JP3408699B2 - Sewage treatment equipment using immersion type membrane separation equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a leachate treatment device,
The present invention relates to a sewage treatment device using an organic sewage treatment device, a dipping device for dioxins contained in sewage, and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for removing nitrogen and phosphorus in domestic wastewater, there is an activated sludge treatment method for biologically treating raw water in an anaerobic tank and an aerobic tank. In this activated sludge treatment method, in the anaerobic tank, a flocculant is added to the raw water flowing from the outside of the system, and the sludge is returned from the aerobic tank in the post process, and the mixed solution in the tank is agitated. In the tank, air is aerated from the air diffuser to the mixed liquid flowing from the anaerobic tank, the mixed liquid is circulated in the tank, and the mixed liquid is filtered by the membrane separation device immersed in the tank, and the membrane separation device The treated water that has passed through is taken out to the treated water tank.

The membrane separation device arranged in the aerobic tank is located above the air diffuser and exposes the membrane surface to the upward flow of the gas-liquid mixed phase generated by the aerated air. The mixed solution is filtered under a cross-flow method (circulation method) in which the solids adhere to the film surface by washing the film surface with the upward flow as a scavenging flow.

[0004]

By the way, in the case of organic wastewater in which the nutritional balance of nitrogen, phosphorus and BOD is disturbed, foaming increases during aeration due to its properties, so that the MLSS concentration is increased. However, there is a problem that the BOD removal efficiency becomes unstable. By the way, the optimum value of nutritional balance is BOD: N: P = 100: 5: 1, but in the case of landfill leachate, BOD: N: P = 5: 5: 0.1. The proper MLSS concentration is 10,000 to 12,000 mg / l, but in the case of organic wastewater as described above, MLSS
The concentration is 2,000 to 4,000 mg / l.

[0005] In order to upward flow arising by aeration fulfill cleaning function of the solids content of the sludge adhering to the membrane surface, aeration intensity required for this washing is the rate-limiting, 10~12m ³ / m ³ /
Although aeration is performed for about hr, this is several times the amount of oxygen required by the microorganisms in the tank. For this,
There is a problem that not only foaming is likely to occur, but also a large blower facility is required to increase the cost and the running cost such as the electricity bill increases.

The present invention is to solve the above-mentioned problems, and enables operation with a small aeration strength, suppresses foaming in the tank to increase the MLSS concentration, and lowers the cost. An object of the present invention is to provide a sewage treatment apparatus using a type membrane separation device.

[0007]

In order to solve the above problems, a sewage treatment apparatus using the submerged membrane separation apparatus of the present invention has an upward flow path and a downward flow which are partitioned by a partition wall in an immersion tank. A tank circulation system consisting of a flow path is formed, and an air diffuser is arranged at the bottom of the upward flow path, and a plurality of tubular membrane elements are provided along the upward flow path in the middle of the upward flow path. The immersion type membrane separation device arranged in the up-down direction is provided, and the in-tank forced circulation means for causing a downward flow is provided above the downward flow path.

With this configuration, in the immersion tank, the aerating air supplied from the air diffuser causes an upward flow of the gas-liquid mixed phase to occur in the upward flow path, and the in-tank forced circulation means causes the downward flow path to flow in the downward flow path. Downflow occurs in the. As a result, the in-tank mixed liquid staying at the bottom of the dipping tank moves to the upper part of the tank through the upward flow path, and the in-tank mixed liquid of the upper tank moves to the bottom part of the tank through the downward flow path. The internal mixed solution circulates and moves in the tank circulation system.

In this state, the submerged membrane separation device filters the in-tank mixed liquid flowing in the upward flow passage, and the permeated liquid that has permeated the membrane of the membrane element passes through the internal flow passage of the membrane element to pass through the membrane. It flows out of the tank through the treated water pipe communicating with the element. On the other hand, the upward flow that flows between the membrane elements becomes a scavenging flow to wash the membrane surface of each membrane element and suppress the adhesion of the solid content to the membrane surface.

At this time, since each membrane element is arranged vertically along the upward flow passage, the flow passage resistance due to the membrane element is sufficiently smaller than in the conventional case, and the membrane surface of the membrane element is cleaned. It is possible to obtain the upward flow velocity required for a low aeration strength. Moreover, since the upward flow flows along the axial direction of the membrane element, the scavenging action acts over the entire length of the membrane element, and the cleaning efficiency per unit power is improved.

By the way, if the aeration air amount is adjusted in accordance with the required oxygen amount standard corresponding to the BOD concentration of the inflowing raw water, B
When the OD concentration is low, it becomes impossible to secure the circulation flow rate in the tank necessary for stirring and mixing or cross-flow filtration, but it is dependent on the aeration air amount by causing the downward flow by the forced circulation means in the tank. Without doing so, it is possible to secure the circulating flow rate in the tank necessary for cross-flow filtration, suppress foaming, increase the MLSS concentration, and stabilize the BOD removal efficiency.

By using an agitator for the in-tank forced circulation means, the circulation flow rate per unit power can be increased as compared with other devices such as pumps, and the equipment cost and power cost can be reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, the immersion tank 1 is
Guide raw water such as organic wastewater and leachate through the inflow pipe 2,
It forms a biological treatment tank for biological treatment with activated sludge, and an in-tank circulation system consisting of an upward flow path 4 and a downward flow path 5 partitioned by a partition wall 3 inside the immersion tank 1. Are formed, and the upward flow paths 4 are radially arranged around the downward flow path 5 located at the center of the tank. The forms of the upward flow path 4 and the downward flow path 5 are not limited to those described above, and the upward flow path 4 and the downward flow path 5 may be arranged in reverse. Various shapes such as a cylindrical shape, a fan shape, and a rectangular shape can be considered as the cross-sectional shape of the flow path.

An air diffuser 6 is arranged below the upward flow path 4, and the air diffuser 6 is connected to a blower 9 via an aerated air supply pipe 7 and a first valve 8. Also, blower 9
Is connected via a second valve 10 and a backwash air supply pipe 11 to a treated water conduit 12 to be described later. A stirrer 13 is arranged above the downward flow path 5 as a forced circulation means in the tank for causing a downward flow. A device such as a pump can be used as the forced circulation means in the tank.

In the middle of the upward flow path 4, the immersion type membrane separator 1
4 are arranged. The submerged membrane separation device 14 arranges a plurality of tubular membrane elements 15 in the up-down direction along the upward flow path 4, and holds each membrane element 15 at the upper end side by a header 16 while connecting and holding the same. 1
The internal channels 6 communicate with each membrane element 15, and the membrane element 15 is connected and held by the connecting plate 17 at the lower end side. The header 16 and the connecting plate 17 are provided with a water passage portion 18 through which an upward flow passes.

The header 16 has an internal flow path of the treated water line 12.
The water supply pipe 21 connected to the treated water pump 20 via the third valve 19 and connected to the treated water pump 20 communicates with the treated water tank 22. A backwash water system 23 is provided between the treated water tank 22 and the treated water pipeline 12, and the backwash water system 23 has a backwash water pipe 24, a backwash pump 25, and a fourth valve 26. An excess sludge discharge system 27 is connected to the bottom of the immersion tank 1, and the excess sludge discharge system 27 has a fifth valve 28, a sludge drawing pipe 29, and a sludge pump 30.

The operation of the above structure will be described below.
Inside the immersion tank 1, the aerating air supplied from the air diffuser 6 causes an upward flow of the gas-liquid mixed phase to occur inside the upward flow passage 4, and the stirrer 13 moves downward into the downward flow passage 5. Since a flow occurs, the in-tank mixed liquid staying at the bottom of the dipping tank 1 moves to the upper part of the tank through the upward flow path 4, the connecting plate 17 and the water passage 18 of the header 16 to move to the upper part of the tank. The in-tank mixed solution moves to the bottom of the tank through the downward flow path 5, and the in-tank mixed solution circulates and moves in the in-tank circulation system, while the in-tank mixed solution is biologically treated with activated sludge.

In this state, the immersion type membrane separation device 14
Receives the suction pressure of the treated water pump 20 and filters the in-tank mixture flowing through the upward flow path 4. The membrane-permeated liquid that has permeated the membrane of the membrane element 15 flows through the inner passage of the membrane element 15 into the inner passage of the header 16, and then the header 16
To the treated water tank through the treated water pipe 12, the third valve 19, the treated water pump 20, and the water supply pipe 21 which communicate with each other.

On the other hand, the upward flow flowing in the flow path between the membrane elements 15 becomes a sweep flow to wash the membrane surface of each membrane element 15 and suppress the solid content from adhering to the membrane surface. At this time, since each membrane element 15 is arranged vertically along the upward channel 4, the channel resistance due to the membrane element 15 becomes sufficiently smaller than in the conventional case, and the membrane surface of the membrane element 15 is reduced. The upward flow velocity required for cleaning can be obtained under a low aeration strength. Moreover, since the upward flow flows along the axial direction of the membrane element 15, the scavenging action acts over the entire length of the membrane element 15, and the cleaning efficiency per unit power is improved.

When the BOD concentration of the raw water inflow is low, it becomes impossible to secure the circulating flow rate in the tank required for stirring and mixing and cross-flow filtration, but since the agitator 13 causes a downward flow, aeration is performed. The circulation flow rate in the tank required for cross-flow filtration can be secured without depending on the air volume, foaming is suppressed, and the MLSS concentration is increased to increase the BOD.
The removal efficiency can be stabilized. Moreover, the stirrer 1
No. 3 can increase the circulation flow rate per unit power as compared with other devices such as pumps, and can reduce equipment costs and power costs.

[0021]

As described above, according to the present invention, by arranging each membrane element in the vertical direction along the upward channel, the channel resistance caused by the membrane element is sufficiently reduced, The upflow velocity required for cleaning the membrane surface of the membrane element can be obtained with a small aeration strength, and the upflow scavenging action acts over the entire length of the membrane element, improving the washing efficiency per unit power. . Since a downward flow is generated by the in-tank forced circulation means, the required in-tank circulation flow rate can be secured without depending on the amount of aerated air, foaming is suppressed, and the MLSS concentration is increased to stabilize the BOD removal efficiency. Can be converted. Moreover, a large circulation flow rate per unit power can be obtained by the stirrer, and the equipment cost and the power cost can be reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a sewage treatment apparatus using an immersion type membrane separation apparatus according to an embodiment of the present invention.

FIG. 2 is a view on arrow AA of FIG.

FIG. 3 is a cross-sectional view of the immersion type membrane separation device according to the same embodiment.

[Explanation of symbols]

1 immersion tank 4 upward flow path 5 Downward flow path 6 Air diffuser 12 Treated water pipeline 13 Stirrer 14 Immersion type membrane separator 15 membrane elements 16 header 18 water passage

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 1/44 ZAB B01D 63 / 06,65 / 02

Claims (2)

(57) [Claims] 1. An in-tank circulation system consisting of an upward flow path and a downward flow path partitioned by a partition wall is formed in the immersion tank, and an air diffuser is disposed below the upward flow path, In the middle of the counter flow channel, a submerged membrane separation device in which a plurality of tubular membrane elements are arranged in the vertical direction along the upward flow channel is provided, and in the tank that produces the downward flow at the upper part of the downward flow channel. A sewage treatment apparatus using an immersion type membrane separation device, which is provided with a forced circulation means. 2. The sewage treatment apparatus using the submerged membrane separation apparatus according to claim 1, wherein the in-tank forced circulation means comprises an agitator having a rotary blade.