JPH07124448A - Chemicals washing method for ceramic film - Google Patents

Abstract

PURPOSE:To provide a chemicals washing method for a ceramic film, by which a washing effect is high, and also, a washing operation can be executed easily. CONSTITUTION:Liquid chemicals 12 which are led into a treating vessel 1 is sucked and filtered by a ceramic film 4, or liquid chemicals 13 are fed forcibly into the inside of the film 4. Accordingly, since chemicals washing can be executed not only from the outside of the film but also from the inside, a high washing effect is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to water purification treatment, sewage treatment,
The present invention relates to a chemical cleaning method for a ceramic membrane of an immersion type membrane separator used in wastewater treatment and the like.

[0002]

2. Description of the Related Art Conventionally, there is an immersion type membrane separation apparatus as shown in FIG. 2 which is used for solid-liquid separation in water purification, sewage treatment, wastewater treatment and the like.
The immersion type membrane separation device is provided with a plurality of membrane modules 3 by being immersed in the water to be treated 2 in the treatment tank 1, and a plurality of ceramic membranes 4 are arranged in parallel inside each membrane module 3 at appropriate intervals. At the same time, a water collecting pipe 5 is provided which is connected to the membrane permeate liquid passage formed inside the ceramic membrane 4. Water collection pipe 5
Is connected to a suction pump 7 via a water passage valve 6,
By applying a negative pressure to the membrane permeate flow path through the water collection pipe 5 by this suction pump 7, the water to be treated 2 is separated into solid and liquid by the ceramic membrane 4, and the treated water 8 as the membrane permeate is taken out to the treated water tank 9. It is stored.

In order to prevent clogging of the film,
The ceramic film 4 is regularly cleaned with a chemical such as hydrochloric acid or sodium hypochlorite. That is, a hydrochloric acid solution having a concentration of about 1000 ppm and a sodium hypochlorite solution having an effective chlorine concentration of about 1000 ppm were introduced into the treatment tank 1 or the chemical cleaning tank, and the ceramic membrane 4 was placed in the hydrochloric acid solution for 2 hours or more and the hypochlorous acid 1 in sodium solution
The cake layer and gel layer attached to the film surface are removed by immersing for 6 hours or more.

[0004]

However, in the conventional cleaning method as described above, since the ceramic membrane is only immersed in the chemical solution, the outer side of the membrane is in contact with the chemical but the inner side of the membrane is not exposed to the chemical. Difficult to penetrate and was not washed sufficiently. Further, since two kinds of chemicals, hydrochloric acid and sodium hypochlorite, are used, the cleaning operation is complicated.

The present invention solves the above problems, and an object of the present invention is to provide a chemical cleaning method for a ceramic membrane, which has a high cleaning effect and is easy to clean.

[0006]

In order to solve the above problems, the present invention relates to a method for cleaning chemicals in a ceramic membrane of an immersion type membrane separator, in which a chemical introduced into a treatment tank is suction-filtered by the ceramic membrane. Alternatively, the surface and the inside of the film are washed with the chemical liquid by performing at least one of the steps of press-fitting the chemical liquid into the inside of the ceramic membrane.

In the present invention, the chemical solution is 500 to 3000 p
It is characterized by having an effective chlorine concentration of pm. Further, the present invention is characterized in that cleaning is performed while aerating air from an air diffusing means installed below the ceramic membrane.

[0008]

With the above structure, the surface and the inside of the membrane can be effectively cleaned by the chemical solution that is pumped from the outside to the inside of the membrane or from the inside to the outside of the membrane. Further, the cleaning effect is enhanced by performing the cleaning while aerating the air from the air diffuser installed below the ceramic film.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Since the submerged membrane separation apparatus in FIG. 1 is almost the same as the conventional membrane separation apparatus described with reference to FIG. 2 above, members having the same configuration and the same action are denoted by the same reference numerals and the description thereof is omitted. To do. Here, the membrane separation device of the present invention is different from the conventional membrane separation device in that the pipeline of the treated water 8 is branched on the upstream side of the water valve 6 and the backwash valve 10 and the backwash pump 11 are installed. And connect to the treated water tank 9,
The point is that the treated water 8 therein can be pressure-fed to the inside of the ceramic membrane 4 of the membrane module 3.

In the above structure, when solid-liquid separation is performed, the backwash valve 10 is closed, the water passage valve 6 is opened, and the suction pump 7
By making the permeated liquid flow path inside the ceramic membrane 4 to have a negative pressure,
Solid-liquid separation. The treated water 8 that has permeated the membrane is stored in the treated water tank 9.

When the ceramic membrane 4 is to be washed regularly, sodium hypochlorite is added to the water 2 to be treated in the treatment tank 1 so that the effective chlorine concentration in the tank is about 1000 pp.
A sodium hypochlorite solution 12 of m is prepared, and the solution 12 is subjected to immersion cleaning by suction filtration through the ceramic membrane 4 in the same manner as above. As a result, the cake layer, gel layer, and the like attached to the ceramic film 4 are removed by the action of the sodium hypochlorite solution 12 that is pressure-fed from the outside to the inside of the film.

Further, sodium hypochlorite is added to the treated water 8 in the treated water tank 9 to obtain an effective chlorine concentration of about 1000 in the tank.
A backwash operation in which a ppm sodium hypochlorite solution 13 is prepared, the water flow valve 6 is closed and the backwash valve 10 is opened, and the solution 13 in the tank 9 is pressure-fed to the inside of the ceramic membrane 4 by the backwash pump 11. Is performed about once every 30 to 60 minutes in parallel with the above immersion cleaning. As a result, the inside of the ceramic film 4 can be cleaned by the sodium hypochlorite solution 13 that is pressure-fed from the inside to the outside of the film, so that the cleaning effect is improved.

According to the above method, the ceramic membrane 4 can be effectively cleaned using one type of sodium hypochlorite solution, so that the cleaning operation is simplified. At this time, the concentration of the sodium hypochlorite solution is about 500 to 3 available chlorine.
It may be 000 ppm, preferably about 1000 ppm.

Further, as shown in the figure, if the air diffuser 15 is installed below the ceramic membrane 4 and connected to the blower 14 outside the tank, and air is aerated from the air diffuser 15, air bubbles will be generated by the aerated air. Since the film surface of the ceramic film 4 is cleaned by the rising liquid flow that is formed, the cleaning effect is increased.

The chemical cleaning test results of the ceramic film according to the method of the present invention will be shown below. In this test,
Chemical solution (Naclo-1
(000 PPM) and washed overnight. The conditions of aeration and backwash were the same as above, and suction was performed only for 4 hours before the completion of chemical cleaning. The pure water permeation amount (m ³ / m ² d) of the ceramic membrane was measured before and after chemical cleaning. The results are shown in Table 1. The pure water permeation amount of the contaminated ceramic membrane before chemical cleaning was 2.2 (m ³ / m ² d), but it was 1 after chemical cleaning.
It recovered to 9.2 (m ³ / m ² d). The pure water permeation amount of the new ceramic membrane is 19 to 20 (m ³ / m ² d).

[0016]

[Table 1]

[0017]

As described above, according to the present invention, the chemical introduced into the processing tank is suction-filtered by a ceramic membrane,
Alternatively, by pressing the chemical solution into the inside of the ceramic membrane, it is possible to wash and remove the film deposits not only from the outside of the membrane but also from the inside of the membrane, so a higher cleaning effect than the conventional cleaning method of just immersing in the chemical solution is achieved. can get. At this time, the washing operation can be simplified because the washing can be performed with one kind of chemical solution, preferably sodium hypochlorite solution. Further, by performing cleaning while aerating the air from below the ceramic film, a higher cleaning effect can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a membrane separation device of an embodiment in which a cleaning method of the present invention is performed.

FIG. 2 is an explanatory diagram showing a configuration of a conventional membrane separation device.

[Explanation of symbols]

 1 Treatment tank 4 Ceramic membrane 12,13 Sodium hypochlorite solution (chemical solution) 15 Aeration means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Nagai 2-6-6 Nishijima, Nishiyodogawa-ku, Osaka-shi, Osaka Kubota Shin-Yodogawa factory

Claims (3)

[Claims] 1. A chemical cleaning method for a ceramic membrane of an immersion type membrane separator, which comprises sucking and filtering a chemical solution introduced into a treatment tank through a ceramic membrane, or at least inserting a chemical solution inside the ceramic membrane. A chemical cleaning method for a ceramic film, characterized in that the surface and the inside of the film are cleaned with a chemical solution by performing the step of. 2. The chemical cleaning method for a ceramic membrane according to claim 1, wherein the chemical solution has an effective chlorine concentration of 500 to 3000 ppm. 3. The chemical cleaning method for a ceramic film according to claim 1, wherein the cleaning is performed while aerating air from an air diffusing unit installed below the ceramic film.