JP3321876B2 - Ozone treatment apparatus, ozone treatment method, and water purification treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ozone treatment, and more particularly to an ozone treatment control system in advanced water purification treatment.

[0002]

2. Description of the Related Art Conventionally, ozone treatment has been used in various fields, and has recently been applied to advanced water purification treatment and the like.
As a conventional water treatment method, there is a method in which turbidity components in raw water are coagulated and precipitated and then chlorination is performed. FIG. 1 shows such a conventional water purification treatment method.

As shown in this figure, raw water taken from rivers and lakes first enters a landing well, and a coagulant is injected in a mixing pond in order to remove turbid components (clay, organic matter, etc.) in the raw water. After mixing, it enters the floc formation pond.

[0004] In this floc forming pond, raw water is kept for a certain period of time and gently stirred to grow larger flocs. Thereafter, the flocs grown in the floc formation ponds are separated in the sedimentation basin, and fine flocs that cannot be separated in the sedimentation basin are removed in the filtration basin.

[0005] Thereafter, a process of injecting chlorine for the purpose of algicidal treatment, iron removal, manganese removal, and chromaticity removal is performed.

However, in recent years, especially in urban areas, the water environment has deteriorated, and water pollution of rivers and lakes has been progressing. The water supply source has been used only in combination with the conventional coagulation sedimentation, filtration, and chlorination. It is difficult to completely remove chromaticity and odor in water.

[0007] In addition, when the amount of chlorine injection is increased due to the deterioration of the quality of raw water, there is a concern that trihalomethane, which is an organic chlorine compound and is a carcinogenic substance, will increase. Furthermore, contamination of trace harmful substances has also become a problem.

[0008] From such a background, "safe and delicious water"
The demand for is growing. Therefore, as a method for effectively removing or reducing these odor components and the like, a combined treatment of an ozone treatment, an activated carbon treatment, or the like and a conventional tap water treatment as shown in FIG. 2 has been considered.

[0009] One of the unit operations, ozone treatment,
The following effects are exhibited during the water purification process.

[0010] 1) Removal and improvement of chromaticity, odor, and taste due to contamination of raw water.

2) Sterilization and algicidal removal of bacteria and viruses.

3) It is easy to remove inorganic substances such as iron and manganese by oxidation treatment.

4) Oxidative decomposition of trace amounts of harmful organic substances.

Various studies have been made on the secondary treatment of sewage (activated sludge method + sedimentation method) as a water purification treatment (water for scenic landscape / environmental maintenance / water for hydrophilic use). An advanced treatment method by ozone treatment is being studied.

In this ozone treatment, chromaticity, organic matter, coliform bacteria, general bacteria MBAS (anionic surfactant causing foaming) and the like in the secondary treatment water are the main substances to be removed.

When performing such ozone treatment, it is said that processing costs such as electricity charges become a considerable burden.
It is required to remove the above substances in a short time and at a low processing cost (minimum O ₃ injection rate).

[0017]

In general, when performing ozone treatment, a method is employed in which ozone gas generated by an ozone generator is continuously injected while water to be treated is continuously flowed into and out of an ozone contact tank.

Therefore, it is necessary to adjust the ratio of the amount of ozone gas to be injected relative to the amount of treated water. When the ozone treatment is performed automatically and efficiently continuously as described above, ozone injection control is required. The measurement items considered to be necessary for performing the ozone injection control include a treated water amount, an injected ozonized air flow rate, an injected ozone concentration, a dissolved ozone concentration, an exhausted ozone concentration, and the like.

As an actual control system, the ozone injection rate ([ozone injection rate] = [injected ozonized air flow rate] ×
[Injected ozone concentration] / [Treatment water amount]) is often set. There are the following methods.

1) The amount of ozone generated is controlled in proportion to the amount of treated water.

2) The amount of ozone generated is controlled according to the treatment effect of the target water quality.

3) The amount of ozone generated is controlled according to the amount of ozone consumed.

Generally, the ozone injection rate is generally changed by the method 1). In the actual water purification process, water quality varies due to season, rainfall, etc., and the amount of ozone generated is controlled according to the treatment effect.

The method of controlling the ozone treatment system according to the method 2), although a stable water quality can be obtained, but it usually takes a long time to evaluate the water quality, so that it is not suitable for promptly responding to a change in water quality. Further, from the viewpoint of the operation of the ozone treatment step, it is necessary to ensure the processability while effectively utilizing the injected ozone.

Therefore, in the current ozone treatment method, a relatively simple ozone injection control method such as a constant ozone injection rate method is adopted, and an injection rate on a safe side is used to some extent so as to cope with fluctuations in raw water quality. Ozone treatment is performed.

As a result, the processing becomes unstable due to the injection of more ozone than the required amount of ozone and the generation of dissolved ozone more than necessary, or conversely the dissolved ozone does not appear because the ozone injection rate is too low. There are cases.

For example, when performing ozone treatment of secondary sewage water, it is difficult to directly know in advance the required ozone amounts of various types of substances to be removed.

Therefore, the amount of required ozone is indirectly detected to be about 5
It is conceivable to perform effective ozone treatment water quality control by effectively reducing and removing the types of substances to be removed (chromaticity, organic matter, coliform bacteria, general sterilization, MBAS, etc.). Gas / liquid phase ozone densitometers, organic matter sensors, etc.) have not been obtained.

Therefore, if the required ozone amount of the test water to be subjected to ozone treatment can be estimated, efficient ozone treatment control can be performed in accordance therewith, but the required ozone amount composed of various types of substances to be removed is estimated as described above. This is difficult both directly and indirectly, and ozone injection control based on the required amount of ozone has not yet been put to practical use.

The present invention has been made under the above-mentioned background, and performs ozone treatment capable of supplying ozone to a test water without excess and deficiency to reduce the dissolved ozone concentration in the test water after the ozone treatment. The purpose is to: It is another object to perform water purification treatment using such ozone treatment.

[0031]

In order to solve the above problems, the present inventors conducted the following experiments.

First, a liquid and a gas are caused to flow in countercurrent using an ozone contact tank having an inner diameter of 154 (mm), a height of 4.5 (m) and an effective water depth of about 4 (m) (effective volume 90 (l)). Ozone treatment is performed by a contact method.

In this countercurrent contact system, ozone gas is diffused and injected from a diffuser tube at the bottom, discharged as ozone gas exhausted from the upper end, and water flows in from the upper end and flows out from the bottom. At this time, the flow rate of the ozone gas injected into the ozone contact tank was 2 (l / min), the processing flow rate was 5 to 6 (l / min), the generated ozone concentration was 4 to 6 (kg / m ³ ), and the ozone injection rate was 1 .
The treatment by continuous water passing was performed under the conditions of 6 to 2.1 (mg / l).

FIG. 3 is a graph showing the concentration distribution of dissolved ozone in the ozone contact tank. In this graph, the measurement result of the distribution of the dissolved ozone concentration was plotted by replacing the contact time from the upper water surface with the dimensionless contact time (t / θ) obtained by dividing the contact time from the hydraulic residence time in the entire contact tank.

FIG. 4 shows the E260 value (wavelength 260 n) with respect to the dimensionless contact time in the downflow direction in the ozone contact tank.
2 shows a graph showing the correlation between the absorbance at m and the spectrophotometer using a 50 mm cell).

This E260 has a high correlation with the concentration of the precursor of trihalomethane (trihalomethane forming ability: THMFP) which is one of the reducing substances in the advanced water purification treatment.

Similarly, FIG. 5 is a graph showing the correlation between the fluorescence intensity and the dimensionless contact time which remarkably show the ozone treatment effect. FIG. 6 is a graph showing the correlation between the tendency of reducing general bacteria used as an evaluation index as a bactericidal property and the dimensionless contact time.

From the results shown in FIGS. 3 to 6, the ozone oxidizing components such as E260 in the raw water are largely reduced at the initial stage of the inflow into the contact tank, but the change decreases as the water flows down, and the water quality level becomes almost constant. You can see that it is approaching.

The concentration of dissolved ozone at each downstream position in the contact tank is determined by the rate of consumption of dissolved ozone used by the ozone oxidizing component for oxidation, and the rate of dissolution of ozone gas from gas phase to liquid phase (dissolution rate). It depends on the balance.

Normally, the amount of dissolved ozone gas from the gas phase to the liquid phase is limited to a fixed value within a limited processing time, but as shown in FIG. I have.

One of the causes is that the ozone dissolved in the test water is consumed by the ozone oxidizing component because the amount of the ozone oxidizing component is large in the initial stage of inflow. Since dissolved ozone is consumed in this way, the concentration of dissolved ozone in the initial stage of inflow becomes a low level.

On the other hand, the ozone oxidizing component is oxidized and removed by dissolved ozone as it flows down, so that the amount of the ozone oxidizing component is reduced, and the excess amount of dissolved ozone appears as the dissolved ozone concentration.

Therefore, the ozone oxidizing component is sufficiently reduced in the lower part of the ozone contact tank, and the dissolved ozone approaches a constant value. Therefore, the change in the measured dissolved ozone concentration is small.
Actually, in FIG. 3, when the dimensionless contact time becomes 0.3 or more, the ozone concentration becomes almost constant and hardly fluctuates.

From the above results, if the operation is performed by controlling the ozone injection rate so that the change in the dissolved ozone concentration is small near the outlet of the contact tank, the ozone oxidizing component is sufficiently oxidized and removed by ozone, and the stable ozone treatment is performed. It turns out that it becomes possible.

Next, the setting of the dissolved ozone concentration at this time was examined.

If the concentration of dissolved ozone in the treated water flowing out of the contact tank is high, the microorganisms are killed or the activity is reduced, so that the subsequent biological activated carbon treatment is hindered. Therefore, the dissolved ozone concentration in the water flowing into the biological activated carbon treatment tank after the ozone treatment needs to be sufficiently low.

Therefore, in order to effectively use the ozone injected into the contact tank, an operation for reducing the concentration of dissolved ozone in the ozonized water as much as possible by reducing the concentration of the injected ozone to a level that does not affect the quality of the treated water. It is desirable to do. In addition, by performing such an operation, the ozone gas absorption efficiency can be maintained at a high level, so that the exhausted ozone concentration can be maintained at a low level.

By minimizing the residual ozone concentration after the ozone treatment as described above, the load on the waste ozone treatment apparatus for detoxifying unused ozone gas discharged from the ozone contact tank is reduced, and The replacement frequency of the ozonizer can be extended.

Therefore, the present inventors have made intensive studies to complete the present invention in order to carry out an efficient ozone treatment that maintains a stable treated water quality and minimizes the residual ozone concentration.

That is, according to the first aspect of the present invention, the flow
An ozone treatment apparatus of the type , wherein an ozone treatment tank in which a test water and an ozone gas are brought into contact reaction with each other, and k points (where k ≧ g) in which the contact time between the test water and the ozone in the ozone treatment tank is different.
2) having an ozone concentration measuring means for measuring the dissolved ozone concentration of the test water, and a water quality controlling means, wherein the water quality controlling means compares each dissolved ozone concentration obtained from the ozone concentration measuring means and An ozone treatment apparatus is provided, wherein the supplied ozone gas concentration is controlled so that the difference in ozone concentration satisfies a predetermined target value.

As described above, the ozone for the sample is
If the supply amount is insufficient, the contact time of ozone in the ozone treatment tank
The difference in the ozone concentration of the test water between different places becomes large. This
On the other hand, if the ozone becomes excessive, the difference in the ozone concentration becomes
Become smaller.

Therefore, by appropriately setting the threshold value,
The difference in the ozone concentration of the test water between places with different contact times
By controlling so as to reach the threshold value,
Ozone can be supplied without excess and deficiency.

The places where the above-mentioned ozone contact time is different are
It is preferable to be near the outlet of the sampled water
No. Dissolved metal at different locations near the outlet of the contact tank
There may be two zones, but more than one.
Can detect load fluctuations such as water quality more quickly
Therefore, quick control becomes possible.

[0054] claims the invention of claim 2, in claim 1, wherein off
In the low-type ozone treatment apparatus, the water quality control means increases the concentration of the supplied ozone gas when the difference in the dissolved ozone concentration is larger than the target value, and the difference in the dissolved ozone concentration is smaller than the target value. In some cases, the present invention provides an ozone treatment apparatus characterized by performing control to reduce the supply ozone gas concentration.

By performing the control as described above, the Ozone
Facilitates ozone concentration between locations with different contact times
It can be controlled around the value.

According to a third aspect of the present invention, there is provided a flow type ozone treatment method in which a test sample and an ozone gas are brought into contact with each other. ≧ 2), measuring the dissolved ozone concentration in the test water, comparing the respective dissolved ozone concentrations, and controlling the supplied ozone gas concentration such that the difference between the dissolved ozone concentrations satisfies a predetermined target value. To provide an ozone treatment method.

The threshold value is appropriately determined as described above, and
Ozone concentration of test water between sites with different contact time
The control is performed so that the difference between
An ozone treatment method that can supply ozone to water without excess or shortage
Can provide law.

[0058] 4. the described invention, according to claim 3, wherein full
Provided is a water purification treatment method comprising an ozone treatment step of raw water using a low-type ozone treatment method.

In the water purification treatment, the ozone treatment is performed as described above.
To reduce the amount of ozone required for ozone treatment.
Can be suppressed. Also keeps the residual ozone concentration low
Impact on biological treatment in the later stage
Can be kept small.

Also, the unused waste discharged from the ozone contact tank
Ozone treatment equipment necessary to detoxify ozone gas
Installation load is reduced, and
Can be extended.

In the above-mentioned ozone treatment apparatus, water detection and
An ozone treatment tank for contacting and reacting with ozone gas, and ozone
Supply ozone gas concentration and exhaust ozone gas concentration during supply
Ozone concentration in the sample water after ozone treatment
Concentration measuring means for measuring water and water quality controlling means.
Wherein the water quality control means is the ozone concentration measurement means.
Supply ozone gas concentration and exhaust ozone gas concentration
Ozone consumption of the test water based on the ozone gas concentration
And the required amount of ozone in the test water is determined.
If the ozone consumption of the water is equal to the
The supply ozone gas concentration may be controlled as described above.

As described above, the required amount of ozone and the sample
Supply ozone gas concentration so that ozone consumption is equal
By reacting with water sample during ozone treatment.
To minimize the amount of surplus ozone remaining in water samples
be able to.

Therefore, the ozone required for the ozone treatment
The amount can be kept low. Also necessary for ozone treatment.
The essential configuration is simple and no special device is required.

Further , in the ozone treatment apparatus,
UV-absorbance measuring means for measuring UV-absorbance of test water
The water quality control means is provided,
Supply ozone so as to be equal to the ozone demand of the test water
In addition to controlling the gas concentration, it also absorbs the UV
So that the luminous intensity is smaller than a preset threshold
Feedback control may be performed.

In general, the UV absorbance is
Is an indicator of the concentration of organic matter,
For each substance to be removed used in water purification, etc., odor ≧
MBAS>Chromaticity> Escherichia coli> General bacteria> Organic matter (UV)
In this order, it is easy to remove by ozone treatment.

Therefore, the ultraviolet absorbance, which is easy to measure, is
By performing control so that it is below a certain value, continuous measurement can be performed.
Measure the concentration of difficult MBAS, coliforms, general bacteria, etc.
These values can be controlled below a certain value without
it can.

In particular, in water purification treatment, each of these removal methods
Because it is important to remove elephant substances, this ozone treatment
The present invention can be suitably applied to water purification treatment.

Further , the sample water is brought into contact with the ozone gas to cause a contact reaction.
Ozone treatment method
Finished ozone gas concentration, exhausted ozone gas concentration and ozone treatment
And the dissolved ozone concentration in the test water
The ozone consumption of the test water and the ozone
Calculate the required amount of ozone and determine the ozone consumption
Supply ozone so that it is equal to the required ozone
The gas concentration may be controlled.

According to the above method, the required amount of ozone in the sample water
Supply ozone gas so that the ozone consumption of the sample is equal.
By controlling the gas concentration, water sampling and
Minimize the amount of excess ozone remaining in the sample without reacting
A controllable ozone treatment method can be provided.

[0070]

【Example】

Example 1 In this Example 1, the dissolved ozone concentration in the ozone contact tank was monitored using the measurement values of a dissolved ozone concentration meter installed at two points in the ozone contact tank, and the dissolved ozone concentration in the lower part of the tank was monitored. The increase pattern was examined.

By adjusting the generated ozone concentration based on the increase pattern of the dissolved ozone concentration, the ozone injection rate is changed and the difference in the dissolved ozone concentration between the two points is controlled to a preset value to generate the generated ozone. An ozone treatment capable of suppressing the concentration to a low level was performed, and a water purification treatment was performed using the ozone treatment.

Embodiment 1 will be described below with reference to the drawings.

In FIG. 7, reference numeral 1 denotes a raw water tank. Raw water flows into the upper part of the ozone treatment tank 4 through the raw water tank 1 by the water supply pump 2. At this time, the flow rate of the raw water is measured by the flow meter 3.

Reference numeral 5 denotes an ozone generator which measures the inflow and concentration of the ozone gas by means of an injection ozone gas flowmeter 6 and a generated ozone concentration meter 7 and then passes through an air diffuser plate 8 provided at the lower part of the ozone treatment tank 4. Send to raw water in treatment tank. As described above, the raw water flows in from the upper part of the ozone treatment tank 4, and the ozone is diffused from the lower part of the ozone treatment tank 4, so that the ozone and the raw water come into contact in a countercurrent manner.

The exhausted ozone which has not been dissolved in the raw water in the ozone treatment tank is defoamed in the defoaming tank 10 after measuring its concentration with the exhausted ozone concentration meter 9, and then O ₂ etc. in the exhausted ozone treatment tank 11. Decompose into The ozone-treated water subjected to the ozone treatment is sent to the ozone-treated water tank 12 and then sent to the activated carbon treatment tank.

Dissolved ozone concentration meters B and A are installed near and above the diffuser plate of the ozone treatment tank 4, respectively. The ozone concentration (DO ₃ (B)) near the diffuser plate is respectively provided.
And the ozone concentration (DO ₃ (A)) above the diffuser plate is measured.

Further, as shown in FIG.
In, the inflow amount of raw water obtained from the flow meter 3, the ozone gas injection amount and the ozone gas concentration obtained from the injected ozone gas flow meter 6 and the ozone concentration meter 7, the exhaust ozone concentration obtained from the exhaust ozone concentration meter 9, and the dissolved ozone meter A, The ozone injection control is performed by controlling the water pump 2 and the ozone generator 5 using the respective ozone concentrations obtained by B as inputs.

Hereinafter, the ozone treatment method in the above ozone treatment system will be described in detail.

In this ozone treatment system, raw water is supplied from the raw water tank 4 to the upper part of the ozone treatment tank by the water supply pump 2. At this time, a constant amount of raw water is supplied based on the measurement value of the flow meter 3. In the ozone treatment tank 4, the ozone gas, which has been made into fine bubbles by a diffuser, is brought into gas-liquid contact with the raw water for treatment in order to increase absorption efficiency.

Further, a plurality of dissolved ozone concentration meters for measuring the dissolved ozone concentration in the ozone contact tank are provided near the outflow portion of the sample. In the embodiment, the measurement is performed at two points A and B.

The location of the dissolved ozone concentration meter is based on B at the outlet of the contact tank, and A is at the upstream of the contact tank. The following control operation is performed by the ozone injection rate control unit 13 based on the absolute value of the difference between these measured values, with the dissolved ozone concentrations being DO ₃ (A) and DO ₃ (B), respectively.

1) In the case of | D03 (A) −D03 (B) |> α, a control signal is output to the ozone generator 5 to increase the generated ozone concentration by ΔC. Also, | D03 (A) -D03
(B) This operation is continued until the condition of | <α is satisfied.

2) In the case of | D03 (A) -D03 (B) | <α, a control signal is output to the ozone generator 5 to reduce the generated ozone concentration by ΔC. This operation is continued until the condition of | D03 (B) -D03 (A) | <α is satisfied with the minimum generated ozone concentration.

The above α is an allowable value, which can be determined by experiment and set by the control device. ΔC is a value of the change width of the generated ozone concentration which can be set externally to the control device.

1) is executed promptly in the case of this condition, and 2) is executed at a predetermined time interval.

[0086] The generated ozone concentration can be changed by using an ozone concentration meter 6
, The gas phase ozone concentration is measured, and the voltage value or the current value of the ozone generator is controlled by the output signal of the control circuit so that the ozone concentration becomes the target generated ozone concentration.

By performing the control as described above, the ozone injection amount can be suppressed to a low level, and the ozone treatment can be performed with higher efficiency.

By performing the control according to the above-described embodiment, a stable treated water quality can be obtained with a minimum generated ozone concentration according to the amount and quality of the treated ozone water. In addition, since the ozone concentration can be suppressed to a low level, it is possible to realize automatic ozone injection control that does not hinder the biological activity of the biological activated carbon in the water purification treatment process.

In addition, this control makes it possible to obtain a stable treated water quality against load fluctuations such as a change in the treated water amount and fluctuations in the water quality, so that stable operation management can be performed without receiving large load fluctuations in the subsequent activated carbon treatment process. It becomes possible. as a result,
This leads to improved reliability of operation management of the whole water purification process and can contribute to stable supply of purified water.

Furthermore, it is possible to reduce the load on the waste ozone treatment device required to detoxify the unused ozone gas discharged from the ozone contact tank, and to increase the frequency of replacement of the waste ozone treatment agent.

Embodiment 2 In this embodiment, the required ozone amount of the test water is determined from the dissolved ozone concentration and the exhaust ozone gas concentration of the test water so that the ozone consumption of the test water is equal to the ozone required amount of the test water. Was controlled.

Further, operation control (ozone absorption efficiency, dissolved ozone concentration) in ozone treatment and water quality control (U
V value), and this ozone treatment method was applied to water purification treatment. .

In this embodiment, ozone treatment was controlled in the ozone treatment system shown in FIG.

In this figure, reference numerals 4 to 11 are the same as in FIG.

15 is a device for measuring dissolved ozone in waste water,
Is a UV measuring device for waste water, which measures the dissolved ozone concentration and the UV value in the waste water, respectively.

In this embodiment, the generated ozone concentration Ci (O ₃ ) and the discharged ozone concentration Co
(O ₃ ) is measured, and the water quality controller 16 controls the ozone injection rate. As shown in FIG. 10, in the ozone injection rate control unit 16, the ozone gas concentration obtained from the supply ozone concentration meter 7, the exhaust ozone concentration obtained from the exhaust ozone concentration meter 9,
Ozone concentration obtained from the dissolved ozone concentration measuring device 15,
The ozone generator 5 controls the ozone generator 5 using the UV value obtained from the UV measurement device 16 as an input to perform ozone injection control.

FIG. 11 shows a flowchart of this control method.

In this figure, in step 101, the generated ozone concentration Ci obtained from the generated ozone concentration meter 7
(O ₃ ) and the exhaust ozone concentration Co (O ₃ ) obtained from the exhaust ozone concentration meter 9 based on the measured values of the absorption efficiency η [= {Ci
(O ₃ ) -Co (O ₃ )} / Ci (O ₃ ) × 100 (%)]
Is calculated.

In step 102, the ozone absorption amount α [= ozone injection rate (D) · (η / 100)] is calculated.

In step 103, the dissolved ozone concentration meter 15
Is calculated from the dissolved ozone concentration (DO ₃ ) obtained from the above.

In step 104, steps 102 and 1
Ozone consumption (CO ₃ ) below the value obtained from 03
Is calculated (CO ₃ = (D · η / 100) −DO ₃ ).

In step 105, the required amount of ozone (RO ₃ ) of the sample is calculated from the value of CO ₃ as shown in the equation in parentheses.
Assuming _{(RO 3 ≒ C O 3 +} ΔC O 3).

In step 106, the concentration of dissolved ozone is minimized by minimizing DO ₃ so that ΔCO ₃ → 0.

In step 107, DO ₃ is minimized (≒ 0.1
D is controlled by minimizing the ozone injection rate so as to be about 0.3 mg O ₃ / l).

In step 108, the concentration of ozone generated from the ozone generator is minimized in order to control D. This increases the ozone absorption efficiency.

In step 109, the following feedback control is performed so that the UV value in the O ₃ treated water becomes equal to or less than the control target value.

First, a relational expression between the respective substances to be removed (chromaticity, odorous Escherichia coli, general bacteria, MBAS, etc.) and the UV value (the odor chromaticity, the coliforms if the UV value is less than or equal to). General bacteria clear the target removal value).

This relationship can be obtained by an arbitrary method. In this embodiment, as shown in FIG. 12, the chromaticity, coliform bacteria, general bacteria, MBAS, and odors to be removed (corresponding to lines A to E, respectively) as shown in FIG. A graph showing the correlation between each value of ()) and the UV value was used.

In this graph, each of the density scales on the vertical axis is set at each value so that the removal target value of the object to be removed is on the L line. In this graph, the UV value (E260 value) with respect to the target value is set. Highest target U
The V value was used.

In FIG. 12, the UV value with respect to the removal target value is the highest on the C line. Therefore, the target UV value was the UV value (UV ₁ ) for this C line.

As described above, first, the ozone injection rate is calculated such that the ozone absorption efficiency is maximized and the dissolved ozone outflow is minimized.

Next, UV ₁ at which each substance becomes equal to or less than the target value is determined using the relationship diagram of FIG.
60) By performing the correction control on the value by the feedback control, the amount of ozone used in the ozone treatment can be minimized and the concentration of each object to be removed can be made lower than the reference value.

In the present embodiment, the ozone treatment was performed using an ozone contact tank as shown in FIG. 7, but the present invention is not limited to such an ozone contact tank. For example, as shown in FIG. Such a flow type processing tank or the like can also be used. Further, by using only the water quality signal (UV signal) of the treated water, the reliability of the sensor such as dirt can be improved.

[0114]

As described above, according to the present invention, the following effects can be obtained.

(1) The ozone absorption rate can be improved and the concentration of dissolved ozone in the ozonated water can be minimized. Therefore, even if the treated water is discharged, the influence on the surrounding environment such as a river can be suppressed.

Further, the ozone injection rate can be minimized,
Processing costs such as electricity charges can be reduced.

(2) Generated ozone concentration, exhausted ozone concentration, dissolved ozone concentration, dissolved UV meter, etc.
Operation control and water quality control can be realized.

(3) Since the ozone treatment time is about 15 to 30 minutes, a control system can be constructed only by feedback control. The feedforward control system can be omitted, and the water quality sensor for the raw water system can be omitted. Therefore, a control system can be constructed only by the feedback control.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a water purification apparatus according to a conventional example.

FIG. 2 is an explanatory diagram of an ozone treatment method according to a conventional example.

FIG. 3 is a graph showing a correlation between a dissolved ozone concentration and a dimensionless contact time.

FIG. 4 is a graph showing a correlation of dissolved E260 with respect to dimensionless contact time.

FIG. 5 is a graph showing a correlation of a fluorescence intensity with a dimensionless contact time.

FIG. 6 is a graph showing the correlation of the general bacterial concentration with the dimensionless contact time.

FIG. 7 is an explanatory view of an ozone treatment apparatus according to one embodiment of the present invention.

FIG. 8 is an explanatory diagram of a water quality control unit according to one embodiment of the present invention.

FIG. 9 is an explanatory diagram of an ozone treatment apparatus according to one embodiment of the present invention.

FIG. 10 is an explanatory diagram of a water quality control unit according to one embodiment of the present invention.

FIG. 11 is a flowchart of a water quality control method according to an embodiment of the present invention.

FIG. 12 is a graph showing the correlation between the concentration of each object to be removed and the UV value.

FIG. 13 is an explanatory diagram of a flow type ozone treatment apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Raw water tank 2 ... Water supply pump 3 ... Flow meter 4 ... Treatment tank 5 ... Ozone generator 6 ... Injected ozone gas flow meter 7 ... Generated ozone concentration meter 8 ... Aeration plate 9 ... Waste ozone concentration meter 10 ... Defoaming tank 11 ... discharge ozone treatment tank 12 ... ozone treatment water tank 13, 14 ... DO ₃ measuring section 15 ... dissolved ozone concentration measuring unit 16 ... UV value measuring unit

Continued on the front page (72) Inventor Keiichi Tsukiari 2-1-17 Osaki, Shinagawa-ku, Tokyo, Japan Inside Meidensha Co., Ltd. (72) Inventor Hiroshi Shimazaki 2-1-1, Osaki, Shinagawa-ku, Tokyo Co., Ltd. 56) References JP-A-4-225895 (JP, A) JP-A-3-224694 (JP, A) JP-A-58-150488 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) C02F 1/78 C02F 1/50 B01F 1/00

Claims (4)

(57) [Claims] 1. An ozone treatment apparatus of a flow type , comprising: an ozone treatment tank for causing a contact reaction between sample water and ozone gas; and k locations (where, however, contact times between sample water and ozone in the ozone treatment tank are different). k ≧ 2), comprising an ozone concentration measuring means for measuring the dissolved ozone concentration of the test water, and a water quality controlling means, wherein the water quality controlling means compares each dissolved ozone concentration obtained from the ozone concentration measuring means. An ozone treatment apparatus characterized in that the supply ozone gas concentration is controlled so that the difference between the dissolved ozone concentrations satisfies a predetermined target value. 2. The flow-type ozone treatment apparatus according to claim 1, wherein the water quality control means increases the concentration of the supplied ozone gas when the difference in the dissolved ozone concentration is larger than the target value.
An ozone treatment apparatus characterized in that when the difference in the dissolved ozone concentration is smaller than the target value, control is performed to lower the supplied ozone gas concentration. 3. A full contacting reaction of the test water and ozone gas
In the low-type ozone treatment method, the dissolved ozone concentration of the test water is measured at k points (where k ≧ 2) where the contact time between the test water and the ozone in the ozone treatment tank is different, and each of these dissolved ozone concentrations is measured. An ozone treatment method comprising controlling the supplied ozone gas concentration so that the difference between the dissolved ozone concentrations satisfies a predetermined target value. 4. A water purification treatment method comprising an ozone treatment step for water sample using the flow type ozone treatment method according to claim 3.