JPH09103661A - Immersion type membrane separation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively separate and remove polluting substances adhering to the surface of a membrane of a membrane element. SOLUTION: As for this apparatus, a plurality of membrane elements 3 are set uprightly at a prescribed distance, a water taking inlet 4 of each membrane element 3 and a suction pump P1 are connected, an air jetting pipe 5 to jet bubbles is laid in the tank bottom, rising current flowing while contacting the membrane is caused in the gaps of the membrane elements 3 by air lifting function of the bubbles which the air jetting pipe 5 jets, permeated water of feed water is sucked to the inside of each membrane element 3 by suction function of a suction pump P1, and water is taken through the water taking inlet 4. A pressurizing and injecting means 10 for a cleaning chemical liquid to inject a cleaning chemical liquid into the inside of each membrane element 3 and permeate the liquid through the membrane to outside is installed and a gas jetting pipe 6 to jet coarse bubbles is laid in the tank bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged membrane separation device using a membrane element in which a membrane such as a flat membrane, a hollow fiber membrane or a tubular membrane is attached to a main body, and permeated water that permeates the membrane is obtained inside the main body. Regarding

[0002]

2. Description of the Related Art As such an immersion type membrane separation device, a plurality of membrane elements are vertically arranged in a raw water in a treatment tank at a predetermined interval and sucked through a header pipe at a water collecting port of each membrane element. A suction pipe is connected to the pump, and an air diffusing pipe for jetting fine bubbles is laid at the bottom of the tank, and an upward flow that flows in contact with the membrane is generated in the space between the membrane elements by the air lift action of the fine bubbles jetting by the diffusing pipe. The permeated water in the raw water is sucked into each membrane element by the suction action of
Also, a device adapted to collect water via a header pipe is conventionally known.

[0003]

In the above conventional apparatus, one of the purposes of ejecting fine bubbles from the air diffusing tube is to prevent contaminants from adhering to the surface of the membrane due to the shearing force of the fine bubbles. However, when the raw water contains a large amount of MLSS, the pollutants gradually adhere to the surface of the membrane due to the continuous operation, and the filtration performance of the membrane deteriorates. Then, when the filtration performance deteriorates to some extent, it is necessary to draw the membrane element out of the treatment tank, wash the surface of the membrane with a chemical solution, and peel off the attached contaminants. I'm sorry.

[0004]

The present invention is intended to solve the above-mentioned problems, and a plurality of membrane elements are arranged side by side in raw water in a treatment tank at a predetermined interval. The water sampling port and suction pump are connected, and a diffusing pipe for ejecting bubbles is laid on the bottom of the tank, and an air-lifting action of the bubbles ejected by the diffusing pipe causes an upward flow that flows in contact with the membrane at the interval between the membrane elements, In the immersion type membrane separation device that sucks the permeated water in the raw water into the inside of each membrane element by the suction action of the suction pump and collects the water through the water sampling port, the cleaning chemical solution is injected into the inside of each membrane element, It is characterized in that a means for pressurizing and injecting a cleaning chemical liquid to be leached to the outside of the tank and an air diffuser for jetting coarse bubbles are provided at the bottom of the tank.

In the illustrated embodiment, reference numeral 1 denotes a treatment tank of an activated sludge treatment apparatus to which raw water containing organic matter is supplied. The activated sludge has an air lift tube 2 set up in the water in a floating tank.
On the air lift cylinder, a plurality of flat sheet membrane elements 3 having permeated water sampling ports 4 are arranged in a row in the front-rear direction at intervals. Below the inside of the air lift cylinder, a diffuser 5 for fine bubbles that ejects air supplied from the blower B in the form of fine bubbles and a diffuser 6 for coarse bubbles that ejects in the form of coarse bubbles are switched by a valve to diffuse air. Has been laid.

When performing the membrane filtration operation, fine bubbles are diffused from the fine bubble diffuser 5. As a result, the activity of the activated sludge that decomposes the organic matter of the raw water is increased, and at the same time, the air-lifting action of the fine bubbles causes an upward flow that flows in contact with the membranes in the space between the facing membrane elements of the flat sheet membrane element 3, thereby shearing the bubbles. The permeated water that permeates the membrane while preventing the gel-like contaminants from adhering to the surface of the membrane was obtained inside the main body of the flat membrane element, and this permeated water was connected to the water intake port 4 of each flat membrane element. Water is drawn by sucking with the pump P1 through the header pipe 7.

The header pipe 7 is connected to a chemical injection pipe 9 for supplying the cleaning chemical in the tank 8 by pressurizing it with a pump P2. The tank 8, chemical injection pipe 9 and pump P2 pressurize the cleaning chemical. The injection means 10 is configured. A valve is provided upstream of the chemical injection pipe 9 and the water sampling pump P1, and the valve of the injection pipe is closed during the membrane filtration operation.

When contaminants adhere to the surface of the membrane and the filtration performance of the membrane deteriorates, the pump P1 is stopped, the valve on the pump side is closed, the valve of the chemical injection pipe 9 is opened, and the pump P2 is operated. Then, the cleaning chemical in the tank 8 is filled with the chemical injection pipe 9 and the header pipe 7.
It is pressurized and injected into the main body of each flat sheet membrane element via Of course, you may inject by a water head difference. The cleaning chemicals used are sodium hypochlorite, sodium hydroxide, sulfuric acid, hydrogen peroxide and the like. At the same time, air diffuser 6 for large bubbles
Diffuse coarse bubbles from.

As a result, the cleaning chemical injected under pressure into the membrane element permeates the membrane, leaches out to the surface of the membrane, contacts the pollutants adhering to the surface of the membrane, and undergoes a chemical change, resulting in pollutants. Reduces the adhesion to the film. Then, the large bubbles rising in contact with the film peel off and remove the pollutant whose adhesive force has been reduced from the film due to the large shearing force. After cleaning with the cleaning chemical for a predetermined time, stop the pump P2, close the valve of the chemical injection pipe, and operate the pump P1.
Fine bubbles are diffused from the diffuser 5 and the membrane filtration operation is restarted.

Although the embodiment of the present invention has been described with respect to the flat membrane element, a membrane element having hollow fiber membranes mounted in a goodwill shape may be vertically arranged in a square frame, and a membrane element similarly mounted with a tubular membrane. It may be a set of. Further, although the diffuser tubes for the fine bubbles and the coarse bubbles are separate, one type of diffuser tube having both functions may be used. In this case, this is dealt with by increasing or decreasing the amount of air supplied to the air diffuser.

[0011]

As is apparent from the above, according to the present invention, a cleaning chemical liquid is pressure-injected into the inside of the membrane element to weaken the adhesion force of the contaminants adhering to the surface of the membrane, and the large shearing force of the coarse bubbles. Since the contaminants are peeled off from the surface of the film and removed, the cleaning can be easily performed and the cleaning effect is great.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an embodiment of the present invention, and B is a cross-sectional view of a state during cleaning.

[Explanation of symbols]

 1 Treatment Tank 2 Air Lift Cylinder 3 Membrane Element 4 Membrane Element Water Collection Port 5 Fine Air Bubble Diffuser 6 Large Coarse Bubble Diffuser 7 Header Pipe 8 Tank 9 Chemical Injection Pipe 10 Pressurizing and Injecting Medication Solution

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 65/08 B01D 65/08 C02F 1/44 C02F 1/44 K

Claims (1)

[Claims] 1. A plurality of membrane elements are vertically arranged in a raw water in a treatment tank at a predetermined interval, a sampling port of each membrane element and a suction pump are connected, and an air diffuser for ejecting bubbles to the bottom of the tank is provided. By laying the air diffuser, the air lift action of the air bubbles ejected from the diffuser creates an upward flow that flows in contact with the membrane in the space between the membrane elements, and the suction action of the suction pump sucks the permeate in the raw water into each membrane element. Then, in the immersion type membrane separation device that collects water through the water sampling port, the cleaning chemical solution is injected into each membrane element, and the cleaning chemical solution is pressurized and injected to the outside of the membrane. An immersion-type membrane separation device, which is provided with an air diffuser for jetting.