JP2002166139A - Membrane separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separator that needs to be less frequently washed with chemicals and is therefore excellent in the ability to treat sewage and the ability to treat living organisms. SOLUTION: The nitrification/denitrification apparatus 10 has an ozone generator 56 that supplies ozone, and the generator 56 is connected to a treatment water tank 38 and to a circulation line 24. Therefore, when ozone is supplied to the treatment liquid 42 in the tank 38 to remove the colorant components from the effluent 42, and ozone is supplied to a treated liquid 20 circulating between the nitrification tank 16 and the denitrification tank 14 to inhibit a gel-like matter from adhering to the filter membrane of the unit 28. The tank 38 is connected to the unit 28 through a pour line 44, and the filter membrane is back-washed with the effluent 42 containing residual ozone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a membrane separation device,
In particular, it relates to a membrane separation device in a wastewater treatment facility using activated sludge treatment.

[0002]

2. Description of the Related Art In a wastewater treatment facility using activated sludge treatment, solid-liquid separation obstacles such as "bulking" and "sludge floating by actinomycetes" in a final sedimentation basin are very serious problems. As a solution to this problem,
The development of a membrane separation activated sludge method combining activated sludge treatment and membrane separation has been promoted. Since this method employs membrane filtration as a solid-liquid separation technique, it can prevent outflow of turbid matter in the processing solution, and can completely remove Escherichia coli, which is hygienic and highly transparent. It has the feature that a processing solution can be obtained stably. Further, since the activated sludge can be maintained at a high concentration, the processing time can be reduced and the processing facility can be made compact.

[0003]

However, the conventional membrane separation apparatus using the membrane separation activated sludge treatment has a serious problem that a chromaticity component remains in the treatment liquid and membrane clogging occurs. . In particular, when the properties of the sludge are poor (that is, the sludge has a fine floc and a large amount of biological metabolites, etc.), not only the chromaticity of the treatment liquid is increased, but also the membrane is easily clogged, Frequently, chemical cleaning of the membrane was required, causing further deterioration of sludge properties, and hindering stable operation.

Further, in the conventional membrane separation apparatus, since the solid-liquid separation means relies solely on the membrane, the hardly decomposable substances (biometabolites) which are hardly biodegraded are not discharged out of the system, but are accumulated in the tank. It suddenly adhered to the film surface and gelled, which was a major cause of increasing the differential pressure of the film.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a membrane separation apparatus which reduces the frequency of chemical cleaning and has excellent membrane treatment performance and biological treatment performance.

[0006]

According to the first aspect of the present invention, in order to achieve the above object, a treatment liquid is provided in a reaction tank, and a liquid to be treated supplied to the reaction tank is filtered through a membrane to obtain a treatment liquid. Filtration unit, backwash means for backwashing the membrane by backflowing the treatment liquid obtained in the filtration unit to the filtration unit,
A circulating means for circulating the liquid to be treated via a circulating line connected to the reaction tank; a liquid to be treated in the circulating line circulated by the circulating means; With the processing solution obtained in the unit,
Ozone supply means for supplying ozone is provided.

According to the first aspect of the present invention, ozone is supplied to the processing liquid obtained by the filtration unit, so that the chromaticity of the processing liquid can be removed, and the film is backwashed with the processing liquid. Therefore, a high cleaning effect of the film can be obtained. Further, since ozone is supplied to the liquid to be treated in the circulation line, it is possible to efficiently add ozone and suppress the gel-like substance from adhering to the film.

According to the second aspect of the present invention, the property of the liquid to be treated in the reaction tank is analyzed, and the amount of ozone supplied to the liquid to be treated in the circulation line is adjusted based on the result of the analysis. An amount of ozone can be supplied to the reactor.
Therefore, the clogging of the filtration membrane of the filtration unit can be effectively suppressed with a necessary minimum amount of ozone.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a membrane separation device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the entire configuration of a nitrification / denitrification apparatus 10 to which a membrane separation device according to the present invention is applied.

As shown in FIG. 1, a nitrification / denitrification device 10
Has a reaction tank partitioned by a partition wall 12 into a denitrification tank 14 and a nitrification tank 16. A supply line 18 is connected to the denitrification tank 14, and a liquid to be treated (raw liquid) 20 is supplied from the supply line 18 and stored in the denitrification tank 14. The denitrification tank 14 communicates with the nitrification tank 16 via a communication passage 22, and the liquid 20 to be treated supplied to the denitrification tank 14 flows into the nitrification tank 16 via the communication passage 22. The nitrification tank 16 is connected to the denitrification tank 14 via a circulation line 24. A pump 26 is provided in the circulation line 24. By driving the pump 26, a part of the liquid 20 to be treated in the nitrification tank 16 is returned to the denitrification tank 14 via the circulation line 24. This allows
The liquid to be treated 20 circulates between the nitrification tank 16 and the denitrification tank 14.

A filtration unit 28 is provided inside the nitrification tank 16.
A diffuser 30 is provided below the filtration unit 28.
Are arranged. The air diffuser 30 is provided with an air supply line 32.
When the air is supplied from the blower 34, the air is diffused into the liquid 20 to be treated as fine bubbles. As a result, the liquid 20 to be treated is agitated, and the deposits attached to the filtration membrane (not shown) of the filtration unit 28 can be peeled off. Further, oxygen is supplied to the activated sludge in the liquid 20 to be treated. can do.

The filtration unit 28 is connected to a treated water tank 38 via a discharge line 36. The discharge line 36 is provided with a valve 46 and a pump 40. By driving the pump 40, the liquid to be treated 20 is sucked into the filtration unit 28. At that time, the liquid 20 to be treated
The solid-liquid separation treatment is performed through a filtration membrane (not shown) of the filtration unit 28, and the treated treatment liquid 42 is discharged through a discharge line 36 and stored in a treatment water tank 38.

The treated water tank 38 is connected via an injection line 44 to a discharge line 36 upstream of a valve 46. The injection line 44 is provided with a valve 48 and a pump 50. By driving the pump 50, the processing liquid 42 in the processing water tank 38 flows back into the filtration unit 28. Thereby, the filtration membrane of the filtration unit 28 can be backwashed.

An ozone diffuser 5 is provided at the bottom of the treated water tank 38.
2 are provided. The ozone diffuser 52 is connected to an ozone generator 56 via an ozone supply line 54. Therefore, when ozone gas is supplied from the ozone generator 56 to the ozone supply line 54, the ozone diffuser 52
Then, the ozone gas is diffused into the processing liquid 42. Thus, the processing liquid 42 contains ozone.

The ozone generator 56 is connected to the circulation line 24 via an ozone supply line 58. Therefore, ozone gas can be supplied to the liquid to be treated 20 circulating from the nitrification tank 16 to the denitrification tank 14. As a result, the liquid to be treated 20 containing ozone circulates through the nitrification tank 16 and the denitrification tank 14.

Next, the operation of the nitrification / denitrification device 10 configured as described above will be described.

During normal operation, the valve 48 is closed and the valve 46 is opened, and the pump 40 is driven. by this,
The liquid to be treated 20 is biologically treated and the filtration unit 28
The suctioned processing liquid 42 flows into the processing water tank 38 via the discharge line 36. Ozone gas is supplied from an ozone generator 56 to the processing liquid 42 flowing into the processing water tank 38, and the chromaticity component of the processing liquid 42 is removed by the ozone gas. Therefore, the processing liquid 42 is drained from the drain pipe 60 in a state suitable for reuse.

During the normal operation, the liquid to be treated 20 is circulated in the nitrification tank 16 and the denitrification tank 14 by driving the pump 26 of the circulation line 24. At this time, since the ozone gas is supplied from the ozone generator 56 to the circulation line 24, the hardly decomposable substances (biological metabolites) contained in the circulating liquid to be treated 20 are reduced in molecular weight. Therefore, biological treatment can be promoted, and the attachment of the gel-like substance to the filtration membrane of the filtration unit 28 can be suppressed. The supply of the ozone gas to the circulation line 24 may be intermittent or continuous.

When the gel substance adheres to the filtration membrane of the filtration unit 28, the pump 40 is stopped to close the valve 46, and the valve 48 is opened to drive the pump 50. As a result, the processing liquid 42 in the processing water tank 38 is
Through the filter unit 28. Filtration unit 2
The treatment liquid 42 flowing back to 8 permeates the filtration membrane in the direction opposite to the filtration direction during normal operation, and peels off the gel-like substance attached to the filtration membrane from the filtration membrane. At this time, since ozone remains in the processing liquid 42, the filtration membrane is sterilized by the strong oxidizing power of ozone. Therefore, the washing effect of the filtration membrane is large, and a high membrane permeation flow rate can be obtained after washing.

As described above, according to the nitrification / denitrification apparatus 10 of the present embodiment, since ozone is supplied to the processing liquid 42, chromaticity can be removed and the effect of backwashing the filtration membrane can be increased. be able to.

According to the nitrification / denitrification apparatus 10, ozone is supplied to the circulation line 24, and the liquid to be treated 20 containing ozone is circulated through the nitrification tank 16 and the denitrification tank 14, so that the filtration unit 28 Blockage of the film can be suppressed. Therefore, the frequency of cleaning the filtration membrane with a chemical solution can be reduced, and the life of the filtration membrane can be improved.

Since ozone is supplied to the circulation line 24 through which a predetermined amount of the liquid to be treated 20 flows, ozone can be efficiently supplied to the denitrification tank 14 and the nitrification tank 16.
It is possible to prevent the ozone concentration in the denitrification tank 14 and the nitrification tank 16 from being biased.

Further, according to the nitrification / denitrification apparatus 10, ozone is supplied to the circulation line 24 by the ozone generator 56 which supplies ozone to the treated water tank 38, so that the apparatus is prevented from being enlarged. it can.

FIG. 2 is a schematic diagram showing the overall configuration of a nitrification / denitrification device 62 provided with an ozone gas injection amount adjusting means.

The nitrification / denitrification tank device 62 shown in FIG. 1 has an ozone supply line 58 provided with a solenoid valve 64. The opening and closing of the solenoid valve 64 is controlled by the controller 66.

The controller 66 controls the amount of ozone gas injected into the circulation line 24 by controlling the opening time of the solenoid valve 64.

The nitrification / denitrification device 62 has a property analyzer 68. The property analyzer 68 is connected to the nitrification tank 16 via a sludge inlet pipe 70 and a sludge return pipe 72, and collects a sludge sample from the nitrification tank 16 via the sludge inlet pipe 70. Then, the sludge sample is analyzed, and data on sludge properties such as TOC concentration and filtration specific resistance are acquired. Then, the sludge sample is returned to the nitrification tank 16 via the sludge return pipe 72.

The controller 66 includes a property analyzer 68
Controls the opening time of the solenoid valve 64, that is, the injection amount of ozone gas, based on the data acquired by the computer. For example, when the property analyzer 68 obtains the data of the TOC concentration, the controller 66
Controls the opening time of the solenoid valve 64 based on the curve shown in FIG. That is, as the TOC concentration of the liquid to be treated 20 is higher, the opening time of the solenoid valve 64 is set longer, and a larger amount of ozone gas is injected into the circulation line 24. T of liquid 20 to be treated
When the OC concentration is high, the filterability of the liquid to be treated 20 is poor, and the filtration membrane of the filtration unit 28 is easily clogged. Therefore,
Blockage of the filtration membrane can be effectively suppressed by increasing the amount of ozone gas injected. Conversely, the TO of the liquid 20 to be treated
When the C concentration is low, the liquid to be treated 20 has good filterability,
Since the filtration membrane is not easily blocked, the injection amount of ozone gas is reduced. Thereby, useless consumption of ozone gas can be suppressed.

As described above, according to the nitrification / denitrification device 62,
Since an appropriate amount of ozone gas is injected into the circulation line 24 according to the properties of the sludge in the nitrification tank 16, clogging of the filtration membrane can be effectively suppressed by a necessary minimum amount of ozone gas.

[0031]

As described above, according to the membrane separation apparatus of the present invention, since ozone is supplied to the processing liquid, the chromaticity of the processing liquid can be removed, and the film is reversed by the processing liquid. Since the cleaning is performed, a high cleaning effect of the film can be obtained. Further, since ozone is supplied to the circulating liquid to be processed, it is possible to suppress the gel-like substance from being attached to the film.
Therefore, the membrane separation device of the present invention can perform wastewater treatment efficiently and at low cost because the frequency of chemical cleaning of the membrane is low and the treatment performance and biological treatment performance of the membrane are excellent.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall configuration of a nitrification / denitrification apparatus to which a membrane separation device according to the present invention is applied.

FIG. 2 is a schematic diagram showing the overall configuration of a nitrification / denitrification device having an ozone gas injection amount adjusting means.

FIG. 3 is a diagram showing a control example based on TOC concentration;

[Explanation of symbols]

10: nitrification / denitrification equipment, 14: denitrification tank, 16: nitrification tank,
18 ... supply line, 20 ... liquid to be treated, 24 ... circulation line, 28 ... filtration unit, 30 ... diffuser tube, 36 ... discharge line, 38 ... treatment water tank, 42 ... treatment liquid, 44 ... injection line, 52 ... ozone dispersion Trachea, 54 ozone supply line, 5
6 ozone generator, 58 ozone supply line, 64 solenoid valve, 66 controller, 68 property analyzer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C02F 3/12 ZAB C02F 3/12 ZABS F-term (Reference) 4D006 GA02 HA93 KA02 KA31 KA63 KB22 KB23 KC03 KC13 KC16 KD21 PA02 PB08 PC62 PC64 4D028 AC03 AC09 BC17 BD00 BD08 BD17 CA00 CB03 CC06 4D050 AA12 AB03 BB02 BD08 CA09 CA17

Claims (2)

[Claims] 1. A filtration unit provided in a reaction tank, wherein a filtration target liquid supplied to the reaction tank is filtered through a membrane to obtain a processing liquid.
A backwash means for backflowing the treatment liquid obtained in the filtration unit to the filtration unit and backwashing the membrane; anda membrane separation device comprising: a circulating line connected to the reaction tank; Circulating means for circulating the liquid to be treated, ozone supplying means for supplying ozone to the liquid to be treated in the circulation line circulated by the circulating means, and the processing liquid obtained by the filtration unit. Characteristic membrane separation device. 2. An adjusting means for adjusting an amount of ozone to be supplied to the liquid to be treated in the circulation line by the ozone supply means; an analyzing means for analyzing the properties of the liquid to be treated in the reaction tank; The membrane separation device according to claim 1, further comprising: a control unit that controls the adjustment unit based on a result.