JP3196228B2 - Membrane cleaning method and membrane cleaning device for membrane separation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and a cleaning apparatus for spraying cleaning water to remove a gel-like viscous substance adhering to a membrane surface of a membrane separation apparatus.

[0002]

2. Description of the Related Art When solid-liquid separation of an activated sludge mixed liquid or these coagulation treatment liquids is performed by a membrane separation device, a gel-like viscous substance which is considered to be derived from the activated sludge mixed liquid with time is formed on the membrane. Without penetrating into the inside, it gradually adheres and deposits on the surface of the film, and the moisture permeability of the film is reduced. For this reason, when the moisture permeability of the membrane is reduced to some extent, it is necessary to wash the membrane surface and remove the deposited gel-like viscous substance.

[0003]

This cleaning involves a chemical cleaning method using an acid such as caustic soda, hydrochloric acid, sodium hypochlorite, and hydrogen peroxide, an alkali, and an oxidizing agent. Although there is a physical cleaning method of rubbing with a brush, the chemical cleaning method does not have a condition under which the viscous substance can be sufficiently removed because there is a risk that the film is chemically deteriorated. The method of rubbing with a sponge or brush is effective for removing a viscous substance, but there is a risk that the sponge or brush may damage the film surface or peel off the skin layer to lose the function of the film.

In the conventional method of spraying cleaning water, the cleaning water is sprayed obliquely to the film. However, this method can only insufficiently remove the viscous substance. And
Increasing the water pressure of the spray improves the removal effect somewhat,
The membrane is damaged.

[0005]

Therefore, in order to efficiently and surely remove viscous substances adhered and deposited on the surface without damaging the film, cleaning water sprayed onto the film surface is pursued. It was developed as a result of experimenting by changing the angle and water pressure in various ways, and the method for cleaning the film of the present invention is perpendicular to the film surface without rubbing the film surface with a brush or sponge, and The cleaning water is sprayed at a pressure of 10 kg / cm ² or more. In this case, it is preferable to further wash the membrane surface with a chemical after spraying the washing water. or,
The membrane cleaning apparatus of the present invention uses a high pressure pump to supply 10 kg / c
A spray nozzle for injecting washing water supplied at a high pressure of at least m ² is fixed to one end of a cylinder also serving as a conduit for the washing water, and the other end of the cylinder has a discharge port of the high-pressure pump. A baffle plate is connected to a center tube of the spray nozzle, and a baffle plate which faces the tip of the spray nozzle and forms a spray port for radially spraying washing water over the entire circumference therebetween is attached to the center tube of the spray nozzle. It is characterized by having.

[0006]

1 (A) shows a tubular membrane separation device in which a membrane 2 such as an RO membrane, a UF membrane or an MF membrane is attached to the inner periphery of a protective tube 1 having a large number of pores on the tube wall by a spray nozzle 3. The spray nozzle 3 moves in the axial direction of the pipe while spraying washing water radially from an injection port 4 opened all around the nozzle, whereby the spray nozzle 3 moves perpendicularly to the inner periphery of the film surface. Spray wash water.

The spray nozzle 3 is fixed to one end of a cylinder 5 serving also as a conduit for washing water by screwing, and the other end of the cylinder 5 is connected to a hose connected to a discharge port of a high-pressure pump. The water pressure of the washing water sprayed from the jet port 4 is set to 10 kg / cm ² or more.

The spray nozzle 3 has a central cylinder 7 supported by a radial arm 6 at the center thereof. The central cylinder 7 has a baffle plate 8 which faces the tip of the spray nozzle and forms the injection port 4 therebetween. A central shaft 9 protruding from the center is attached by screwing or the like.

Therefore, the water pressure supplied to the spray nozzle 3 from the high pressure pump via the hose and the tube 5 is 10 kg / cm ^2.
The high-pressure washing water passes through the space between the arms 6 and the baffle 8
From the baffle plate 8 and the spray nozzle 4 which is formed on the entire circumference and formed between the baffle plate 8 and the tip of the spray nozzle.

The spray nozzle 3 is located at the center of the inside of the pipe 1 due to the water pressure of the washing water radiating radially from the entire circumference of the injection port 4. For this reason, by setting the length of the cylinder 5 to which the spray nozzle 3 is attached at one end longer than the length in the axial direction of the tubular membrane separation device, the cylinder 5 is held by hand and washed from the spray port 4 of the spray nozzle. While spraying water, a spray nozzle is inserted into one of the tubular membrane separators from one end and gradually moved to the other end, so that the viscous substance adhered and deposited on the inner periphery of the membrane 2 is removed from the membrane surface. Can be reliably removed without damage. After the spray nozzle is moved to the other end inside the tubular membrane separation device, the cylinder 5 may be pulled back to the front, and the washing may be continued until the spray nozzle reaches one end inside the device.

FIG. 1B shows a filter plate 1 of a filter press type.
1 shows a state in which a flat membrane separator having a semipermeable flat membrane 12 such as an RO membrane, a UF membrane, or an MF membrane is washed by a spray nozzle 13 longer than the width of a filter plate. The spray nozzle 13 is inserted into the space created between the two filter plates 11 and 11 and the washing water is sprayed vertically on the two membranes 12 and 12 stretched on the opposing surfaces of the two filter plates.

Such a flat membrane separator is known from Japanese Patent Application Laid-Open No. 63-49204 proposed by the present applicant. The spray nozzle 13 has one end vertically movable and rotatably mounted on a column 16 standing from a movable table 15 movable by a reciprocating device 14 along one side of a group of a large number of filter plates 11 arranged in a line. During operation of the membrane separation device, it is located at the lower end of the column 16 and rotates upward to be parallel to the column.

A hose 18 extending from the discharge port of the high-pressure pump 17 is connected to one end of the spray nozzle.
The high-pressure pump 17 uses a water pressure of 10 kg / c from the spray nozzle.
spraying wash water in m ² or more pressure.

In order to wash the membrane, the leading filter plate is moved, a gap is maintained between the leading filter plate and the second filter plate, and the moving table 15 is moved so as to be located near the gap. Then, the upward spray nozzle 13 is turned downward to be horizontal by turning it downward, so that the spray nozzle enters the above interval, and then, while spraying the washing water from the spray nozzle, the spray nozzle is raised along the support, and Filter plate,
Washing water is applied vertically to the ^two membranes 12 on opposite surfaces of the second filter plate at a water pressure of 10 kg / cm ² or more to wash viscous substances adhering and depositing on the membrane surfaces. Remove. If necessary, raise the spray nozzle to the maximum, then lower it, and perform cleaning during that time.

After the washing is performed, the spray nozzle is turned upward, the second filter plate is moved to form a space between the filter plate and the third filter plate, and the moving table 15 is placed beside the space. Move slightly so that it is positioned, and perform the same operation as above to wash the two membranes stretched on the opposing surfaces of the No. 2 filter plate and the No. 3 filter plate.

This work is repeated, and the work is completed by washing the final filter plate and the membrane stretched on the opposing surfaces of the filter plate in front of it.

Regardless of whether the tubular membrane separator shown in FIG. 1 (A) is washed or the above-mentioned flat membrane separator shown in FIG. 1 (B) is washed, after the washing with the washing water by the spray nozzle, NaOH is removed. The cleaning effect is further improved by performing chemical cleaning with a 0.5% aqueous solution, a 0.05% aqueous NaOCl solution, or a 0.1% aqueous H ₂ SO ₄ solution.

The results of cleaning a white semi-permeable flat membrane of a flat membrane separator having a membrane area of 26 m ² by the conventional method and the present invention are shown below. As a conventional method, the washing water was sprayed at a water pressure of 5 kg / cm ² at an oblique angle almost horizontal to the membrane,
The treated water amount (flux) of 0.85 m ³ / hr before washing was 0.95 m ³ / hr. However, sludge remained on the membrane surface, the membrane surface was brown, and the surface was slimy. Also, spray the washing water in the same manner, then, it was subjected to chemical cleaning, one volume of treated water before washing was 0.90 m ³ / hr became 1.30 m ³ / hr. However, sludge still remained on the membrane surface, the membrane surface was light brown, and the surface was slimy.

According to the present invention, the washing water is applied vertically to the semipermeable flat membrane,
When spraying with a water pressure of 10 kg / cm ² , the treated water amount before washing was 0.90 m ³ / hr, but 1.80 m ³ / hr.
³ / hr, sludge remaining on the surface of the membrane disappears,
The film surface was light brown, and the surface was slimy. Also, spray the washing water under the same conditions, then, was subjected to chemical cleaning, one volume of treated water before washing was 0.88 m ³ / hr becomes 2.20 m ³ / hr, the surface of the membrane The remaining sludge disappeared, the membrane surface was white, and the surface was slimy.

[0020]

According to the present invention, without damaging the membrane surface,
Viscous substances adhering and depositing on the surface can be reliably removed, the performance of the film can be maintained, and the cost of the film can be reduced. Moreover, the chemical cleaning effect is improved by combining with the chemical cleaning.

[Brief description of the drawings]

FIG. 1A is an explanatory view of a cleaning state of a tubular membrane separation device,
(B) is an explanatory view of the cleaning state of the flat membrane separator.

FIG. 2 is a side view of FIG.

FIG. 3 is an enlarged side view showing a part of the cleaning device of FIG. 2 in section;

FIG. 4 is a front view of a spray nozzle of the cleaning device of FIG. 2 without a baffle plate.

FIG. 5 is a perspective view schematically showing the cleaning device of FIG. 1 (B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Protective tube 2 Membrane 3 Spray nozzle 4 Injection port 5 Tube 6 Arm 7 Center tube 8 Baffle plate 9 Center axis 11 Filter plate 12 Membrane 13 Spray nozzle 14 Reciprocating device 15 Moving table 16 Column 17 High-pressure pump 18 Hose

Claims (3)

(57) [Claims] 1. Cleaning of a membrane in a membrane separation apparatus, wherein cleaning water is sprayed at a pressure of 10 kg / cm ² or more perpendicular to the membrane surface without rubbing the membrane surface with a brush or sponge. Method and membrane cleaning device. 2. The method for cleaning a membrane of a membrane separation device according to claim 1, further comprising spraying cleaning water and further cleaning the membrane surface with a chemical. 3. A spray nozzle for injecting washing water supplied at a high pressure of 10 kg / cm ² or more from a high-pressure pump is fixed to one end of a cylinder also serving as a conduit for the washing water. A hose connected to a discharge port of the high-pressure pump is connected to the other end, and a baffle plate that forms a jet port for injecting washing water radially across the entire circumference between the spray nozzle and the tip of the spray nozzle. Is attached to the center cylinder of the spray nozzle.