WO2020021635A1

WO2020021635A1 - Water treatment system and water treatment method

Info

Publication number: WO2020021635A1
Application number: PCT/JP2018/027718
Authority: WO
Inventors: 学生沼; 皓貴内藤; 佑神谷; 稲永　康隆
Original assignee: 三菱電機株式会社
Priority date: 2018-07-24
Filing date: 2018-07-24
Publication date: 2020-01-30
Also published as: JP6529705B1; JPWO2020021635A1

Abstract

Provided is a water treatment system which is capable of efficiently treating organic compounds in water to be treated by successively adjusting pH of the water to be treated on the basis of the pH of the water to be treated. The water treatment system includes: an electric discharge device 30 which is provided inside a treatment tank 4 that stores treated water 3 and forms a discharge 35; a water sprinkling part 11 which is provided inside the treatment tank 4 and supplies water to be treated 1 which is alkaline waste water to a discharge space which is a space in which the discharge 35 is formed; a pH meter 27 which measures the pH of the treated water 3 which is the water to be treated 1 that has passed through the discharge space; a gas supply unit 20 which supplies oxygen and nitrogen to the treatment tank 4; and a control device 12 which controls the gas supply unit 20 on the basis of the pH and adjusts the amount of nitrogen to be supplied to the treatment tank 4.

Description

Water treatment system and water treatment method

The present invention relates to a water treatment system and a water treatment method for treating water to be treated using oxidizing particles such as ozone and radicals generated by electric discharge.

オゾン Conventionally, ozone or chlorine has been widely used in water and wastewater treatment. However, industrial wastewater and the like sometimes contain a hardly decomposable substance that cannot be decomposed by ozone or chlorine, which is a problem. To solve this problem, a hydroxyl radical having a higher activity than ozone or chlorine (hereinafter referred to as an OH radical) is generated by electric discharge and acts on the water to be treated such as industrial wastewater, so that it is difficult to include the radical in the water to be treated. Methods for removing degradable substances have been proposed.

In the method for treating an alkylsulfoxide-containing waste liquid described in Patent Document 1, a technique for performing biological treatment after passing water to be treated through a high-pressure discharge space under a gas component containing nitrogen and oxygen is disclosed. In the method for treating an alkylsulfoxide-containing waste liquid described in Patent Literature 1, nitrogen and oxygen supplied into a treatment tank are adjusted by a gas supply means, and the pH of treated water as water to be treated after passing through a high-pressure discharge space is adjusted. The biological treatment of the treated water is carried out efficiently by adjusting the pH to about four.

JP 2012-35199A

In the method for treating an alkylsulfoxide-containing waste liquid described in Patent Document 1, since the supply of nitrogen and oxygen is performed at a predetermined gas component ratio, the pH of the treated water cannot be successively adjusted based on the pH of the treated water. Further, the method for treating an alkylsulfoxide-containing waste liquid described in Patent Literature 1 is applicable only to a waste liquid containing an alkylsulfoxide, and cannot perform efficient treatment for alkaline wastewater.

An object of the present invention is to provide a water treatment system and a water treatment method capable of efficiently treating organic compounds in alkaline water to be treated by sequentially adjusting the pH of the treated water based on the pH of the treated water. .

The water treatment system according to the present invention is provided in a treatment tank that stores treated water, and a discharge device that forms a discharge, and an alkaline wastewater that is provided in the treatment tank and that is a discharge space that is a space where a discharge is formed. A sprinkler for supplying treated water, a pH meter for measuring the pH of treated water that has passed through the discharge space, a gas supply unit for supplying oxygen and nitrogen into the treatment tank, A control device that controls the gas supply unit based on the control information to adjust the amount of nitrogen supplied into the processing tank.

A water treatment system according to the present invention is provided in a treatment tank that stores treated water that is alkaline wastewater supplied from upstream of the treatment tank as treated water, and is provided in the treatment tank with a discharge device that forms a discharge. A sprinkling unit that supplies treated water into a discharge space, which is a space where a discharge is formed, a pH meter that measures the pH of treated water that is water to be treated that has passed through the discharge space, and oxygen and oxygen in the treatment tank. A gas supply unit that supplies nitrogen and a control device that controls the gas supply unit based on pH to adjust the amount of nitrogen supplied into the processing tank are provided.

The water treatment system according to the present invention is provided in a treatment tank that stores treated water, and a discharge device that forms a discharge, and an alkaline wastewater that is provided in the treatment tank and that is a discharge space that is a space where a discharge is formed. A sprinkling unit that supplies the water to be treated, a pH meter that measures the pH of the treated water that has passed through the discharge space, a storage tank that stores the water to be treated, and oxygen supply to the treatment tank. Controlling the gas supply unit based on the pH, and a gas supply unit having an oxygen supply unit to perform the treatment, and an aeration device for aerating the water to be treated stored in the storage tank using a part of the oxygen supplied by the oxygen supply unit. And a controller for adjusting the amount of oxygen supplied to the storage tank.

In the water treatment method according to the present invention, a gas supply unit that supplies oxygen and nitrogen in a treatment tank that stores treated water, a step of supplying oxygen into the treatment tank, and a discharge device that forms a discharge, A step of supplying water to be treated, which is alkaline wastewater, into a discharge space, which is a space where a discharge is formed, and a pH meter measuring a pH of the treated water, which is water to be treated passing through the discharge space, And supplying the nitrogen into the processing tank by controlling the gas supply unit based on the pH.

水 The water treatment system according to the present invention can sequentially adjust the pH of the treated water based on the pH of the treated water, and thus can efficiently decompose organic compounds in the alkaline treated water.

水 In the water treatment method according to the present invention, since the pH of the treated water can be sequentially adjusted based on the pH of the treated water, organic compounds in the alkaline treated water can be efficiently decomposed.

1 is a schematic diagram illustrating an entire configuration of a water treatment system according to Embodiment 1. It is a figure which illustrated the structure of the control apparatus of the water treatment system which concerns on Embodiment 1. FIG. 2 is a diagram illustrating a relationship between the pH of treated water and the amount of nitrogen supplied into a treatment tank in the water treatment system according to Embodiment 1. FIG. 3 is a control flow chart of the water treatment system according to the first embodiment. It is the schematic which shows the whole structure of the water treatment system which concerns on Embodiment 2. It is the schematic which shows the whole structure of the water treatment system which concerns on Embodiment 3. FIG. 9 is a diagram illustrating a relationship between the pH of treated water and the amount of nitrogen supplied into a treatment tank in a water treatment system according to Embodiment 3. It is the schematic which shows the whole structure of the water treatment system which concerns on Embodiment 4. FIG. 10 is a diagram illustrating a relationship between the pH of treated water, the concentration of carbonate ions in treated water, and the amount of nitrogen supplied into a treatment tank in the water treatment system according to Embodiment 4. It is the schematic which shows the whole structure of the water treatment system which concerns on Embodiment 5. FIG. 14 is a schematic diagram illustrating an overall configuration of a water treatment system according to a sixth embodiment. It is the schematic which shows the whole structure of the water treatment system which concerns on Embodiment 7. FIG. 15 is a schematic diagram illustrating an overall configuration of a water treatment system according to an eighth embodiment.

Hereinafter, embodiments of a water treatment system and a water treatment method disclosed in the present application will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments are merely examples, and the present invention is not limited by these embodiments.

Embodiment 1 FIG.
The configuration of the water treatment system 100 according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram of a water treatment system 100 according to the first embodiment. As shown in FIG. 1, the water treatment system 100 includes a storage tank 2 for storing alkaline wastewater containing an organic compound (hereinafter, referred to as “treatment water 1”), and an organic compound in the treatment water 1 sent from the storage tank 2. A treatment tank 4 for storing treated water 3 and a treated water tank 6 for storing treated water 5 which is treated water 3 that has passed through treatment tank 4. Further, the water treatment system 100 has a gas supply unit 20 that supplies oxygen and nitrogen into the treatment tank 4. In addition, a discharge device 30 is installed in an upper part in the processing tank 4. Further, the water treatment system 100 has a water supply pump 7 and a water supply pipe 8 as means for sending the water to be treated 1 stored in the storage tank 2 to the treatment tank 4. Further, the water treatment system 100 includes a drain pump 9 and a drain pipe 10 as means for discharging the treated water 3 in the treatment tank 4 to the treated water tank 6. Further, the water treatment system 100 includes a control device 12 that controls the gas supply unit 20 to adjust the amount of nitrogen supplied into the treatment tank 4.
Hereinafter, the upstream of the processing tank 4 refers to the side on which the water 1 to be treated is supplied to the processing tank 4, that is, the storage tank 2 side, and the downstream of the processing tank 4 discharges the processing water 3 from the processing tank 4. Side, that is, the treatment water tank 6 side.

The water to be treated 1 is alkaline wastewater, for example, domestic wastewater, industrial wastewater, business wastewater and mixed wastewater, wastewater such as business wastewater, rainwater collected from a gutter, etc. through a rainwater pipe, domestic wastewater or factory wastewater. Wastewater, etc.

The alkaline wastewater means wastewater in which the pH of the water to be treated 1 is higher than 7 or wastewater in which the pH of the treated water 3 is higher than 7 due to decomposition products during the treatment. The alkaline wastewater is, for example, wastewater containing a cyanide, an amine compound, an amide compound, or the like.

被 The water 1 to be treated stored in the storage tank 2 is sent to the treatment tank 4 via the water supply pipe 8 by the operation of the water supply pump 7. One end of the water supply pipe 8 is connected to the vicinity of the bottom of the storage tank 2, and the other end of the water supply pipe 8 is connected to a water sprinkling section 11 disposed above the inside of the processing tank 4. The water sprinkling section 11 supplies the water to be treated 1 into a discharge space in which a plurality of pores are formed on a side surface of the cylindrical pipe and a discharge 35 is formed by the discharge device 30. In addition, as a method of supplying the to-be-treated water 1 to the discharge space by the water sprinkling part 11, it is preferable to spray the to-be-treated water 1 into the discharge space in order to make the to-be-treated water 1 efficiently contact the discharge 35. .

The configuration for supplying the water to be treated 1 into the discharge space is not limited to the water sprinkling section 11, and for example, a spray nozzle or a shower plate is used as a configuration for supplying the water to be treated 1 into the discharge space. be able to. Further, the water sprinkling section 11 does not need to be cylindrical. Further, the water sprinkling section 11 does not necessarily need to be above the discharge device 30, and the water to be treated 1 is supplied into the discharge space of the discharge device 30 from below the discharge device 30 or from the side of the discharge device 30. You may.

被 The water 1 to be treated supplied from the water sprinkling section 11 passes through the discharge space and is stored as the treated water 3 at the bottom of the treatment tank 4. The treated water 3 stored at the bottom of the treatment tank 4 is sent to the treated water tank 6 via the drain pipe 10 by the operation of the drain pump 9. One end of the drainage pipe 10 is connected near the bottom of the treatment tank 4, and the other end of the drainage pipe 10 is connected near the bottom of the treatment tank 6.

硝酸 A nitric acid removing unit 13 that removes nitric acid dissolved in the treated water 3 using a nitric acid remover is installed downstream of the treatment tank 4. Specifically, a nitric acid removing unit 13 is installed in a drain pipe 10 installed downstream of the processing tank 4. The water treatment system 100 can store the treated water 5 from which the nitric acid dissolved in the treated water 3 has been removed by the nitric acid removing unit 13 in the treated water tank 6. The nitric acid removing unit 13 is not indispensable, and the necessity of the treatment can be determined according to the identity of the water to be treated 1 or the discharge standard of the treated water 5.

The water 1 to be treated is supplied to the treatment tank 4 at a predetermined flow rate by the operation of the water supply pump 7. The treated water 3 stored at the bottom of the treatment tank 4 is discharged to the treated water tank 6 as treated water 5 at a predetermined flow rate by the operation of the drain pump 9.
The operation of the water supply pump 7 and the operation of the drainage pump 9 are controlled by the control device 12. Further, the control device 12 controls the organic compound contained in the water to be treated 1 during the residence time of the water to be treated 1 until the water to be treated 1 is sent to the treatment tank 4 and discharged as the treated water 5 to the treatment water tank 6. The amount of the treated water 3 stored in the treatment tank 4, the flow rate at which the water supply pump 7 supplies the treated water 1 to the treatment tank 4, and the drainage pump 9 The flow rate at which the treated water 3 stored at the bottom is discharged to the treated water tank 6 is adjusted.

酸素 An oxygen supply port 21, a nitrogen supply port 22, and a processing tank exhaust port 23 are provided above the processing tank 4. The gas supply unit 20 includes a flow controller 24, an oxygen supply unit 25, and a nitrogen supply unit 26. An oxygen supply unit 25 that supplies oxygen into the processing tank 4 via a flow rate controller 24 is connected to the oxygen supply port 21, and a nitrogen supply unit 26 that supplies nitrogen into the processing tank 4 is connected to the nitrogen supply port 22. Connected. The flow rate controller 24 controls the flow rate of oxygen supplied from the oxygen supply unit 25 into the processing tank 4.

As the oxygen supply unit 25, for example, an oxygen generator such as PSA (Pressure Swing Adsorption) for concentrating oxygen from air, a vaporized gas from liquefied oxygen, or an oxygen cylinder can be used. The nitrogen supply unit 26 can use, for example, an air pump that supplies air outside the processing tank 4 to the processing tank 4. In addition, the nitrogen supply unit 26 can use, for example, a gas cylinder containing nitrogen, a nitrogen generator that concentrates nitrogen from air such as vaporized gas from liquefied nitrogen or PSA in combination with a flow rate control unit. In addition, as a configuration for supplying nitrogen to the processing tank 4, a configuration in which air is supplied to the processing tank 4 by using an air pump that supplies air outside the processing tank 4 to the processing tank 4 is such that nitrogen is easily introduced. Can be.

ＰＨ Inside the treatment tank 4, a pH meter 27 for measuring the pH of the treated water 3 stored at the bottom of the treatment tank 4 is installed. The pH meter 27 is connected to the control device 12. The pH meter 27 outputs the measured pH of the treated water 3 in the treatment tank 4 to the control device 12.

The discharge device 30 includes a ground electrode 31, a high-voltage electrode 32, and a high-voltage conductor 33. The ground electrode 31 and the high voltage electrode 32 are plate members made of a metal material. The high-voltage conductor 33 is a rod-shaped member made of a metal material. The plurality of high-voltage electrodes 32 are arranged in the vertical direction at intervals from the high-voltage conductor 33. The ground electrode 31 and the high-voltage conductor 33 are alternately arranged at predetermined intervals in the horizontal direction, and a discharge space is formed between the ground electrode 31 and the high-voltage electrode 32. A pulse power supply 34 for applying a voltage to the discharge device 30 is provided outside the processing tank 4. The voltage output terminal of the pulse power supply 34 is connected to the high voltage conductor 33. The cable connecting the voltage output terminal of the pulse power supply 34 and the high-voltage conductor 33 is covered with an insulating member. The ground terminal of the pulse power supply 34 and the processing tank 4 are electrically grounded. The X direction shown in FIG. 1 is a horizontal direction, and the Y direction is a vertical direction.

The discharge device is not limited to the configuration of the first embodiment, but may be any configuration as long as it can generate a discharge. The discharge device has, for example, a form in which the high-voltage electrode and the ground electrode are coaxial cylindrical, a form in which the plate electrode is provided inclined with respect to the horizontal direction, and a form in which the wire electrode and the plate electrode are arranged to face each other, or a plate electrode. May be provided to be inclined with respect to the horizontal direction, and the needle electrode and the plate-like electrode may be arranged to face each other.

The polarity of the voltage output from the pulse power supply 34, the voltage peak value, the repetition frequency, the pulse width, and the like can be appropriately determined according to various conditions such as the electrode structure and the gas composition in the processing tank 4. In general, when the voltage peak value is less than 1 kV, stable discharge is not formed, and when the voltage peak value is more than 50 kV, it is difficult to electrically insulate, and the cost is significantly increased to secure the insulation. . If the voltage peak value is more than 50 kV, the power supply becomes large. Therefore, it is desirable to set the voltage peak value to be 1 kV or more and 50 kV or less.
Generally, when the repetition frequency is less than 10 pps (pulse-per-second), a very high voltage is required to supply sufficient discharge power, and when the repetition frequency is more than 100 kpps, a voltage pulse is applied. Is applied, and the voltage pause period from the application of the next voltage pulse is shortened. When the voltage pause period is shortened, the residual amount of charged particles such as ions or electrons remaining in the discharge space immediately before the application of the high-voltage pulse increases, or the temperature of the discharge space increases due to heat generated by the discharge, thereby causing the discharge. Spark discharge easily occurs in the space. Therefore, it is desirable to set the repetition frequency to 10 pps or more and 100 kpps or less.

The power supply for applying a voltage to the discharge device 30 is not limited to a pulse power supply, and may be an AC power supply or a DC power supply as long as a stable discharge can be formed by applying a voltage to the discharge device 30. You may.

The controller 12 controls the nitrogen supply unit 26 based on the pH of the treatment water 3 stored at the bottom of the treatment tank 4 measured by the pH meter 27 to adjust the amount of nitrogen supplied to the inside of the treatment tank 4. . The adjustment of the amount of nitrogen supplied into the treatment tank 4 based on the pH of the treatment water 3 by the control device 12 will be described later in detail.

The controller 12 controls the flow rate controller 24 to control the flow rate of oxygen supplied from the oxygen supply unit 25 into the processing tank 4. The flow rate of oxygen supplied from the oxygen supply unit 25 into the treatment tank 4 is determined according to the treatment flow rate of the water treatment system, the concentration of organic substances in the water 1 to be treated, and the like.

制御 Furthermore, the control device 12 controls the operation of the water supply pump 7, the drainage pump 9 and the pulse power supply 34. FIG. 2 is a diagram illustrating the configuration of the control device 12. The control device 12 can be realized by software control in which the CPU 1000 shown in FIG. 2 executes a program stored in the memory 1001.

Next, the principle of decomposing organic compounds in the water to be treated 1 and the treated water 3 in the treatment tank 4 will be described. Here, the decomposition of an organic compound will be described as an example, but it is well known that ozone and OH radicals generated by electric discharge are effective for sterilization, decolorization, and deodorization. Oxygen molecules (O ₂ ) in the processing tank 4 and water molecules (H ₂ O) generated by vaporizing a part of the water to be processed 1 and the processing water 3 collide with high-energy electrons generated by the discharge 35. , (1) and (2) occur. Note that e is an electron, O is atomic oxygen, H is atomic hydrogen, and OH is an OH radical.
e + O ₂ → e + 2O (1)
e + H ₂ O → e + H + OH (2)

Most of the atomic oxygen generated by the reaction represented by the formula (1) becomes ozone (O ₃ ) by the reaction represented by the formula (3). In the reaction represented by the formula (3), M is a third body of the reaction, and represents all molecules and atoms in the air.
O + O ₂ + M → O ₃ + M (3)
Further, a part of the OH radical generated by the reaction shown in the formula (2) is converted into hydrogen peroxide (H ₂ O ₂ ) by the reaction shown in the formula (4).
OH + OH → H ₂ O ₂ (4)

The oxidizing particles (O, OH, O ₃ , H ₂ O ₂ ) generated by the reaction represented by the formula (1) to the formula (4) fall into the processing tank 4 by the reaction represented by the formula (5). The organic compounds in the treated water 1 are oxidatively decomposed. In particular, OH radicals react rapidly with many organic compounds including hardly decomposable substances. R is an organic compound to be decomposed.
R + (O, OH, O ₃ , H ₂ O ₂ ) → decomposition product (5)

Atomic oxygen and OH radicals that have not reacted with the organic compound are converted into long-lived ozone and hydrogen peroxide by the reactions shown in the formulas (3) and (4). It is dissolved in the water to be treated 1 by the reaction shown in the formula (7). In addition, (liq.) Means a liquid phase.
O ₃ → O ₃ (liq.) (6)
H ₂ O ₂ → H ₂ O ₂ (liq.) (7)

Further, part of H ₂ O ₂ (liq.) Is dissociated into HO ₂ ⁻ and H ⁺ in the water to be treated 1 and the treated water 3 by the reaction represented by the formula (8).
H ₂ O ₂ (liq.) ⇔HO ₂ ⁻ + H ⁺ (8)
The reaction shown in equation (8) is in equilibrium on the right and left sides. Further, HO ₂ ^— and O ₃ (liq.) Generate OH (liq.) In the water to be treated 1 and the treated water 3 by the reaction represented by the formula (9).
HO ₂ ⁻ + O ₃ → OH (liq.) + O ₂ ⁻ + O ₂ (9)

O ₃ (liq.), H ₂ O ₂ (liq.), And OH (liq.) Generated by the reaction represented by the formula (9) from the formula (6) convert the water to be treated by the underwater reaction represented by the formula (10). 1 and the organic compound in the treated water 3 are decomposed. In particular, OH (liq.) Reacts quickly with many organic compounds including hardly decomposable substances.
R + (O ₃ (liq.), H ₂ O ₂ (liq.), OH (liq.))
→ Decomposition products (10)

The water treatment in the treatment tank 4 is performed by decomposition of the oxidizing particles present in the air (formula (5)) and decomposition of the oxidizing particles present in the water (formula (10)). And the decomposition of organic compounds in the treated water 3 by decomposition by oxidizing particles present in the water (formula (10)). Generally, the treated water 3 is stored at the bottom of the treatment tank 4 for a longer time than the time when the water to be treated 1 passes through the discharge space, so that the decomposition reaction of the organic compound mainly occurs at the bottom of the treatment tank 4. It proceeds by an underwater reaction (Equation (10)) in the stored treated water 3.

Next, the relationship between the decomposition of the organic compounds in the treated water 3 and the pH of the treated water 3 in the water treatment system 100 according to the first embodiment will be described. The organic compounds in the water 1 to be treated and the water 3 to be treated are finally decomposed into inorganic carbon and water by the reactions shown in the formulas (5) and (10). The inorganic carbon produced by the reactions shown in the formulas (5) and (10) is in an equilibrium state shown in the formulas (11) and (12). Note that CO ₂ is carbon dioxide, HCO ₃ ⁻ is bicarbonate ion, and CO ₃ ^2- is carbonate ion.
CO ₂ + H ₂ O⇔HCO ₃ ⁻ + H ⁺ (11)
_{^{_{^{^{HCO 3 - ⇔CO 3 2- + H}}}}} + (12)

In the reactions represented by the formulas (11) and (12), the main substance of inorganic carbon is generally carbon dioxide when the pH is less than 6, bicarbonate ion when the pH is 6 or more and less than 8.5, and the pH is 8 or less. If it is .5 or more, it becomes a carbonate ion. Carbon dioxide is quickly desorbed from the water to be treated 1 and the treated water 3 as a gas, but bicarbonate ions and carbonate ions remain in the water to be treated 1 and the treated water 3 and are expressed by the formulas (13) and (14), respectively. And OH (liq.).
OH (liq.) + HCO ₃ ⁻ → reaction product (13)
OH (liq.) + CO ₃ ^2- → reaction product (14)
The reaction rate of the reaction shown in the equation (13) is K = 1 × 10 ⁷ (mol / L / s), and the reaction rate of the reaction shown in the equation (14) is K = 4 × 10 ⁸ (mol / L). / S). That is, the reaction rate between carbonate ions and OH (liq.) Is higher by one digit or more than the reaction rate between heavy carbon ions and OH (liq.). Since the reaction rate of a general organic compound with OH (liq.) Is K = 1 × 10 ⁷ to 1 × 10 ¹⁰ (mol / L / s), the carbonic acid in the water 1 to be treated and the water 3 to be treated is When the ion concentration increases, the reaction between the organic compound and OH (liq.) Is inhibited, and efficient water treatment cannot be performed.

平衡 Further, the equilibrium reaction shown in the equation (8) is closer to the right side as the pH of the treated water 3 is higher. Therefore, the generation rate of OH (liq.) By the reaction shown in equation (9) increases as the pH of the treated water 3 increases, and decreases significantly when the pH of the treated water 3 is less than 6. On the other hand, the accumulation of carbonate ions becomes more remarkable when the pH of the treated water 3 is higher, more specifically, when the pH of the treated water 3 is about 8.5 or more. Further, in alkaline wastewater having a pH exceeding 8.5, an ineffective consumption reaction of OH (liq.) Occurs remarkably, and organic compounds cannot be decomposed efficiently. From the above, in the first embodiment, it is preferable to set the pH of the treated water 3 to 6 or more and 8.5 or less from the viewpoint of decomposition of the organic compound by the oxidizing particles generated by the discharge.

Next, an operation of adjusting the pH of the treated water 3 in the water treatment system 100 according to the first embodiment will be described. When the nitrogen supply unit 26 is not operated, the inside of the processing tank 4 is in a mixed state of oxygen supplied from the oxygen supply unit 25 and steam generated by volatilization of the water 1 to be treated. When the nitrogen supply unit 26 is operated, nitrogen (N ₂ ) is supplied to the processing tank 4, so that the inside of the processing tank 4 becomes an atmosphere of a mixed gas containing oxygen, nitrogen, and water vapor. When the inside of the processing tank 4 is an atmosphere of a mixed gas containing oxygen, nitrogen, and water vapor, the nitrogen is converted into atomic nitrogen (N) by touching the discharge 35 by the reaction shown in the equation (15).
e + N ₂ → e + 2N (15)

Atomic nitrogen combines with atomic oxygen generated by the reaction represented by the formula (1) to generate nitric oxide (NO) by the reaction represented by the formula (16).
O + N + M → NO + M (16)
Nitric oxide produces nitrogen dioxide (NO ₂ ) and nitric oxide (NO ₃ ) by the reactions shown in equations (17) and (18).
NO + O ₃ → NO ₂ + O ₂ (17)
NO ₂ + O ₃ → NO ₃ + O ₂ (18)

Further, nitrogen dioxide and nitrogen trioxide are combined by the reaction shown in the formula (19), so that dinitrogen pentoxide (N ₂ O ₅ ) is generated.
NO ₂ + NO ₃ → N ₂ O ₅ (19)
Further, nitrous oxide (HNO ₃ ) is generated by the reaction of dinitrogen pentoxide with water by the reaction shown in the formula (20).
N ₂ O ₅ + H ₂ O → 2HNO ₃ (20)
In addition, nitrogen dioxide reacts with OH generated by the reaction represented by the formula (2) or OH (liq.) Generated by the reaction represented by the formula (9) to form nitric acid by the reaction represented by the formula (21).
NO ₂ + OH → HNO ₃ (21)

反応 The reactions shown in equations (20) and (21) can occur both in air and in water. That is, there are cases where nitric acid generated in the air dissolves in the water to be treated 1 and the treated water 3 and cases where nitrogen dioxide or nitrous oxide dissolves in the water to be treated 1 and the treated water 3 to become nitric acid. . In any case, the pH of the treated water 3 is reduced by the nitric acid.

The reaction rate of the reaction shown in Equations (15) to (21) depends on the gas composition in the treatment tank 4, the state of the discharge 35, and the contact state between the water 1 and the treated water 3 and the gas in the treatment tank 4. Dependent. In addition, since the reaction rate of the reaction represented by the equations (15) to (21) greatly depends on the nitrogen concentration in the processing tank 4, the amount of nitric acid generated by adjusting the amount of nitrogen supplied into the processing tank 4 is adjusted. The speed and, moreover, the pH of the treated water 3 can be adjusted.

FIG. 3 is a diagram illustrating the relationship between the pH of the treated water 3 and the amount of nitrogen supplied into the treatment tank 4 of the water treatment system 100 according to the first embodiment. The adjustment of the amount of nitrogen supplied into the treatment tank 4 based on the pH of the treatment water 3 by the control device 12 will be described with reference to FIG.
Note that the amount of nitrogen supplied into the processing tank 4 is a product of the nitrogen flow rate and time indicated by oblique lines in FIG.

As shown in FIG. 3A, when the pH of the treated water 3 exceeds the set value, the control device 12 controls the nitrogen supply unit 26 to supply the outside air (nitrogen) into the treatment tank 4 at a constant flow rate. Supply. When nitrogen is supplied into the treatment tank 4 by the control device 12 controlling the nitrogen supply unit 26, nitric acid is generated by the above-described reaction, and the pH of the treated water 3 decreases. When the pH of the treated water 3 is equal to or less than the set value, the control device 12 stops the nitrogen supply unit 26. When the control device 12 stops the nitrogen supply unit 26, the nitric acid generation rate decreases due to a decrease in the nitrogen concentration in the treatment tank 4, and the pH of the treatment water 3 is reduced by the treatment water 1 which is the alkaline wastewater sent from the storage tank 2. Rises. Note that the control device 12 continues to supply oxygen from the oxygen supply unit 25 regardless of the pH of the treated water 3.

The controller 12 increases the flow rate of nitrogen supplied from the nitrogen supply unit 26 into the processing tank 4 when the pH of the treated water 3 is higher than a set value, and increases the nitrogen flow when the pH of the treated water 3 is lower than the set value. By reducing the flow rate of nitrogen supplied into the processing tank 4 by the supply unit 26, the amount of nitrogen supplied into the processing tank 4 is adjusted based on the pH of the processing water 3 to adjust the pH of the processing water 3 to a value close to a set value. Adjust to

The set value of the pH is a value determined according to the components of the target wastewater to be treated and the like, and can be set to a value of 6 or more and 8.5 or less, which is preferable from the viewpoint of decomposition of the organic compound. For example, pH = 7. The reason why the set value of the pH of the treated water 3 is set to neutral (pH = 7) is that the response of the pH of the treated water 3 to a change in the nitrogen concentration is not high. Since the response of the pH of the treated water 3 to a change in the nitrogen concentration is not high, the pH of the treated water 3 overshoots from the set value. Therefore, even when the pH of the treated water 3 overshoots from the set value, the pH of the treated water 3 is adjusted in order to adjust the pH of the treated water 3 to 6 or more and 8.5 or less which is preferable from the viewpoint of decomposing the organic compound. The value is neutral (pH = 7).

The water treatment system 100 adjusts the amount of nitrogen supplied to the treatment tank 4 based on the pH of the treated water 3 so that the pH of the treated water 3 becomes a value within a suitable range from the viewpoint of predetermined decomposition. For example, a set value (first set value) for supplying nitrogen into the processing tank 4 and a set value (second set value) for stopping the supply of nitrogen into the processing tank 4 may be used. May be set to different values.

Further, as shown in FIG. 3B, the control device 12 controls the nitrogen flow rate supplied by the nitrogen supply unit 26 into the processing tank 4 according to the difference between the measured value of the pH of the treated water 3 and the set value. Can also be controlled to change. That is, when the pH of the treated water 3 is higher than the set value, the controller 12 increases the nitrogen flow rate supplied by the nitrogen supply unit 26 into the treatment tank 4 as the pH of the treated water 3 is higher than the set value. If the pH of the treated water 3 is lower than the set value, the nitrogen supply unit 26 is stopped. In FIG. 3B, when the pH of the treated water 3 is lower than the set value, the nitrogen supply unit 26 is stopped. However, as the pH of the treated water 3 is lower than the set value, the nitrogen supply unit is stopped. 26 may be configured to reduce the flow rate of nitrogen supplied into the processing tank 4.
By controlling the nitrogen supply unit 26 using the control device 12 as shown in FIG. 3B, comparison with the case where the nitrogen supply unit 26 is controlled using the control device 12 as shown in FIG. Thus, the pH of the treated water 3 can be adjusted with higher accuracy.

It is needless to say that a known control method such as feedback control can be used as a method for controlling the supply amount of nitrogen into the processing tank 4 using the control device 12. Further, as the water treatment method of the water treatment system 100, a configuration in which the control device 12 controls only the nitrogen supply unit 26 based on the pH of the treated water 3 in the treatment tank 4 measured by the pH meter 27 has been described. A configuration in which the flow rate controller 24 and the nitrogen supply unit 26 are controlled based on the pH of the treated water 3 in the treatment tank 4 measured by the meter 27 to adjust the ratio of the amount of oxygen and the amount of nitrogen supplied into the treatment tank 4. It may be.

FIG. 4 is a control flow chart of the water treatment system 100 according to Embodiment 1. The procedure of the water treatment method using the water treatment system 100 will be described with reference to a control flowchart shown in FIG. The case where the water 1 to be treated is alkaline and the set value of the pH of the treated water 3 is neutral (pH = 7) will be described.

In step S <b> 1, when the control device 12 operates the flow controller 24, the oxygen supply unit 25 supplies oxygen from the oxygen supply port 21 to the inside of the processing tank 4 via the flow controller 24, and Inside is a high oxygen concentration atmosphere. Gas equivalent to the amount of oxygen supplied into the processing tank 4 is exhausted from the processing tank 4 through the processing tank exhaust port 23.

In step S2, the control device 12 operates the pulse power supply 34 to apply a pulsed high voltage to the high voltage conductor 33, so that the discharge device 30 discharges to the discharge space between the ground electrode 31 and the high voltage electrode 32. 35 is formed.

In step S3, the control device 12 operates the water supply pump 7 and the drainage pump 9. The water 1 to be treated stored in the storage tank 2 is pumped up by a water supply pump 7 and supplied from a water sprinkling section 11 through a water supply pipe 8. The to-be-treated water 1 supplied from the water sprinkling section 11 falls in a shower shape in the discharge space, and a part of the to-be-treated water 1 adheres to the ground electrode 31 and falls in a water film form. When the for-treatment water 1 passes through the discharge space, it comes into contact with the discharge 35, and the organic compounds in the for-treatment water 1 are decomposed by oxidation. The water to be treated 1 takes in the oxidizing particles generated by the discharge 35, passes through the discharge space, and is stored as the treated water 3 at the bottom of the treatment tank 4. In the treated water 3 stored at the bottom of the treatment tank 4, the organic compounds in the treated water 3 are oxidized and decomposed by the reaction of the oxidized particles taken in. The treated water 3 stored at the bottom of the treatment tank 4 is sent to the treated water tank 6 via a drain pipe 10 by a drain pump 9.

In step S4, the pH meter 27 measures the pH of the treated water 3 stored in the bottom of the treatment tank 4, and outputs the measured pH to the control device 12. The control device 12 compares the received pH with a set value. When the pH of the treated water 3 measured by the pH meter 27 exceeds the set value, the process proceeds to step S5, and when the pH of the treated water 3 measured by the pH meter 27 is equal to or less than the set value, the process proceeds to step S6.

In step S5, the control device 12 operates the nitrogen supply unit 26 to supply nitrogen into the processing tank 4. In step S6, the control device 12 stops the nitrogen supply unit 26.

In the water treatment system 100 according to the first embodiment, the control device 12 controls the nitrogen supply unit 26 based on the pH of the treated water 3 in the treatment tank 4 measured by the pH meter 27 and supplies the nitrogen into the treatment tank 4. The pH of the treated water 3 can be adjusted by adjusting the amount of nitrogen to be supplied. Therefore, the water treatment system 100 can efficiently decompose the organic compound in the alkaline wastewater by the oxidizing particles generated by the discharge, and can perform efficient water treatment.

The water treatment system according to Embodiment 1 is provided in a treatment tank that stores treated water and forms a discharge, and a discharge device that is provided in the treatment tank and forms a discharge space that is a space where a discharge is formed. A sprinkling unit that supplies the water to be treated, which is alkaline wastewater, a pH meter that measures the pH of the treated water that is the water to be treated that has passed through the discharge space, and a gas supply unit that supplies oxygen and nitrogen into the treatment tank. a controller that controls the gas supply unit based on the pH to adjust the amount of nitrogen supplied into the processing tank.

The control device of the water treatment system according to Embodiment 1 is characterized in that the amount of nitrogen supplied into the treatment tank is adjusted so that the pH of the treated water becomes a predetermined value.

Further, the control device of the water treatment system according to the first embodiment increases the amount of nitrogen supplied by the gas supply unit when the pH exceeds the set value, and increases the amount of nitrogen supplied by the gas supply unit when the pH is equal to or less than the set value. Characterized in that the amount of nitrogen used is reduced.

Further, a nitric acid removing unit is provided downstream of the treatment tank and removes nitric acid from treated water treated in the treatment tank.

With the above-described configuration, the water treatment system 100 according to Embodiment 1 can control the inside of the treatment tank by the control device even when the pH of the water to be treated fluctuates or the pH of the treated water fluctuates due to decomposition products during the treatment process. The pH of the treated water can be adjusted to a set value in order to successively adjust the nitrogen concentration of the treated water. Therefore, the water treatment system 100 according to Embodiment 1 can efficiently decompose the organic compound in the treated water 3, and can perform efficient water treatment.

In addition, the water treatment system 100 according to the first embodiment adjusts the amount of nitrogen supplied into the treatment tank according to the pH of the treatment water. The amount of nitric acid required to adjust the amount of nitric acid can be produced. Therefore, the water treatment system 100 according to Embodiment 1 can suppress the total nitrogen concentration in the treated water.

In addition, the water treatment system 100 according to the first embodiment can adjust the pH of the treated water without injecting the medicine, so that it is not necessary to provide a medicine storage facility and a medicine injection facility, and the simplification and low cost of the apparatus can be achieved. Costs can be reduced. Further, the water treatment system 100 according to the first embodiment does not need to periodically replenish the chemicals for adjusting the pH, so that the operation can be simplified and the operation cost can be reduced.

In the water treatment method according to Embodiment 1, the gas supply unit that supplies oxygen and nitrogen into the treatment tank that stores the treated water supplies oxygen into the treatment tank, and the discharge device forms a discharge. And a step of supplying water to be treated, which is alkaline wastewater, into a discharge space, which is a space where a discharge is formed, by the water sprinkling unit, and treating the treated water, which is the water to be treated that has passed through the discharge space, with a pH meter. The method includes a step of measuring pH and a step of controlling the gas supply unit based on the pH to supply nitrogen into the processing tank.

With the above configuration, the water treatment method according to the first embodiment can adjust the amount of nitrogen supplied into the treatment tank based on the pH of the treated water and sequentially adjust the pH of the treated water. Organic compounds can be efficiently decomposed.

Embodiment 2 FIG.
The configuration of the water treatment system 200 according to Embodiment 2 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 5 is a schematic diagram of a water treatment system 200 according to Embodiment 2. As shown in FIG. 5, the water treatment system 200 includes an intake port 41 provided above the treatment tank 4, and an air diffuser 42 immersed and disposed in the treatment water 3 stored at the bottom of the treatment tank 4. And a circulation pipe 43 that communicates the intake port 41 and the air diffuser 42. The circulation pipe 43 is provided with a circulation pump 44 for sucking the gas in the processing tank 4 from the suction port 41 and supplying the gas sucked from the suction port 41 to the diffuser 42. The air diffuser 42 supplies the treated water 3 with the gas in the treatment tank 4 sucked from the intake port 41. The gas diffuser 42, the circulation pipe 43, and the circulation pump 44 constitute the gas circulation unit 40.

The gas circulation unit 40 does not necessarily need to be composed of the air diffusion unit 42, the circulation pipe 43, and the circulation pump 44. For example, a blower or a compressor may be used instead of the circulation pump 44. Further, instead of directly circulating the gas, the processing water 3 stored at the bottom of the processing tank 4 may be circulated by a pump, and the gas in the processing tank 4 may be sucked and mixed by an ejector or the like. . That is, the configuration of the gas circulation unit 40 is not limited to the air diffuser 42, the circulation pipe 43, and the circulation pump 44 as long as the gas can be circulated so that the gas in the treatment tank 4 comes into contact with the treatment water 3.

In the water treatment system 100 according to the first embodiment, the case where nitric acid generated in the air is dissolved in the water to be treated 1 and the treated water 3 and the case where nitrogen dioxide or nitrous oxide is added to the water to be treated 1 and the treated water 3 The pH of the treated water 3 drops depending on the case of dissolving into nitric acid. However, since the process of lowering the pH of the treated water 3 by nitric acid, nitrogen dioxide and nitrous oxide generated in the air takes a long time, the nitrogen concentration in the treatment tank 4 is changed before the treatment water 3 The response time until the pH changes becomes longer.

On the other hand, in the water treatment system 200 according to the second embodiment, nitric acid, nitrogen dioxide, and nitrous oxide generated in the air are supplied to the treated water 3 stored at the bottom of the treatment tank 4 by the gas circulation unit 40. Dissolves in the treated water 3 quickly. Therefore, in the water treatment system 200 according to the second embodiment, the responsiveness of the pH of the treated water 3 to the change in the nitrogen concentration in the treatment tank 4 is improved, so that the pH of the treated water 3 is close to the target pH. Efficient water treatment can be performed.

The water treatment system according to Embodiment 2 includes a gas circulation unit that sucks gas in the treatment tank and supplies gas to the treatment water stored in the treatment tank.

With the above configuration, the water treatment system 200 according to Embodiment 2 improves the responsiveness of the pH of the treated water to a change in the nitrogen concentration in the treatment tank, so that the pH of the treated water is maintained close to the target pH. Thus, efficient water treatment can be performed.

Embodiment 3 FIG.
A configuration of a water treatment system 300 according to Embodiment 3 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 6 is a schematic diagram of a water treatment system 300 according to the third embodiment. As shown in FIG. 6, the water treatment system 300 has the same configuration as the water treatment system 100 according to the first embodiment.
In the water treatment system 300 according to the third embodiment, when the pH of the treated water 3 is higher than a set value, the pH is stabilized when air is continuously supplied for a predetermined time, and when the supply of air is stopped for a predetermined time. The time is alternately set. That is, the control device 12 of the water treatment system 300 according to Embodiment 3 controls the nitrogen supply unit 26 by an intermittent operation.

The water treatment system 100 according to the first embodiment has a configuration in which the nitrogen supply unit 26 is operated to continuously introduce air into the treatment tank 4 when the pH of the treated water 3 is higher than a set value. is there. However, since there is a time difference between the change in the nitrogen concentration in the treatment tank 4 and the change in the pH of the treated water 3, the pH of the treated water 3 falls below the set value, and the pH of the treated water 3 overshoots from the set value. May be. When the pH of the treated water 3 becomes lower than the set value and becomes acidic, a required amount or more of nitric acid is taken into the treated water 3 to increase the total nitrogen concentration. The decomposition rate is slow. Therefore, it is desirable to stably adjust the pH of the treated water 3 near the set value so that the pH of the treated water 3 does not overshoot from the set value.

FIG. 7 is a diagram illustrating the relationship between the pH of the treated water 3 and the amount of nitrogen supplied into the treatment tank 4 in the water treatment system 300 according to the third embodiment. In the water treatment system 300 according to the third embodiment, when the pH of the treated water 3 exceeds the set value, the supply of nitrogen is continued at a constant flow rate for a predetermined time and the supply of nitrogen is stopped for a predetermined time. The pH stabilization is performed alternately. That is, the control device 12 operates the nitrogen supply unit 26 only during the nitrogen supply, and stops the nitrogen supply unit 26 during the pH stabilization.

Since the control device 12 controls the nitrogen supply unit 26 by the intermittent operation, the pH of the treated water 3 asymptotically approaches the set value. Therefore, the water treatment system 300 can suppress the pH of the treated water 3 from overshooting from the set value. In the water treatment system 300, as a result, the production of excessive nitric acid is suppressed, so that the pH of the treated water 3 is maintained close to the set value, and efficient water treatment can be performed.

The gas supply unit of the water treatment system according to Embodiment 3 includes an oxygen supply unit that supplies oxygen into the treatment tank, and a nitrogen supply unit that supplies nitrogen into the treatment tank. Is controlled by an intermittent operation to adjust the amount of nitrogen supplied into the processing tank.

With the above configuration, the water treatment system 300 according to Embodiment 3 can suppress the pH of the treated water from overshooting from the set value, and can execute highly efficient water treatment.

Embodiment 4 FIG.
A configuration of a water treatment system 400 according to Embodiment 4 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 8 is a schematic diagram of a water treatment system 400 according to Embodiment 4. As shown in FIG. 8, in the water treatment system 400, a carbonate ion concentration meter 51 for measuring the carbonate ion concentration of the treated water 3 stored at the bottom of the treatment tank 4 is installed inside the treatment tank 4.
In the water treatment system 400 according to the fourth embodiment, the pH of the treated water 3 is adjusted based on the carbonate ion concentration of the treated water 3 in addition to the pH of the treated water 3.

The carbonate ion concentration meter 51 is connected to the control device 12. The carbonate ion concentration meter 51 outputs the measured carbonate ion concentration of the treated water 3 stored at the bottom of the treatment tank 4 to the control device 12.

FIG. 9 is a diagram illustrating a relationship between the pH of the treated water 3, the carbonate ion concentration of the treated water 3, and the amount of nitrogen supplied into the treatment tank 4 in the water treatment system 400 according to the fourth embodiment. . As shown in FIG. 9, the control device 12 adjusts the pH of the treatment water 3 stored at the bottom of the treatment tank 4 measured by the pH meter 27 and the pH of the treatment tank 4 measured by the carbonate ion concentration meter 51. When the carbonate ion concentration of the stored treated water 3 exceeds the set value, the nitrogen supply unit 26 increases the flow rate of nitrogen supplied into the treatment tank 4, and the treatment tank 4 measured by the pH meter 27. When at least one of the pH of the treated water 3 stored at the bottom of the treatment water 3 and the carbonate ion concentration of the treated water 3 stored at the bottom of the treatment tank 4 measured by the carbonate ion concentration meter 51 is equal to or less than the set value. The nitrogen supply unit 26 reduces the flow rate of nitrogen supplied into the processing tank 4.

That is, the controller 12 increases the amount of nitrogen supplied by the nitrogen supply unit 26 when both the pH and the carbonate ion concentration of the treated water 3 exceed the set values, and at least the pH and the carbonate ion concentration of the treated water 3 If one of them is equal to or less than the set value, the amount of nitrogen supplied by the nitrogen supply unit 26 is reduced.

設定 The set value of the pH is a value determined according to the identity of the water to be treated or the discharge standard, for example, pH = 7. The set value of the carbonate ion concentration is a value determined according to the physical properties and the concentration of the organic compound to be treated, and is, for example, 10% or more and 100% or less of the organic compound to be treated.

(4) In a situation where the pH of the treated water 3 is high, the concentration of carbonate ions in the treated water 3 increases, and OH (liq.) Is ineffectively consumed by the reaction shown in the equation (14), thereby reducing the efficiency of the water treatment. However, when the concentration of the organic compound in the water to be treated 1 is low and when the concentration of the organic compound in the water 5 after the treatment does not need to be significantly reduced as compared with the water 1 to be treated, the pH of the treated water 3 becomes the set value. Even in a higher state, the carbonate ion concentration of the treated water 3 is kept relatively low, and the reaction of ineffective consumption of OH (liq.) By the reaction shown in the equation (14) does not cause much problem.

Even if the pH of the treated water 3 is higher than the set value, if the reaction of ineffective consumption of OH (liq.) By the reaction shown in the equation (14) does not pose a problem, nitric acid is generated to It is not necessary to lower the pH, and it is desirable not to increase the total nitrogen concentration of the treated water 3 without generating nitric acid. On the other hand, in a situation where both the pH of the treated water 3 and the carbonate ion concentration in the treated water 3 exceed the set values and inhibit the decomposition reaction of the organic compounds in the treated water 3, the pH of the treated water 3 It is preferable to carry out efficient water treatment by adjusting the temperature.

The water treatment system according to Embodiment 4 includes a carbonate ion concentration meter that measures the concentration of carbonate ions in the treated water stored in the treatment tank, and the control device is configured to control the case where both the pH and the carbonate ion concentration exceed the set values. The amount of nitrogen supplied by the gas supply unit is increased, and the amount of nitrogen supplied by the gas supply unit is decreased when at least one of the pH and the carbonate ion concentration is equal to or less than a set value.

With the above configuration, the water treatment system 400 according to Embodiment 4 suppresses the generation of unnecessary nitric acid, suppresses the increase in the total nitrogen concentration in the treated water, and effectively decomposes organic compounds. Will be

Embodiment 5 FIG.
A configuration of a water treatment system 500 according to Embodiment 5 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 10 is a schematic diagram of a water treatment system 500 according to Embodiment 5. As shown in FIG. 10, in the water treatment system 500, a PSA (Pressure Swing Adsorption) oxygen generator 61 is connected as the gas supply unit 20.

The PSA oxygen generator 61 separates oxygen from air by utilizing a difference in oxygen and nitrogen adsorption characteristics with respect to an adsorbent such as zeolite. That is, when air passes through the adsorbent under pressure, nitrogen that is relatively easily adsorbed is selectively adsorbed, and oxygen that is relatively hard to adsorb passes. In other words, the PSA oxygen generator 61 extracts high-purity oxygen from air by repeatedly pressurizing and depressurizing the adsorbent using the adsorption characteristics of oxygen and nitrogen to the adsorbent such as zeolite.

純度 The purity of oxygen generated by the PSA oxygen generator 61, that is, the concentration of nitrogen contained as an impurity varies depending on the operating conditions of the PSA oxygen generator 61. Specifically, the higher the pressure of the air supplied to the adsorbent, the smaller the amount of supplied air, the higher the purity of oxygen is obtained, and the lower the pressure of the supplied air, the higher the amount of supplied air, the lower the purity of oxygen. Is obtained.

Although the case where the PSA oxygen generator is used as the gas supply unit in the water treatment system 500 has been described, for example, a VPSA (Vacuum Pressure Swing Adsorption) method or a cryogenic oxygen generator may be used.

The controller 12 reduces the purity of the oxygen supplied into the processing tank 4 by the PSA oxygen generator 61 when the pH of the processing water 3 exceeds the set value. That is, the controller 12 increases the amount of nitrogen supplied into the treatment tank 4 when the pH of the treatment water 3 exceeds the set value.

Since cost is required to obtain high-purity oxygen, the high-purity oxygen is supplied into the processing tank 4 by the oxygen supply unit 25 as shown in Embodiment 1, while the high-purity oxygen is supplied based on the pH of the processing water 3. Rather than controlling the nitrogen supply unit 26 to adjust the amount of nitrogen supplied into the treatment tank 4, the PSA oxygen generator 61 is controlled based on the pH of the treated water 3 as described in the fifth embodiment. Adjusting the amount of nitrogen supplied into the tank 4 can reduce costs.

The gas supply unit of the water treatment system according to Embodiment 5 is characterized in that it is an oxygen generator that separates oxygen from air.

With the above configuration, the water treatment system 500 according to Embodiment 5 controls the oxygen generator that separates oxygen from air based on the pH of the treated water, and adjusts the amount of nitrogen supplied to the treatment tank. Power consumption can be suppressed.

Embodiment 6 FIG.
The configuration of a water treatment system 600 according to Embodiment 6 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 11 is a schematic diagram of a water treatment system 600 according to Embodiment 6. As shown in FIG. 11, the water treatment system 600 is configured to supply a part of the oxygen supplied from the oxygen supply unit 25 to the water to be treated 1 stored in the storage tank 2. In addition, FIG. 11 illustrates a configuration in which the water treatment system 600 does not include the nitrogen supply unit 26. However, the water treatment system 600 may include a configuration that includes the nitrogen supply unit 26.

The gas supply unit 20 of the water treatment system 600 is connected to an aeration unit 71 immersed in the water to be treated 1 stored in the storage tank 2, and one end is connected to a pipe between the oxygen supply unit 25 and the flow controller 24. And an aeration pipe 72 having the other end connected to the aeration unit 71. Further, the aeration pipe 72 has a supply amount regulator 73 for adjusting the flow rate of oxygen supplied from the oxygen supply unit 25 to the water 1 to be treated. In addition, a storage tank exhaust port 74 is provided above the storage tank 2. The aeration unit 71, the aeration pipe 72, and the supply amount controller 73 constitute an aeration device 70.

(4) When the content of the buffer component in the water to be treated 1 is small, a small amount of nitric acid is dissolved in the treated water 3, so that the pH of the treated water 3 is significantly lower than a set value, and the efficiency of the water treatment may be impaired. In addition, when the buffer component in the water to be treated 1 is small, the dissolved nitrogen dissolved in the water to be treated 1 is volatilized in the treatment tank 4 as the nitrogen partial pressure decreases even when nitrogen is not supplied into the treatment tank 4. As a result, nitric acid is generated, and the pH of the treated water 3 may be significantly lowered.

The water treatment system 600 performs aeration on the water to be treated 1 having a small buffer component, and replaces dissolved nitrogen in the water to be treated 1 with a small buffer component with oxygen. When the pH of the treated water 3 is equal to or less than the set value, the control device 12 of the water treatment system 600 controls the supply amount regulator 73 to increase the flow rate of oxygen supplied to the aeration unit 71, and the pH of the treated water 3 is set. If it exceeds the value, the supply amount regulator 73 is controlled to reduce the flow rate of oxygen supplied to the aeration unit 71.

The water treatment system according to Embodiment 6 is provided in a treatment tank that stores treated water and forms a discharge, and a discharge device that is provided in the treatment tank and forms a discharge space that is a space where a discharge is formed. A sprinkling section for supplying the treated water as alkaline wastewater, a pH meter for measuring the pH of the treated water that has passed through the discharge space, a storage tank for storing the treated water, and oxygen in the treatment tank. A gas supply unit having an oxygen supply unit for supplying water, an aeration device for aerating the water to be treated stored in the storage tank using a part of the oxygen supplied by the oxygen supply unit, and a gas supply unit based on pH. And a controller for controlling the amount of oxygen supplied to the storage tank.

Further, the control device of the water treatment system according to Embodiment 6 increases the flow rate of oxygen supplied from the oxygen supply unit to the aeration device when the pH is equal to or less than the set value, and increases the oxygen supply unit when the pH exceeds the set value. Reduces the flow rate of oxygen supplied to the aeration device.

With the above configuration, the water treatment system 600 according to Embodiment 6 can effectively adjust the pH even for treated water in which the pH is significantly changed by a small amount of nitric acid. Can perform processing. In the sixth embodiment, since the amount of the generated nitric acid is very small, there is no need to install a nitric acid removing unit, and the apparatus can be simplified.

Embodiment 7 FIG.
A configuration of a water treatment system 700 according to Embodiment 7 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described. In the first embodiment, the pulse power source 34 is not sequentially controlled. However, the water treatment system 700 according to the seventh embodiment is configured to sequentially control the pulse power source 34.

The characteristics of the discharge 35 formed by the discharge device 30 change because the gas composition in the processing tank 4 changes when nitrogen is supplied to the processing tank 4 by the gas supply unit 20. Generally, the voltage required to form the discharge 35 decreases as the nitrogen concentration in the processing tank 4 increases. That is, when the applied voltage is constant and the nitrogen concentration in the processing tank 4 increases, the discharge energy increases. Due to the increase in the discharge energy, the discharge 35 is destabilized, so that the water treatment efficiency may decrease or spark discharge may occur.
However, in the water treatment system 700 according to the seventh embodiment, since the pulse power supply 34 is sequentially controlled, the discharge 35 can be stably formed even when the nitrogen concentration in the treatment tank 4 changes.

FIG. 12 is a schematic diagram of a water treatment system 700 according to Embodiment 7. As shown in FIG. 12, the control device 12 of the water treatment system 700 determines the peak value of the voltage output of the pulse power supply 34 based on the amount of nitrogen supplied to the treatment tank 4 or the current or voltage output signal sent from the pulse power supply 34. In this configuration, at least one of the repetition frequency and the pulse width is controlled.

The pulse power supply 34 is connected to the control device 12. The pulse power supply 34 outputs at least one of a voltage output signal and a current output signal of the pulse power supply 34 to the control device 12.

Further, the control device 12 receives the voltage output signal or the current output signal of the pulse power supply 34, determines whether the formation state of the discharge 35 is normal, and when the formation state of the discharge 35 is not normal, 34, at least one of the peak value, the repetition frequency, and the pulse width of the voltage output may be controlled.

The control device of the water treatment system according to Embodiment 7 is a power supply that applies a voltage to the discharge device, based on at least one of a voltage output signal and a current output signal, based on the power supply, the peak value of the voltage output, the repetition frequency, or It is characterized in that at least one of the pulse widths is controlled.

The control device for the water treatment system according to the seventh embodiment includes at least one of a peak value, a repetition frequency, and a pulse width of a voltage output of a power supply that applies a voltage to the discharge device based on the amount of nitrogen supplied to the treatment tank. Is controlled.

With the above configuration, the water treatment system 700 according to the seventh embodiment can stably form a discharge and perform highly efficient water treatment even when the nitrogen concentration in the treatment tank changes.

Embodiment 8 FIG.
The configuration of a water treatment system 800 according to Embodiment 8 of the present invention will be described. The description of the same or corresponding components as those in the first embodiment will be omitted, and only different components will be described.

FIG. 13 is a schematic diagram of a water treatment system 800 according to Embodiment 8. As shown in FIG. 13, the water treatment system 800 includes a treated water circulation unit 80 that supplies treated water 3 stored at the bottom of the treatment tank 4 from the water sprinkling unit 11 to the discharge space of the discharge device 30.

The water treatment system 800 includes a water circulation pipe 81 having one end connected to the vicinity of the bottom of the treatment tank 4 and the other end connected to the water sprinkling section 11. The water circulation pipe 81 is provided with a water circulation pump 82. The treated water circulation unit 80 is configured by a water circulation pipe 81 and a water circulation pump 82.

一端 One end of the water supply pipe 8 is connected near the bottom of the storage tank 2, and the other end of the water supply pipe 8 is connected near the bottom of the processing tank 4. The water supply pipe 8 is provided with a water supply pump 7.

In the water treatment system 800, the water to be treated 1 is supplied to the treatment tank 4 as the treated water 3 at a predetermined flow rate through the water supply pipe 8 by the operation of the water supply pump 7. The treated water 3 is supplied from the water sprinkling section 11 into the discharge space of the discharge device 30 via the water circulation pipe 81 by the operation of the water circulation pump 82. The treated water 3 stored at the bottom of the treatment tank 4 is discharged to the treated water tank 6 as treated water 5 at a predetermined flow rate by the operation of the drain pump 9.

When the concentration of the organic compound in the water to be treated 1 is high and when the water to be treated 1 contains a hardly decomposable substance, the water to be treated 1 is sufficiently treated only once through the discharge space of the discharge device 30. May not be. However, the water treatment system 800 according to the eighth embodiment operates the water circulation pump 82 to supply the treated water 3 from the water sprinkling section 11 to the discharge space of the discharge device 30 via the water circulation pipe 81. , And the treatment is repeated while circulating the treated water 3.

Since the water treatment system 800 repeatedly supplies the treated water 3 into the discharge space of the discharge device 30, the water treatment system 800 is effective even when the concentration of the organic compound in the treated water 1 is high and when it contains a hardly decomposable substance. Water treatment can be performed. In addition, since the water treatment system 800 repeatedly supplies the treated water 3 into the discharge space of the discharge device 30, the nitric acid, nitrogen dioxide, and nitrous oxide generated by the discharge device 30 are rapidly dissolved in the treated water 3. Thus, the responsiveness of the pH of the treated water 3 to a change in the nitrogen concentration in the treatment tank is improved. Therefore, the water treatment system 800 can maintain the pH of the treated water 3 close to the target pH, and can execute efficient water treatment.

The control device 12 controls the operation of the water circulation pump 82 in addition to the control of the operation of the water supply pump 7 and the drainage pump 9.
The flow rate at which the water supply pump 7 supplies the treated water 1 to the treatment tank 4, the flow rate at which the water circulation pump 82 supplies the treated water 3 to the sprinkling unit 11, and the drainage pump 9 stores the water at the bottom of the treatment tank 4. The flow rate at which the treated water 3 is discharged to the treatment water tank 6 means that the organic compound contained in the treatment water 3 is decomposed during a period until the water 1 to be treated is sent to the treatment tank 4 and discharged to the treatment water tank 6. This is the flow rate that can be processed.

The water treatment system according to Embodiment 8 is provided in a treatment tank that stores, as treated water, treated water that is alkaline wastewater supplied from upstream of the treatment tank, and a discharge device that forms a discharge; A sprinkler that supplies treated water into a discharge space, which is a space where a discharge is formed, a pH meter that measures the pH of treated water that is water to be treated that has passed through the discharge space, and a treatment tank. The apparatus includes a gas supply unit that supplies oxygen and nitrogen, and a control device that controls the gas supply unit based on pH to adjust the amount of nitrogen supplied into the processing tank.

With the above configuration, the water treatment system 800 according to Embodiment 8 can perform effective water treatment both when the concentration of the organic compound in the water to be treated 1 is high and when the water to be treated contains a hardly decomposable substance. . Further, since the responsiveness of the pH of the treated water to the change in the nitrogen concentration in the treatment tank is improved, the pH of the treated water is maintained close to the target pH, and efficient water treatment can be performed.

Within the scope of the present invention, it is possible to freely combine the embodiments, and to appropriately modify and omit the embodiments.

100, 200, 300, 400, 500, 600, 700, 800 water treatment system,
1 treated water, 2 storage tanks, 3 treated waters, 4 treated tanks, 5 treated waters, 6 treated water tanks,
7 water supply pump, 8 water supply pipe, 9 drainage pump, 10 drainage pipe, 11 water sprinkling section,
12 control device, 13 nitric acid removal unit,
20 gas supply unit, 21 oxygen supply port, 22 nitrogen supply port, 23 processing tank exhaust port,
24 flow controller, 25 oxygen supply unit, 26 nitrogen supply unit, 27 pH meter,
30 discharge device, 31 ground electrode, 32 high voltage electrode, 33 high voltage conductor, 34 pulse power supply,
35 discharge,
40 gas circulation part, 41 intake port, 42 diffuser part, 43 circulation pipe, 44 circulation pump,
51 carbonate ion concentration meter,
61 PSA oxygen generator,
71 aeration unit, 72 aeration pipe, 73 supply amount controller, 74 storage tank exhaust port,
80 treated water circulation section, 81 water circulation pipe, 82 water circulation pump,
1000 CPU, 1001 memory.

Claims

A discharge device that is provided in a treatment tank that stores treated water and forms a discharge,
A sprinkling unit that is provided in the treatment tank and supplies treated water that is alkaline wastewater into a discharge space that is a space where the discharge is formed,
A pH meter that measures the pH of the treated water that is the water to be treated that has passed through the discharge space;
A gas supply unit for supplying oxygen and nitrogen into the processing tank,
A controller that controls the gas supply unit based on the pH to adjust the amount of nitrogen supplied into the processing tank;
A water treatment system comprising:
A discharge device that is provided in the treatment tank that stores treated water that is alkaline wastewater supplied from upstream of the treatment tank as treated water, and forms a discharge,
A sprinkler that is provided in the treatment tank and supplies the treated water into a discharge space that is a space where the discharge is formed;
A pH meter that measures the pH of the treated water that is the water to be treated that has passed through the discharge space;
A gas supply unit for supplying oxygen and nitrogen into the processing tank,
A controller that controls the gas supply unit based on the pH to adjust the amount of nitrogen supplied into the processing tank;
A water treatment system comprising:
3. The water treatment system according to claim 1, further comprising a water circulation unit that sends the treated water stored in the treatment tank to the water sprinkling unit. 4.
4. The water treatment system according to claim 1, further comprising a gas circulation unit that sucks gas in the treatment tank and supplies the gas to the treatment water stored in the treatment tank. 5.
The gas supply unit includes an oxygen supply unit that supplies oxygen into the processing tank, and a nitrogen supply unit that supplies nitrogen into the processing tank.
5. The water according to claim 1, wherein the control device controls the nitrogen supply unit by an intermittent operation to adjust an amount of nitrogen supplied into the processing tank. 6. Processing system.
The water treatment system according to any one of claims 1 to 4, wherein the gas supply unit is an oxygen generator that separates oxygen from air.
7. The control device according to claim 1, wherein the controller adjusts an amount of nitrogen supplied into the processing tank so that a pH of the processing water becomes a predetermined value. 8. A water treatment system according to claim 1.
The controller increases the amount of nitrogen supplied by the gas supply unit when the pH exceeds a set value, and decreases the amount of nitrogen supplied by the gas supply unit when the pH is equal to or less than a set value. The water treatment system according to any one of claims 1 to 7, wherein:
A carbonate ion concentration meter that measures a carbonate ion concentration of the treated water stored in the treatment tank,
The controller increases the amount of nitrogen supplied by the gas supply unit when both the pH and the carbonate ion concentration exceed a set value, and at least one of the pH and the carbonate ion concentration is equal to or less than a set value. The water treatment system according to any one of claims 1 to 6, wherein an amount of nitrogen supplied by the gas supply unit is reduced in the case.
A discharge device that is provided in a treatment tank that stores treated water and forms a discharge,
A sprinkling unit that is provided in the treatment tank and supplies treated water that is alkaline wastewater into a discharge space that is a space where the discharge is formed,
A pH meter that measures the pH of the treated water that is the water to be treated that has passed through the discharge space;
A storage tank for storing the water to be treated,
A gas supply comprising: an oxygen supply unit that supplies oxygen into the treatment tank; and an aeration device that aerates the water to be treated stored in the storage tank using a part of the oxygen supplied by the oxygen supply unit. Unit and
A control device that controls the gas supply unit based on the pH to adjust the amount of oxygen supplied to the storage tank,
A water treatment system comprising:
The controller increases the flow rate of oxygen supplied by the oxygen supply unit to the aeration device when the pH is equal to or lower than a set value, and supplies the oxygen supply unit to the aeration device when the pH exceeds a set value. The water treatment system according to claim 10, wherein a flow rate of the generated oxygen is reduced.
The control device is a power supply for applying a voltage to the discharge device, based on at least one of a voltage output signal or a current output signal, the power supply, the peak value of the voltage output, at least one of the repetition frequency or pulse width. The water treatment system according to any one of claims 1 to 11, wherein the system is controlled.
The control device controls at least one of a peak value, a repetition frequency, and a pulse width of a voltage output of a power supply that applies a voltage to the discharge device, based on the amount of nitrogen supplied to the processing tank. The water treatment system according to any one of claims 1 to 9, wherein
The water treatment system according to any one of claims 1 to 13, further comprising a nitric acid removing unit disposed downstream of the treatment tank and configured to remove nitric acid from the treated water.
A gas supply unit that supplies oxygen and nitrogen into a processing tank that stores the processing water, and supplies oxygen into the processing tank.
A discharge device, forming a discharge;
A step of supplying the water to be treated, which is an alkaline wastewater, into a discharge space that is a space in which the discharge is formed,
A pH meter measures the pH of the treated water, which is the water to be treated that has passed through the discharge space,
A controller controls the gas supply unit based on the pH to supply nitrogen into the processing tank,
A water treatment method comprising: