JPH09225484A - Membrane separation device and water purifying tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separation device capable of widening the membrane surface area. SOLUTION: Water in a raw water storage tank 7 flows in a denitrificating tank 9 through an advection cylinder 8, flows in a nitrification tank 11 through an advection cylinder 10 and is aerated by a diffusing pipe 12, to which air is supplied by a blower 13. A separation membrane module 16 is provided in an inner tank 15 and the water permeates the membrane to take out a permeated water by sucking the inside of the separation membrane module 16 with a pump 17. The nitrificated water in the inner tank 15 is aerated by diffusing pipe 19, to which air is supplied from a blower 18. A part of the water in the inner tank 15 is returned to the denitrificating tank 9 by an airlift pump 20.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a membrane separation device and a septic tank for treating wastewater and the like.

[0002]

2. Description of the Related Art Separation membranes are sometimes incorporated in septic tanks for treating sewage (JP-A-4-354592, JP-A-6-218247, etc.). The former JP-A-4-35
4592 discloses a precipitation separation tank or an anaerobic filter bed tank;
A sewage treatment apparatus comprising a contact aeration tank, a sewage return pipe for returning the nitrification liquid from the contact aeration tank to the precipitation separation tank or the anaerobic filter bed tank, and a separation membrane module provided in the contact aeration tank. Have been described.

By the way, an air lift is sometimes used to pump water between tanks in a sewage treatment apparatus. For example, Japanese Utility Model Publication No. 2-61495 discloses a sewage treatment apparatus including a primary treatment tank such as a settling tank and a secondary treatment tank such as a contact aeration tank. It is described that water is pumped to the adjusting tank by an air lift, and water in the water level adjusting tank is pumped to a secondary treatment tank by an air lift.

[0004]

In the conventional septic tank, since the water level in the tank in which the separation membrane module is installed varies, the separation membrane module is placed below the lower limit water level in the tank. Therefore, it is difficult to increase the membrane area of the separation membrane module.

An object of the present invention is to provide a membrane separation device and a septic tank which can have a large membrane area.

[0006]

The membrane separation device of the present invention comprises:
In a membrane separation device having a separation membrane module that permeates water, an outer tank, an inner tank installed inside the outer tank,
A pump that supplies water from the outer tank to the inner tank and overflows water from the inner tank to the outer tank to keep the water level in the inner tank constant; It is characterized by being installed in.

The septic tank of the present invention comprises a denitrification tank, a nitrification tank, and
In a septic tank equipped with a separation membrane module for permeating nitrification-treated water in the nitrification tank, an inner tank is provided in the nitrification tank, and the nitrification-treated water in the nitrification tank is supplied to the inner tank. A pump for overflowing from the inner tank to keep the water level in the inner tank constant is provided, and the separation membrane module is installed in the inner tank.

In the membrane separation device and the septic tank,
Since the water level in the inner tank is always constant (overflow water level), the separation membrane can be spread to the upper part in the inner tank, and the membrane area of the separation membrane module can be increased.

In the septic tank of the present invention, since the water level in the inner tank is constant, when the nitrifying water in the inner tank is pumped back to the denitrification tank by the air lift pump and returned, the amount of water fed by the air lift pump is constant. Becomes

[0010]

1 is a cross-sectional view of a septic tank according to an embodiment. Raw water is introduced from the inflow port 1 into the contaminant removal tank 2, passes through the screen 3, and flows into the raw water storage tank 7. It should be noted that some of the impurities fall into the sludge storage tank 4. Air bubbles are diffused from the diffuser pipe 6 in the vicinity of the screen 3 by the blower 5.

The water in the raw water storage tank 7 flows into the denitrification tank 9 through the advection tube 8 and is denitrified. This water is then
It flows into the nitrification tank 11 through the advection cylinder 10 and is aerated by the air diffuser 12 to which air is supplied from the blower 13. The nitrification-treated water is pumped to the inner tank 15 in the nitrification tank 11 by the air lift pump 14. Air is supplied from the blower 13 to the air lift pump 14.

A separation membrane module 16 is provided in the inner tank 15, and the inside of the separation membrane module 16 is a pump 17.
The water permeates the membrane by being sucked in and the permeated water is taken out. The nitrification-treated water in the inner tank 15 is aerated by an air diffuser 19 to which air is supplied from a blower 18. Part of the water in the inner tank 15 is returned to the denitrification tank 9 by the air lift pump 20. Air is supplied to the air lift pump 20 from the blower 18.

The nitrification-treated water, which is sufficiently larger than the total amount of the returned water of the air lift pump 20 and the amount of permeated water taken out through the pump 17, is supplied into the inner tank 15 by the air lift pump 14. Water always overflows from 15 to the nitrification tank 11, and the water level in the inner tank 15 is always constant.

The sludge in the nitrification tank 11 is regularly withdrawn to the sludge storage tank 4 by a pipe 22 having a pump 21.

In the septic tank constructed as described above,
Since the water level in the inner tank 15 is constant due to the overflow, the separation membrane module 16 can be spread to the upper part in the inner tank 15, and the membrane area can be increased.

The nitrifying water in the inner tank 15 is sent to the denitrification tank 9 by the air lift pump 20 for denitrification treatment. However, since the water level in the inner tank 15 is always constant, this air lift is required. The amount of water sent by the pump 20 is also constant.

The pump 17 is stopped when the water level in the septic tank falls below the lower limit water level LWL. Further, the steady operation is performed when the water level in the septic tank is between the lower limit water level LWL and the upper limit water level HWL, and when the water level is equal to or higher than the upper limit water level HWL, the operation is performed at double speed as in the steady operation. By controlling the pump 17 in this way, even if a large amount of raw water temporarily flows into the septic tank, it can be sufficiently dealt with.

During the operation of the pump 17, the raw water always flows from the raw water storage tank 7 into the denitrification tank 9, and the denitrification performance is stabilized.

In this septic tank, the separation membrane module 16 is assembled in advance to the inner tank 15, and the inner tank 15 is inserted into the nitrification tank 11, so that the separation membrane module 16 can be installed together.

[0020]

As described above, the membrane separation device and the septic tank of the present invention have the separation membrane module installed in the inner tank having a constant water level. The film area can be increased.

In the septic tank of the present invention, the amount of water returned from the inner tank to the denitrification tank can be made constant even if an air lift pump is used.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a septic tank according to an embodiment.

[Explanation of symbols]

 2 Contaminant removal tank 6 Sludge storage tank 7 Raw water storage tank 8, 10 Advection cylinder 9 Denitrification tank 11 Nitrification tank 14, 20 Air lift pump 15 Inner tank 16 Separation membrane module

Claims (4)

[Claims] 1. A membrane separation apparatus having a separation membrane module for permeating water, wherein an outer tank, an inner tank installed inside the outer tank, and water in the outer tank are supplied to the inner tank. And a pump for overflowing water from the inner tank to the outer tank to keep the water level in the inner tank constant, wherein the separation membrane module is installed inside the inner tank. apparatus. 2. A decontamination tank comprising a denitrification tank, a nitrification tank, and a separation membrane module for permeation treatment of water nitrified in the nitrification tank, wherein an inner tank is provided in the nitrification tank and A nitrification-treated water of (1) is supplied to the inner tank, a pump for overflowing from the inner tank to keep the water level of the inner tank constant is provided, and the separation membrane module is installed in the inner tank. 3. The septic tank according to claim 2, further comprising a water feed means for sending the nitrification-treated water inside the inner tank to the denitrification tank. 4. The septic tank according to claim 3, wherein the water supply means is an air lift pump.