of the
load value. F2 is a graph indicating the predicted value of
the load value. D1 is a graph indicating the aeration amount
10 based on the load value F1. D2 is a graph indicating the
aeration amount based on the load value F2. In FIG. 4, N1 is
a graph indicating the ammonia nitrogen concentration
(hereinafter, referred to as "ammonia nitrogen concentration
of treated water") of the treated water having undergone the
15 water treatment in the water treatment tank 1 and discharged
from the water treatment tank 1, in a case of performing the
treatment using the aeration amount D1. N2 is a graph
indicating the ammonia nitrogen concentration of the treated
water in a case of performing the treatment using the
20 aeration amount D2.
[0043] In FIG. 5, F3 is a graph indicating the actual
value of the load value. F4 is a graph indicating the
predicted value of the load value. D3 is a graph indicating
the aeration amount based on the load value F3. D4 is a
25 graph indicating the aeration amount based on the load value
2 5
F4. In FIG. 6, N3 is a graph indicating the ammonia nitrogen
concentration of the treated water in a case of performing
the treatment using the aeration amount D3. N4 is a graph
indicating the ammonia nitrogen concentration of the treated
5 water in a case of performing the treatment using the
aeration amount D4.
[0044] First, in a comparative example, as shown in FIG. 3,
in a case of using the load value F1 "SIN٬N, QIN" at the
present for calculation of the aeration amount, the aeration
10 amount D1 is increased at the same timing T0 as increase in
the load value F1. However, it takes time for the activated
sludge to increase in its purification function through
aeration. Therefore, in particular, in a case where the load
value F1 sharply increases, increase in the purification
15 function of the activated sludge due to increase in the
aeration amount D1 does not catch up, so that the ammonia
nitrogen concentration N1 of the treated water might exceed
SOUT٬cont which is an upper limit value for management, as
shown in FIG. 4.
20 [0045] On the other hand, in the present disclosure, in a
case where the second load value of the treatment target
water at the second time point T2 which is the predetermined
period later from the first time point T1 at the present is
predicted to become greater than the first load value at the
25 present, the predicted second load value "S’IN٬N, Q’IN" of
2 6
the treatment target water is inputted in the above
Expressions (1) to (3). Thus, at the stage when the load
value F2 is predicted to increase, values greater than the
present values of the ammonia nitrogen concentration and the
5 flow rate of the treatment target water are inputted as the
load value in the above Expressions (1) to (3). As a result,
the aeration amount D2 can be increased from the third time
point T3 which is before the load value actually increases.
Thus, the aeration amount is increased in advance in prospect
10 of increase in the load value, and the treatment target water
with high load flows into the water treatment tank 1 in a
state in which the purification function of the activated
sludge has increased sufficiently. In this way, as shown in
FIG. 4, increase in the ammonia nitrogen concentration N2 of
15 the treated water due to increase in the load value can be
suppressed to the minimum level, and even in a case where the
load value sharply increases, the ammonia nitrogen
concentration N2 of the treated water can be reduced to
SOUT٬cont or smaller.
20 [0046] In addition, in a comparative example, as shown in
FIG. 5, in a case of using the load value "SIN٬N, QIN" at the
present for calculation of the aeration amount, the aeration
amount D3 is decreased at the same timing T0 as decrease in
the load value F3. However, in particular, in a case where
25 the load value F3 sharply decreases, control for the aeration
2 7
amount D3 is delayed relative to decrease in the load value
F3, so that an excessive aeration amount D3 might be supplied.
[0047] On the other hand, in the present disclosure, in a
case where the second load value of the treatment target
5 water at the second time point T2 which is the predetermined
period later from the first time point T1 at the present is
predicted to become smaller than the first load value at the
present, the predicted second load value "S’IN٬N, Q’IN" of
the treatment target water is inputted in the Expressions (1)
10 to (3) shown above. Thus, at the stage when the load value
F4 is predicted to decrease, values smaller than the present
values of the ammonia nitrogen concentration and the flow
rate of the treatment target water are inputted as the load
value in the above Expressions (1) to (3). As a result, the
15 aeration amount D4 can be decreased from the third time point
T3 which is before the load value actually decreases. Thus,
the aeration amount is decreased in advance in prospect of
decrease in the load value, and accordingly, the ammonia
nitrogen concentration N4 of the treated water temporarily
20 increases, but thereafter, the treatment target water with a
decreased load value actually flows into the water treatment
tank 1. Therefore, the ammonia nitrogen concentration N4 of
the treated water does not exceed SOUT٬cont which is the
upper limit value for management, and in a state in which the
25 water quality of the treated water is kept preferable, it is
2 8
possible to suppress excessive aeration, i.e., an aeration
amount M indicated by a hatched area representing the
difference between the aeration amount D3 and the aeration
amount D4 in FIG. 5.
5 [0048] As described above, the load value of the treatment
target water flowing into the water treatment tank 1 is
predicted, and the air amount supplied into the water
treatment tank 1 is set on the basis of the predicted load
value. Therefore, in a case where the load value increases,
10 the aeration amount is increased in advance, whereby
deterioration in the water quality of the treated water can
be suppressed. In addition, in a case where the load value
decreases, the aeration amount is decreased in advance,
whereby excessive aeration can be suppressed while the water
15 quality of the treated water is kept below the upper limit
value for management.
[0049] Alternatively, there is a case where the water
quality of the treated water that flows out is desired to be
kept as preferable as possible relative to the above20
described case. In the above method, in a case where the
predicted load value decreases, decreasing the aeration
amount in advance temporarily deteriorates the water quality
of the treated water. Therefore, in order to prevent this,
control is performed such that the predicted load value
25 "S’IN٬N, Q’IN" is inputted only in a case where the predicted
2 9
load value increases, and the load value "SIN٬N, QIN" at the
present is inputted in a case where the predicted load value
decreases.
[0050] Still alternatively, there is a case where the
5 aeration amount is desired to be reduced as much as possible
so as to minimize the operation cost relative to the abovedescribed
case. In a case where the predicted load value
increases, as described above, the aeration amount is
increased in advance of increase in the load value, so that
10 the operation cost increases. Therefore, control is
performed such that the predicted load value "S’IN٬N, Q’IN"
is inputted only in a case where the predicted load value is
decreased, and the load value "SIN٬N, QIN" at the present is
inputted in a case where the predicted load value increases,
15 whereby the operation cost can be reduced.
[0051] According to the water treatment apparatus of
embodiment 1 configured as described above, a water treatment
apparatus for performing water treatment by supplying a
treatment agent to treatment target water flowing into a
20 water treatment tank includes:
a load measurement unit which measures, as a first
load value, a load value of the treatment target water
flowing into the water treatment tank at a first time point;
a prediction unit which predicts, as a second load
25 value, a load value of the treatment target water flowing
3 0
into the water treatment tank at a second time point after
the first time point, on the basis of the first load value
measured by the load measurement unit; and
a supply unit which supplies the treatment agent in
5 a supply amount corresponding to the second load value
predicted by the prediction unit, to the treatment target
water in the water treatment tank, at a third time point
between the first time point and the second time point.
In addition, a water treatment method for
10 performing water treatment by supplying a treatment agent to
treatment target water includes:
a first step of measuring, as a first load value, a
load value of the treatment target water at a first time
point;
15 a second step of predicting, as a second load value,
a load value of the treatment target water at a second time
point after the first time point, on the basis of the first
load value measured in the first step; and
a third step of supplying the treatment agent in a
20 supply amount corresponding to the second load value
predicted in the second step, to the treatment target water,
at a third time point between the first time point and the
second time point.
Thus, the treatment agent in the supply amount
25 corresponding to the second load value is supplied at the
3 1
third time point, whereby variation in the water quality of
the treated water obtained through water treatment on the
treatment target water can be suppressed and the operation
cost can be reduced.
5 [0052] In addition, if the second load value at the second
time point predicted by the prediction unit is determined to
be greater than the first load value at the first time point,
the supply unit supplies, at the third time point, the
treatment agent in a larger supply amount than a supply
10 amount of the treatment agent corresponding to the first load
value at the first time point.
Thus, variation in the water quality of the treated
water obtained through water treatment on the treatment
target water can be assuredly suppressed.
15 [0053] In addition, if the second load value at the second
time point predicted by the prediction unit is determined to
be smaller than the first load value at the first time point,
the supply unit supplies, at the third time point, the
treatment agent in a smaller supply amount than a supply
20 amount of the treatment agent corresponding to the first load
value at the first time point.
Thus, variation in the water quality of the treated
water obtained through water treatment on the treatment
target water can be suppressed and the operation cost can be
25 reduced.
3 2
[0054] In addition, in a case where activated sludge is
stored in the water treatment tank, the supply unit supplies
air as the treatment agent to the water treatment tank.
Thus, the operation cost can be assuredly reduced
5 in the water treatment on the treatment target water using
air and activated sludge.
[0055] In addition, the load measurement unit measures the
load value by a flow rate of the treatment target water
flowing into the water treatment tank, or measures the load
10 value by a contaminant concentration of the treatment target
water flowing into the water treatment tank, or measures the
load value by a product of a flow rate of the treatment
target water flowing into the water treatment tank and a
contaminant concentration of the treatment target water
15 flowing into the water treatment tank.
Thus, the load value of the treatment target water
to be subjected to the water treatment can be assuredly
measured, whereby variation in the water quality of the
treated water can be suppressed and the operation cost can be
20 reduced.
[0056] Embodiment 2
FIG. 7 is a diagram showing the configuration of a
water treatment apparatus according to embodiment 2. In FIG.
7, the same parts as those in the above embodiment 1 are
25 denoted by the same reference characters, and the description
3 3
thereof is omitted. A concentration measurement unit 8 is
provided for taking, from the pipe 102, treated water
discharged from the water treatment tank 1, and measuring the
contaminant concentration of the treated water.
5 [0057] The concentration measurement unit 8 is formed by a
concentration meter for a contaminant that is a water quality
management target in water treatment. Specific examples
include an ammonia nitrogen concentration meter, a total
nitrogen concentration meter, a BOD meter, and a COD meter.
10 Further, for considering the influence of the temperature
depending on the seasons or the like, a water temperature
meter may be provided in addition to the contaminant
concentration meter. Here, a case of not providing a water
temperature meter will be described.
15 [0058] The contaminant concentration measured by the
concentration measurement unit 8 is transmitted to the
calculation units 91 to 93 via a signal line 81. Therefore,
unlike embodiment 1 described above, the calculation units 91
to 93 have calculation formulas for calculating optimum
20 supply amounts of the treatment agents, i.e., aeration
amounts, on the basis of the first load value at the present
(first time point) measured by the load measurement unit 5
and the contaminant concentration measured by the
concentration measurement unit 8.
25 [0059] Specifically, the calculation units 91 to 93 have
3 4
coefficients set in advance for the aeration units 31 to 33
respectively connected thereto, and each calculate the sum of
the following (A), (B), and (C).
(A) A supply amount obtained by multiplying the
5 load value of treatment target water flowing into the water
treatment tank 1 measured by the load measurement unit 5, by
a first coefficient set in advance for each aeration unit 31
to 33
(B) Constant
10 (C) A supply amount obtained by multiplying an
operation quantity for performing feedback control so that
the contaminant concentration of treated water measured by
the concentration measurement unit 8 becomes a predetermined
target value of the contaminant concentration of treated
15 water, by a second coefficient set in advance for each
aeration unit 31 to 33
[0060] The above coefficients are values set in advance so
as to obtain, through the above calculation, optimum aeration
amounts for causing the contaminant concentration of treated
20 water discharged from the water treatment tank 1 to approach
the predetermined target value of the contaminant
concentration, and these values can be set to different
values in accordance with the positions or the number of the
aeration units.
25 [0061] For example, in a case where the load measurement
3 5
unit 5 is provided with the flowmeter and the ammonia
nitrogen concentration meter as the contaminant concentration
meter, and the concentration measurement unit 8 is provided
with the ammonia nitrogen concentration meter as the
5 contaminant concentration meter, the first calculation unit
91 calculates a setting value G1 [Nm3/hr] for the aeration
amount to be supplied from the first aeration unit 31, by the
following Expression (4).
G1 = k11•SIN٬N•QIN + k12•(GP + GI + GD) + k13
10 ... (4)
SIN٬N: the ammonia nitrogen concentration [mg/L] of
treatment target water flowing into the water treatment tank
1
QIN: the flow rate [m3/hr] of treatment target
15 water flowing into the water treatment tank 1
k11, k12, k13: constant
It is noted that k11 is the first coefficient and
k12 is the second coefficient.
[0062] In addition, GP, GI, GD are set as shown by the
20 following Expressions (5), (6), (7).
GP = KP•(SOUT٬N - S0٬N) ... (5)
GI = KP/TI•∫(SOUT٬N - S0٬N)dt ... (6)
GD = KP•TD•d(SOUT٬N - S0٬N)/dt ... (7)
SOUT٬N: the ammonia nitrogen concentration [mg/L]
25 of treated water
3 6
S0٬N: the target value [mg/L] of the ammonia
nitrogen concentration of treated water
KP: proportional gain
TI: integral time
5 TD: derivative time
[0063] Similarly as in the above case, the calculation
units 92, 93 calculate setting values G2, G3 [Nm3/hr] for the
aeration amounts by the following Expressions (8), (9),
respectively.
10 G2 = k21•SIN٬N•QIN + k22•(GP + GI + GD) + k23
... (8)
k21, k22, k23: constant
It is noted that k21 is the first coefficient and
k22 is the second coefficient.
15 G3 = k31•SIN٬N•QIN + k32•(GP + GI + GD) + k33
... (9)
k31, k32, k33: constant
It is noted that k31 is the first coefficient and
k32 is the second coefficient.
20 [0064] In the above Expressions (4), (8), (9), the first
coefficients k11, k21, k31 and the second coefficients k12,
k22, k32 set in advance correspondingly for the aeration
units 31 to 33 are values set in advance so as to obtain,
through the calculation, optimum aeration amounts for causing
25 the ammonia nitrogen concentration of treated water to
3 7
approach the predetermined target value of the contaminant
concentration, as described above. The first coefficients
k11, k21, k31 and the second coefficients k12, k22, k32 are
not necessarily all equal to each other, and may be set to
5 different values in accordance with the positions of the
aeration units. In addition, even after the first
coefficients k11, k21, k31 and the second coefficients k12,
22, 32 are set once, it is possible to set optimum values
again as appropriate in accordance with season change, change
10 in a target water quality of the treated water, and the like.
[0065] As described above, the calculation units 91 to 93
calculate the aeration amounts to be supplied from the
aeration units 31 to 33 at the third time point between the
first time point and the second time point, on the basis of
15 the aeration amount calculation formulas provided in the
calculation units 91 to 93, the second load value of
treatment target water at the second time point calculated by
the prediction unit 7, and the contaminant concentration
measured by the concentration measurement unit 8. The
20 aeration amount calculation formulas provided in the
calculation units 91 to 93 are calculation formulas for
calculating optimum aeration amounts with respect to the load
value "SIN٬N, QIN" at the present. However, in the
calculation units 91 to 93, the second load value "S’IN٬N,
25 Q’IN" of treatment target water at the second time point,
3 8
instead of the load value at the present, is inputted in the
above calculation formulas, thereby calculating the aeration
amounts corresponding to the second load value of treatment
target water.
5 [0066] Specific description will be given on the basis of
Expressions (4), (8), (9) shown above. In Expressions (4),
(8), (9) shown above, the first load value "SIN٬N, QIN" of
treatment target water at the present is inputted, whereby
optimum aeration amounts for the first load value of
10 treatment target water at the present are calculated.
However, in the calculation units 91 to 93, the second load
value "S’IN٬N, Q’IN" of treatment target water predicted for
the second time point is inputted, to calculate target
aeration amounts (at the third time point) for the respective
15 aeration units 31 to 33.
[0067] The setting values G1 to G3 for the aeration
amounts at the third time point calculated as described above
are respectively transmitted to the supply units 41 to 43 via
the signal lines 911 to 931. The supply units 41 to 43
20 supply air in the amounts set respectively, via the pipes 411
to 431 and the aeration units 31 to 33, into the water
treatment tank 1.
[0068] As described above, after the first load value of
treatment target water at the present is measured by the load
25 measurement unit 5, the second load value of treatment target
3 9
water for the predetermined period later is calculated by the
prediction unit 7, the supply amounts of the treatment agents
at the third time point are calculated by the calculation
units 91 to 93, the aeration amounts are controlled in the
5 supply units 41 to 43, and air is moved through the pipes 411
to 431, whereby the target aeration amounts are supplied from
the aeration units 31 to 33 to the water treatment tank 1.
At this time, until the aeration amounts at the third time
point calculated by the calculation units 91 to 93 are
10 actually supplied from the aeration units 31 to 33 after the
first load value of treatment target water at the present is
measured by the load measurement unit 5, there is a time lag
including a calculation time for predicting the load value, a
calculation time for the target value of the aeration amount,
15 a control time for the aeration units 31 to 33, a movement
time of air in the pipes, and the like. Therefore, it is
necessary to set the predetermined period used for prediction
of the second load value of treatment target water in the
prediction unit 7 so that the time lag becomes shorter than
20 the predetermined period. Thus, the aeration amounts can be
controlled in advance before the load value actually reaches
the predicted value.
[0069] In FIG. 7, the concentration measurement unit 8 is
connected to the pipe 102. However, it is only necessary
25 that the contaminant concentration of treated water that has
4 0
undergone purification treatment using the activated sludge
in the water treatment tank 1 can be measured, and therefore
the concentration measurement unit 8 may be connected in the
sedimentation tank 2 or to the pipe 103. Further, in order
5 to assuredly prevent contaminants from flowing out with the
treated water discharged from the water treatment tank 1, the
concentration measurement unit 8 may be provided on the
downstream side in the water treatment tank 1. Thus, the
contaminant concentration of treated water is controlled so
10 as to be the target value before finishing of the
purification treatment in the water treatment tank 1. As a
result, more purified treated water is discharged from the
water treatment tank 1, whereby the water quality of the
treated water can be kept preferable. This also applies in
15 the subsequent embodiments, and the description thereof is
omitted as appropriate.
[0070] The difference between the present embodiment 2 and
the above embodiment 1 is that calculation formulas for
performing feedback control so that the contaminant
20 concentration of treated water measured by the concentration
measurement unit 8 becomes the predetermined target value of
the contaminant concentration of treated water, are added to
the aeration amount calculation formulas (1) to (3). Thus,
it becomes possible to finely control the contaminant
25 concentration, whereby not only variation in the water
4 1
quality of treated water due to variation in the load value
can be further suppressed but also energy consumption of the
supply units 41 to 43 and the aeration units 31 to 33 can be
suppressed owing to aeration without excess and insufficiency.
5 [0071] As described above, not only the load value of the
treatment target water flowing into the water treatment tank
1 is predicted and the aeration amount to be supplied into
the water treatment tank 1 is set on the basis of the
predicted load value, but also calculation for performing
10 feedback control with respect to the contaminant
concentration of treated water that has undergone water
treatment is added, whereby it is possible to finely control
the contaminant concentration in accordance with the target
value and set the aeration amount without excess and
15 insufficiency. Further, in a case where the water quality of
treated water is desired to be kept as preferable as possible,
in order to prevent the water quality of treated water from
being temporarily deteriorated when the aeration amount is
decreased in advance in a case where the load value decreases,
20 control may be performed such that the predicted load value
"S’IN٬N, Q’IN" is inputted only in a case where the predicted
load value increases, and the load value "SIN٬N, QIN" at the
present is inputted in a case where the predicted load value
decreases. Meanwhile, in a case where the aeration amount is
25 desired to be reduced as much as possible so as to minimize
4 2
the operation cost, increasing the aeration amount in advance
in a case where the load value increases leads to increase in
the operation cost. Therefore, control may be performed such
that the predicted load value "S’IN٬N, Q’IN" is inputted only
5 in a case where the load value decreases, and the load value
"SIN٬N, QIN" at the present is inputted in a case where the
load value increases.
[0072] The water treatment apparatus of embodiment 2
configured as described above provides, as a matter of course,
10 the same effects as those in the above embodiment 1, and also,
the water treatment apparatus further includes a
concentration measurement unit which measures a contaminant
concentration of treated water obtained through the water
treatment on the treatment target water in the water
15 treatment tank, and
the supply unit supplies the treatment agent in a
supply amount for which the contaminant concentration of the
treated water obtained through the water treatment in the
water treatment tank, measured by the concentration
20 measurement unit, is taken into consideration.
Thus, the contaminant concentration of the treated
water obtained through the water treatment in the water
treatment tank is taken into consideration for the supply
amount of the treatment agent, whereby it is possible to
25 further suppress variation in the water quality of the
4 3
treated water obtained through the water treatment on the
treatment target water and further reduce the operation cost.
[0073] Embodiment 3
FIG. 8 is a diagram showing the configuration of a
5 water treatment apparatus according to embodiment 3. In FIG.
8, the same parts as those in the above embodiments are
denoted by the same reference characters, and the description
thereof is omitted. The water treatment apparatus in the
present embodiment 3 is a water treatment apparatus which
10 supplies ozone gas as the treatment agent to treatment target
water, to oxidize and decompose contaminants in the treatment
target water. In the present embodiment 3, since ozone gas
is used as the treatment agent, unlike the above embodiments,
activated sludge is not needed for the water treatment tank 1
15 and thus the sedimentation tank 2 and the configuration
relevant to the sedimentation tank 2 are not present.
[0074] In the present embodiment 3, since ozone gas is
used as the treatment agent, the supply amount may be
referred to as an ozone gas concentration. The supply unit
20 in the present embodiment 3 is composed of the aeration units
31 to 33, a supply unit 44, and a calculation unit 94.
[0075] The load measurement unit 5 includes at least one
measurement device of a flowmeter or a contaminant
concentration meter (an organic substance concentration meter,
25 an odor substance concentration meter, a color meter, a virus
4 4
detector, etc.). The load measurement unit 5 measures the
load value continuously or intermittently at predetermined
time intervals, as in the above embodiments. All the load
values are associated with times at which the load values are
5 measured. The load measurement unit 5 may include both of
the flowmeter and the contaminant concentration meter
described above. In this case, the product of the flow rate
and the contaminant concentration of the treatment target
water flowing into the water treatment tank 1 may be
10 calculated as the load value. Thus, the load measurement
unit 5 measures the load value of the treatment target water
substantially flowing into the water treatment tank 1. As an
alternative for the flowmeter, the opening degree of a weir
of an inflow ditch may be used instead of the flow rate.
15 Further, for considering the influence of the temperature
depending on the seasons or the like, a water temperature
meter may be provided in addition to the flowmeter and the
contaminant concentration meter. Here, a case of not
providing a water temperature meter will be described.
20 [0076] The concentration measurement unit 8 is formed by a
concentration meter for a contaminant that is a water quality
management target in water treatment. Specific examples
include an organic substance concentration meter, an odor
substance concentration meter, a color meter, and a virus
25 detector. Further, for considering the influence of the
4 5
temperature depending on the seasons or the like, a water
temperature meter may be provided in addition to the
contaminant concentration meter. Here, a case of not
providing a water temperature meter will be described.
5 [0077] The supply unit 44 supplies ozone gas as the
treatment agent. The supply unit 44 generates ozone gas by
means of electric discharge, an ultraviolet lamp, or the like,
using air or oxygen as source gas, for example. In a case of
using oxygen as source gas, nitrogen, air, or carbon dioxide
10 may be added as necessary in an amount of 0.05% to 5%
relative to the flow rate of oxygen to be supplied.
[0078] The calculation unit 94 has a calculation formula
for calculating the ozone gas concentration of the treatment
agent to be supplied from each aeration unit 31 to 33 at the
15 third time point between the first time point and the second
time point, using the first load value of treatment target
water at the present as the first time point, measured by the
load measurement unit 5, or the second load value of
treatment target water for the predetermined period later as
20 the second time point after the first time point, predicted
by the prediction unit 7. In addition, the supply unit 44
has a function of controlling its output by an inverter or
the like so that the concentration of ozone gas supplied from
the supply unit 44 becomes the ozone gas concentration
25 calculated by the calculation unit 94.
4 6
[0079] In the water treatment method of the water
treatment apparatus of embodiment 3 configured as described
above, treatment target water flowing in via the pipe 101 is
mixed and stirred with ozone gas in the water treatment tank
5 1, so that contaminants in the water are oxidized and
decomposed, whereby purification treatment is performed.
[0080] Next, calculation in the calculation unit 94 will
be specifically described. The calculation unit 94
calculates the sum of the following (A), (B), and (C).
10 (A) A supply amount obtained by multiplying the
load value of treatment target water flowing into the water
treatment tank 1 measured by the load measurement unit 5, by
a predetermined first coefficient
(B) Constant
15 (C) A supply amount obtained by multiplying an
operation quantity for performing feedback control so that
the contaminant concentration of treated water measured by
the concentration measurement unit 8 becomes a predetermined
target value of the contaminant concentration of treated
20 water, by a predetermined second coefficient
[0081] The above coefficients are values set in advance so
as to obtain, through the above calculation, an optimum ozone
gas concentration for causing the contaminant concentration
of treated water discharged from the water treatment tank 1
25 to approach the predetermined target value of the contaminant
4 7
concentration.
[0082] For example, in a case where the load measurement
unit 5 is provided with the flowmeter and the organic
substance concentration meter (ultraviolet absorption
5 spectrometer, etc.), and the concentration measurement unit 8
is provided with the organic substance concentration meter,
the calculation unit 94 calculates a setting value SO3
[g/Nm3] for the ozone gas concentration of ozone gas to be
supplied from the aeration units 31 to 33, by the following
10 Expression (10).
SO3 = k1•SIN٬TOC•QIN + k2•(GP + GI + GD) + k3
... (10)
SIN٬TOC: the organic substance concentration
measured value [mg/L] of treatment target water flowing into
15 the water treatment tank
QIN: the flow rate measured value [m3/hr]
k1, k2, k3: constant
It is noted that k1 is the first coefficient and k2
is the second coefficient.
20 [0083] In addition, GP, GI, GD are set as shown by the
following Expressions (11), (12), (13).
GP = KP•(SOUT٬TOC - S0٬TOC) ... (11)
GI = KP/TI•∫(SOUT٬TOC - S0٬TOC)dt ... (12)
GD = KP•TD•d(SOUT٬TOC - S0٬TOC)/dt ... (13)
25 SOUT٬TOC: the organic substance concentration
4 8
measured value [mg/L] of treated water
S0٬TOC: the target value [mg/L] of the organic
substance concentration in the treatment
KP: proportional gain
5 TI: integral time
TD: derivative time coefficient
[0084] Even after k1, k2, k3 are set once, it is possible
to set optimum values again as appropriate in accordance with
change in the water temperature or a target water quality of
10 treated water, and the like. The calculation unit 94
calculates the target value of the concentration of ozone gas
to be supplied from the aeration units 31 to 33, on the basis
of the ozone gas concentration calculation formula provided
in the calculation unit 94, the second load value of
15 treatment target water at the second time point calculated by
the prediction unit 7, and the contaminant concentration of
treated water measured by the concentration measurement unit
8.
[0085] The ozone gas concentration calculation formula
20 provided in the calculation unit 94 is a calculation formula
for calculating an optimum ozone gas concentration with
respect to the first load value at the present (first time
point). However, in the calculation unit 94, the second load
value "S’IN٬TOC, Q’IN" of treatment target water at the
25 second time point, instead of the first load value "SIN٬TOC,
4 9
QIN" of treatment target water at the present, is inputted in
the above calculation formula, thereby calculating the
concentration of ozone gas to be supplied.
[0086] Specific description will be given on the basis of
5 Expression (10) shown above. In Expression (10) shown above,
the first load value "SIN٬TOC, QIN" of treatment target water
at the present is inputted, whereby an optimum ozone gas
concentration for the first load value of treatment target
water at the present is calculated. However, in the
10 calculation unit 94, the second load value "S’IN٬TOC, Q’IN"
of treatment target water at the second time point is
inputted, to calculate the ozone gas concentration of ozone
gas to be supplied from the aeration units 31 to 33.
[0087] The setting value SO3 for the ozone gas
15 concentration calculated as described above is transmitted to
the supply unit 44 via a signal line 941. The supply unit 44
supplies ozone gas with the set concentration into the water
treatment tank 1 via the pipes 441 to 443 and the aeration
units 31 to 33. After the first load value of treatment
20 target water at the present is measured by the load
measurement unit 5, the second load value of treatment target
water for the predetermined period later is predicted by the
prediction unit 7, the target value of the supply amount of
the treatment agent is calculated by the calculation unit 94,
25 ozone gas concentration control is performed in the supply
5 0
unit 44, and ozone gas is moved through the pipes 441 to 443,
whereby ozone gas with the target ozone gas concentration is
supplied from the aeration units 31 to 33 to the water
treatment tank 1.
5 [0088] At this time, until ozone gas with the ozone gas
concentration calculated by the calculation unit 94 is
actually supplied from the aeration units 31 to 33 after the
first load value of treatment target water at the present is
measured by the load measurement unit 5, there is a time lag
10 including a calculation time for flow-in prediction, a
calculation time for the ozone gas concentration, a control
time for an ozone generator, a movement time of ozone gas in
the pipes, and the like. Here, it is necessary to set the
predetermined period used for prediction of the second load
15 value of treatment target water in the prediction unit 7 so
that the time lag becomes shorter than the predetermined
period. Thus, the ozone gas concentration can be controlled
in advance before the load value actually reaches the
predicted value.
20 [0089] The second load value of treatment target water at
the second time point is inputted in the above Expression
(10). Thus, in a case where the second load value of
treatment target water at the second time point becomes
greater than the first load value at the first time point, at
25 a stage when the second load value of treatment target water
5 1
is predicted to increase (at the third time point between the
first time point and the second time point), the ozone gas
concentration is increased in advance before the load value
actually increases. As a result, treatment target water with
5 high load flows into the water treatment tank 1 in a state in
which the dissolved ozone gas concentration in the water
treatment tank 1 is sufficiently increased.
[0090] Thus, the treatment target water with high load is
purified immediately, whereby deterioration in the water
10 quality of treated water due to increase in the load value
can be suppressed. On the other hand, in a case where the
second load value of treatment target water at the second
time point becomes smaller than the first load value at the
first time point, at a stage when the load value is predicted
15 to decrease (at the third time point between the first time
point and the second time point), the ozone gas concentration
is decreased before the load value actually decreases. Since
the ozone gas concentration is decreased beforehand, the
water quality of treated water is temporarily deteriorated,
20 but thereafter, treatment target water with decreased load
flows into the water treatment tank 1. Therefore, the water
quality of treated water does not exceed the upper limit
value for management, and excessive supply of ozone gas can
be suppressed while the water quality of treated water is
25 kept preferable.
5 2
[0091] Further, through calculation for performing
feedback control so that the contaminant concentration of
treated water measured by the concentration measurement unit
8 becomes the predetermined target value of the contaminant
5 concentration of treated water, it becomes possible to finely
control the contaminant concentration of treated water in
accordance with the target value. Thus, not only variation
in the water quality of treated water due to variation in the
load value can be further suppressed but also the source
10 material for ozone gas and energy required for generating
ozone can be reduced owing to ozone gas supply without excess
and insufficiency.
[0092] As described above, the second load value of
treatment target water flowing into the water treatment tank
15 1 is predicted, and the ozone gas concentration of ozone gas
to be supplied into the water treatment tank 1 at the third
time point is set on the basis of the predicted second load
value of treatment target water. Therefore, in a case where
the second load value of treatment target water increases,
20 the ozone gas concentration is increased in advance, whereby
deterioration in the water quality of treated water can be
suppressed. In addition, in a case where the second load
value of treatment target water decreases, the ozone gas
concentration is decreased in advance, whereby excessive
25 supply of ozone gas can be suppressed while the water quality
5 3
of treated water is kept below the upper limit value for
management.
[0093] Further, in a case where the water quality of
treated water is desired to be kept as preferable as possible,
5 in order to prevent the water quality of treated water from
being temporarily deteriorated when the ozone gas
concentration is decreased in advance in a case where the
load value decreases, control may be performed such that the
second load value "S’IN٬TOC, Q’IN" is inputted only in a case
10 where the second load value of treatment target water
increases, and the first load value "SIN٬TOC, QIN" of
treatment target water at the present is inputted in a case
where the second load value of treatment target water
decreases.
15 [0094] Meanwhile, in a case where supply of ozone gas is
desired to be reduced as much as possible so as to minimize
the operation cost, increasing the ozone gas concentration in
advance in a case where the second load value of treatment
target water increases leads to increase in the operation
20 cost. Therefore, control may be performed such that the
predicted load value "S’IN٬TOC, Q’IN" is inputted only in a
case where the second load value of treatment target water
decreases, and the first load value "SIN٬TOC, QIN" of
treatment target water at the present is inputted in a case
25 where the second load value of treatment target water
5 4
increases.
[0095] The water treatment apparatus of embodiment 3
configured as described above provides, as a matter of course,
the same effects as those in the above embodiments.
5 In addition, in a case where at least one of
organic substance removal, odor substance removal, virus
removal, or decoloring is performed as the water treatment on
the treatment target water, the supply unit supplies ozone
gas as the treatment agent to the water treatment tank.
10 Thus, it is possible to suppress variation in the
water quality of treated water and reduce the operation cost
in water treatments such as organic substance removal, odor
substance removal, virus removal, and decoloring for the
treatment target water.
15 [0096] Embodiment 4
FIG. 9 is a diagram showing the configuration of a
water treatment apparatus according to embodiment 4. In FIG.
9, the same parts as those in the above embodiments are
denoted by the same reference characters, and the description
20 thereof is omitted. The water treatment apparatus in the
present embodiment 4 is a water treatment apparatus which
supplies a flocculant as the treatment agent to treatment
target water, to react contaminants in the treatment target
water with the flocculant, thereby settling the contaminants
25 as a metal salt and a calcium salt and thus performing
5 5
purification treatment. In the present embodiment 4, since
the flocculant is used as the treatment agent, unlike the
above embodiments, the aeration units 31 to 33 and the
configuration relevant to the aeration units 31 to 33 are not
5 present. The supply unit in the present embodiment 4 is
composed of a treatment agent tank 45, a supply unit 46, and
a calculation unit 95.
[0097] The load measurement unit 5 includes at least one
measurement device of a flowmeter or a contaminant
10 concentration meter (a phosphate phosphorus concentration
meter, a total phosphorus concentration meter, etc.). The
load measurement unit 5 measures the load value continuously
or intermittently at predetermined time intervals, as in the
above embodiments. All the load values are associated with
15 times at which the load values are measured. The load
measurement unit 5 may include both of the flowmeter and the
contaminant concentration meter described above. In this
case, the product of the flow rate and the contaminant
concentration of the treatment target water flowing into the
20 water treatment tank 1 may be calculated as the load value.
Thus, the load measurement unit 5 measures the load value of
the treatment target water substantially flowing into the
water treatment tank 1. As an alternative for the flowmeter,
the opening degree of a weir of an inflow ditch may be used
25 instead of the flow rate. Further, for considering the
5 6
influence of the temperature depending on the seasons or the
like, a water temperature meter may be provided in addition
to the flowmeter and the contaminant concentration meter.
Here, a case of not providing a water temperature meter will
5 be described.
[0098] The concentration measurement unit 8 is mounted to
the pipe 103 and measures the contaminant concentration of
treated water discharged from the sedimentation tank 2. The
concentration measurement unit 8 is formed by a concentration
10 meter for a contaminant to be cleaned out by the flocculant
among contaminants that are water quality management targets
in the water treatment. Specific examples include a
phosphate phosphorus concentration meter and a total
phosphorus concentration meter. Further, for considering the
15 influence of the temperature depending on the seasons or the
like, a water temperature meter may be provided in addition
to the contaminant concentration meter. Here, a case of not
providing a water temperature meter will be described.
[0099] The treatment agent tank 45 stores a flocculant as
20 the treatment agent. Examples of the types of the flocculant
include poly aluminum chloride (PAC), ferric chloride, poly
ferric sulfate, and iron hydroxide. The supply unit 46
receives the flocculant stored in the treatment agent tank 45
via a pipe 451 by a pump, and supplies the flocculant into
25 the water treatment tank 1 via a pipe 461.
5 7
[0100] The calculation unit 95 has a calculation formula
for calculating an optimum supply amount of the flocculant to
be supplied from the supply unit 46 on the basis of the first
load value of treatment target water at the present as the
5 first time point, measured by the load measurement unit 5,
and the contaminant concentration measured by the
concentration measurement unit 8. The supply amount
calculated by the calculation unit 95 is transmitted to the
supply unit 46 via a signal line 951. In addition, the
10 supply unit 46 has a function of controlling the supply
amount by an inverter or the like so that the supply amount
of the flocculant supplied from the supply unit 46 becomes
the supply amount calculated by the calculation unit 95.
[0101] In the water treatment method of the water
15 treatment apparatus of embodiment 4 configured as described
above, the flocculant is supplied to the water treatment tank
1, whereby contaminants such as phosphorus that can be
cleaned out by chemical flocculation reaction are settled and
separated in the sedimentation tank 2, thus performing
20 purification treatment for contaminants in the treatment
target water.
[0102] Next, calculation in the calculation unit 95 will
be specifically described. The calculation unit 95
calculates the sum of the following (A), (B), and (C).
25 (A) A supply amount obtained by multiplying the
5 8
load value of treatment target water flowing into the water
treatment tank 1 measured by the load measurement unit 5, by
a predetermined first coefficient
(B) Constant
5 (C) A supply amount obtained by multiplying an
operation quantity for performing feedback control so that
the contaminant concentration of treated water measured by
the concentration measurement unit 8 becomes a predetermined
target value of the contaminant concentration of treated
10 water, by a predetermined second coefficient
[0103] The above coefficients are values set in advance so
as to obtain, through the above calculation, an optimum
supply amount of the flocculant for causing the contaminant
concentration of treated water discharged from the water
15 treatment tank 1 to more approach the predetermined target
value of the contaminant concentration of treated water.
[0104] For example, in a case where the load measurement
unit 5 is provided with the flowmeter and the phosphate
phosphorus concentration meter, and the concentration
20 measurement unit 8 is provided with the phosphate phosphorus
concentration meter, the calculation unit 95 calculates a
setting value QF [g/nm3] for the supply amount of the
flocculant to be supplied from the supply unit 46 by the
following Expression (14).
25 QF = k1•SIN٬P•QIN + k2•(GP + GI + GD) + k3
5 9
... (14)
SIN٬P: phosphate phosphorus concentration measured
value [mg/L] of treatment target water flowing into the water
treatment tank
5 QIN: the flow rate measured value [m3/hr]
k1, k2, k3: constant
It is noted that k1 is the first coefficient and k2
is the second coefficient.
[0105] In addition, GP, GI, GD are set as shown by the
10 following Expressions (15), (16), (17).
GP = KP•(SOUT٬P - S0٬P) ... (15)
GI = KP/TI•∫(SOUT٬P - S0٬P)dt ... (16)
GD = KP•TD•d(SOUT٬P - S0٬P)/dt ... (17)
SOUT٬P: the phosphate phosphorus concentration
15 measured value [mg/L] of flowed-out water
S0٬P: the target value [mg/L] of the phosphate
phosphorus concentration of flowed-out water
KP: proportional gain
TI: integral time
20 TD: derivative time coefficient
[0106] Even after k1, k2, k3 are set once, it is possible
to set optimum values again as appropriate in accordance with
change in the water temperature or a target value of treated
water, and the like. The calculation unit 95 calculates the
25 target value of the supply amount of the flocculant to be
6 0
supplied from the supply unit 46, on the basis of the
flocculant supply amount calculation formula provided in the
calculation unit 95, the second load value at the second time
point calculated by the prediction unit 7, and the
5 contaminant concentration of treated water measured by the
concentration measurement unit 8.
[0107] The flocculant supply amount calculation formula
provided in the calculation unit 95 is a calculation formula
for calculating an optimum supply amount of the flocculant
10 with respect to the first load value of treatment target
water at the present (first time point). However, in the
calculation unit 95, the second load value "S’IN٬P, Q’IN" of
treatment target water at the second time point, instead of
the first load value "SIN٬P, QIN" of treatment target water
15 at the present, is inputted in the above calculation formula,
thereby calculating the supply amount of the flocculant.
[0108] Specific description will be given on the basis of
Expression (14) shown above. In Expression (14) shown above,
the first load value "SIN٬P, QIN" of treatment target water
20 at the present is inputted, whereby an optimum supply amount
of the flocculant for the first load value of treatment
target water at the present is calculated. However, in the
calculation unit 95, the second load value "S’IN٬P, Q’IN" of
treatment target water is inputted, to calculate the supply
25 amount of the flocculant to be supplied from the supply unit
6 1
46.
[0109] The setting value QF for the supply amount of the
flocculant calculated as described above is transmitted to
the supply unit 46 via the signal line 951. The supply unit
5 46 supplies the flocculant into the water treatment tank 1.
After the first load value at the present is measured by the
load measurement unit 5, the second load value for the
predetermined period later is measured by the prediction unit
7, the target value of the supply amount of the treatment
10 agent is calculated by the calculation unit 95, and
flocculant supply amount control is performed in the supply
unit 46, whereby the flocculant in the target supply amount
is supplied to the water treatment tank 1.
[0110] At this time, until the flocculant in the supply
15 amount calculated by the calculation unit 95 is actually
supplied after the first load value at the present is
measured by the load measurement unit 5, there is a time lag
including a calculation time for flow-in prediction, a
calculation time for the supply amount of the flocculant, a
20 control time for the supply unit 46, and the like. Here, it
is necessary to set the predetermined period used for
prediction of the second load value in the prediction unit 7
so that the time lag becomes shorter than the predetermined
period. Thus, the supply amount of the flocculant can be
25 controlled in advance before the second load value actually
6 2
reaches the predicted value.
[0111] In the present embodiment, the case of cleaning out
phosphorus is described. However, the same treatment can be
applied to contaminants such as fluorine, boron, and heavy
5 metal that can be chemically flocculated by being supplied
with the flocculant, besides phosphorus.
[0112] The second load value of treatment target water at
the second time point is inputted in the above Expression
(14). Thus, in a case where the second load value of
10 treatment target water at the second time point increases, at
a stage when the second load value of treatment target water
at the second time point is predicted to increase (at the
third time point between the first time point and the second
time point), the supply amount of the flocculant is increased
15 in advance before the load value actually increases. As a
result, treatment target water with high load flows into the
water treatment tank 1 in a state in which the flocculant is
sufficiently supplied in the water treatment tank 1 and the
sedimentation tank 2.
20 [0113] Thus, the treatment target water with high load is
purified immediately, whereby deterioration in the water
quality of treated water due to increase in the load value
can be suppressed. On the other hand, in a case where the
second load value of treatment target water at the second
25 time point decreases, at a stage when the load value is
6 3
predicted to decrease (at the third time point between the
first time point and the second time point), the supply
amount of the flocculant is decreased before the load value
actually decreases. Since the supply amount of the
5 flocculant is decreased beforehand, the water quality of
treated water is temporarily deteriorated, but thereafter,
treatment target water with decreased load flows into the
water treatment tank 1. Therefore, the water quality of
treated water does not exceed the upper limit value for
10 management, and excessive supply of the flocculant can be
suppressed while the water quality of treated water is kept
preferable.
[0114] Further, through calculation for performing
feedback control so that the contaminant concentration
15 measured by the concentration measurement unit 8 becomes the
predetermined target value of the contaminant concentration,
it becomes possible to finely control the contaminant
concentration in accordance with the target value. Thus, not
only variation in the water quality of treated water due to
20 variation in the load value can be further suppressed but
also the usage amount of the flocculant can be reduced owing
to flocculant supply without excess and insufficiency.
[0115] As described above, the second load value of
treatment target water flowing into the water treatment tank
25 1 is predicted, and the supply amount of the flocculant to be
6 4
supplied into the water treatment tank 1 at the third time
point is set on the basis of the predicted second load value
of treatment target water. Therefore, in a case where the
second load value of treatment target water increases, the
5 supply amount of the flocculant is increased in advance,
whereby deterioration in the water quality of treated water
can be suppressed. In addition, in a case where the second
load value of treatment target water decreases, the supply
amount of the flocculant is decreased in advance, whereby
10 excessive supply of the flocculant can be suppressed while
the water quality of treated water is kept below the upper
limit value for management.
[0116] Further, in a case where the water quality of
treated water is desired to be kept as preferable as possible,
15 in order to prevent the water quality of treated water from
being temporarily deteriorated when the supply amount of the
flocculant is decreased in advance in a case where the second
load value of treatment target water decreases, control may
be performed such that the second load value "S’IN٬P, Q’IN"
20 of treatment target water is inputted only in a case where
the load value increases, and the first load value "SIN٬P,
QIN" of treatment target water at the present is inputted in
a case where the load value decreases.
[0117] Meanwhile, in a case where supply of the flocculant
25 is desired to be reduced as much as possible so as to
6 5
minimize the operation cost, increasing the supply amount of
the flocculant in advance in a case where the second load
value of treatment target water increases leads to increase
in the operation cost. Therefore, control may be performed
5 such that the predicted second load value "S’IN٬P, Q’IN" of
treatment target water is inputted only in a case where the
second load value of treatment target water decreases, and
the first load value "SIN٬P, QIN" of treatment target water
at the present is inputted in a case where the second load
10 value of treatment target water increases.
[0118] The water treatment apparatus of embodiment 4
configured as described above provides, as a matter of course,
the same effects as those in the above embodiments.
In addition, in a case where contaminants in the
15 treatment target water are settled and separated through
chemical flocculation reaction as the water treatment on the
treatment target water, the supply unit supplies a flocculant
as the treatment agent to the water treatment tank.
Thus, it is possible to suppress variation in the
20 water quality of treated water and reduce the operation cost
in sedimentation separation water treatment through chemical
flocculation reaction between the flocculant and contaminants
in the treatment target water.
[0119] Although the disclosure is described above in
25 terms of various exemplary embodiments and implementations,
6 6
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
5 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.
10 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
15 embodiment.
DESCRIPTION OF THE REFERENCE CHARACTERS
[0120] 1 water treatment tank
101 pipe
20 102 pipe
103 pipe
104 pipe
105 pipe
2 sedimentation tank
25 31 first aeration unit
6 7
32 second aeration unit
33 third aeration unit
41 first supply unit
411 pipe
5 42 second supply unit
421 pipe
43 third supply unit
431 pipe
44 supply unit
10 45 treatment agent tank
451 pipe
46 supply unit
461 pipe
5 load measurement unit
15 51 signal line
52 signal line
6 recording unit
61 signal line
7 prediction unit
20 71 signal line
8 concentration measurement unit
81 signal line
91 first calculation unit
911 signal line
25 92 second calculation unit
6 8
921 signal line
93 third calculation unit
931 signal line
94 calculation unit
5 941 signal line
95 calculation unit
951 signal line
6 9
We Claim :
[1] A water treatment apparatus for performing water
treatment by supplying a treatment agent to treatment target
water flowing into a water treatment tank, the water
5 treatment apparatus comprising:
a load measurement unit which measures, as a first
load value, a load value of the treatment target water
flowing into the water treatment tank at a first time point;
a prediction unit which predicts, as a second load
10 value, a load value of the treatment target water flowing
into the water treatment tank at a second time point after
the first time point, on the basis of the first load value
measured by the load measurement unit; and
a supply unit which supplies the treatment agent in
15 a supply amount corresponding to the second load value
predicted by the prediction unit, to the treatment target
water in the water treatment tank, at a third time point
between the first time point and the second time point.
20 [2] The water treatment apparatus according to claim 1,
wherein
if the second load value at the second time point
predicted by the prediction unit is determined to be greater
than the first load value at the first time point, the supply
25 unit supplies, at the third time point, the treatment agent
7 0
in a larger supply amount than a supply amount of the
treatment agent corresponding to the first load value at the
first time point.
5 [3] The water treatment apparatus according to claim 1
or 2, wherein
if the second load value at the second time point
predicted by the prediction unit is determined to be smaller
than the first load value at the first time point, the supply
10 unit supplies, at the third time point, the treatment agent
in a smaller supply amount than a supply amount of the
treatment agent corresponding to the first load value at the
first time point.
15 [4] The water treatment apparatus according to any one
of claims 1 to 3, wherein
in a case where activated sludge is stored in the
water treatment tank, the supply unit supplies air as the
treatment agent to the water treatment tank.
20
[5] The water treatment apparatus according to any one
of claims 1 to 3, wherein
in a case where at least one of organic substance
removal, odor substance removal, virus removal, or decoloring
25 is performed as the water treatment on the treatment target
7 1
water, the supply unit supplies ozone gas as the treatment
agent to the water treatment tank.
[6] The water treatment apparatus according to any one
5 of claims 1 to 3, wherein
in a case where contaminants in the treatment
target water are settled and separated through chemical
flocculation reaction as the water treatment on the treatment
target water, the supply unit supplies a flocculant as the
10 treatment agent to the water treatment tank.
[7] The water treatment apparatus according to any one
of claims 1 to 6, wherein
the load measurement unit measures the load value
15 by a flow rate of the treatment target water flowing into the
water treatment tank, or measures the load value by a
contaminant concentration of the treatment target water
flowing into the water treatment tank, or measures the load
value by a product of a flow rate of the treatment target
20 water flowing into the water treatment tank and a contaminant
concentration of the treatment target water flowing into the
water treatment tank.
[8] The water treatment apparatus according to any one
25 of claims 1 to 7, further comprising a concentration
7 2
measurement unit which measures a contaminant concentration
of treated water obtained through the water treatment on the
treatment target water in the water treatment tank, wherein
the supply unit supplies the treatment agent in a
5 supply amount for which the contaminant concentration of the
treated water measured by the concentration measurement unit
is taken into consideration.
[9] A water treatment method for performing water
10 treatment by supplying a treatment agent to treatment target
water, the water treatment method comprising:
a first step of measuring, as a first load value, a
load value of the treatment target water at a first time
point;
15 a second step of predicting, as a second load value,
a load value of the treatment target water at a second time
point after the first time point, on the basis of the first
load value measured in the first step; and
a third step of supplying the treatment agent in a
20 supply amount corresponding to the second load value
predicted in the second step, to the treatment target water,
at a third time point between the first time point and the
second time point.