JPH11244877A - Sewage septic tank with built-in membrane separation vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the removal of ammoniacal nitrogen, nitrate nitrogen, etc., in addition to the decrease of BOD by providing a sewage septic tank having at least intermittent aerator with a membrane sepn. vessel separated from this intermittent aerator and providing the septic tank with an air diffusion pipe for applying air bubbles to the membrane in this membrane sepn. vessel from below the membrane at all times. SOLUTION: The sewage flowing in from an inflow port 9 is subjected to the removal of the extraneous matter and coarse solids, etc., in the sewage by an aeration type screen and is admitted into a flow rate regulation vessel 11. Next, the sewage is advected to a metering measure 13 and is subjected to flow rate regulation and thereafter, the small extraneous matter and coarse solids, etc., in the sewage are removed by a fine mesh screen 14 and is then admitted into the intermittent aerator 5. The sewage is mixed with the liquid mixture flowing in from the membrane sepn. vessel 6 therein to repeat aeration and agitation and the oxygen is supplied from the air diffusion pipe 3, etc., by which the decrease of the BOD in the raw water and the nitrification of the ammonia nitrogen and nitrate nitrogen are effected. The sewage flowing over to the membrane sepn. vessel 6 from the intermittent aerator 5 is subjected to permeation filtration with the membrane 1 and is released to the outside of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment tank, and more particularly to a sewage treatment tank with a built-in membrane separation tank having an intermittent aeration tank and a membrane separation tank used as a part of the sewage treatment process.

[0002]

2. Description of the Related Art A conventional sewage purifying tank will be described with reference to FIG. 4. A sewage purifying tank using a membrane 1 has a membrane 1 installed in a tank which continuously aerates (hereinafter referred to as an aeration tank 2). I have. The installation location of the membrane 1 is above the air diffuser 3, and aerobic biological treatment from the air diffuser and washing of the membrane are performed to prevent clogging of the membrane. Water flowing from the inflow port 4 is subjected to biochemical oxygen demand (hereinafter referred to as BOD) in the aeration tank.
) And the suspended substance (hereinafter referred to as SS) is filtered by the membrane.

[0003]

However, in the aeration tank 2, the BOD can be reduced, but the ammonia nitrogen,
Nitrate nitrogen and nitrite nitrogen cannot be removed.

[0004] In view of the above problems, the present invention provides a BO
An object of the present invention is to provide a sewage purification tank with a built-in membrane separation tank that removes ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, etc. in addition to reducing D, and obtains a stable treated water quality and an appropriate amount of discharged water. .

[0005]

The present invention, as shown in FIG. 1, is a sewage purification tank having at least an intermittent aeration tank 5, in which a membrane separation tank 6 separated from the intermittent aeration tank 5 is provided. In addition, an air diffuser 3 for constantly applying air bubbles from below the membrane 1 in the membrane separation tank 6 is provided.

In the present invention, the intermittent aeration tank 5 is used as the aeration tank to reduce BOD and to remove ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and the like. is there. However, if the aeration tank is simply changed to the intermittent aeration tank 5, it is possible to remove ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, etc., but when the aeration is stopped, cleaning of the membrane 1 is not possible. Since it becomes possible, the membrane 1 is clogged and an appropriate amount of discharged water cannot be obtained, or the membrane needs to be enlarged in order to obtain an appropriate amount of treated water. Therefore, in the present invention, the intermittent aeration tank 5 and the membrane separation tank 6 are further separated by a partition plate 7, and the air diffuser 3 is provided at the bottom of the membrane separation tank 6 to constantly send air.
This prevents clogging of the film 1 and eliminates the need to increase the size of the film 1.

[0007]

Next, an embodiment of the present invention will be described. In FIG. 1, reference numeral 5 denotes an intermittent aeration tank, and the intermittent aeration tank 5 and the membrane separation tank 6 are separated by a partition plate 7.
A diffuser 3 is provided at the bottom of the membrane separation tank 6 so that air is always sent. 8 is a submersible agitator, and 16 is a mixed liquid transfer pump.

The intermittent aeration tank 5 in the present invention has been used for a long time as one of the methods for purifying sewage, and the mechanism thereof will be described with reference to FIG. 1. In FIG. It flows into the intermittent aeration tank 5. The raw water is a primary treatment that has undergone a solid-liquid separation treatment or a secondary treatment water that has undergone a solid-liquid separation treatment and an aerobic biological treatment.

The raw water that has flowed into the tank is supplied to a membrane separation tank 6.
Mixed with the mixed liquid (sewage water that has undergone aerobic biological treatment), and aeration and agitation are repeated.
Oxygen (oxygen in the air) is supplied from a diffuser, diffuser 3, diffuser, etc. connected to a blower, air compressor, etc., at a position away from the center of the membrane, thereby reducing BOD in raw water, The nitrification of ammoniacal nitrogen and organic nitrogen is carried out, and at the time of stirring, a water flow is generated in the longitudinal direction by a submerged stirrer 8 installed near the bottom of the longitudinally central vertical section of the intermittent aeration tank, and the activity in the tank is increased. Sludge is sufficiently agitated, and nitrate nitrogen and nitrite nitrogen generated during aeration are denitrified and BOD is reduced.

Next, an example of the membrane separation tank 6 will be described. As shown in FIG. 1, raw water (tertiary treated water obtained by further performing aerobic biological treatment or filtration of primary treated water or secondary treated water) is applied to the membrane 1 as shown in FIG. To remove SS (suspended matter) contained in the raw water. The membrane 1 is installed above the air diffuser 3, and its surface is constantly cleaned by bubbles from the air diffuser 3 to prevent clogging.

The intermittent aeration tank and the separated membrane separation tank 6 used in the present invention are separated by partitioning the inside of the tank with a partition plate 7 as shown in FIG. 1, or the tank body as shown in FIG. Independently (intermittent aeration tank 5 and membrane separation tank 6 are independent),
It is connected by the advection tube 21.

Next, a more specific embodiment of the present invention will be described with reference to FIG. FIG. 3 shows an embodiment of the entire sewage purification tank incorporating the wastewater treatment apparatus of the present invention shown in FIG.

The sewage flowing from the inlet 9 is subjected to an aeration screen (not shown) to remove impurities and coarse solids in the sewage, and flows into the flow control tank 11. Note that the aerated screen may use a coarse screen instead.

The sewage flowing into the flow control tank is transferred to the measuring mass 13 by the flow control pump 12 and adjusted to the planned sewage amount. Then, the fine screen 14 removes small impurities and solids in the sewage. Thereafter, it flows into the intermittent aeration tank 5. The small contaminants and solids in the sewage removed by the fine screen are stored in the sludge storage tank 15.

The raw water flowing into the intermittent aeration tank 5 is mixed with the mixed solution flowing from the membrane separation tank 6 in the tank, and is repeatedly aerated and agitated. Oxygen is supplied from a diffuser, diffuser 3, diffuser, etc. connected to a blower, air compressor, etc., thereby reducing BOD in raw water and nitrifying ammoniacal nitrogen and organic nitrogen. Occasionally, a water flow is generated in the longitudinal direction by a submersible agitator 8 installed near the bottom of the longitudinally central vertical section of the intermittent aeration tank, and the activated sludge in the tank is sufficiently stirred, and the nitric acid generated during aeration is generated. The denitrification of nitrogen and nitrite nitrogen is performed, and the BOD is reduced.

The sewage flowing from the intermittent aeration tank 5 to the membrane separation tank 6 is permeated and filtered by the membrane 1, transferred to a disinfecting cylinder 17 by a pump (not shown), and discharged to a discharge pump tank 18 after disinfection. , And is discharged out of the system by operating the discharge pump 19. Here, the membrane separation tank 6 is constantly supplied with air by the air diffuser 3 and is washed by air bubbles. The mixed liquid in the membrane separation tank 6 is returned to the intermittent aeration tank by the mixed liquid transfer pump 16 or the like, and performs the above-described denitrification. Further, the sludge return pump 20 and the like are periodically operated to activate the sludge storage tank 1.
The returned sludge is transferred to 5, and the sludge concentration in the intermittent aeration tank is controlled.

[0017]

According to the present invention, there is provided a sewage purifying tank with a built-in membrane separation tank capable of obtaining a stable treatment performance and good discharge water quality. That is, in addition to the reduction of BOD, the removal of ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and the like is performed by the intermittent aeration tank, and the removal of SS is performed by the membrane separation tank. Further, by providing an air diffuser at the bottom of the membrane separation tank separated from the intermittent aeration tank and constantly sending air, it is possible to prevent clogging of the membrane and eliminate the need to increase the size of the membrane.

[Brief description of the drawings]

FIG. 1 is a partial schematic view of a sewage purification tank with a built-in membrane separation tank according to one embodiment of the present invention.

FIG. 2 is a partial schematic view of a sewage purification tank with a built-in membrane separation tank according to one embodiment of the present invention.

FIG. 3 is a schematic diagram of a wastewater treatment apparatus including an intermittent aeration tank and a membrane separation tank according to one embodiment of the present invention.

FIG. 4 is a partial schematic view of a sewage purification tank with a built-in membrane separation tank, which is an example of a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Membrane, 2 ... Aeration tank, 3 ... Aerator, 4 ... Inlet, 5 ...
Intermittent aeration tank, 6: membrane separation tank, 7: partition plate, 8: underwater stirrer, 9: inflow port, 11: flow control tank, 12: flow control pump, 13: measuring mass, 14: fine mesh screen, 1
5: Sludge storage tank, 16: Mixed liquid transfer pump, 17: Disinfection cylinder, 18: Discharge pump tank, 19: Discharge pump, 20: Sludge return pump, 21: Transfer pipe.

Continued on the front page (72) Inventor Satoshi Arai 1250 Shimoe-ren, Shimodate-shi, Ibaraki Pref.

Claims (3)

[Claims] 1. A sewage purifying tank having at least an intermittent aeration tank, comprising a membrane separation tank separate from the intermittent aeration tank, and an air diffuser pipe constantly blowing air bubbles from below the membrane in the membrane separation tank. A sewage treatment tank with a built-in membrane separation tank, which is provided with: 2. The sewage purification tank with a built-in membrane separation tank according to claim 1, wherein the membrane separation tank separated from the intermittent aeration tank is separated by partitioning the inside of the tank with a partition plate. 3. The sewage purification tank with built-in membrane separation tank according to claim 1, wherein the membrane separation tank separated from the intermittent aeration tank has a tank main body made independent.