JP2000218286A - Membrane septic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently clean the surface of a membrane even with less aeration in a membrane septic tank provided with an aeration tank contg. plural membrane elements by mixing many carriers each capable of carrying a microorganism with the diameter smaller than the interval between the adjacent elements in the aeration tank. SOLUTION: Night soil and domestic waste water 4 (raw water) are introduced into a membrane septic tank 1 from an inlet 5, passed through a filter medium 23 and a foreign matter removing tank 24 to remove the foreign matter and then sent to an aeration tank 7 by a transfer pump 6. Plural membrane elements 12 are dipped in the raw water 4 in the aeration tank 7, the raw water 4 is filtered by a biological membrane 14 depositing on the membrane face 13, and the filtered water 15 in the membrane is sucked out by a suction pump 16. In this case, carriers 21 previously mixed in the aeration tank 7 are agitated by the circulation of the raw water 4 in the aeration tank 7 and brought into contact with the membrane face 13 to release the clogging of the membrane due to suction filtration, and the membrane 14 is cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a membrane treatment type septic tank.

[0002]

2. Description of the Related Art Conventionally, in a membrane treatment type septic tank, aeration is performed from a diffuser pipe provided at a lower portion of an aeration tank to prevent clogging of the membrane due to suction filtration by a membrane element. Suction is performed while cleaning the biofilm attached to the surface.

[0003]

However, in the above-mentioned conventional technology, it is necessary to increase the amount of aeration for cleaning the surface of the membrane, which is more than the amount of aeration necessary for supplying oxygen necessary for ordinary biological treatment. Since the blower for aeration is large in size, there is a problem that a large power load is required for the operation.

[0004] In addition, overaeration is caused by supply of oxygen in an amount more than necessary for biological treatment, and a large amount of nitrogen oxides is generated by the biological treatment reaction in the aeration tank, and acidification in the tank proceeds. Affected.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a membrane treatment type septic tank that can efficiently perform membrane surface cleaning even with a small amount of aeration.

[0006]

In order to achieve the above object, a membrane treatment type septic tank according to the present invention has a membrane provided with an aeration tank in which a plurality of membrane elements for solid-liquid separation are arranged. The treatment type septic tank is characterized in that a large number of carriers capable of supporting microorganisms with a diameter smaller than the distance between adjacent membrane elements are mixed in the aeration tank. In this case, the carrier moves in the aeration tank by circulating by aeration and comes into contact with the membrane surface to clean the membrane surface.

It is preferable that the carrier is formed of a flexible foam. In this case, the contact between the carrier and the membrane surface is performed softly, and the microorganisms easily live in the carrier.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first or second embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an embodiment corresponding to FIG. FIG.
FIG. 1 is a sectional view of a main part showing an embodiment corresponding to claim 1 or 2. Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The septic tank 1 of this embodiment is buried and fixed in the ground, and inspection from the outside is performed through an opening 3 shielded by a manhole 2. Human waste and domestic wastewater (hereinafter referred to as raw water 4) are supplied to the membrane treatment type septic tank 1
From the inflow port 5 provided at one end of the filter material, the filter material 23, the foreign matter removal tank 24, the state where impurities are removed,
It is sent to the aeration tank 7 by the transfer pump 6.

In the aeration tank 7, a diffusion tube 8 for supplying oxygen is provided below the aeration tank 7 in order to activate microorganisms by oxygen and promote decomposition of organic substances. From the air diffuser 8, air taken in via an air supply pipe 11 from an aeration blower 10 having a control unit 9 installed outside the membrane treatment type septic tank 1 is aerated at regular intervals. At regular intervals, activation of microbial activity and stabilization of the amount can be achieved.

In the aeration tank 7, a plurality of membrane elements 12 are immersed in raw water 4, and the raw water 4
Filtration is performed by the biofilm 14 attached to the filter 3, and filtered water 15 that has appeared in the membrane by the filtration is sucked out by a suction pump 16 and taken out from a filtered water outlet 19 that is connected to a disinfection tank 18 through a pipe 17. The filtered water 15 that has been finally purified by the disinfection tank 18 is discharged to the discharge port 2 connected to the outside.
Released from 0.

In order to remove the clogging of the membrane due to the suction filtration, in this embodiment, as shown in FIG. 2, the carrier mixed in the aeration tank 7 in advance by the circulation of the raw water 4 in the aeration tank 7 by aeration. The biofilm 14 is washed by flowing the fluid 21 and bringing it into contact with the membrane surface 13. As a result, compared to the conventional method in which the biofilm 14 attached to the membrane surface was washed only by the circulation of the bubbles 22 by aeration, the same effect was obtained even with a smaller amount of aeration. Therefore, the amount of aeration can be greatly reduced as compared with the conventional case, so that the size of the aeration blower 10 can be reduced and power consumption can be reduced accordingly.

The diameter of the carrier 21 is adjusted so that the carrier 21 can enter between the adjacent membrane elements 12.
Needless to say, the size is smaller than the size between them, but in this embodiment, the distance between the adjacent membrane elements 12 is 7 mm, and the carrier 21 is a 5-mm square continuous foam.

The carrier 21 may be made of any material as long as it can flow in the raw water 4. However, since the carrier 21 is in contact with the biofilm 14, it is as flexible as possible to prevent the biofilm 14 from being damaged. Is desirable. In this example, a sponge made of polyolefin was used, but no damage to the biofilm 14 was observed, and good cleaning results were obtained. In addition, since the foam is a foam having many cavities, microorganisms can easily live in the carrier 21, an increase in biomass can be seen, the treatment efficiency can be improved, and the capacity of the aeration tank 7 can be reduced.

[0015]

The membrane treatment type septic tank of the present invention is implemented as in the above-described embodiment, and the carrier moves in the aeration tank by circulating flow by aeration and is cleaned by contact with the membrane surface. Can be.

[0016] Compared with the conventional method in which the biofilm adhered to the membrane surface is washed only by circulation by aeration, the same effect can be obtained with a small amount of aeration. Power saving can be achieved.

Further, the carrier made of a flexible foam is softly contacted with the membrane surface, so that the biofilm is not damaged and a good washing result can be obtained. In addition, since the microorganisms easily live in the carrier having many cavities due to the foam, the biomass is increased, the treatment efficiency is improved, and the capacity of the aeration tank can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a membrane treatment type septic tank according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a main part of the membrane treatment type septic tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Membrane treatment type septic tank 7 Aeration tank 12 Membrane element 21 Carrier

Claims (2)

[Claims] 1. In a membrane treatment type septic tank provided with an aeration tank in which a plurality of membrane elements for solid-liquid separation are arranged, microorganisms can be carried with a diameter smaller than the distance between adjacent membrane elements. A membrane treatment type septic tank wherein a large number of carriers are mixed in an aeration tank. 2. The membrane treatment type septic tank according to claim 1, wherein the carrier is made of a flexible foam.