JP3832232B2 - Membrane separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane separation device, and more particularly to a membrane separation device in a wastewater treatment facility using activated sludge treatment.
[0002]
[Prior art]
In wastewater treatment facilities using activated sludge treatment, solid-liquid separation problems such as “bulking” and “sludge floating by actinomycetes” in the final sedimentation basin have become very serious problems. As a means for solving this problem, development of a membrane separation activated sludge method combining activated sludge treatment and membrane separation is in progress. Since this method employs membrane filtration as a solid-liquid separation technique, it can prevent the turbidity of the processing liquid from flowing out and can completely remove E. coli, so it is hygienic and highly transparent. It has the characteristic that a processing liquid can be obtained stably. In addition, since the activated sludge can be kept at a high concentration, the processing time can be shortened and the processing facility can be made compact.
[0003]
[Problems to be solved by the invention]
However, the conventional membrane separation apparatus using the membrane separation activated sludge treatment has a big problem that the chromaticity component remains in the treatment liquid or the membrane is clogged. In particular, when the sludge has poor properties (that is, sludge flocs are fine, biological metabolites are very large, etc.), not only the chromaticity of the treatment liquid becomes high, but the membrane is likely to be clogged. Frequent cleaning of the membrane with chemicals was required, causing further deterioration of sludge properties and hindering stable operation.
[0004]
In addition, since conventional membrane separation devices rely only on membranes for solid-liquid separation means, hardly degradable substances (biological metabolites) that are difficult to biodegrade are not discharged out of the system, but accumulated in the tank. It adhered to the surface and gelled, which was a major cause of increasing the differential pressure of the film.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a membrane separation device that reduces the frequency of chemical cleaning and has excellent membrane treatment performance and biological treatment performance.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 is provided in a reaction tank, and a filtration unit that obtains a treatment liquid by filtering the liquid to be treated supplied to the reaction tank through a membrane, and obtained by the filtration unit. And backwashing means for backwashing the membrane by causing the treated liquid to flow back to the filtration unit, and circulating the liquid to be treated through a circulation line connected to the reaction vessel. An ozone supply means for supplying ozone to the circulation means to be circulated, the liquid to be treated in the circulation line circulated by the circulation means, and the treatment liquid obtained by the filtration unit, the ozone supply means being the circulation An adjusting means for adjusting the amount of ozone supplied to the liquid to be treated in the line, a sludge sample collected from the reaction tank, a TOC concentration is measured to obtain data, and the adjusting means is controlled based on the data Control means , Comprising the.
[0007]
According to the invention described in claim 1, since ozone is supplied to the treatment liquid obtained by the filtration unit, the chromaticity of the treatment liquid can be removed and the film is backwashed with the treatment liquid. In addition, since ozone is supplied to the liquid to be treated in the circulation line, it is possible to efficiently add ozone and prevent the gel substance from adhering to the film.
[0008]
According to the first 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 analysis result. Can be fed to the reaction vessel. Therefore, the filtration membrane of the filtration unit can be effectively suppressed with the minimum amount of ozone.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a membrane separation apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0010]
FIG. 1 is a schematic diagram showing the overall configuration of a nitrification / denitrification apparatus 10 to which a membrane separation apparatus according to the present invention is applied.
[0011]
As shown in FIG. 1, the nitrification / denitrification apparatus 10 includes a reaction tank partitioned by a partition wall 12 into a denitrification tank 14 and a nitrification tank 16. Among them, a supply line 18 is connected to the denitrification tank 14, and a liquid to be treated (raw solution) 20 is supplied from the supply line 18 and stored in the denitrification tank 14. The denitrification tank 14 is communicated with the nitrification tank 16 via a communication path 22, and the liquid 20 to be treated supplied to the denitrification tank 14 flows into the nitrification tank 16 via the communication path 22. Further, the nitrification tank 16 is connected to the denitrification tank 14 via a circulation line 24. The circulation line 24 is provided with a pump 26, and 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. Thereby, the liquid 20 to be treated circulates between the nitrification tank 16 and the denitrification tank 14.
[0012]
A filtration unit 28 is provided inside the nitrification tank 16, and an air diffuser 30 is disposed below the filtration unit 28. The air diffuser 30 is connected to a blower 34 via an air supply line 32. When air is supplied from the blower 34, the air is diffused as fine bubbles in the liquid 20 to be treated. Thereby, while the to-be-processed liquid 20 is stirred, the deposit | attachment adhering to the filtration membrane (not shown) of the filtration unit 28 can be peeled, and also oxygen is supplied to the activated sludge in the to-be-processed liquid 20 can do.
[0013]
The filtration unit 28 communicates with the treated water tank 38 via the discharge line 36. The discharge line 36 is provided with a valve 46 and a pump 40. By driving the pump 40, the liquid 20 to be treated is sucked into the filtration unit 28. At that time, the liquid 20 to be treated passes through a filtration membrane (not shown) of the filtration unit 28 and is subjected to a solid-liquid separation process, and the treated liquid 42 is discharged via the discharge line 36 and stored in the treated water tank 38. Is done.
[0014]
The treated water tank 38 is connected to the discharge line 36 on the upstream side of the valve 46 via the injection line 44. The injection line 44 is provided with a valve 48 and a pump 50. When the pump 50 is driven, the treatment liquid 42 in the treatment water tank 38 flows back into the filtration unit 28. Thereby, the filtration membrane of the filtration unit 28 can be backwashed.
[0015]
An ozone diffusing tube 52 is disposed at the bottom of the treated water tank 38. The ozone diffusing pipe 52 communicates with an ozone generator 56 through an ozone supply line 54. Accordingly, when ozone gas is supplied from the ozone generator 56 to the ozone supply line 54, the ozone gas is diffused into the treatment liquid 42 from the ozone diffuser tube 52. Thereby, the processing liquid 42 contains ozone.
[0016]
The ozone generator 56 is connected to the circulation line 24 through an ozone supply line 58. Therefore, ozone gas can be supplied to the liquid 20 to be treated that circulates from the nitrification tank 16 to the denitrification tank 14. Thereby, the to-be-processed liquid 20 containing ozone circulates through the nitrification tank 16 and the denitrification tank 14.
[0017]
Next, the operation of the nitrification / denitrification apparatus 10 configured as described above will be described.
[0018]
During normal operation, the valve 48 is closed and the valve 46 is opened, and the pump 40 is driven. As a result, the liquid 20 to be treated is biologically processed and sucked into the filtration unit 28, and the sucked processing liquid 42 flows into the treated water tank 38 through the discharge line 36. Ozone gas is supplied from the ozone generator 56 to the treatment liquid 42 flowing into the treatment water tank 38, and the chromaticity component of the treatment liquid 42 is removed by the ozone gas. Therefore, the treatment liquid 42 is drained from the drain pipe 60 in a state suitable for reuse.
[0019]
Further, the liquid to be treated 20 is circulated through the nitrification tank 16 and the denitrification tank 14 by driving the pump 26 of the circulation line 24 during normal operation. At this time, since ozone gas is supplied from the ozone generator 56 to the circulation line 24, the hardly decomposable substance (biological metabolite) contained in the circulating liquid 20 is reduced in molecular weight. Therefore, biological treatment can be promoted, and adhesion of the gel substance to the filtration membrane of the filtration unit 28 can be suppressed. The supply of ozone gas to the circulation line 24 may be intermittent or continuous.
[0020]
When the gel substance adheres to the filtration membrane of the filtration unit 28, the pump 40 is stopped and the valve 46 is closed, and the valve 48 is opened and the pump 50 is driven. As a result, the treatment liquid 42 in the treatment water tank 38 flows back to the filtration unit 28 via the injection line 44. The treatment liquid 42 that has flowed back to the filtration unit 28 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 treatment liquid 42, the filtration membrane is sterilized by the strong oxidizing power of ozone. Therefore, the cleaning effect of the filtration membrane is large, and a high membrane permeation flow rate can be obtained after cleaning.
[0021]
Thus, according to the nitrification / denitrification apparatus 10 of the present embodiment, ozone is supplied to the treatment liquid 42, so that chromaticity can be removed and the backwashing effect of the filtration membrane can be increased. .
[0022]
Further, according to the nitrification / denitrification apparatus 10, ozone is supplied to the circulation line 24, and the treatment liquid 20 containing ozone is circulated through the nitrification tank 16 and the denitrification tank 14. Blockage can be suppressed. Therefore, the frequency with which the filtration membrane is chemically washed can be reduced, and the lifetime of the filtration membrane can be improved.
[0023]
Further, since ozone is supplied to the circulation line 24 through which a predetermined amount of the liquid 20 to be treated always flows, ozone can be efficiently supplied to the denitrification tank 14 and the nitrification tank 16, and the ozone concentration inside the denitrification tank 14 and the nitrification tank 16 Can be prevented from being biased.
[0024]
Furthermore, according to the nitrification / denitrification apparatus 10, since ozone is supplied to the circulation line 24 by the ozone generator 56 that supplies ozone to the treated water tank 38, it is possible to prevent the apparatus from becoming large.
[0025]
FIG. 2 is a schematic diagram showing the overall configuration of a nitrification / denitrification apparatus 62 provided with ozone gas injection amount adjusting means.
[0026]
In the nitrification / denitrification tank device 62 shown in the figure, an electromagnetic valve 64 is disposed in an ozone supply line 58. The electromagnetic valve 64 is controlled to be opened and closed by a controller 66.
[0027]
The controller 66 adjusts the amount of ozone gas injected into the circulation line 24 by controlling the opening time of the electromagnetic valve 64.
[0028]
The nitrification / denitrification device 62 includes a property analysis device 68. The property analyzer 68 communicates with 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, after analyzing the sludge sample and acquiring data on sludge properties such as TOC concentration and filtration specific resistance, the sludge sample is returned to the nitrification tank 16 via the sludge return pipe 72.
[0029]
The controller 66 controls the opening time of the electromagnetic valve 64, that is, the injection amount of ozone gas, based on the data acquired by the property analyzer 68. For example, when the property analyzer 68 obtains TOC concentration data, the controller 66 controls the opening time of the electromagnetic valve 64 based on the curve shown in FIG. That is, the higher the TOC concentration of the liquid to be treated 20 is, the longer the opening time of the electromagnetic valve 64 is set, and a larger amount of ozone gas is injected into the circulation line 24. When the TOC concentration of the liquid to be treated 20 is high, the filterability of the liquid to be treated 20 is poor and the filtration membrane of the filtration unit 28 is likely to be blocked. Therefore, the filtration membrane can be effectively blocked by increasing the amount of ozone gas injected. Conversely, when the TOC concentration of the liquid to be treated 20 is low, the liquid to be treated 20 has good filterability and the filtration membrane is not easily clogged, thereby reducing the amount of ozone gas injected. Thereby, useless consumption of ozone gas can be suppressed.
[0030]
As described above, according to the nitrification / denitrification apparatus 62, an appropriate amount of ozone gas is injected into the circulation line 24 according to the property of the sludge in the nitrification tank 16, so that the filtration membrane is effectively blocked by the minimum amount of ozone gas. Can be suppressed.
[0031]
【The invention's effect】
As described above, according to the membrane separation apparatus according to the present invention, since ozone is supplied to the treatment liquid, the chromaticity of the treatment liquid can be removed, and the membrane is backwashed with the treatment liquid. In addition, since ozone is supplied to the circulating liquid to be treated, it is possible to suppress adhesion of a gel substance to the film. Therefore, the membrane separation apparatus of the present invention has a low chemical cleaning frequency of the membrane and is excellent in membrane treatment performance and biological treatment performance, so that wastewater treatment can be performed efficiently and at low cost.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a nitrification / denitrification apparatus to which a membrane separation apparatus according to the present invention is applied. FIG. 2 is a schematic diagram showing an overall configuration of a nitrification / denitrification apparatus having an ozone gas injection amount adjusting means. FIG. 3 is a diagram showing an example of control by TOC concentration.
DESCRIPTION OF SYMBOLS 10 ... Nitrification / denitrification apparatus, 14 ... Denitrification tank, 16 ... Nitrification tank, 18 ... Supply line, 20 ... Liquid to be processed, 24 ... Circulation line, 28 ... Filtration unit, 30 ... Air diffuser, 36 ... Discharge line, 38 ... treatment tank, 42 ... treatment liquid, 44 ... injection line, 52 ... ozone diffuser, 54 ... ozone supply line, 56 ... ozone generator, 58 ... ozone supply line, 64 ... solenoid valve, 66 ... controller, 68 ... Property analyzer

Claims (1)

A filtration unit that is provided in a reaction tank and obtains a treatment liquid by filtering the liquid to be treated supplied to the reaction tank through a membrane;
Backwashing means for backwashing the membrane by allowing the treatment liquid obtained by the filtration unit to flow back to the filtration unit,
A circulation means for circulating the liquid to be treated through a circulation line connected to the reaction tank; a liquid to be treated in the circulation line circulated by the circulation means; a treatment liquid obtained by the filtration unit; And an ozone supply means for supplying ozone ,
Adjusting means for adjusting the amount of ozone supplied by the ozone supply means to the liquid to be treated in the circulation line;
A control means for collecting a sludge sample from the reaction tank and measuring the TOC concentration to obtain data, and controlling the adjusting means based on the data;
Membrane separation apparatus characterized by comprising a.

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