JP2001219185A - Advanced water treatment apparatus and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ozone treatment efficiency by supplying ozone generated by an ozone generator using oxygen as a raw material to an ozone treatment tank, and to efficiently use an ozone exhaust gas to activate activated sludge. Provided is an advanced water treatment apparatus capable of improving the water quality and an operation method thereof. SOLUTION: In an advanced water treatment apparatus provided with an ozone treatment tank 13 using ozone generated by an ozone generator 15 using oxygen as a raw material in a later stage of the oxygen activated sludge treatment tank 11, the water discharged from the ozone treatment tank 13 is provided. Ozone treatment device 16 for decomposing ozone remaining in the ozone exhaust gas into oxygen
And a path 36 for supplying a gas derived from the waste ozone treatment device 16 to the oxygen activated sludge treatment tank 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an advanced water treatment apparatus and an operating method thereof, and more particularly to an apparatus for performing advanced treatment of sewage by combining an oxygen activated sludge treatment apparatus and an ozone treatment apparatus, and an apparatus therefor. Related to driving method.

[0002]

2. Description of the Related Art As an apparatus for treating urban sewage and industrial wastewater,
In recent years, after the wastewater treatment equipment by the standard activated sludge method,
An advanced wastewater treatment apparatus provided with an ozone treatment tank for decomposing and removing COD, sterilizing, deodorizing, and decoloring is increasingly used.

In a conventional general advanced treatment apparatus, a method of bubbling and supplying air to raw water is used as a standard activated sludge method. An ozone treatment tank for performing ozone treatment is provided with an ozone generator using oxygen as a raw material. A gas containing ozone (ozone-containing oxygen) generated by an (ozonizer) is supplied.

[0004]

Conventionally, toxic ozone in ozone exhaust gas discharged from an ozone treatment tank is decomposed into oxygen by a waste ozone treatment device and then released into the atmosphere. Did not use. This is because the pressure of the ozone exhaust gas is originally as low as about 1 kPa (gauge pressure, the same applies hereinafter), so the pressure of the oxygen generated by decomposition is also low. This does not raise the pressure to about 5 kPa using the above, and considering the power cost of the pump, it could not be said to be a very effective measure.

Accordingly, the present invention aims at improving ozone treatment efficiency by supplying ozone generated by an ozone generator using oxygen as a raw material to an ozone treatment tank, and efficiently utilizing ozone exhaust gas to improve activated sludge treatment efficiency. It is an object of the present invention to provide an advanced water treatment apparatus that can be improved and an operation method thereof.

[0006]

In order to achieve the above object, an advanced water treatment apparatus according to the present invention uses an ozone using ozone generated by an ozone generator using oxygen as a raw material in a stage subsequent to an oxygen activated sludge treatment tank. In an advanced water treatment apparatus provided with a treatment tank, an exhaust ozone treatment apparatus that decomposes residual ozone in ozone exhaust gas discharged from the ozone treatment tank into oxygen, and a gas derived from the exhaust ozone treatment apparatus is used as the oxygen activated sludge. A path for supplying to the processing tank is provided.

In order to achieve the above object, the method for operating an advanced water treatment apparatus according to the present invention comprises an oxygen activated sludge treatment tank, an ozone treatment tank using ozone generated by an ozone generator using oxygen as a raw material, An oxygen supply device that supplies oxygen to the activated sludge treatment tank, an exhaust ozone treatment device that decomposes residual ozone in the ozone exhaust gas discharged from the ozone treatment tank into oxygen, and a gas derived from the exhaust ozone treatment device, A method for operating an advanced water treatment apparatus comprising a path for supplying to an activated sludge treatment tank, wherein the supply of oxygen to the oxygen-activated sludge treatment tank is more ozone-treated than the supply of oxygen from the oxygen supply device. It is characterized in that the supply of gas from a tank through an exhaust ozone treatment device is preferentially performed.

The method of operating an advanced water treatment apparatus according to the present invention is characterized in that the amount of exhaust gas is adjusted so that the oxygen concentration in the exhaust gas discharged from the oxygen activated sludge treatment tank becomes a predetermined value, and the oxygen activity is controlled. In adjusting the supply amount of the gas passing through the waste ozone treatment device and the supply amount of oxygen from the oxygen supply device so that the pressure in the sludge treatment tank becomes a predetermined value, the gas passing through the waste ozone treatment device is adjusted. The supply of oxygen from the oxygen supply device is started after the supply amount reaches the maximum amount.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system diagram showing an embodiment of an advanced water treatment apparatus according to the present invention, and FIG. The advanced water treatment apparatus includes an oxygen activated sludge treatment tank 11 for performing activated sludge treatment of raw water under an oxygen atmosphere near normal pressure,
A sedimentation tank 12 for separating the sludge by performing a sedimentation treatment of the treated water in the oxygen-activated sludge treatment tank 11, and a decomposition, sterilization, deodorization, and the like of organic substances remaining in the treated water by strong oxidizing power of ozone;
An ozone treatment tank 13 for performing ozone treatment such as decolorization, and an oxygen supply device for supplying oxygen used in the oxygen activated sludge treatment tank 11 and oxygen used as an ozone raw material, for example, a pressure fluctuation type oxygen generator (oxygen PSA) 14 And the oxygen PSA14
An ozone generator 15 that generates ozone using the oxygen generated in the above as a raw material, and an exhaust ozone treatment device 16 filled with an ozone decomposing agent for decomposing ozone in the ozone exhaust gas discharged from the ozone treatment tank 13 into oxygen. Have.

[0010] Raw water flowing into the advanced treatment apparatus from the first sedimentation basin or the like flows into the oxygen activated sludge treatment tank 11 from the path 21 and is subjected to the activated sludge treatment under a high-concentration oxygen atmosphere to produce BOD, which is an organic pollutant in the raw water. Is decomposed and removed. The treated water treated in the oxygen-activated sludge treatment tank 11 flows into the sedimentation tank 12 through the path 22 and sedimentation and separation of sludge are performed. Part of the sludge settled in the sedimentation tank 12 is withdrawn from the passage 23 as surplus sludge, and the remainder is returned to the oxygen activated sludge treatment tank 11 from the path 24 as return sludge. The treated water in the sedimentation tank 12 flows into the ozone treatment tank 13 from the path 25, and after being subjected to the above-described ozone treatment including COD removal, flows out through the path 26.

On the other hand, the oxygen generated by the oxygen PSA 14, for example, oxygen having a purity of about 93% (other components are mainly argon and nitrogen) is branched into a path 31 and a path 32, and the oxygen in the path 31 is subjected to the oxygen activated sludge treatment. The gas is supplied to the tank 11 as an atmospheric gas, and the oxygen in the path 32 is supplied to the ozone generator 15 as an ozone raw material. Ozone generator 1
Oxygen containing ozone generated in 5, for example, 5 to 10% by volume
The oxygen containing ozone passes through the path 33 and passes through the ozone treatment tank 1
3 is supplied.

The exhaust gas discharged from the oxygen activated sludge treatment tank 11 is discharged to the atmosphere through a passage 34, and the ozone exhaust gas discharged from the ozone treatment tank 13 is discharged to a passage 35.
Through the exhaust ozone treatment device 16. The gas after the residual ozone in the ozone exhaust gas is decomposed into oxygen by the waste ozone treatment device 16 is supplied to the oxygen activated sludge treatment tank 11 through a path 36.

On the other hand, as shown in FIG. 2, the oxygen activated sludge treatment tank 11 generally has a plurality of partitions 40a, 40b inside.
And a closed space partitioned into a plurality of stages 41, 42, and 43. In each stage, an underwater blade 44a for stirring a mixed solution of raw water and activated sludge, and a liquid surface portion for stirring are provided. The aerator 44 is provided with stirring blades 44b for promoting gas-liquid contact between the liquid phase part and the gas phase part.

In the first stage 41, the path 21 into which raw water flows, the path 31 to which oxygen generated by the oxygen PSA 14 is supplied, and the gas derived from the ozone treatment apparatus 16 are supplied. A path 36 and a pressure controller 45 for measuring the pressure in the oxygen activated sludge treatment tank 11
The third stage 43, which is the final stage, is provided with the path 22 through which the treated water flows out and the path 34 through which the gas in the oxygen activated sludge treatment tank 11 is discharged. An oximeter 46 for measuring the oxygen concentration in the exhaust gas discharged through the passage 34 is provided.

The raw water from the path 21 flows into a first stage 41, and after predetermined processing is sequentially performed in a second stage 42 and a third stage (final stage) 43, the raw water flows from the third stage 43 to the path 22. Leaked to Further, oxygen for converting the gas phase atmosphere in the tank into an oxygen-enriched state also flows into the first stage 41 from the paths 31 and 36, and is discharged to the path 34 via the second stage 42 and the third stage 43. Is done.

The pressure of the gas phase of the oxygen-activated sludge treatment tank 11 having the closed type and having the aerator 44 is usually 49.
0 to 980 Pa, and the exhaust ozone treatment device 1
6 normally has a pressure of about 1 kPa, so that the gas from the waste ozone treatment device 16 can be supplied to the oxygen activated sludge treatment tank 11 without increasing the pressure. The pump or the like need not be provided.

Further, the composition of the ozone exhaust gas flowing from the ozone treatment tank 13 into the waste ozone treatment apparatus 16 is several percent, since the efficiency of use of ozone in the ozone treatment tank 13 is generally about 40%. Since it is oxygen containing residual ozone and also contains argon and nitrogen, most of the composition of the gas discharged from the waste ozone treatment device 16 after the ozone decomposition treatment is oxygen.

Accordingly, the activated sludge treatment equipment provided in the preceding stage of the ozone treatment tank 13 is replaced with a closed type oxygen activated sludge method from a conventional open type activated sludge method and is discharged from a waste ozone treatment device 16. By supplying a gas containing a large amount of oxygen to the oxygen activated sludge treatment tank 11 through the passage 36, the oxygen in the gas can be effectively used as oxygen used in the oxygen activated sludge treatment.
Moreover, since the amount of oxygen supplied from the oxygen PSA 14 to the oxygen activated sludge treatment tank 11 can be reduced, the size of an oxygen supply device such as the oxygen PSA 14 laid in the oxygen activated sludge method and the running cost can be reduced. be able to.

The oxygen concentration meter 46 is for maintaining the oxygen concentration in the oxygen activated sludge treatment tank 11 at a predetermined concentration by adjusting the amount of gas discharged from the oxygen activated sludge treatment tank 11. For example, when the reference value of the oxygen concentration in the exhaust gas is 40% by volume, the detected oxygen concentration is 4%.
When the volume became less than 0% by volume, the flow control valve 51 provided in the passage 34 was operated in the opening direction to discharge more gas having a low oxygen concentration, and the oxygen concentration in the exhaust gas exceeded 40% by volume. At times, the flow control valve 51 is operated in the closing direction to prevent the gas having a high oxygen concentration from being discharged. Thereby, the oxygen concentration of the gas phase in the oxygen activated sludge treatment tank 11 can be maintained at a predetermined concentration. In addition,
The oxygen concentration meter 46 is not provided in the path 34 and the third stage 4
3 can be provided in the vicinity of the exhaust gas outlet. As described above, in order to keep the oxygen concentration in the oxygen-activated sludge treatment tank 11 constant, the amount of gas discharged from the treatment tank varies, whereby the flow rate of oxygen introduced into the treatment tank varies.

The pressure controller 45 is connected to the path 3
This is for adjusting the amount of oxygen supplied from 1, 36 to the oxygen activated sludge treatment tank 11, and the amount of oxygen consumed by the activated sludge increases, and the amount of exhaust gas from the passage 34 increases. When the pressure in the tank decreases, the flow control valves 52 and 53 provided in the paths 31 and 36 are operated in the opening direction to increase the oxygen supply amount, and when the pressure in the tank increases, the flow control valves 52 and 53 increase.
53 is actuated in the closing direction to reduce the oxygen supply. For example, when the reference value of the pressure in the tank is 700 Pa, when the detected pressure becomes less than 700 Pa, the oxygen supply amount is increased,
If it exceeds 700 Pa, the oxygen supply amount is reduced.

When the oxygen supply amount is increased or decreased, the oxygen supplied from the passage 36, that is, the gas after the residual ozone in the ozone exhaust gas is decomposed into oxygen by the waste ozone treatment device 16 is preferentially used. By setting to supply the oxygen PSA, the amount of oxygen supplied from the oxygen PSA 14 can be reduced, so that the oxygen PSA 14 can be further downsized.

As a method of preferentially supplying the oxygen from the passage 36, the entire amount of the gas from the waste ozone treatment device 16 is supplied into the oxygen activated sludge treatment tank 11 without providing a valve or the like in the passage 36, A method of supplying only the shortage from the oxygen PSA 14 by the operation of the pressure controller 45 and the flow control valve 52 can be adopted.

As described above, the flow control valves 52 and 53 are provided in the paths 31 and 36, respectively. When the detected pressure of the pressure controller 45 decreases, the flow control valves 53 of the path 36 are first opened in the opening direction. When the flow control valve 53 is fully opened, the flow control valve 52 of the path 31 is operated in the opening direction, and when the detected pressure of the pressure controller 45 increases, the flow rate of the flow The control valve 52 may be operated in the closing direction, and the flow control valve 53 of the path 36 may be operated in the closing direction after the flow control valve 52 is fully closed. By setting like this,
The oxygen concentration in the oxygen activated sludge treatment tank 11 can be maintained in a certain range, and the oxygen activated sludge treatment can be performed in a stable state.

In this case, a pressure control valve (not shown) for releasing the air for adjusting the pressure in the passage 36 to a set value or less is provided in the passage 36, and the flow control valve 53 is throttled. When the gas flow rate is reduced, the excess is released from the pressure control valve to the outside, so that a pressure increase in the passage 36 can be prevented.

The oxygen supply device is not limited to the oxygen PSA, but may use an oxygen generating means such as a membrane air separation device or a cryogenic air separation device. It is also possible to use a gasified liquefied oxygen that is supplied. Furthermore, the supply to the oxygen activated sludge treatment tank and the supply to the ozone raw material can be separately provided.

[0026]

As described above, according to the present invention,
Oxygen in the gas discharged from the ozone treatment tank and treated by the waste ozone treatment device can be effectively used as the atmospheric gas in the oxygen activated sludge treatment tank, so that the size of the oxygen supply device such as oxygen PSA can be reduced. And running costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of an advanced water treatment apparatus of the present invention.

FIG. 2 is a system diagram of the main part.

[Explanation of symbols]

11: oxygen activated sludge treatment tank, 12: sedimentation tank, 13: ozone treatment tank, 14: oxygen PSA, 15: ozone generator,
16 ... waste ozone treatment device, 40a, 40b ... partition walls, 4
1, 42, 43 ... stage, 44 ... aerator, 45 ...
Pressure controller, 46: oxygen concentration meter, 51, 52, 53: flow control valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 520 C02F 1/50 520P 531 531R 540 540A 550 550B 550D 560 560H 1/78 1/78

Claims (3)

[Claims] In an advanced water treatment apparatus provided with an ozone treatment tank using ozone generated by an ozone generator using oxygen as a raw material, an ozone discharged from the ozone treatment tank is provided at a stage subsequent to the oxygen activated sludge treatment tank. An advanced water treatment apparatus comprising: an exhaust ozone treatment device for decomposing ozone remaining in exhaust gas into oxygen; and a path for supplying gas derived from the exhaust ozone treatment device to the oxygen activated sludge treatment tank. 2. An oxygen activated sludge treatment tank, an ozone treatment tank using ozone generated by an ozone generator using oxygen as a raw material, an oxygen supply device for supplying oxygen to the oxygen activated sludge treatment tank, and an ozone treatment tank Of an advanced water treatment apparatus comprising: an exhaust ozone treatment device that decomposes residual ozone in ozone exhaust gas discharged from oxygen into oxygen; and a path for supplying gas derived from the exhaust ozone treatment device to the oxygen activated sludge treatment tank. An operation method, wherein supply of oxygen to the oxygen-activated sludge treatment tank is performed by giving priority to supply of gas from the ozone treatment tank through the waste ozone treatment apparatus to supply of oxygen from the oxygen supply apparatus. A method for operating an advanced water treatment apparatus, comprising: 3. The amount of exhaust gas is adjusted so that the oxygen concentration in the exhaust gas discharged from the oxygen activated sludge treatment tank has a predetermined value, and the pressure in the oxygen activated sludge treatment tank has a predetermined value. In adjusting the supply amount of gas passing through the exhaust ozone treatment device and the supply amount of oxygen from the oxygen supply device, the supply amount of gas passing through the exhaust ozone treatment device becomes The method for operating an advanced water treatment apparatus according to claim 2, wherein the supply of oxygen from the supply apparatus is started.